Upload
leminh
View
243
Download
2
Embed Size (px)
Citation preview
Rev Environ Contam Toxicol 182:1–195 Springer-Verlag 2004
Photodegradation of Pesticideson Plant and Soil Surfaces
Toshiyuki Katagi
Contents
I. Introduction ....................................................................................................... 2II. Photophysical and Photochemical Processes ................................................... 3
A. Photophysical Processes .............................................................................. 3B. Photochemical Processes ............................................................................. 5
III. Factors Controlling Photolysis on Plant Surfaces ........................................... 10A. Environmental Factors ................................................................................. 10B. Illumination Conditions ............................................................................... 10C. Effect of Formulation .................................................................................. 12D. Anatomy of the Leaf ................................................................................... 13E. Wax Chemistry ............................................................................................. 14F. Photoinduced Reactions ............................................................................... 15
IV. Factors Controlling Photolysis on Soil Surfaces ............................................. 17A. Soil Components .......................................................................................... 17B. Environmental Factors Affecting Soil Properties ....................................... 19C. Mass Transport in Soil ................................................................................. 19D. Photic Depth in Soil .................................................................................... 21E. Effects of Soil Properties on Photolysis ...................................................... 22F. Photophysical and Photochemical Processes of Soil Components ............. 23
V. Atmospheric Oxygen Species .......................................................................... 29VI. Experimental Design and Kinetic Analysis ..................................................... 31
A. Light Source ................................................................................................. 31B. Photolysis Chambers .................................................................................... 32C. Kinetic Analysis ........................................................................................... 34
VII. Photodegradation of Pesticides in Model Systems .......................................... 35A. Soil Surface Models .................................................................................... 35B. Plant Surface Models ................................................................................... 36C. Photodegradation of Pesticides on Glass and Silica Gel Surfaces ............. 36D. Photodegradation of Pesticides in Organic Solvents and
Plant Model Systems ............................................................................... 47VIII. Photodegradation of Pesticides on Soil and Clay Surfaces ............................ 56
IX. Photodegradation of Pesticides on Plants ........................................................ 69Summary .................................................................................................................... 77
Communicated by George W. Ware
T. KatagiSumitomo Chemical Co., Ltd., Environmental Health Science Laboratory, 2-1 Takatsukasa4-Chome, Takarazuka, Hyogo 665-8555, Japan.
1
2 T. Katagi
Table Listing .............................................................................................................. 79Appendices ................................................................................................................. 129Directory of Pesticide Chemical Structures .............................................................. 130References .................................................................................................................. 157
I. Introduction
Sunlight photodegradation is one of the most destructive pathways for pesticidesafter their release into the environment. Plant surfaces, especially leaf surfaces,are the first reaction environment for a pesticide molecule after application, andspray drift would indirectly present a similar situation. Photolysis on soil sur-faces becomes important when a pesticide is directly applied to soil or not sig-nificantly intercepted by plants, providing that the leaf cover does not shade theground from sunlight. Because the foliar interception of pesticides depends onplant species and usually increases with their growth stage (Linders et al. 2000),the importance of soil photolysis is considered to be lessened when plants be-come mature. Spray drift after pesticide application or washoff from plants byrain is the indirect route by which a pesticide reaches the soil.
To elucidate the photodegradation profiles of pesticide in the environment,many investigators have focused on solution photolysis in organic solvents orin a dilute aqueous solution. The heterogeneity of soil and plant surfaces to-gether with the capricious transmission of sunlight onto these media also makesphotolysis on them more difficult to understand. Although there are many excel-lent reviews on photolysis of pesticides (Roof 1982; Miller and Zepp 1983;Choudhry and Webster 1985; Marcheterre et al. 1988; Parlar 1990; Wolfe et al.1990; Cessna and Muir 1991; Meallier 1999; Floesser-Mueller and Schwack2001; Burrows et al. 2002), photolysis on soil is still only partially understoodbecause of the limited number of investigations, whereas that on plants is mostlyspeculation derived from plant metabolism studies. Under these circumstances,photodegradation on soil and plant surfaces requires more examination, not onlyexperimentally but also theoretically, to reveal the mechanisms controlling pho-tophysical and photochemical processes in pesticides on solid phases and toapply such knowledge to better understand the dissipation profiles of pesticidesin the field.
This review first considers the background and basis of photophysics andphotochemistry relevant to the photodegradation of pesticides. Molecular excita-tion and deactivation processes together with subsequent chemical processes arediscussed, and reactivity toward active oxygen species is briefly summarized.Second, constituents of soil and plant surfaces are reviewed from the point ofview of the factors controlling photodegradation, together with meteorologicalfactors. After reviewing the experimental design of photodegradation on thesesurfaces, the analysis of experimental data in consideration of the photodegrada-tion mechanism is discussed briefly. Based on the literature survey, both modelsystems and the actual photodegradation in soil and plant systems are reviewed
Photodegradation of Pesticides 3
for every chemical class of pesticide. The chemical structure of each pesticide1
appearing in this review, together with a corresponding number in bold type, isprovided in the Appendices.
II. Photophysical and Photochemical ProcessesA. Photophysical Processes
The extent of sunlight photolysis is highly dependent on UV absorption profilesof the pesticide, the surrounding medium, and the emission spectrum of sunlight.Because the energy to break chemical bonds in pesticide molecules usuallyranges from 70 to 120 kcal mol−1, corresponding to light at wavelengths of250–400 nm (Watkins 1974), spectral irradiance of sunlight detected near theground becomes important in determining the photodegradation profiles of pes-ticide. By passing through the atmosphere, sunlight intensity significantly de-creases to about 10% in the troposphere, and no light is transmitted at wave-lengths from <290 to 295 nm, mainly due to absorption by ozone (Zepp andCline 1977; Parlar 1990). As a result, sunlight near the ground exhibits a maxi-mum at around 440–460 nm, and its intensity at the UV region responsiblefor photodegradation of pesticide becomes approximately 5%–6% of the totalintensity. There are many photophysical pathways of sunlight absorption (Fig.1) (Turro 1978; Roof 1982; Parlar 1990). When a photon passes close to apesticide molecule, molecular excitation occurs via interaction between the elec-tric field of a pesticide molecule and that of light at a time scale of femtosecondswithout a change of molecular geometry (Franck–Condon principle). Each pho-ton can activate only one molecule in the ground state (S0) with a certain proba-bility to the excited singlet state (Stark–Einstein rule), and usually the lowestexcited state (S1) is involved in further photoprocesses. Generally, pesticide mol-ecules exhibiting a UV-vis absorption spectrum at >290 nm have a substitutedaromatic moiety, sometimes being conjugated with the lone-pair electrons or theunsaturated bonds such as carbonyl or carbamoyl group, and hence π → π* orn → π* transition takes place upon irradiation.
There are three possible photophysical pathways from the S1 state: nonradia-tive internal conversion, emission of fluorescence, and intersystem crossing tothe excited triplet state (T1) (see Fig. 1). The first pathway means the relaxationfrom higher vibrational levels (�1012 sec−1) in the S1 state followed by decay toa lower electronic state with the same multiplicity (106–1012 sec−1). The secondone is a radiative deactivation process. The fluorescence spectrum is usuallyclose to a mirror image of that of absorption due to the Franck–Condon princi-ple but shifted to the red. The lifetime of fluorescence is very short (nanosec-
1All pesticides are identified by their common name and parenthetical identification number, andtheir structures are illustrated in the Appendices. Preceding the Appendices is a Directory of Pesti-cide Chemical Structures listing all pesticides in alphabetical order to aid the reader in locatingspecific structures.
4 T. Katagi
Fig. 1. Energy state diagram.
onds to microseconds) due to the transition between states with the same multi-plicity. The last pathway is a spin-forbidden process (S1 → T1), followed byslow radiationless deactivation or emission of phosphorescence. The T1 → S0
process is also spin-forbidden, and hence the lifetime of phosphorescence usu-ally becomes an order of milliseconds to 102 sec. The profiles of fluorescenceand phosphorescence spectra of pesticides, based on the literature survey, aresummarized in Table 1 (see table on page 80). Although there are many chemi-cal classes and either a solvent system or temperature difference in measuringspectra, their maximum wavelengths are located in the range of 280–450 and380–530 nm, respectively. Based on the following equation of conversion whereE and λ are the energy level and the emission wavelength, respectively (Gould1989b), the energy levels of the excited singlet (Es) and triplet (ET) states can beestimated to be 64–102 and 54–75 kcal mol−1 for these pesticides, respectively.
E (kcal mol−1) = 2.864 × 104/λ (nm)
Because intersystem crossing is facilitated by the presence of heavy atoms in amolecule, the fluorescence spectrum of a pesticide is usually difficult to measureat room temperature, but in such cases phosphorescence can be efficiently de-tected instead.
The foregoing consideration can also be applied to pesticide molecules in thesolid phase, but adsorption onto these media is most likely to affect the photo-physical processes. Molecular motion would be highly restricted, and interac-tions with these heterogeneous surfaces result in modification of their electronicstates. In this case, the reflectance spectrum of a pesticide gives more usefulinformation than an absorption spectrum, and this is described by the relation-
Photodegradation of Pesticides 5
ship of Schuster and Kubelka-Munk (Parlar 1984) instead of the Beer–Lambertlaw.
F(R∞) = (1 − R∞)2/2R∞ = K/S
The diffuse reflectance, F(R∞), represents the radiation penetrating into the pow-der and resembles the usual transmission spectrum. R∞ is the ratio of reflectanceof a sample to that of a standard and thus the relative diffuse reflectance of aninfinitely thick layer compared to a nonabsorbing standard such as magnesiumoxide; K and S are the absorption and scattering coefficients, respectively. Ad-sorption can produce unequal displacement of the ground- and excited-state po-tential curves, which would result in a different vibronic band shape. Thus,spectral changes by adsorption are characterized by a spectral shift, changes ofextinction coefficient, broadening of absorption bands, and appearance of newbands (Wendlandt and Hecht 1966; Nicholls and Leermakers 1971; Parlar1984). Examples of spectral changes by adsorption of organic molecules includ-ing pesticides to silica gel and clays, listed in Table 2 (see table on page 85),are based on the literature survey. Both bathochromic (red) and hypsochromic(blue) shifts on adsorption have been reported, which are considered to dependon the type of an electronic transition. It is known that a blue shift almost alwaysoccurs with n → π* transition and often a red shift with π → π* transitions(Nicholls and Leermakers 1971). In the case of the former transitions, thechange of a nonpolar environment to polar causes more stabilization of theground state via hydrogen-bonding and dipole–dipole interactions than the ex-cited state, resulting in a blue shift. For π → π* transitions, the excited state ismore stabilized by polarization in the polar environment, resulting in a red shift.The alteration of emission spectrum by adsorption is likely, but the correspond-ing information is limited. Villemure et al. (1986) have reported the significantincrease of fluorescence intensity of paraquat (225) when adsorbed onto clays.Fluorescence with an emission maximum of 345 nm was very weak in aqueoussolution, but adsorption resulted in the increase of its intensity with a blue shiftby �20 nm. The increase of intensity is most likely to stem from an inhibitionof radiationless quenching by counteranion Cl− by intercalation of molecules of(225) into the interlayer of clays.
B. Photochemical Processes
Unless the energy of an excited-state molecule is lost as heat or emission oflight, it causes various types of chemical reactions in the excited molecule.There are two types of photochemical reactions, well known as “direct” and“indirect” photolysis (Roof 1982; Miller and Zepp 1983). Direct photolysismeans the photoreaction proceeds by absorbing light energy, whereas indirectphotolysis is defined as reaction of a ground-state molecule with the other ex-cited molecule or photochemically produced reactive species. The former indi-rect photolysis is called photosensitization or quenching, and the latter is a pho-toinduced reaction with a reactive oxygen species. The average rate of direct
6 T. Katagi
photolysis in a well-mixed system can be estimated by using the GCSOLARprogram based on spectral irradiance of sunlight, absorption profiles, and quan-tum yield of pesticide (Leifer 1988). In contrast, when pesticide molecules existas deposits on soil and plant surfaces, the heterogeneous microenvironmentmakes such estimation difficult. For example, many researchers have reportedthe quantum yield for pesticides in solution photolysis, but the information isvery limited on solid-phase photolysis (Krieger et al. 2000; Samsonov and Pok-rovskii 2001). In the case of soil photolysis, Balmer et al. (2000) introduced amodel function of light attenuation in soil with diffusion of a pesticide moleculeto better describe the dissipation profiles.
The molecule in the S1 or T1 state undergoes various chemical reactions.Typical reactions observed in photolysis on soil and plant surfaces are summa-rized in Fig. 2. One of the most important photoreactions is initiated by carbonyln → π*excitation. The photoinduced cleavage of a C−C bond generates theketyl radical (Norrish type I), or the carbonyl carbon in the excited state ab-stracts hydrogen from a neighboring alkyl group (Norrish type II) or a solventmolecule. The electronic excitation also occurs at the C=C bond or aromaticmoiety, which results in cis/trans (or E/Z) geometric isomerization or R/S opticalone. The photoinduced homolytic bond cleavage is also a main reaction pathwayin photolysis. When it occurs at an ester or ketone moiety, decarboxylation ordecarbonylation proceeds in addition to the apparent photoinduced hydrolysis,and its extent depends on solvent structure in relation to stabilization of pro-duced radicals. The C-halogen (Cl, Br, and I) bond is known to also undergophotoinduced cleavage. Dealkylation via oxidation with O2 or reactive oxygenspecies such as the hydroxyl radical (OH�) is also known. Oxidation at eithercarbon or sulfur is one of the most important routes of photodegradation. Themost familiar rearrangement is thiono-thiolo for O-aryl phosphorothioate insec-ticides whose O-alkyl group (typically a methyl group) shifts to the P=S sulfuratom (reaction 9a). The other is a photo-Fries rearrangement for amides andcarbamates where the ketyl radical generated via cleavage of an N−C(=O) bondmostly migrates to the o- or p-position of the phenyl ring (reaction 9b). Theformation of a new bond is typically observed for intramolecular cyclization fororganochlorine cyclodiene insecticides (reaction 10a).
Incidentally, an energy transfer can proceed between the excited donor (D*)and acceptor (A) molecules. The spectral overlap between the emission spec-trum of D* and absorption spectrum of A is prerequisite (Fig. 3), and energytransfer proceeds efficiently when the process is spin-allowed and exothermic(Turro 1978; Roof 1982). There are two mechanisms known for energy transfer,coulombic and exchange interactions. The former mechanism involves the in-duction of a dipole oscillation in A by D* via a magnetic field and does notrequire physical contact of the interacting D* and A. Forester theory indicatesthat the rate of energy transfer according to this mechanism is proportional tothe spectral overlap and inversely proportional to intermolecular distance be-tween D* and A to the sixth power. Therefore, the energy transfer efficiency isgreatly reduced as the distance increases up to approximately 50 A and thus is
Photodegradation of Pesticides 7
Fig. 2. Types of photoreactions.
sensitive to diffusion of D* and A. In contrast, the exchange interaction involvesa double electron substitution, that is, jump of an electron from D* to the unoc-cupied orbital of A and the simultaneous jump of an electron from A to thehalf-occupied orbital of D* via overlap of electron clouds, which requires physi-cal contact (collision) between D* and A. Singlet energy transfer is spin-allowedfor both long-range coulombic and short-range exchange mechanisms. However,
8 T. Katagi
Fig. 2. Continued.
because an acceptor molecule is in the S0 state, the triplet energy transfer isbasically spin-forbidden and only proceeds via a short-range exchange mecha-nism. The interatomic distance expected for the triplet energy transfer is esti-mated to be 10–15 A. The longer a molecule remains in an excited state thegreater the probability that it will transfer energy to a suitable neighboring mole-cule. Therefore, the triplet energy transfer is the most common and most impor-tant type of energy transfer involved in photolysis of pesticides.
Fig. 3. Schematic description of the spectral overlap.
Photodegradation of Pesticides 9
When photolysis on soil and plant surfaces is considered, diffusion of pesti-cide molecules is likely to be limited by adsorption and very high viscosity ofthe medium. These situations may imply less possibility of energy transfer ex-cept for the case where pesticide molecules are located in the neighborhood ofD* or A. There are many candidates in the environment playing a role as D* orA, and some of them are listed in Table 3 (see table on page 86) together withsynthetic chemicals. Because flavonoids and long-chain alkyl ketones are someof the wax components in plant foliage (see Section III.E), photosensitizationby these components may be possible by taking account of the ET values ofpesticides (54–75 kcal mol−1). In the case of soil surface, either photosensitiza-tion or quenching by humic substances with the ET value of 60–62 kcal mol−1
is considered to proceed. Although concrete demonstrations by measurement arelimited, the importance of spectral overlap between pesticide and synthetic dyescoadsorbed on clay surfaces has been reported in relation to stabilization ofphotolabile pesticides (Margulies et al. 1988; El-Nahhal et al. 2001).
Among natural products, molecular oxygen (O2), whose ground state is atriplet, is the most effective quencher. The very low lying singlet states withapproximate energy levels of 23 and 38 kcal mol−1 can easily react with theexcited states of pesticides and natural products, resulting in the formation ofsinglet oxygen (1O2). In addition, the other active species such as OH� and ozone(O3) are deeply involved in photoinduced reactions. It is not easy to identifyactive oxygen species in photolysis on soil and plant surfaces, but the basicreactivity of some pesticides is known (Table 4 [see table on page 88]). Sulfuroxidation is one of the characteristic reactions. Concrete evidence on theinvolvement of 1O2 was given for fenitrothion (138)2 by Verma et al. (1991),who showed the significant decrease of oxon formation when the 1O2 scavengerwas added. Formation of peroxide at the isobutenyl moiety of pyrethroid (Fig.2, reaction 7) was found sensitive to 1O2 scavenger (Ruzo et al. 1980, 1982) andwas greatly reduced by introduction of halogen atoms instead of the geminalmethyl groups (Holmstead et al. 1978a; Ruzo 1983). Hirahara et al. (2003)confirmed the photoinduced formation of 1O2 in the phosphate buffer solutionof fenthion (143) without any dye by ESR (electron spin resonance) using thespin trap reagent and supposed that (143) is a photosensitizer for O2. Severalmethods, including Fenton’s reagent and illumination in the presence of hydro-gen peroxide (H2O2), O3, Fe3+, humic substances, or a semiconductor, have beenutilized to generate OH�. The oxidative desulfuration and N-dealkylation to-gether with hydroxylation proceeded via reactions with OH�. The involvementof OH� in photolysis of atrazine (185) was demonstrated by retardation of thereaction in the presence of mannitol as a radical scavenger, and the attack at theα-position of the N-ethyl moiety was evidenced by formation of the N-acetylderivative. Concerning O3, aqueous ozonization has been extensively investi-gated (Reynolds et al. 1989) but the reaction on solid surfaces seems to be
2See footnote 1, p. 3.
10 T. Katagi
limited. Spencer et al. (1980) reported the desulfuration of parathion (135) onsoil dusts and clay minerals in the presence of O3, which was recently confirmedby Kromer et al. (1999). The sulfur atom was finally oxidized to sulfate ion(Gunther et al. 1970). In the case of pyrethroids, ozonization of the isobutenylmoiety was found to proceed to give the corresponding aldehyde derivatives(Ruzo et al. 1982).
III. Factors Controlling Photolysis on Plant SurfacesA. Environmental Factors
A number of factors such as meteorological conditions, formulation type,sprayer characteristics, and affinity of plant surface to formulation are consid-ered to determine the amount of pesticide attached to the surface as well asground cover and canopy thickness of plants (Willis and McDowell 1987).Zongmao and Haibin (1997) extensively investigated factors controlling dissipa-tion from tea plant surfaces for 16 pesticides. Photodegradation was found to beone of the most important factors in dissipation process except for evaporation,rainfall elution, and growth dilution. Both photolysis and rainfall elution werefound to play a great role in the dissipation of diflubenzuron (159) in a coniferforest (Rodriguez et al. 2001). Garau et al. (2002) examined the extent of pesti-cide loss from a cellulose membrane due to evaporation and codistillation inthe presence or absence of underlying water. Evaporation, codistillation, andphotolysis all contributed to dissipation of pyrimethanil (209) and cyprodinil(210) but with each varying to some extent, while only photolysis was the con-trolling factor for azoxystrobin (244) and fludioxinil (208). The existence oftomato fruit wax mostly retarded evaporation and codistillation of pesticides andexhibited a screening effect against sunlight. For a pesticide with higher vaporpressure and less photoreactivity, volatilization loss became predominant in dis-sipation as observed for chloropyrifos (145) (Meikle et al. 1983). Through aglass wind tunnel study for 14C-fenpropimorph (227) individually applied tobean, sugar beet, and radish, the importance of reactive species (OH� and/or O3)in air was demonstrated (Ophoff et al. 1999). Furthermore, either soil dusts orclay minerals enhanced oxidation of parathion (135) to its oxon in the presenceof O3 (Spencer et al. 1980). In addition to these factors, penetration of pesticideinto cuticle and biotic metabolism therein are also considered important (Bent-son 1990; Katagi and Mikami 2000).
B. Illumination Conditions
Spectral irradiance of sunlight at the plant surface is most important to under-stand the effect of photolysis (Fig. 4). Because the window glass used in ordi-nary greenhouses absorbs a considerable amount of light in the UV-B region
1All pesticides are identified by their common name and parenthetical identification number, andtheir structures are illustrated in the Appendices. Preceding the Appendices is a Directory of Pesti-cide Chemical Structures listing all pesticides in alphabetical order to aid the reader in locatingspecific structures.
Photodegradation of Pesticides 11
Fig. 4. Photodegradation of pesticide on plant: (a) precipitation, (b) wind, (c) volatiliza-tion, (d) sunlight outdoors, (e) sunlight in the borosilicate glass greenhouse.
(280–320 nm), this filtering effect is likely to reduce the overlap between thesolar emission spectrum and the near-UV absorption spectrum of many pesti-cides (Kleier 1994). Photodegradation was measurably reduced by covering thePetri dish as a model of the greenhouse window (Garau et al. 2002). Fukushimaet al. (2003) examined the photolysis of 14C-fenitrothion (138) on tomato fruitin a greenhouse with a ceiling made of quartz or borosilicate glass. The intensityof sunlight at <360 nm was significantly reduced in the borosilicate glass green-house, and neither the corresponding oxon nor the S-isomer generated by photol-ysis in the quartz greenhouse was detected. Furthermore, transmission throughthe greenhouse window is also known to be reduced by glass pollution, and itsextent was larger in the shorter wavelength region (Van Koot and Dijkhuizen1968). The structure of greenhouse changing the intensity and spectral irradianceof the transmitted sunlight gave an insignificant effect on dissipation of chlor-pyrifos (145). Type of crop and season were the most relevant factors (MartınezVidal et al. 1998). Similar results were obtained for fenpropathrin (24) (MartınezGalera et al. 1997), while degradation of methomyl (70) was found to dependon the type of greenhouse (Gil Garcia et al. 1997).
Degradation of pesticides in the greenhouse or outdoors was compared toexamine the controlling factors in foliar dissipation. The application of pirimi-
12 T. Katagi
carb (78) to lettuce was conducted both in greenhouse and field (151; Cabras etal. 1990). No significant differences occurred in half-lives of total carbamates,but greater formation of these degradates was observed in the field. The compar-ative degradation study of parathion (135) using a growth chamber, greenhouse,and open field with and without motorized covering exhibited more formationof the oxon and S-isomer in the field (Joiner and Baetcke 1973). Based on theseresults, the experimental conditions of growing plants should be monitored andcompared with the real environment as much as possible to investigate the mostrealistic pesticide photodegradation process.
C. Effect of Formulation
Pesticide formulation is composed of an active ingredient, carrier such as clay,surfactants as wetting and spreading agents, nonevaporating viscous stickers,humectants, and penetrating agents such as crop oils (Hazen 2000). These addi-tives having hydrophobic and hydrophilic parts in a molecule provided a verycomplex medium for photolysis of pesticides, and their aromatic moiety becomesa possible photosensitizer or quencher (Nutahara and Murai 1984; Thomas andHarrison 1990). Baker et al. (1983) investigated extensively the changing natureof epicuticular waxes on the impact of several formulations containing 14C-labeled pesticide using scanning electron microscopy, X-ray analysis, and mi-croautoradiography. Oil formulations were found to immediately spread throughcrystalline wax whereas aqueous solutions distributed most readily over smoothsurfaces. Lipophilic pesticides are partitioned favorably into the organic phase,separating as a zone at the outer edge of the droplet residue, but hydrophilicpesticides are concentrated in the central region. Furthermore, the fluidity ofepicuticular waxes is known to change with hydrophobicity and lipophilicitybalance of the surfactant (Hess and Foy 2000). In addition, surfactants in formu-lations are considered to affect either uptake of pesticide molecules across thecuticle to plant tissues or photodegradation profiles on plant surfaces. The for-mer phenomenon by monodispersing alcohol ethoxylates has been demonstratedfor several pesticides on barley leaves. Larger effects on diffusion coefficientwere observed for the larger-size molecule (Burghardt et al. 1998). The lattereffect was first pointed out in aqueous solution by Tanaka et al. (1979, 1981).Instead of formation of 4-OH and N-CHO derivatives, monuron (52) in aqueoussolutions of surfactants Tergitol TMN-6 or Triton X-100 underwent dechlorina-tion followed by dimerization and N-demethylation. Furthermore, photodegrada-tion of 17 herbicides was found to be accelerated by the presence of thesesurfactants.
Based on these results, pesticide molecules were thought to be partitioned tohydrophobic cores of micelles where photolysis such as that in an organic sol-vent proceeded favorably and surfactants such as Triton X-100 having an aro-matic moiety could act as a photosensitizer. Such photosensitization was alsoreported when oxysorbic or plant oil concentrate was used as the surfactant(Harrison and Wax 1985). In contrast, it is supposed that some surfactants hav-
Photodegradation of Pesticides 13
ing a lower triplet excited energy than that of the pesticide can act as a quencher,which has been demonstrated for TMN-6 and nonaethoxylated p-(1,1,3,3-tetra-methylbutyl)phenol (Tanaka et al. 1986, 1991). The other possible effect bysurfactants would be stabilization of photoproduced radicals in a cage. In thecase of 2,4-D (1), a few products formed via Norrish type II or photo-Friesmechanism were detected through photolysis in aqueous solution containing sur-factant (Que Hee et al. 1979). There was no significant effect of Tween 80 orTrion X-100 on photolysis of metsulfuron (97) and chlorimuron (101) on glasssurfaces (Thomas and Harrison 1990), whereas in the other study acceleratedphotolysis was observed (Harrison and Thomas 1990). On corn leaves, similaracceleration was observed for (97) but with no clear effect for (101). In pyre-throids, reduced photolysis on glass surfaces was reported when surfactantswhere included (Megahed et al. 1987).
D. Anatomy of the Leaf
As shown in Fig. 5, leaves are covered with protective cuticles that function bydecreasing water loss and protecting the plant from infection by various patho-gens. The cuticle is a complex structure consisting of a pectin layer that bindsthe cutin to the epidermal cell walls and a layer of epicuticular wax on theoutside, this structure is known to depend on plant species (McFarlane 1995;Bianchi 1995). When the stomata are open, gas molecules can diffuse in andout and interact with a large hydrophilic area of water-covered mesophyll cells.Most pesticides are hydrophobic molecules, and thus the large lipid-coveredsurface of leaves (cuticles) forms an ideal sink for accumulation of pesticides.The fine structure of the wax layer greatly differs between plant species and ismorphologically classified by using light microscopy into four main forms: nee-dles, rods, granular layers and films (Baker 1982). Use of the electron micro-scope has revealed that the aerial surfaces of all higher plants carry a partial orcontinuous coverage of amorphous wax and that formation of crystalline wax is
Fig. 5. Transverse view of the typical surface structure of plant foliage: (a,d) epidermalcell, (b) stoma, (c) mesophyll, (e) pectin, (f) cutin and embedded waxes, (g) epicuticularwaxes.
14 T. Katagi
frequently superimposed on amorphous layers. Penetration through these waxregions and the underlying cutin layer has been extensively studied, for exam-ple, by using the diffusion cell method (Schonherr and Riederer 1989).
Radiant energy of sunlight is considered to interact with the leaf structure byabsorption and scattering. As shown in Fig. 5, most leaves have a distinct layerof long palisade parenchyma cells in the upper part of the mesophyll and moreirregularly shaped spongy parenchyma cells in the lower part. Sunlight is re-flected and scattered by hairs, leaf pubescence, and the glaucous leaf surface,and a portion of the light enters into the leaf (Robberecht and Caldwell 1980;Holmes and Keiller 2002). This light is critically reflected internally at the cellwalls in the intercellular space as a result of the difference of refractive indexbetween air and water in tissues (Gates et al. 1965). Pesticides by foliar applica-tion are considered to distribute mainly on the epicuticular wax layer, but aportion may enter into the plant directly through stomata or diffusion; thus,depth and spectral distribution of penetrated sunlight would be important whenphotodegradation is considered. Many studies have been conducted to investi-gate this using a fiberoptic probe (Vogelmann and Bjorn 1984). About 90% ofthe penetrating monochromatic light (310 nm) was attenuated within the initialone third of the leaf (100–150 µm) of Brassica napus L., mostly at the epider-mal cells; polychromatic radiation (280–320 nm) exhibited a relatively uniformspectral distribution within the leaf (Bornman and Vogelmann 1991; Cen andBornman 1993). UV-B radiation was found to reach the epidermis and meso-phyll in other measurements for this leaf (Alenius et al. 1995). Day et al. (1994)measured UV absorption spectra and the epidermal transmittance spectra at280–350 nm of foliage from 42 plant species and demonstrated that some flavo-noids act as a UV-absorbing agent. These observations imply that pesticide mol-ecules in the leaf can absorb some part of the radiation energy of sunlight irre-spective of their location, and not only the anatomy of the leaf but alsochromophores in leaf tissue can greatly affect their photodegradation.
E. Wax Chemistry
Epicuticular waxes are basically aliphatic compounds and are readily solubilizedby organic solvents with minimal contamination by lipids from the inner cuticu-lar layers. A mixture of chloroform and diethyl ether (1 : 1, v/v) was found tobe efficient to isolate waxes containing cyclic compounds (Baker 1982). Leavesof many herbaceous plants carry delicate membranes with only sparse wax de-posits (5–10 µg cm−2) and many weed species also have thin wax layers. Waxdeposits on rapidly expanding leaves of leek and Brassica spp. are heavier(30–60 µg cm−2), similar to those on leaves of many fruit crops. Wax layers onfruits are invariably much thicker than those on the corresponding leaves (50–400 µg cm−2), and thick deposits were also found for pistachio and olive (60–300 µg cm−2). As a result, the average thickness of the cuticle varies with plantspecies from 3 to 15 µm (Lendzian and Kerstiens 1991). Wax chemistry, espe-cially of epicuticular waxes, has been systematically investigated for many plant
Photodegradation of Pesticides 15
species, sometimes with different growth stages, first by thin-layer chromatogra-phy (TLC) and gas chromatography (GC) of the derivatized extracts and later bygas chromatography-mass spectrometry (GC-MS), nuclear magnetic resonance(NMR), and infrared (IR) (Baker 1982; Walton 1990; Bianchi 1995). Waxes arebasically classified into even- and odd-carbon-numbered straight chain homo-logues and cyclic compounds (Baker 1982; Bianchi 1995). The first class con-sists dominantly of acids (C12–C18 and C20–C32), aldehydes (C22–C32), primaryalcohols (C22–C32), and alkyl esters (C36–C72). The odd-numbered homologuesare hydrocarbons (C17–C35), secondary alcohols (C21–C33), ketones (C23–C33),β-diketones (C29–C33), and hydroxy-β-diketones (C29–C33). The last class con-sists of triterpenoid acids such as ursolic and oleanolic acids, triterpenols suchas α- and β-amyrin, triterpenoid esters, and ketones. Among them, the followingchemicals are known to be common major constituents of epicuticular waxes:nonacosane and hentriacontane for hydrocarbons: hexacosanol, octacosanol, andtriacontanol for primary alcohols; nonacosan-10-ol for secondary alcohols; hen-triacontane-14,16-dione and tritriacontane-16,18-dione for β-diketones; and ur-solic acid for triterpenoids.
Typical wax constituents with major homologues for representative plants,fruits, and leaves are briefly summarized in Table 5 (see table on page 89). Inthe case of leaf waxes, composition was found to vary with not only growthstage but also the parts of the leaf, that is adaxial and abaxial surfaces (Bukovacet al. 1979; Baker and Hunt 1981; Riederer and Schneider 1990). Unique com-ponents such as anthraquinone in the leaf waxes of perennial rye grass (Alleboneet al. 1971), a long-chain 1,4-benzoquinone in a wide variety of leaves (Kofleret al. 1959), and novel fatty acid esters of E- and Z-p-coumaryl alcohols in cv.Gala apples (Whitaker et al. 2001) have been reported.
F. Photoinduced Reactions
There has been no systematic investigation on the contribution of these waxcomponents to photolysis of pesticides. Pirisi et al. (1998) have measured UVabsorption spectra of epicuticular waxes of nectarines, oranges, and mandarinoranges extracted by chloroform and/or methanol. These waxes basically exhib-ited featureless absorption at 290–400 nm with small shoulders around 320 nm,but no clear correlation with photolysis rates of pirimicarb (78) could be de-tected. The wax of annual spruce needles also showed the featureless spectrumbut with significant absorption at 300–400 nm (Niu et al. 2003). Furthermore,although no absorption maximum was observed for leaf waxes of caster bean,UV absorption at about 300 nm was observed for Scotch pine, cabbage, andCarnauba waxes (Wuhrmann-Meyer and Wuhrmann-Meyer 1941). Concerningeach chemical class of waxes, the theory of UV absorption indicates no absorp-tion by simple hydrocarbons, but many chemicals containing a carbonyl moietycan absorb UV light at >290 nm (Jaffe and Orchin 1962). n-Hentriacontane, themajor component of green tobacco leaf, was shown to be transparent to the UVregion (Carruthers and Johnstone 1959). As β-diketones and α,β-unsaturated
16 T. Katagi
ketones (aldehydes) show UV absorption maxima around 270 nm and 320–370nm (Cookson and Dandegaonker 1955; Horn and Lamberton 1962), these com-ponents as well as anthraquinone and 1,4-benzoquinone already described aremost likely to be involved in photolysis of pesticides on plant foliage.
Triterpenoid derivatives are detected as major to dominant components ofleaf waxes, but their UV absorption maxima are usually located at 200–210 nmin hexane (Wheeler and Mateos 1956; Weizmann and Mazur 1958; Turner1959), which may indicate less importance in photolysis of pesticides. Phenyl-propanoids including flavones, flavonols, and cinnamoyl esters in higher plantsare known to exhibit UV screening effect (Cockell and Knowland 1999; Kolbet al. 2001). These flavonoids are also known to show an antioxidant activity(McPhail et al. 2003) similar to β-diketones (Osawa 1994). Because the complexmixture of wax components is the primary reaction medium for pesticides, itshould be kept in mind whether these components simply act as highly viscousorganic solvents or are involved in photochemistry of pesticides as photosensi-tizer or quencher. As an example of wax effects on photolysis, either enhance-ment or retardation of photolysis was reported for 14C-fenarimol (239) spreadon glass surface with extracted waxes from barley, rape, strawberry, and appleleaves (Watkins 1987). On the bean leaf, more S-oxidation of carboxin (42)proceeded as compared with that on a glass surface (Buchenauer 1975). Acceler-ated photolysis was also reported for 2,4-D (1) on Zea mays leaves (Venkateshand Harrison 1999).
When 14C-dieldrin (123) was applied to bean foliage with flavone, formationof photodieldrin (124) was enhanced by a factor of 5–7 via triplet photosensiti-zation (Ivie and Casida 1971b). Rotenone exhibited the strongest sensitizationand effect of 15 pesticides tested, but anthraquinone had an insignificant effect.The chromanone moiety of rotenone common to flavone was found essential toshow its activity (Ivie and Casida 1970). Accelerated photodegradation in thepresence of flavone, triplet sensitizers, and extracts from plant was also reportedfor pyridafenthion (150), naproanilide (41), and flutolanil (39), all of whichwere resistant to photolysis by themselves (Tsao et al. 1989; Tsao and Eto1990a, 1991). Chlorophyll and furanocoumarins are also possible sensitizers inplants, affecting photodegradation profiles of pesticides (Dodge and Knox 1986;Dixon and Wells 1987). Although a reactive species has not been identified inmost cases, either possible hydrogen abstraction from wax components by thephotoproduced radicals originating from the pesticide or formation of a covalentbond with the unsaturated bond of waxes via a radical reaction was demon-strated by using model waxes such as cyclohexene and methyl oleate (Draperand Casida 1985; Schwack 1988; Schynowski and Schwack 1996; Breithauptand Schwack 2000). Nutahara and Murai (1984) have reported the enhancedphotodegradation of many pesticides by oleic and linoleic acids, possibly viasimilar mechanisms as above. Because the unsaturated alkyl chain of these com-pounds is known to undergo oxidation by reaction with 1O2, giving the corre-sponding monohydroperoxide (Nakajima and Hidaka 1993), this peroxide or itsphotodegradates may alter photodegradation of pesticides.
Photodegradation of Pesticides 17
Formation of possible photosensitizers on foliage has also been reported. 6-Methyl-5-hepten-2-one (6-MHO) has been detected in significant amounts onfoliage of orange, oak, and pine trees together with 4-oxopentanal, geranylace-tone, and acetone, whose origin is considered to be unsaturated wax componentssuch as sesquiterpenes and triterpenes (Fruekilde et al. 1998). By using epicutic-ular waxes extracted from these leaves, oxidation by O3 produced these carbonylcompounds, possibly acting as an efficient photosensitizer on foliage. Beren-baum and Larson (1988) have reported the formation of 1O2 (�4 × 1012 1O2
molecules cm−2 sec−1) by illuminating intact leaves of wild parsnip and pricklyash. The reaction of ascorbic acid in plant cell walls with O3 was also found togenerate 1O2, and a similar reaction was found for gluthathione, methionine, anduric acid (Chameides 1989). Kanofsky and Sima (2000) utilized chemilumines-cence at 1270 nm due to 1O2 to monitor its formation under O3 from illuminatedtissue fluids prepared by vacuum infiltration technique or intact leaf of whitestonecrop. Emission of 1O2 with consumption of O3 was clearly demonstrated,and its retardation in the presence of ascorbate oxidase showed involvement ofascorbic acid in this reaction. Because O3 is a very familiar component of airover vegetation, the photochemical and/or chemical generation of 1O2 may playa substantial role in the degradation of some pesticides on foliage.
IV. Factors Controlling Photolysis on Soil SurfacesA. Soil Components
Soil is a variable mixture of minerals, organic matter, and water, capable ofsupporting plant life on the earth’s surface (Manahan 1994). The solid fractionof a typical productive soil is approximately 5% organic matter, originatingfrom plant debris in various stages of decay, and 95% inorganic matter. Soilusually contains air spaces and generally has a loose texture. The majority ofinorganic components (>90%) are crystalline and noncrystalline amorphousminerals including primary and secondary minerals; the former includes quartzand micas and the latter phyllosilicates (clay minerals), allophanes, and metaloxides. Quartz and micas are simple SiO2 minerals whereas clay minerals arebasically aluminosilicates. Therefore, their surface property and photoreactivitymay be estimated from those of silica gel as a surrogate surface. There are threetypes of hydroxyl groups existing on silica gel with a different acidity: geminalsilanol (Si(OH)2), nongeminal (SiOH), and hydrated silanol (SiOH���OH2), asdemonstrated by 19Si- and H-NMR and fluorescence analysis (Thomas 1993).Clay minerals possess layered structures consisting of silica tetrahedral and alu-mina octahedral sheets with a ratio of 1 : 1 or 2 : 1 (Takagi and Shichi 2000).Kaolinite is the typical clay in the former type and pylophyllite, smectite, andvermiculite groups constitute the latter. The isomorphous substitution of centralatoms in tetrahedral and octahedral structures with another of a lower valencyresulted in a net negative charge for clay sheets and electrostatic force via count-ercations, making them loosely bound to each other (Caine et al. 1999). Thepresence of interlayer space thus gives a sterically constrained reaction environ-
18 T. Katagi
ment for pesticide molecules when intercalated. Iron is one of the most abundanttransition metals in soil and is considered to play a large role in photoinducedredox reactions generating active oxygen species such as OH�. Sherman (1989)demonstrated by Mossbauer spectroscopy that most Fe3+ and Fe2+ ions werefound to occupy the octahedral sites and that some ions might occur as aninterlayer species such as a Fe2+-aquo complex in the 2 : 1 clay minerals. Insteadof the Fe3+-aquo complex, Fe(OH)2(H2O)4 would condense to form ferric hy-droxy polymers.
Humic substances account for 60%–70% of soil organic matter, consistingof a series of highly acidic, yellow to black, high molecular weight polyelectro-lytes and characterized by their high content of oxygen-containing functionalgroups such as COOH, phenolic, aliphatic, and enolic OH and C=O, togetherwith amino, heterocyclic amino, imino, and sulfhydryl groups (Stevenson 1976;Ruggiero 1999). The higher total acidity of fulvic acid (FA, �10 mEq g−1) thanhumic acid (HA, �7 meq g−1) can be accounted for by the higher content of aCOOH group in FA. The typical content of each functional group was reportedto be 3.6–8.2 mEq g−1 (COOH), 3.0–3.9 mEq g−1 (phenolic OH), 2.6–6.1 mEqg−1 (alcoholic OH), 2.7–2.9 meq g−1 (quinoid and ketonic C=O), and 0.6–0.8mEq g−1 (OCH3) (Choudhry 1984b). Similar results have been confirmed bySenesi et al. (1989) by using several soil humic substances and Suwannee Riversoil. The clay surface is usually covered with these humic substances, probablyvia formation of clay–metal–organic complexes. Through adsorption study ofatrazine (185), the contribution of clay surface on adsorption was proposed tobe important when organic matter content was less than �6% (Stevenson 1976).Based on their nature, interactions with HA and FA should be primarily consid-ered in soil photolysis of pesticides. As an adsorption isotherm, Freundlich,Langmuir, and Rothmund–Kornfeld equations are well known and the shape ofthe related isotherm would shed light on the adsorption mechanism. Proposedmechanisms of interactions are ionic bonding via cation exchange, hydrogenbonding, charge-transfer interaction with a quinoid moiety embedded in a humicstructure, cation-bridged ligand exchange with humic carboxyl moiety, covalentbinding, hydrophobic adsorption, and partitioning via dipole–dipole and/or vander Waals interaction (Stevenson 1976; Senesi and Testini 1984; Senesi andMiano 1995).
Another unique feature characteristic of soil humic substances is the presenceof stable radical species detected by ESR. Senesi and Schnitzer (1977) havereported the ESR signal at g = 2.0032–2.0050 without a hyperfine splitting forFA whose intensity increased with either chemical reduction under more acidicconditions or UV irradiation. They proposed semiquinones or its ions as themost likely partial structure of stable radical species. Further investigation onvarious soil HAs and FAs has shown the presence of two types of ESR signalsoriginating from a quinhydron-type structure and a phenoxide ion (Choudhry1981). These stable radicals would be involved in photoinduced transformationof pesticides as well as formation of active oxygen species, especially when atransition metal or its oxide coexists (Ruggiero 1999).
Photodegradation of Pesticides 19
B. Environmental Factors Affecting Soil Properties
Many soil photolysis studies have not strictly controlled and monitored basicsoil properties, especially such as moisture, until the recent development by theChib’s group (Misra et al. 1997; Frank et al. 2002). As stated later, the penetra-tion depth of light into soil is known to be very limited, approximately to thetop 0.5 cm of soil surface, and so its influence is considered to be very differentfrom that in the bulk soil (Fig. 6). In this region, solid, solution, and vaporphases are all in close proximity to the soil–atmosphere interface under sunlightirradiation. Miller et al. (1989) concisely reviewed the effect of sunlight onsoil properties. They introduced a simulation on a typical diurnal variation oftemperature near the soil surface (0–2 cm) where the temperature increased upto near 40 °C at midday with a difference of about 20° during a day. A tempera-ture gradient even at this shallow depth can be suspected and, in fact, the mea-sured temperature at the irradiated surface, interior, and bottom of a soil thinlayer (0.5–1 mm thickness) attached to a cooling bath was reported to be 31°,29.9°, and 25.6 °C, respectively (Moore et al. 1989). This diurnal fluctuation oftemperature results in variation of soil moisture, that is, drying of soil duringdaytime and rewetting during nighttime. These variations together with sunlightirradiation would cause some effects on microbial activity, but its details arenot known for shallow soil. Recently, Reichman et al. (2000a,b) developed aone-dimensional nonisothermal model to examine the dynamic behaviour of asurface-applied pesticide under outdoor conditions. By using the diurnal varia-tion of meteorological data such as wind speed, air temperature and relativehumidity and sunlight irradiation, they have simulated changes of depth-depen-dent soil temperature and moisture.
C. Mass Transport in Soil
Diffusion of a pesticide molecule is considered to be basically described byFick’s law; however, the heterogeneous character of soil results in a more com-
Fig. 6. Structure of soil surface.
20 T. Katagi
plex description of a diffusion constant (D) than that in water (Graham-Bryce1969). Do is the diffusion coefficient in free solution and λ is the tortuosityfactor:
D = Do λθv/(Kd ρd + θv)
where θv is the volumetric water content, Kd is the linear partition coefficient,and ρd is the bulk density of soil. The tortuosity factor is a diffusion ratio ofpathlength in soil to that in aqueous solution (Scott and Phillips 1973). Graham-Bryce (1969) has developed diffusion cylinder methods to determine the diffu-sion constants of pesticides. Information on the diffusion constant of a pesticidein soil is very limited, but it seems to range from 0.05 to 50 mm2 d−1 (Table 6[see table on page 92]). When pesticide molecules are homogeneously distrib-uted in uniform soil, the mean movement after time t is given by (2Dt)1/2. There-fore, it would take about 2.4 hr and 1–2.5 d for parathion (135) and trifluralin(232) to move through the 1-mm-thick soil thin layer. The foregoing consider-ation shows the importance of mass movement in photodegradation on soil sur-faces, but many other factors would operate in the field. Walker and Crawford(1970) have demonstrated that diffusion constant was inversely proportional tosoil adsorption coefficient. Smaller diffusion with a higher water content wasreported for dinitroaniline herbicides (Jacques and Harvey 1979), whereas theopposite relationship was observed for triazines (Scott and Phillips 1972). Ehlerset al. (1969a,b) have reported the contribution to diffusion from vapor- andnonvapor-phase mechanisms. In contrast to soil, several investigators have re-ported diffusion of pesticides in plant waxes and intact cuticles using the diffu-sion cell method (Schonherr and Riederer 1989; Lendzian and Kerstiens 1991;Bauer and Schonherr 1992; Schreiber and Schonherr 1993), but their diffusionseemed much slower than in soil.
Balmer et al. (2000) conducted the photolysis of trifluralin (232) and p-nitro-anisole on kaolinite thin layers under constant temperature and humidity usingUV light at 300–800 nm. By kinetic analysis, assuming first-order direct photol-ysis and diffusion following Fick’s law, greater contribution of diffusion wasdemonstrated for (232) than p-nitroanisole. For niclosamide (40), photodegrada-tion in/on air-dried soil was greatly reduced in proportion to thickness of soilthin layer, whereas a very slight increase of photolytic half-life was observedfor the moisture-maintained soil (Frank et al. 2002). Because the photic depthof soil is usually less than 1 mm, as described in Section IV.D, migration of(40) to the photic zone with the aid of soil moisture was considered most likelyto account for the observation. The importance of vapor-phase transport in air-dried sandy loam soil was briefly examined for aryl ketones undergoing Norrishtype II photoelimination (Kieatiwong and Miller 1992). The existence of surfac-tant seemed to affect the migration of pesticides in soil. Gong et al. (2001)showed that the faster photodegradation of atrazine (185) in the soil thin layerwith sodium dodecylbenzene sulfonate and proposed that solubilization of (185)results in greater availability for photodegradation. A similar effect by hexade-
Photodegradation of Pesticides 21
cane in soil photolysis was reported for 2,3,7,8-TCDD (129) (Kieatiwong et al.1990).
In addition, other factors such as the depth of the water table may have someinfluence on pesticide movement. The upward movement of chlorsulfuron (96)and triasulfuron (100) in a packed soil column was clearly demonstrated whenaddition of water to soil surface and drying in a growth chamber were cycledor the bottom of the column was dipped into water (Mahnken and Weber 1988).Capillary movement of pesticide, similar to the latter case, was also reportedfor norflurazon (214) and found to contribute to volatilization loss (Hubbs andLavy 1990). The effect of this type of upward movement on photolysis has beenconfirmed for 14C-napropamide (47) in soil under sunlight at the different watertable levels (Donaldson and Miller 1996).
D. Photic Depth in Soil
Soils are highly heterogeneous and unmixed as compared with solution, andillumination produces a light field difficult to define accurately (Wolfe et al.1990; Senesi and Loffredo 1997). The depth of light penetration (photic depth)in soil cannot be precisely defined but has been estimated by direct measurementof transmitted fraction of light or using probe molecules selectively undergoingdirect or indirect photolysis. Transmission of xenon arc light through soil thinlayers with 0.17-mm thickness was measured and UV light was found to bemore than 90% attenuated (Herbert and Miller 1990). Frank et al. (2002) exam-ined transmittance of UV light by varying the soil layer thickness from 0.5 to 4mm. Even a 0.5-mm-thick soil layer was enough to block about 95% of theincident light, but very slight light penetrated soil depths of 1.5 mm or greater.There was no significant difference of transmission at three wavelengths (280,365, and 440 nm). When soil thickness was less than 1.5 mm, more transmissionof light by a factor of 4–5 was observed for dry soil as compared with moistsoil, which may be accounted for by the difference in soil packing. As anotherapproach, Hebert and Miller (1990) utilized disulfoton (163) and flumetralin(233) as chemical probes to estimate the photic depth in soil. Flumetralin (233)absorbing light at wavelengths of 300–500 nm undergoes direct photolysis,whereas (163) has no UV absorption at >290 nm and only indirect photolysistakes place, that is, oxidation to the corresponding sulfoxide via reaction with1O2. By using these pesticides as probes, mean photic depths were estimated tobe 0.23 and 0.28 mm for direct and indirect photolysis, respectively, in thelaboratory, with larger values obtained for the outdoor study, 0.32 and 0.62 mm,respectively. The larger values for either indirect photolysis or outdoor studymay show contribution from diffusion of 1O2 to a deeper region of soil thanexpected for light penetration and that from convective and evapotranspirativetransport of pesticide by thermal heating at the soil–air interface. It is unclearif light reduction originates from bulk attenuation or as an inner filter phenome-non by soil. If an adsorbing substrate is relatively porous and highly colored, itwould be possible for an adsorbed pesticide to be “filtered” from the incident
22 T. Katagi
light. Yokley et al. (1986) investigated photodegradation of pyrene and benzo-[a]pyrene on silica gel, alumina, controlled pore glass (100 A on average),graphite, and various coal ashes by using a xenon arc lamp and reported theimportance of both adsorption to pores and UV screening. The UV screeningeffect by soil was also reported for photodegradation of polyaromatics whereslower degradation was observed for soil with lower reflectance (Moore et al.1989). Similar reduction of light has also been reported for sediments suspendedin aqueous solutions of pesticides (Miller and Zepp 1979; Oliver et al. 1979;Zepp and Schlotzhauer 1981).
E. Effects of Soil Properties on Photolysis
Konstantinou et al. (2001) have shown the possible involvement of photosensiti-zation based on faster photodegradation of herbicides in soil with higher organicmatter. In contrast, soil organic matter reduced the photodegradation of chlorim-uron ethyl (102) (Choudhury and Dureja 1997a), triasulfuron (100) and thifen-sulfuron-methyl (105) (Albanis et al. 2002), and fipronil (220) (Bobe et al.1998b), indicating involvement of either quenching or a shielding effect. Forniclosamide (40), modification of soil by addition of 3% HA was found toreduce photodegradation (Graebing et al. 2002). An insignificant effect of or-ganic matter on photolysis was observed for mecoprop (4) but its retardation bysoil amendment with 10% peat was detected under dry conditions, also implyingthe quenching effect (Romero et al. 1998). Clay is the other important soilcomponent and may affect the photodegradation profiles of pesticides. Sukuland Spiteller (2001) reported the linear relationship between photolytic half-lifeof metalaxyl (37) and clay percentage in soil. Because (37) does not have anysignificant UV absorption at >290 nm, photolysis was considered via indirectphotolysis, and the lower rate in soil with a higher clay percentage was likelyto originate from more intercalation of (37) into the intralattice structure of claywhere the incident light was screened.
Surface pH was an important factor, and such a pH effect would be operativefor acid-labile pesticides such as sulfonylurea herbicides (Schroeder 1997). Oneof the other important factors to control photolysis would be soil moisture con-tent. Faster photodegradation was detected in moistened than air-dried soils foralachlor (34) (Fang 1977), imidazolinone herbicides (Curran et al. 1992), andflorasulam (48) (Krieger et al. 2000), and photoinduced hydrolysis and/or migra-tion of pesticides to the photic zone of the soil thin layer might operate in thesecases. Enhancement of photolysis with soil moisture was observed for mecoprop(4), but at higher moisture the photodegradation rates decreased (Romero et al.1998). The significant decrease of photolysis rates in moistened soil was re-ported for fenpropathrin (24), which originated mainly from the increase ofsurface pH on soil with moisture (Katagi 1993b). As clearly seen from theseexamples, there are different mechanisms affecting photolysis with change ofsoil moisture, and thus it is not easy to estimate its effect a priori.
Photodegradation of Pesticides 23
F. Photophysical and Photochemical Processes of Soil Components
Soil is a heterogeneous system where clay minerals are coated with humic sub-stances and metal (hydr)oxides and the various photochemical reactions such asphotosensitization, quenching, and photoinduced reaction proceed (Fig. 7).
Humic Substances and Intact Soils There are many excellent reviews on pho-toprocesses of soil and aquatic humic substances (Zepp et al. 1981; Choudhry1984a; Zepp 1988, 1991; Hoigne et al. 1989; Cooper 1989; Frimmel 1994).UV-vis spectra of various HA and FA exhibited mostly featureless absorptionwith their tail extending up to 500–600 nm. The primary photoprocess is excita-tion to the short-lived (�1 nsec) singlet states (Fig. 8). These excited states canreact with a pesticide molecule via a diffusional or static bimolecular process,and the latter would play a greater role on soil surfaces. Zepp et al. (1985)estimated the triplet energy of most humic substances to be around 60 kcal mol−1
(250 kJ mole−1) by using photoisomerization of 1,3-pentadiene as an index. Itdepends on the energy level of triplet states of humic substances as comparedwith that of a pesticide molecule which process predominates, sensitization orquenching. Many pesticides are known to undergo photosensitized degradationby humic substances (Jensen-Korte et al. 1987), whereas aqueous photodegrada-tion of imazapyr (229) was slowed in the presence of HA due to the UV screen-ing effect (Elazzouzi et al. 1999). In the photoinduced E/Z isomerization of fouralkyl cinnamates having a different association ability toward Fluka HA, only2-fold increase in the rate of isomerization was observed for the cinnamate
Fig. 7. Photoreactions on soil surface: (A) sensitization, (B) quenching, (C) photoinducedreaction, (D) adsorption/desorption, (E) spectral change, (F) inner-filter effect. P: pesti-cide; D: degradate(s); HS: humic substances; M: metal (oxides: hydroxides etc.).
24 T. Katagi
Fig. 8. Photophysical and photochemical processes of humic substances. HS: humic sub-stances; RH: substrate.
having a 40-fold-higher affinity to HA (Van Noort et al. 1988), indicating thatthe associated form was hardly available for triplet energy transfer.
The presence of reactive excited triplet states has been suggested for humicsubstances through investigation of photoinduced degradation of cumene andbenzene (Kotzias et al. 1986). Because diffusion of pesticide molecules is con-sidered to be restricted on soil surfaces, the possible reactions of a pesticidemolecule with an excited triplet of humic substances are transfer of electron orhydrogen instead of direct energy transfer. These processes have been demon-strated for aqueous humic substances in photodegradation of the several methyland methoxy phenols (Canonica et al. 1995; Aguer and Richard 1996a). Theyproposed an aromatic ketone moiety as a reactive site model in humic sub-stances that underwent electron or hydrogen transfer via its excited n-π* state.Their contribution as well as energy transfer has been examined by using ureaherbicides including fenuron (51) and monuron (52) (Aguer and Richard 1996b;Richard et al. 1997; Aguer and Richard 1999; Gerecke et al. 2001). Aguer et al.(2001) showed the higher reactivity of HA fractions with a smaller molecularsize in photolysis of (51). They also demonstrated that soil FA having a smallerspecific absorption coefficient shows a higher activity, but that no meaningfulcorrelation is detected for HAs (Aguer et al. 2002). The weak photoinductiveefficiency of highly absorbing humic substances implied that the majority ofabsorbing components had no photoinductive effect. There may be various smallorganic molecules existing except for humic substances, and therefore they maybe involved in photolytic processes on soil. Kieber and Blough (1990) showedthe possible photoinduced formation of various carbon-centered radicals thatmay react with pesticides under some photolytic conditions on soil surfaces.
Humic substances are known to react with O2 via energy or electron transferprocess to generate the very reactive 1O2, OH�, superoxide anion (O2
−), and
Photodegradation of Pesticides 25
peroxide radical species (see Fig. 7). The contribution of each process wasroughly estimated for dissolved organic matter on an excited singlet state basis(Zepp 1991). Thermal deactivation was a dominant process (97%–99%), andonly 1%–3% of energy would be transferred to an excited triplet state, most ofwhich was involved in formation of 1O2. In an aqueous solution of HA, Taka-hashi et al. (1988) confirmed the formation of OH�, O2H�, and 1O2 in the pres-ence of O2 by ESR measurements using spin-trapping reagents. Nanosecondlaser spectroscopic methods were applied, and two short-lived transients fromfour illuminated natural waters were estimated to be an excited triplet state of aquinoid structure of humic substances and hydrated electron (e−
aq) (Fischer et al.1985, 1987; Power et al. 1987; Zepp et al. 1987). Photoinduced generation ofe−
aq from natural waters also has been confirmed by its conversion to OH� withN2O (Thomas-Smith and Blough 2001), and the steady-state concentration ofe−
aq was estimated to be approximately 1.1 × 10−17 M (Breugem et al. 1986).Because e−
aq quickly reacts with water molecules to give O−2 and O2H� if gener-
ated (Hoigne et al. 1989), its importance would be greatly lessened, especiallyon soil surfaces.
The steady-state concentration of 1O2 in natural water has been estimated tobe 10−14–10−12 M (Zepp et al. 1977; Wolfe et al. 1981; Haag and Hoigne 1986).The quantum yield of the photoinduced generation of 1O2 from aqueous solu-tions of soil HA and FA was estimated by both ESR and chemical analysisusing furoin (1,2-dimethyl-2-hydroxyethanone) to be 0.39–5.5 × 10−3 (Aguer etal. 1997). On soil surfaces, Gohre and Miller (1983) first demonstrated photoin-duced formation of 1O2 by using tetramethylethylene and 2,5-dimethylfuran aschemical probes. Gohre and Miller (1985) demonstrated that nontransition metaloxide powders such as silica gel, aluminum oxide, and magnesium oxide cata-lyze the formation of 1O2. They proposed the reaction of an exciton bound to adefect on a solid surface with adsorbed oxygen via transfer of electronic energy,and no correlation between 1O2 generation and the content of soil organic matterwas reported (Gohre et al. 1986). The existence of 1O2 was supported by obser-vation of chemiluminescence at 615–650 nm possibly due to 1O2 dimoles, butrecently a direct spectrophotometric method for the very weak chemilumines-cence at 1270 nm (1O2 → 3O2, spin-forbidden process) has been developed(Rodgers 1987; Kanofsky 2000).
The reaction types of photosensitized oxidation via 1O2 can be classified intoformation of endo-peroxide, ‘ene’ reaction giving allyl hydroperoxide, and for-mation of 1,2-dioxetane (Foote 1968a,b; Wilkinson and Brummer 1981). Thethioether-containing pesticides on soil were found to be transformed to the cor-responding sulfoxide by sunlight exposure most likely via reaction with 1O2
(Gohre and Miller 1986). The other example was photoinduced degradation ofbioresmethrin, 1R-trans isomer of (15), whose degradation was clearly reducedin the presence of β-carotene as an efficient 1O2 quencher (Clements and Wells1992). The enhanced degradation of 2-dimethylamino-5,6-dimethylpyrimidin-4-ol in D2O inhibited by sodium azide also showed involvement of 1O2 in itsdegradation, possibly attacking the 5,6-double bond (Dixon and Wells 1983).
26 T. Katagi
Under exposure to sunlight, OH� is photochemically generated via (1) reac-tion of humic substances in the excited triplet with water, (2) dissociation ofnitrate ion followed by protonation, and (3) degradation of H2O2 formed byreaction of e−
aq with water (Hoigne et al. 1989; Zepp 1991); in addition, coexis-tence of metal cations such as ferric ion with humic substances was consideredto play a great role in generating OH� via (4) the photo-Fenton reaction. Thesecond mechanism is considered to be predominant in the aquatic environment,but investigation has demonstrated that about half of OH� is generated viaphoto-Fenton reaction, and an O2-independent pathway also exists (Vaughamand Blough 1998). Among these four mechanisms, the first and last proceduresare considered to be more important to soil photodegradation. Photoinducedformation of OH� was confirmed in photolysis of 2,6-dimethoxyphenol with soilextracts by ESR (Suflita et al. 1981). Many investigations on OH�-generatingability of metal–humate complex through the Fenton or Haber–Weiss mecha-nism have been reported. Paciolla et al. (1999) demonstrated the intrinsic abilityof Fe3+– or Cu2+–HA complexes to generate OH� from H2O2 in darkness. Moss-bauer spectroscopy of this complex showed that about 5% of iron ion was pres-ent as Fe2+, indicating involvement of the above mechanisms.
Fukushima and Tatsumi (1999) studied the photocatalytic activity of theFe3+–soil humate complex giving OH� and H2O2 at >370 nm. Photoinduced one-electron transfer from HA to O2 followed by protonation was considered to yieldO2H�, which was then disproportioned into H2O2 and O2. They demonstratedthat the majority of Fe3+ was complexed with the HA fraction in a higher molec-ular weight and that the substrates were incorporated into the molecular skeletonof HA through photolysis (Fukushima et al. 2000, 2001; Fukushima and Tat-sumi 2001). Similar photo-Fenton reactions can be considered for small organicmolecules (Zepp et al. 1992; Balmer and Sulzberger 1999). Because soil compo-nents such as humic substances and silicate surface can trap a peroxy radical(Pohlman and Mill 1983), contribution from the aforementioned processes maybe lessened on soil surfaces.
As described, H2O2 is an another important reactive oxygen species in theenvironment whose generated humic substances are known to be deeply in-volved, and its steady-state concentration in an aquatic environment is estimatedto be 10−5–10−7 M (Draper and Crosby 1983; Cooper 1989). H2O2 on soil sur-faces would be degraded by various interactions with soil components or reactwith a pesticide molecule under sunlight irradiation. Petigara et al. (2002) inves-tigated the degradation processes of H2O2 in soils and revealed the possibleinvolvement of three pathways: a metal-catalyzed Harber–Weiss reaction, two-electron process achieved by catalase, and a peroxidic-type reaction. OH� wasfluorometrically determined using spin-trapping reagent and fluorescamine(Vaugham and Blough 1998). Retarded loss of H2O2 by autoclaving or additionof sodium azide or formaldehyde showed that 65%–75% of loss was due toabiotic processes on soil particles. Among minerals, goethite was found morereactive in generation of OH� than hematite. The photoinduced reaction of H2O2
with pesticide was not reported on soil surfaces, but aqueous photolysis of the
Photodegradation of Pesticides 27
several pesticides in the presence of H2O2 clearly showed involvement of photo-generated OH� as evidenced by product analysis (Draper and Crosby 1981,1984).
Clays The flat organosilicate sheets with reactive edges give a unique reactionenvironment on clay. Furthermore, a geometric constraint by pore or sheet struc-tures in clay may alter the photochemistry of pesticides (Thomas 1993). A claysurface may exhibit a cage effect for radicals generated via photoinduced homo-lytic cleavage of a bond similarly observed for benzyl derivatives on silica gel(Avnir et al. 1981). As one of the basic properties on clay surfaces, it should benoted that the sites possessing a high Brønsted acidity may show catalysis onsome pesticides (Caine et al. 1999). Using these properties, Takagi and Shichi(2000) reviewed organic photochemistry in/on the clay surface. The efficienttransfer of electron or excited energy occurs between molecules adsorbed onclay surfaces, and ferric ion as an impurity in clay may act as an efficientquencher. Spectral shift by adsorption, steric constraint, and hydrogen bondingare known to result in the different profiles for photoinduced isomerization ofstyrene derivatives, Norrish type I and II reactions of aromatic ketones, andphoto-Fries rearrangement of carbamates.
One-electron transfer from an adsorbed chemical to clay is known for thian-threne on laponite, as evidenced by ESR (Mao and Thomas 1993). A similarphotoinduced electron transfer to laponite, silica gel, and silica-alumina wasreported for pyrene (Liu et al. 1994). Extent of a cation radical formation wasfound to gradually decrease at above 340 nm, indicating the existence of vari-able active sites having a different capacity of accepting electrons. There is alsoevidence that ferric ion included in montmorillonite clay as an impurity acts asan electron mediator between excited 10-methylacridinium hexafluorophosphateand iodide as an acceptor (Theng et al. 1997). The other type of electron transferis directed from clay surface to adsorbed species such as O2 and transition metalions in clay is considered to be deeply involved, as already described.
Various kinds of energy transfer on clay have been investigated. Detailedanalysis of difference IR spectra implied the possible interaction of bioresme-thrin, 1R-trans isomer of (15), with methyl green (MG) on clay surfaces, andphotostabilization of bioresmethrin by MG could be accounted for by an effi-cient energy transfer (Margulies et al. 1985, 1987, 1993). Margulies et al. (1988)have reported the red shift of absorption spectrum when NMH (242) was ad-sorbed on montmorillonite. Its photostablity was improved by coadsorption ofthioflavin (TFT) or MG and its extent was greater in the former dye. The UV-vis absorption maximum of TFT (410 nm) was closer to that of (242) comparedto MG (630 nm), implying more efficient energy transfer from (242) to TFT.The interaction of (242) with clay surface was considered to take place at thecyclic enamine moiety of (242) as estimated by difference IR spectrum. Further-more, the direct energy transfer to clay surface was also reported for (242)(Rosen and Margulies 1991). Less photostabilization of (242) adsorbed to non-tronite than hectorite and montmorillonite could be accounted for by the differ-
28 T. Katagi
ent contents of Fe3+ (29.46%, 0.26%, and 3.72% as Fe2O3, respectively), whichacted as a quencher via a charge-transfer mechanism. Efficient overlap of theemission with the absorption spectrum is indispensable for this energy transfer,which has been well established for norflurazon (214) coadsorbed with TFT onmontmorillonite (Undabeytia et al. 2000). They also proposed the photoinducedgeneration of OH� by montmorillonite accelerating its degradation. The involve-ment of reactive oxygen species in photodegradation of pesticides on clay sur-faces has been reported for tolclofos-methyl (142), esfenvalerate (28), and PB-acid (243) (Katagi 1990, 1991, 1992). A simple organic cation such asbenzyltrimethyl-ammonium has been demonstrated to modify adsorption ofalachlor (34) to a clay surface, leading to its protection against photolysis (El-Nahhal et al. 1999). The IR spectral shift of carbonyl and C(aromatic)-N bondsto lower and higher wave numbers, respectively, indicated the possible interac-tion of carbonyl oxygen with an exchangeable countercation on the clay surfacethrough a water bridge (Nir et al. 2000). The red shift of the UV absorptionspectrum (π-π*) of phenyltrimethylammonium was observed when coadsorbedto montmorillonite, indicating the interaction between the phenyl rings of (34)and the organic cation.
In addition, clay surfaces also give a steric constraint on an adsorbed pesti-cide molecule (Margulies et al. 1993; El-Nahhal et al. 2001). Photostabilizationof trifluralin (232) was realized by adsorption to montmorillonite, but the addi-tion of TFT did not give further improvement (Margulies et al. 1992). Differ-ence IR spectra clearly demonstrated interaction of one nitro group of (232)with the clay interface. It is known that (232) undergoes photo-induced cycliza-tion between nitro nitrogen and the C1 carbon of the N-propyl moiety to givebenzimidazole derivatives (see Fig. 2, reaction 10b). Because the intramolecularcyclization requires a conformational change of the N-propyl moiety, which isrestricted by adsorption to the clay, the observed photostabilization is mostlikely to be accounted for by imposition of a steric constraint on (232).
Metal Oxides and Hydroxides Transition metals such as iron and manganeseexist in the environment as their oxides, hydroxides, and sulfides or impuritiesin clay being substituted with aluminum ions. These compounds can becomequenchers of an excited energy and catalytic sites by acting as an electron medi-ator. It has been reported on silica gel that dye-sensitized photooxidation ofbromacil (198) by 1O2 is significantly reduced by addition of FeO, Fe2O3, Fe3O4,or FeO(OH), which can be accounted for by an electron transfer from the ex-cited dyes or energy transfer from 1O2 (Riter et al. 1990). In addition, as repre-sented by titanium dioxide, some materials also can act as semiconductors wherethe photoexcited valence band electron reduces an organic chemical and theaccompaning hole oxidizes (Balkaya 2003). Irradiation at >340 nm accelerateddegradation of (185) in the presence of typical semiconductors TiO2, ZnO, andWO3 to give N-dealkylated derivatives possibly via oxidation by OH�, whereasα-Fe2O3 and Al2O3 did not show any photocatalytic action (Pelizzetti et al.1993). Further examination was conducted by Lackhoff and Niessner (2002) to
Photodegradation of Pesticides 29
estimate such a photocatalytic activity for environmental particles. Both TiO2
and ZnO exhibited a significant acceleration of degradation by a factor of 30–300, but much less activity was detected only for the other oxides such asSrTiO3, Fe2O3, and FeTiO3. Fine particles from natural sand, soot, and ash didnot show any meaningful acceleration compared with direct photolysis, whichwould be due to less occurrence of photocatalytic Ti (<1%) in these materials.Only very weak photocatalytic activity was observed for three soils when (185)was irradiated at >340 nm in aqueous suspension (Pelizzetti et al. 1993).
Similar trends of photocatalysis were briefly reported for dicarboximide fun-gicides (Hustert and Moza 1997) and azo dyes (Hustert and Moza 1994). Incontrast, the direct reaction with a positive hole was proposed for photolysis of2,6-dimethylphenol in aqueous suspension of goethite (α-FeOOH) (Mazellierand Bolte 2000). Not only the surfaces of these metal (hydro)oxides but alsospecies dissolved from the surface are considered to show catalytic acitivity ingenerating active oxygen species. Voelker et al. (1997) demonstrated this in themixture of lepidocrocite (γ-FeOOH) and FA, and Fenton-like degradation ofH2O2 has also been reported for goethite (Chen and Watts 2000). Many ironspecies are considered to exist in an aqueous phase after dissolution, andFe(OH)2+ species have been found most efficient in generating OH� under irradi-ation (Feng and Nansheng 2000). When H2O2 is enzymatically or abioticallyformed in soil, OH� is likely to be produced via Fenton-like reaction as demon-strated by ESR (Huling et al. 1998). These reactions may occur in real soil andcontribute, at least in part, to photodegradation of pesticides. In contrast to ironspecies, manganese oxides seem to show much less photocatalytic activity (Ber-tino and Zepp 1991; Lee and Huang 1995).
V. Atmospheric Oxygen Species
Reaction with oxygen species in air at a solid–air interface is considered to beanother important degradation pathway for pesticides deposited on soil and plantsurfaces. In the troposphere, O2 is the most abundant reactive species from itsbiradical structure in the ground state and is involved in either autooxidation orcoupling with radical species to give the corresponding peroxy species. Theother important species are O3 and OH� because of their high reactivity (Crosby1983; Marcheterre et al. 1988). In fact, their possible contribution to degradationof pesticides has been demonstrated on plant foliage (Spear et al. 1978; Ophoffet al. 1999) and soil surfaces (Spencer et al. 1980; Kromer et al. 1999). 1O2 isalso the other candidate, but its contribution may be limited to its specific reac-tivity toward a thiol moiety and C=C double bonds (Wilkinson and Brummer1981; Larson and Marley 1999). The formation and decline processes of thesereactive species in air are known to be very complex (Prinn 1994). O3 in thetroposphere originates from that in the stratosphere formed by direct photolysisof O2 or reaction between O2 and singlet oxygen atom O(1D) and dissipates viaUV photolysis to O(1D) or reaction with NO. OH� is mainly generated via reac-tion between O(1D) and H2O and deactivated by reaction with air pollutants
30 T. Katagi
such as CH4, SO2, and CO. The lifetime of O3 and OH� in air is estimated to be3 × 105 sec and 2.7 sec, respectively.
Concentrations of O3 and OH� are significantly low and known to vary withmany factors such as climate, geographical features, vegetation, and pollutionby human activities. The monthly mean value of troposheric O3 was 35–50ppb in the western North Atlantic (Oltmans and Levy 1992). The yearly meanconcentration at 13 stations in the United States was about 30 ppb with a sea-sonal variation, the maximum value (80–90 ppb) being detected in spring (Singhet al. 1978). The diurnal variation was also reported, and the maximum concen-tration was observed in the morning due to low photochemical destruction (Olt-mans 1981). Logan (1999) found that rural sites downwind of urban areas mighthave particularly high values of O3 in the middle of the day; 40–70 ppb insummer and 20–30 ppb in winter. The steady-state concentration of OH� wasestimated to be 5–6 × 105 molecules cm−3 (Crutzen 1982). Direct measurementshave been conducted by using laser long-path absorption or laser-induced fluo-rescence method based on the X2Π (ν″ = 0) → A2Σ+ (ν′ = 0) transition of OH�.The former method gave the OH� concentration of 4.3 (±0.4) × 106 moleculescm−3 in a sunny period but less in the nighttime (<1.5 × 106 molecules cm−3)(Dorn et al. 1995). The latter method showed similar values (3.4–6 × 106 mole-cules cm−3) in May and June (Holland et al. 1995). As laser irradiation alsoproduces OH� from the coexisting O3 as an artifact, ion-assisted mass spectrom-etry using 34SO2 has been applied (Crosley 1995). Estimated values in Coloradowere 2–4 × 106 molecules cm−3 smaller than expected from a photochemicalmodel, which could be accounted for by the presence of a quencher such asisoprene (2 ppb) in air. In other places, 1–10 × 106 molecules cm−3 was correctlyestimated.
O3 and gaseous pollutants in air are considered to be sorbed to plants andsoil surfaces, and such deposition is one of the important factors controllingtheir air concentrations. In the case of plant foliage, not only the direct interac-tion of O3 and OH� via sorption or reaction with epicuticular waxes but alsoreaction with epidermal and mesophyll cells and substomatal cavities after pas-sage through stomata is considered to play a role (Runeckles 1992; Cape 1997).The soil surface also acted as a sink of O3 (Turner et al. 1974; Fontan et al.1992; Cieslik and Labatut 1997). The uptake of O3 by plants was considered tobe mainly through stomata, and its flux over the vegetation was monitored (East-man et al. 1981). As a result, the deposition velocity over maize (max., 0.84 cmsec−1) was found to be about twice as large as that over grass, suggesting thatthe size of the stomatal aperture may be the predominant mechanism in O3
uptake. Wet and dry O3 deposition via stomatal or nonstomatal mechanismshave been studied in conjunction with aerodynamics over vegetation (Fowleret al. 2001; Zhang et al. 2002). Kerstiens and Lendzion (1989) examined non-stomatal deposition of O3 using isolated cuticle from various plant leaves anddemonstrated that its permeance via leaf is highly dependent on plant speciesand that either dust or hairs on leaf surface provides more degradation sites forO3. Based on these considerations, atmospheric conditions, especially for the
Photodegradation of Pesticides 31
concentration of O3 and OH�, should also be taken into account when photodeg-radation pathways of pesticides on plant and soil surfaces are examined.
VI. Experimental Design and Kinetic AnalysisA. Light Source
Many kinds of conventional light sources with different spectral irradiance(Gould 1989a) have been utilized especially for photolysis studies of pesticides(Guth 1981; Roof 1982; Miller and Zepp 1983; Parlar 1990). The spectral com-parison of artificial light with natural sunlight indicates great differences (Fig.9) (Hirt et al. 1960). The most suitable light source is a xenon arc lamp; as itemits at <290 nm, an appropriate UV filter should be used. The glass and solu-tion filters commonly used in photolysis studies are each characterized by trans-mission of light at a specific wavelength range (Gould 1989a), and glass hasbeen preferred because of its simplicity. The most popular filter is Pyrex (orDuran) glass and its thickness (�4 mm) is also important for effective cutoff ofthe undesired shorter wavelengths (Zepp 1982). Cellulose acetate sheet is some-times unfavorable due to its solarization. If an appropriate glass and/or solutionfilter is used, the wavelength dependency of photolysis can be convenientlyestimated for better understanding of the photolytic mechanism (Schwack and
Fig. 9. Spectral irradiance of typical light sources used in photolysis studies. Graph isbased on data from Hirt et al. (1960).
32 T. Katagi
Kopf 1993; Schwack et al. 1995c). Even if natural sunlight is used, it should bekept in mind that a reaction vessel or the glass of the greenhouse can partiallyabsorb sunlight.
B. Photolysis Chambers
Ebing and Schuphan (1979) introduced a closed cultivating system made ofPyrex or Duran glass (3-mm thickness) and equipped with volatile traps underirradiation by fluorescent tubes to examine degradation profiles of dichlofluanid(205) with a good 14C recovery (96%–99%) in soil–plant (spinach, potato, andcress) systems. A volatilization chamber elaborately designed to simulate wellreal environmental conditions was developed to evaluate the dissipation profilesof methyl parathion (136) applied to French beans (Muller et al. 1995). Thechamber was connected with an air-conditioning unit to obtain the desired tem-perature, humidity, and flow rate of air that passes over the plants into volatiletraps, and the ceiling of the chamber was made of a special glass transmittimglight from a metal-halogenide lamp to simulate exposure to natural sunlight. Asimilar wind tunnel apparatus was successfully introduced to estimate volatiliza-tion and degradation profiles of fenpropimorph (227) on dwarf beans, sugarbeet, and radish (Ophoff et al. 1999). However, these apparati are not readilyavailable and their maintenance is difficult; therefore, photodegradation of pesti-cides on plants has been mostly examined with metabolism studies.
Many researchers have developed an apparatus for soil photolysis that canbe classified as a rotatory reaction vessel made of glass or thin-layer plate in achamber (Guth 1981; Choudhry and Webster 1985; Parlar 1990). The formersystem was introduced to examine the mineralization of pesticides on a silicagel surface (Parlar 1990), and its concept has been used to examine photolysisof diuron (53) adsorbed on sand, clays, and iron oxide (Jirkovsky et al. 1997).The latter system has been widely utilized, and its common design is illustratedin Fig. 10, based on the literature (Klehr et al. 1983; Katagi 1990; Misra et al.1997; Kromer et al. 1999; Balmer et al. 2000). The soil thin layer (thickness <2mm) prepared on a plate or vessel made of glass or stainless steel is attached tothe controlled temperature water bath, and sometimes a thermocouple buried inthe soil is utilized to monitor and control the soil temperature. Light intensityand its spectral distribution are monitored by a spectroradiometer. Because ei-ther diffusion of a pesticide molecule or photodegradation profiles in or on soilis very sensitive to soil temperature and humidity, some investigators (Misra etal. 1997; Kromer et al. 1999; Graebing et al. 2003) have also introduced arelative humidity sensor to the chamber equipped with a water spray nozzle andestablished a computerized system to automatically control humidity.
Good material balance is indispensable for precisely evaluating the photolyticprofiles of pesticides and thus the selection of appropriate traps is very impor-tant. Not only do volatile pesticides have a higher vapor pressure, most volatilesconsist mainly of CO2 and organic degradates with a small molecular size. Airflow under reduced pressure conditions was obtained using a suitable pump to
Photodegradation of Pesticides 33
Fig. 10. Soil photolysis chamber. 1, soil thin layer (<2-mm thickness); 2, thermocouple;3, thermometer; 4, photoprobe connected by glass fiber; 5, spectroradiometer; 6, glassfilter (Pyrex); 7, thermostat-controlled water bath; 8, circulator; 9, xenon arc lamp; 10,power supply; 11, CO2-free humidified air; 12, traps.
avoid undesirable leakage from glass joints or seals instead of the pressurizedsystem. One of the traps is a liquid type, represented by aqueous alkaline solu-tion and organic solvents and the other is a solid type, for example, ascarite,charcoal, and porous polymers (Lewis 1976). CO2 is usually collected by using0.1–0.5 M KOH or NaOH in a gas-washing bottle and quantified by precipita-tion as BaCO3. Monoethanolamine is also used as a trapping medium (Yamaokaet al. 1988; Tanaka et al. 1991), and its efficiency can be improved by addingmethanol and a scintillation cocktail (Abbott et al. 1992). Ascarite has beenconveniently used to trap CO2 generated during photolysis of florasulam (48)(Krieger et al. 2000). When CO is generated, it can be catalytically convertedto CO2 using a combustion furnace (CuO at 650° C) followed by trapping asabove (Tanaka et al. 1991) or chemically trapping as cuprous complex using anacidic CuCl solution (Busch and Franklin 1979). Small organic volatiles areusually collected by using nonvolatile ethylene glycol, and its low solubilizingability toward organic molecules can be improved, for example, by addition ofa small volume of xylene. Evaporation of an organic solvent usually causesdifficulty in its use as a trapping medium, especially for longer periods, butcooling of the medium can improve its utility (Koshy et al. 1983). The cryogenictechnique using a dry ice–acetone mixture at −78° C can also be effective(Lewis 1976). As a solid trapping medium, acetone-washed polyurethane foam(Kromer et al. 1999) and porous polymeric sorbent such as Amberlite XADresins, Chromosorb, and Tenax (Lewis 1976; Smith et al. 1995; Ophoff et al.
34 T. Katagi
1999) have been used effectively. If organic volatiles can undergo fast and spe-cific chemical reaction in a trapping medium, it can become a useful trappingmethod. Tanaka et al. (1991) used dimedone (5,5-dimethylcyclohexane-1,3-dione) with a trace amount of pyridine to trap formaldehyde. For formic acidand acetic acid, Yamaoka et al. (1988) derivatized these using p-bromophenacylbromide in the presence of 18-crown-6.
C. Kinetic Analysis
When the reaction environment of a pesticide varies with its movement andadsorption, a simple first-order kinetics cannot be applied. In the foliar dissipa-tion of pesticides, the decline curve sometimes follows a two- or three-phasekinetics, each of which consists of a single exponential decline (first order).These are considered to correspond to the compartment models where move-ment of a pesticide between each compartment can be neglected. Gunther (1969)demonstrated the involvement of two dissipation processes for pesticides ap-plied to citrus fruit and found that the first faster dissipation stems from surfacedeposits in epicuticular waxes and the slower process from metabolism in therind. Similar approaches are utilized for many studies. Figure 11 shows the dif-ferences in decline profiles among simple first-order (single-phase), two- andthree-phase kinetics as examples. By considering a weight of vaporization lossfrom plant surfaces in the early stage after application, Stamper et al. (1979)analyzed crop residue data by ln-ln plots and statistically obtained the betterrelationship; R = a*t−3/2 (R, residue; t, days after application; a, constant). WhenFick’s second law of diffusion is applied, the dissipation of a pesticide can beapproximated by y0/(4πDt)3/2 (y0, initial deposit; D, diffusion constant), whichis in accordance with the statistical analysis. This information indicates the im-portance of controlling factors such as volatilization besides basic degradationmechanisms, and such an approach has been undertaken to account for dissipa-tion of pesticides from tea plants (Zongmao and Haibin 1997). The quantumchemical parameters were also introduced to examine photodegradation of poly-chlorodibenzodioxins on laurel cherry (Chen et al. 2001), and such an approachmay be useful.
In the case of soil photolysis studies, the decline of a pesticide usually doesnot follow the first-order kinetics and slows down with time, possibly due toeither adsorption to soil or movement out of a photic zone. Many investigatorshave applied the single- to three-phase models, but in some cases the second-order rate constant or Hoerl function [a * exp (b*t) * tc], where a, b, and c areconstants and t is an incubation period, has been proposed as a better relation-ship (Emmelin et al. 1993; Romero et al. 1998). The simpler equation based ona meaningful physicochemical assumption is desirable in the usual analysis ofexperimental data. Gustafson and Holden (1990) have focused on a spatial vari-ability in factors affecting dissipation rate in soil such as microbial population,light intensity, temperature, and soil properties. They assumed an infinite com-partment model where each compartment with a different dissipation rate is
Photodegradation of Pesticides 35
distributed with some probability and introduced the concept that the rate con-stants follow the Γ distribution. The simple equation, y = (1 + b*t)−a, can bederived with a half-life of (0.5−(1/a) − 1)/b (y, % of the applied dose; t, time; a, b,constants); the dissipation curve is shown in Fig. 11. Data analysis using theseapproaches helps to understand not only persistence of a pesticide but also thedissipation mechanisms involved.
VII. Photodegradation of Pesticides in Model SystemsA. Soil Surface Models
Glass, silica gel, or clay have been utilized as simple models by consideringheterogeneity and variability of soil affecting photodegradation profiles of pesti-cides (Hulpke et al. 1983). However, the adsorptive nature of soil cannot betaken into account on glass. This effect may be partly realized in silica gel orclay, but the higher reactivity of their surface originating from many types ofsilanol groups and adsorbed water would give different reaction environments.Furthermore, more tightly packing may reduce the depth of light penetrationcompared with soil. Although the contribution of soil humic substances actingas a photosensitizer, quencher, or solubilizing medium is completely neglectedin either of these models, their easier handling makes them the first useful ap-proach to evaluate soil photolysis of pesticides. Treatment of silica gel or clay
Fig. 11. Typical decline curves. When period and percent (%) of the applied dose are“t” and “y,” respectively, each curve can be defined as follows: single-phase, y =exp(−a*t), a = 0.139; two-phase, y = a*exp(−b*t) + c*exp(−d*t), a = 0.6, b = 0.139,c = 0.4, d = 0.0139; three-phase, y = a*exp(−b*t) + c*exp(−d*t) + e*exp(−f*t), a = 0.4,b = 0.139, c = 0.3, d = 0.0139, e = 0.3, f = 0.00693; Gustafson, y = (1 + b*t)−a, a = 1.5,b = 0.117.
36 T. Katagi
with humic substances can be alternatively considered, but such approaches arevery limited (Schafmeier et al. 1998). The most frequently reported system isthe aqueous soil suspension (Pelizzetti et al. 1990; Mansour et al. 1997; Hustertet al. 1999), but the excess amount of water may alter the reaction environmentor unexpectedly increase the contribution either from direct or indirect photoly-sis in an aqueous phase containing dissolved humic substances. Furthermore,the filter effect by suspended matters may reduce the rate of photolysis (Zeppand Schlotzhauer 1981), and the adsorption to soil may be underestimated forpartially water-soluble pesticides. Furthermore, even if the soil thin layer with1- to 2-mm thickness is used, diurnal variation of soil temperature and moistureis difficult to determine (Miller et al. 1989; Reichman et al. 2000b). Thesedifferences would change the extent of vaporization loss of pesticide from soilsurface and misstate the rate of photoinduced dissipation by neglecting transportof pesticide or reactive oxygen species via diffusion along with the movementof water or air in soil (Ehlers et al. 1969b; Hubbs and Lavy 1990; Donaldsonand Miller 1996; Balmer et al. 2000). The few approaches elaborately control-ling these factors have been carefully developed (Misra et al. 1997; Kromer etal. 1999; Frank et al. 2002).
B. Plant Surface Models
The simplest model is the glass surface, but the reaction environment is verydifferent from the cuticular surface. From this point of view, Peacock et al.(1994) have briefly examined an inactive polytetrafluoroethylene plate. Consid-ering the wax chemistry described in Section III.E, many researchers have con-veniently examined photodegradation of a pesticide in simple organic solventsas surrogates of waxes, but their significantly different fluidity and simple struc-tures should be kept in mind together with easier photoaddition of a solventmolecule. Schwack (1988, Schwack et al. 1994) used methyl oleate and 12-hydroxystearate as more elaborate models of epicuticular wax. Photolysis of2,4-D (1) has been reported to be enhanced on Zea mays leaves and thus a morerealistic model has been considered (Venkatesch and Harrison 1999). Photodeg-radation of carbamate and organophosphate pesticides was examined in thinfilm of epicuticular waxes extracted from a variety of citrus fruits (Cabras et al.1997b; Pirisi et al. 1998, 2001). Schuler et al. (1998) examined photodegrada-tion of dibenzo-p-dioxins including (129) on glass coated with waxes of laurelcherry leaves. The photolysis rate of fenarimol (239) was dependent on plantspecies (Watkins 1987). Because plant cuticles can be isolated from intact leavesby treatment with pectinase and cellulase, Schynowski and Schwack (1996) con-ducted photodegradation of parathion (135) on enzymatically isolated cuticles.
C. Photodegradation of Pesticides on Glass and Silica Gel Surfaces
Glass plates (Chukwudebe et al. 1989) and silica gel (Hirayama et al. 1998)were utilized to examine the comparative photoreactivity of various pesticides.Any significant relationship between the photolysis rate on glass at λmax = 300
Photodegradation of Pesticides 37
nm and the extinction coefficient of each pesticide at 295–305 nm could not beidentified, but the slower degradation was observed for the thicker layer ofpesticide on glass (Chen et al. 1984). Photolysis rates were greatly reduced atthe concentration of 3.3 µg cm−2, corresponding to the thin-layer thickness of�100 A. Since Kitchener (1946) reported that most of light passing through acrystal is absorbed along the pathlength of �100 A, this reduction was likely tooriginate from light attenuation. Furthermore, the different profiles of UV ab-sorption in the solid state from those in solution (Gab et al. 1975b; Leermakerset al. 1966) may account, at least in part, for this insignificant relationship. Incontrast, Calumpang et al. (1984) found a good correlation between maximummolar absorptivity in solution and photolysis rate for eight organophosphateinsecticides on silica gel. On these solid surfaces, the photoinduced homolyticcleavage of a bond to produce radicals is considered to be one of the mostimportant degradation pathways. Johnston et al. (1984) studied photodegrada-tion of azobis(isobutyronitrile) on dry silica gel by using UV light and demon-strated that some portion of radicals could escape from their original partnersby a translational motion. Avnir et al. (1981) also examined the reaction profilesof radicals by using benzyl phenylacetate and dibenzyl ketone. By comparingthe amount of dibenzyl formed in potassium dodecanoate micelles via recombi-nation of radicals, they concluded that radical pairs separated more easily onsilica gel surface by a translational motion. Furthermore, this trend was moreemphasized for dibenzyl ketone generating radicals via the triplet state com-pared with benzyl phenylacetate via the singlet state. Therefore, if the pesticidemolecule deposited on silica gel surface undergoes photoinduced homolyticcleavage of some bond, the recombination process may be less important. Thephotodegradation profiles of pesticides on glass and silica gel are summarizedin Table 7 (see table on page 94) from a survey of the existing literature.
Organochlorines Photoinduced dechlorination of pentachlorophenol (121)gave the π-radical and successively the phenoxide (Piccinini et al. 1998). Thephotolytic half-life was dependent on the solvent used to prepare a thin film onglass, and a residual amount of water was found to increase the photolysis rate.Aldrin (122) on glass underwent epoxidation to dieldrin (123) followed by fur-ther isomerization to photodieldrin (124) (Rosen and Sutherland 1967). In thecase of endosulfan (125), the ring opening to form the diol derivative via releaseof SO was a major pathway but without S-oxidation (Dureja and Mukerjee1982). The other cyclodienes, including chlordane (128), were found to formthe corresponding cage structure derivatives (Benson et al. 1971). More epoxi-dation and hydroxylation of (128) on silica gel implied involvement of reactiveoxygen species on the surface formed by irradiation (Gab et al. 1975a). DDT(130) on glass primarily underwent photoinduced homolytic cleavage of theC−Cl bond at the trichloromethyl group to form DDD (132) by exposure to UVlight at 254 nm (Mosier et al. 1969). The radical mechanism was also supportedby comparative photolysis of eight 3H-diethoxy analogues of (130) on glass(Coats et al. 1979). Relative photostability decreased by substituting the CCl3
38 T. Katagi
moiety with other groups as follows: CCl3 (130) >> CHCl2 (132) > CHCl2CH3
>> CCl(CH3)2. This order was in agreement with the stability of radical speciesformed via C–Cl cleavage.
Organophosphorus Esters Photoinduced oxidation of the P=S moiety was ob-served for parathion (135) and its methyl analogue (136) on glass (El-Refai andHopkins 1966; Calumpang et al. 1984), together with formation of S-isomers(Chukwudebe et al. 1989). Fenitrothion (138) on silica gel underwent oxidationat the aryl methyl group to COOH and/or P=S moiety to the oxon together withan ester cleavage giving the corresponding phenol (Ohkawa et al. 1974b). O-Demethylation was observed for the rapid photodegradation of cyanophos (137)on silica gel in addition to oxon formation and cleavage of the P−O aryl bond(Mikami et al. 1976). The photoinduced S-oxidation of the methylthio group tosulfoxide was the primary reaction on glass for fenthion (143) (Cabras et al.1997b). Hirahara et al. (2001) examined comparative photodegradation of (143)using UV-A (320–400 nm), UV-B (280–320 nm), and UV-C (250–260 nm)light. Because (143) has a UV absorption at the UV-B–UV-C region, the easeof photodegradation was UV-C > UV-B > UV-A. Photoinduced dehalogenationwas additionally observed for iodofenphos (141) on glass (Walia et al. 1989b).Similar photodegradation profiles of chlorpyrifos (145) were more quantitativelyinvestigated (Walia et al. 1988; Racke 1993). Although the degradation productswere not identified, Meikle et al. (1983) utilized Whatman No. 1 filter paper asa leaf model and examined rates of either photolysis or volatilization in thepresence of carruba wax. When the aryl moiety is transformed from simplephenyl rings to heterocycles, similar phototransformation is basically observed.Oxidation of the P=S moiety concomitant with the P-Oaryl ester cleavage pro-ceeded on glass for quinalophos (148) (Dureja et al. 1988) and pyridafenthion(150) (Tsao et al. 1989). Although dioxabenzofos (183) possesses a unique cy-clic structure, the photoreactions on silica gel obeyed similar mechanisms (Mi-kami et al. 1977b). Phoxim (152) gave the same photoproducts on glass andtomato leaf but their chemical identification was not extensively conducted(Makary et al. 1981).
When 14C- or 32P-phenthoate (168) on glass was exposed to sunlight, about90% was lost by volatilization after 40 hr, and 20%–35% of the residual radio-activity was due to its oxon. The volatilization loss was greatly reduced on silicagel, with the main product being the oxon (Mikami et al. 1977b). 14C-Sulprofos(161) was oxidized to the sulfoxide and sulfone similarly as (143) (Ivie and Bull1976). The basic photochemistry was almost the same for propaphos (159) ei-ther on glass or silica gel and was characterized by the significant formation ofthe S-oxidized derivatives (Fujii et al. 1979). Direct photolysis is consideredmost unlikely for dimethoate (165), malathion (167), phorate (162), and disulfo-ton (163) not having chromophores in the molecules. The hydrolysis productswith a trace amount of the oxon were detected only for sunlight photolysis of32P-(165) (Dauterman et al. 1960). Loss of (167) from the glass surface wasmainly due to thermal vaporization (Awad et al. 1967; El-Refai and Hopkins
Photodegradation of Pesticides 39
1972). Phorate (162) was only photodecomposed to the oxon at 254 nm andthus sunlight photolysis was considered unlikely (Sharma and Gupta 1994). In-significant involvement of direct photolysis for (163) was clearly demonstratedby degradation only at 250–260 nm by Hirahara et al. (2001). UV irradiationof phosalone (170) on glass resulted in dechlorination and cleavage of eachbond at the PSCH2N linkage but without any P=S oxidation (Walia et al.1989a). Edifenphos (173) exhibited slow degradation under UV irradiation (Ishi-zuka et al. 1973).
Stereospecific oxidation of the P=S moiety to the oxon was reported for 3H-S-2571 (176) on silica gel using UV light (Mikami et al. 1977a). Katagi (1993a)proposed, in photolysis of butamifos (177), the N-sec-butyl analogue of (176),the photoinduced intramolecular oxidation of the P=S moiety by the adjacentnitro group attached to the o-position of the phenyl ring, which may account forthis stereospecificity. Dureja et al. (1989) reported photoinduced oxidation ofthe P=S moiety and ester cleavage for isofenphos (175) on glass. 32P-Leptophos(181) on silica gel was photodegraded with formation of oxon, O-demethylatedand debrominated derivatives, and O-methyl phenyl thiophosphonic acid thatwere finally degraded to phenyl phosphonic acid (Zayed et al. 1978). Both oxi-dation of the P=S moiety and ester cleavage were the main pathways for (181)on glass (Riskallah et al. 1979) and for cyanofenphos (180) on silica gel (Mi-kami et al. 1976) under sunlight. These results show the insignificant differencesin photochemistry among phosphorothioates, phosphoramidothioates, and phos-phonothioates. Monocrotophos (156) (Dureja 1989; Lindquist and Bull 1967),phosphamidon (158) (Bull et al. 1967), dichlorvos (153), and trichlorfon (179)(Derek et al. 1979) do not have any chromophore to absorb sunlight and thusdirect photolysis was most unlikely.
Pyrethroids Chen and Casida (1969) studied photodegradation of the 14C-labels of pyrethrin I (9) and allethrin (10) on glass and identified three possibleoxidation pathways. One of these was the successive oxidation of the trans-methyl group of the 2-methylprop-1-enyl moiety via CH2OH and CHO andfinally to the COOH derivative; the other two pathways were formation of trans-caronic acid derivative, possibly via ozonide and oxidation at 1-position of the2-methylprop-1-enyl moiety. Involvement of oxygen species was separatelydemonstrated by the increased stability in the presence of an antioxidant suchas dibutylhydroxytoluene (Abe et al. 1972). Isobe et al. (1984) reported thephotoinduced opening of the cyclopropyl ring of (10) followed by either sigma-tropic rearrangement to the acrylate or oxidadtive destruction to the mixtures ofglyoxylates. Ruzo et al. (1980) detected the di-π-methane rearrangement of the2-(prop-2-enyl)cyclopent-2-enone moiety of S-bioallethrin (12) on glass to formthe cyclopropyl derivatives, but the cis/trans isomerization was minimal. 14C-Resmethrin (15) on silica gel, glass, or filter paper underwent either epoxidationof the 2-methylprop-1-enyl moiety or ester cleavage similarly as (10) (Ueda etal. 1974). These unique reactions were initiated by oxidation of the furan ring,possibly to give a cyclic ozonide-type peroxide intermediate (Fig. 12). Reduc-
40 T. Katagi
Fig. 12. Photooxidative rearrangement of resmethrin (15).
tion of this intermediate to the diol followed by rearrangement resulted in forma-tion of the cyclopentenolone derivative, especially on silica gel. Migration ofproton or hydrogen radical from the position symmetrical to the benzyl groupor that of the benzyl cation or radical gave the hydroxylactone and benzyloxy-lactone derivatives, respectively.
Samsonov and Makarov (1996) examined the photostability of (15) on glassunder sunlight and found that the oxidative degradation by O2 was insensitiveto thickness of thin film and likely to be controlled by a filter effect of thinfilm. Tetramethrin (23) underwent successive photooxidation at the acid moietysimilar to (10) (Chen and Casida 1969). Ruzo et al. (1982) investigated thephotodegradation of phenothrin (13) and (23) on glass and demonstratedinvolvement of oxygen species such as 3O2,
1O2, and O3. The ene reaction of 1O2
(see Fig. 2, reaction 7) was confirmed by formation of 2-methyl-1-hydroperoxy-prop-2-ene-1-yl and 2-methyl-1-hydroxyprop-2-ene-1-yl derivatives. For (23),hydroxylation at the 3-position of the 3,4,5,6-tetrahydrophthaloyl moiety oc-curred but to a lesser extent. Although the degradation products were not re-ported, the very rapid photodegradation of cyphenothrin (14) was observed onsilica gel possibly via photoreactions similar to (13) (Dureja et al. 1984). Inaddition to the usual photoinduced isomerization in the acid moiety togetherwith epoxidation, kadethrin (16) underwent opening of the 2-oxo-3-thiacyclo-pentylidene ring on glass (Ohsawa and Casida 1979). Trace amounts of benzy-loxylactone derivatives were detected similarly to (15) but without formation ofthe hydroxycyclopentenolone.
Photoinduced cis/trans isomerization mainly proceeded for deltamethrin (22)on glass under sunlight, and neither photooxidation nor debromination was de-tected (Ruzo et al. 1977). Maguire (1990) reported the isomerization of 1R-cis-isomer to 1S-cis-, 1R-trans-, and 1S-trans forms by chiral HPLC analysis. The
Photodegradation of Pesticides 41
other reactions were ester cleavage to form the corresponding acid, α-cyano-3-phenoxybenzyl alcohol, and 3-phenoxybenzaldehyde together with decarboxyl-ation (see Fig. 2, reaction 4). The dimethylacrylate derivative was also detectedat a trace amount similar to (10). Cyhalothrin (21) exhibited the similar photore-actions to (22) on glass (Ruzo et al. 1987). Tralomethrin (25) and tralocythrin(26) were mainly phototransformed to (22) and cypermethrin (19) with theirtrans-isomers, respectively (Ruzo and Casida 1981). The 1′-bromo derivativeswere also formed possibly via intramolecular abstraction of hydrogen at the 1′-position by bromine homolytically being photodissociated. Many pyrethroidshave the 3-phenoxybenzyl or α-cyano-3-phenoxybenzyl moiety, and the intro-duction of the cyano group has been demonstrated not to significantly affectphotoreactivity either in solution or on glass (Ruzo and Casida 1982). Holm-stead et al. (1978b) reported that the main photo-reaction of fenvalerate (27) onglass is decarboxylation. Homolytic cleavage of either (C=O)O−CH orC(=O)−OCH bond has been evidenced by detection of many relevant photo-products. By exposure to sunlight, flucythrinate (29) was photodegraded onglass via almost the same pathways as (27) (Chattopadhyaya and Dureja 1991).Although the NH linkage was additionally introduced to the acid moiety, almostthe same photoreactions were reported for fluvalinate (30) (Quinstad and Staiger1984). Sunlight exposure resulted in formation of formanilide, probably due toreaction of haloanilide with photochemically produced formaldehyde, but nodecarboxylated derivative of (30) was detected on glass. Acrinathrin (31) onglass was photodegraded to the corresponding acid and alcohol moieties viaester cleavage (Samsonov and Pokrovskii 2001). The predominant photodegra-dation process of etofenprox (32) on glass was the photooxidation of the benzylmoiety to benzoyl, whereas the unique product formed by loss of the CH2Omoiety in solution photochemistry was not detected (Fig. 13). The benzyl radical
Fig. 13. Photodegradation of etofenprox (32).
42 T. Katagi
would be possibly formed by hydrogen abstraction, which reacted with O2 tothe hydroperoxy derivative followed by its dehydration to the benzoyl derivative(Class et al. 1989; Tsao and Eto 1990b).
Carbamates Substituted phenyl N-methylcarbamates are commonly photode-graded via successive oxidation of the N-methyl group on glass or silica gel(see Fig. 2, reaction 6) (Abdel-Wahab et al. 1966). Aminocarb (66) or mexacar-bate (67) were photodegraded on silica gel at 254 nm to more than 10 photo-products including the N(CH3)CHO and NHCHO derivatives (Abdel-Wahab andCasida 1967). Because the same products were detected in photolysis of (66)on glass at >290 nm, the oxidation process was likely to occur in the environ-ment (Pirisi et al. 2001). This oxidation was also reported for pirimicarb (78)on glass and cellulose plates, and involvement of OH� was assumed (Pirisi etal. 1996, 1998). Methiocarb (68) underwent photoinduced oxidation of the meth-ylthio group on wax-coated glass to form the corresponding sulfoxide and sul-fone, while it was degraded to unknowns on glass (Pirisi et al. 2001). In thecase of benfuracarb (89) on glass, the photocleavage of carbamate linkage atthe N−C(=O) bond gave carbofuran (72), which was further photodegradedto the corresponding phenol (Dureja et al. 1990). At the same time, eitherN(CH3)−C or N(CH3)−S bond was cleaved by irradiation to form N-(2-ethoxy-carbonylethyl)-N-isopropylsulfenamine and its derivative (Fig. 14). Photodegra-dation of benthiocarb (86) gave mainly 4-chlorobenzoic acid via the correspond-ing alcohol and aldehyde with insignificant S-oxidation (Ishikawa et al. 1977).Either N-deethylation or hydroxylation at the 2-position of the phenyl ring wasa minor pathway, the latter of which was characteristic of photolysis on glass.These photoreactions were also observed on silica gel but with a slower photo-degradation rate (Cheng and Hwang 1996). Photoinduced homolytic cleavage
Fig. 14. Photodegradation of benfuracarb (89).
Photodegradation of Pesticides 43
of the carbonyl C−S bond gave the benzyl thiol and its dimer (Ruzo and Casida1985). The radicals produced via cleavage of the benzylic C−S bond reactedwith O2 to form the series of alcohol-to-acid derivatives or gave benzyl N,N-diethyl carbamate or benzylamine via release of either sulfur or O=C=S, fol-lowed by recombination with the 4-chlorobenzyl radical. N-Methylcarbonyl-N-ethyl derivative was also detected as a major product on glass, and involvementof OH� was proposed. Cartap (91) was thought to undergo photocleavage of thethiocarbamate S−C(=O) bond to give the radical, followed by intramolecularcyclization to nereistoxin on either glass or silica gel (Tsao and Eto 1989). Thephotoinduced homolytic cleavage of the carbamate C(=O)−O linkage was mostlikely for phenmedipham (84) on silica gel by detection of N,N′-ditolylurea fromthe reactive isocyanate (Emmelin et al. 1998). Schafmeier et al. (1998) reportedthat the photolysis of (84) on silica gel was highly dependent on coexistinghumic substances. In the case of fenothiocarb (85), photoinduced oxidation atsulfur mainly proceeded on silica gel, followed by cleavage of the carbamatelinkage to the very reactive intermediate sulfenic acid that was readily decom-posed to 4-phenoxybutylsulfonic acid (Unai and Tomizawa 1986). Thiophanatemethyl (92) was rapidly photodegraded on glass via conversion of the C−Sgroup to ketone and via intramolecular cyclization to MBC (93) (Soeda et al.1972). MBC (93) was found rather stable on silica gel, but its photodegradationwas accelerated by a sensitizer such as riboflavin (Fleeker and Lacy 1977).
Amides, Anilides, and Dicarboximides Alachlor (34) underwent photoinducedcleavage of either the N−CH2 or N−C(=O) bond on glass finally to the corre-sponding aniline, together with dechlorination and intramolecular cyclizationto the indoline derivative (Fang 1977). Similar photodegradation profiles werereported for butachlor (36) when irradiated at 254 nm, together with the photo-substitution of Cl with OH followed by intramolecular cyclization to N-2′,6′-diethylphenyl-2,5-dihydrooxazol-4-one (Chen and Chen 1978). These herbicidespossess insignificant absorption at >290 nm and thus the direct photolysis wasconsidered unlikely in the environment. Either N−C(=O) or N-aryl bond ofmepronil (38) was slowly cleaved on silica gel by sunlight to form benzamideand benzoic acid, followed by stepwise oxidation of the o-methyl group togetherwith p-hydroxylation at the aniline moiety, but only as a trace amount (Yumitaand Yamamoto 1982). Although photodegradation was found insignificant at 254nm, flutolanil (39) underwent O-deisopropylation and photo-Fries rearrangement(see Fig. 2, reaction 9b) to give 2-aminobenzophenone derivative on either silicagel or glass (Tsao and Eto 1991). The photo-Fries rearrangement of amides at254 nm has been reported on dry silica gel by Abdal-Malik and de Mayo (1984),and radical pairs formed were considered not to separate on the surface. Thephotolysis mechanism on silica gel was investigated for analogues of (38) hav-ing different o-substituents (Yumita et al. 1984). They proposed involvement oftwo pathways: one is the N−C(=O) bond cleavage with the formed anilinebeing polymerized and the other is the hydroxylation at p-position of the anilinemoiety followed by cleavage of the N-aryl bond. Carboxin (42) exhibited rapid
44 T. Katagi
photodegradation on glass, probably via oxidation at the oxathiine sulfur to sulf-oxide and sulfone (Buchenauer 1975). Niclosamide (40) underwent extensivephotodegradation either on glass or silica gel to chlorosalicylic acid via cleavageof the N−C(=O) bond (Schultz and Harman 1978). In contrast, naproanilide(41) exhibited homolytic cleavage of the CH−O bond or photooxidation at themethine carbon to form 2-hydroxypropananilide at >254 nm on glass (Tsao andEto 1990a). Unique photoreactions were observed for isoxaben (46) on silicagel (Mamouni et al. 1992). The N-O bond in the isoxazole ring was first photo-cleaved and recyclized to the three-membered azirine derivative whose ring wasagain opened at the C-C bond to form the oxazole derivative (Fig. 15). It wasconsidered that these compounds converted to each other under irradiation, andthe azirine and oxazole derivatives were photodegraded to 2,6-dimethoxyben-zamide followed by reduction to the corresponding benzonitrile. Concerningimide pesticides, Sumida et al. (1973) examined the photolysis of experimentalfungicide DDOD (113) on glass but without detailed information on degradates.
Ureas Diflubenzuron (59) was photodegraded on glass or silica gel to 4-chlo-rophenyl isocyanate and 2,6-dichlorobenzamide, indicating involvement of pho-toinduced cleavage of the central C-N bond via NH hydrogen abstraction by theexcited-state carbonyl oxygen in the six-membered ring transition state (Ruzoet al. 1974). Almost half of 14C-(59) was lost from silica gel during 28 d withtrace formation of unknowns (Bull and Ivie 1976). Diafenthiuron (57) was rap-idly photodegraded on Teflon sheets to give the corresponding urea throughcarbodiimide by reaction with 1O2 (Drabek et al. 1992). Chlorsulfuron (96) on
Fig. 15. Photoinduced rearrangement of isoxaben (46).
Photodegradation of Pesticides 45
silica gel exhibited slow photodegradation to give the corresponding aminotri-azine and benzenesulfonamide derivatives via cleavage of the sulfonylureabridge (Herrmann et al. 1985). UV spectrum of (96) in methanol did not showany absorbance at >290 nm and no bathochromic shift was observed by adsorp-tion onto silica gel, implying involvement of indirect photolysis such as thereaction with OH�. Very insignificant photodegradation on glass was reportedfor the few sulfonylurea herbicides, and the presence of surfactants in formula-tion may play a great role in its indirect photolysis in the real environment(Thomas and Harrison 1990; Harrison and Thomas 1990). Photoinduced cleav-age of either bond at the NH−C(=O)−N(CH3)-triazine moiety or contractionof the sulfonylurea bridge was reported for tribenuron-methyl (99) on glass(Bhattacharjee and Dureja 2002).
Azoles and Triazines Rapid photodegradation of triadimefon (188) was ob-served on glass, and the cleavage either of O-CH or CH−C(=O) bond gave thecorresponding 1N-substituted 1,2,4-traizole derivatives (Nag and Dureja 1996).Especially under UV light, 1-(4-chlorophenoxy)-1-(1H-1,2,4-triazol-1-yl)-2,2-dimethylpropane was identified as a main photoproduct, suggesting that a con-certed process involving simultaneous combination with loss of CO might pro-ceed rather than simple coupling of the discrete free radicals after loss of theCO moiety. Triadimenol (189) underwent dechlorination and cleavage of eitherCH-Oaryl or C-N bond when irradiated on glass (Clark and Watkins 1986).Diniconazole-M (190) showed photoinduced E/Z isomerization followed by in-tramolecular cyclization between 5-positions of the 2,4-dichlorophenyl and1,2,4-triazolyl rings (Sharma and Chibber 1997). The secondary alcohol moietyof this cyclized product was oxidized to the corresponding ketone, and succes-sive opening of the hetero ring gave the isoquinoline derivative (Fig. 16). Photo-induced cleavage of the C-triazole bond eliminating 1,2,4-triazole was observedfor propiconazole (191) on glass (Dureja et al. 1987a). Fluotrimazole (195) ex-
Fig. 16. Photoinduced isomerization of diniconazole-M (190) followed by cyclization.
46 T. Katagi
hibited the similar homolytic cleavage of the C-triazole bond on glass followedby reaction with water to give the corresponding triphenylmethanol (Clark et al.1983). The photolytic stability of triazine herbicides on glass was briefly studiedin comparison with their solution photolysis (Chen et al. 1984).
Miscellaneous Direct photolysis was found to be of minor importance for 2,4-D (1) in accordance with its insignificant UV absorption at >300 nm (Venkateshand Harrison 1999). In contrast, the dimethylamino derivative of MCPA (3) wasphotochemically produced from the countercation N,N-dimethylamine (Crosbyand Bowers 1985). In the presence of trace water, (3) was considered to bephotodegraded via dechlorination, decarboxylation, and oxidation to many smallmolecules. Significant photodegradation of trifluralin (232) by exposure to sun-light was demonstrated by reduced herbicidal activity, but no information onthe degradation pathway was given (Wright and Warren 1965). 14C-Fluchloralin(236) on silica gel and glass was photodegraded via either release of the chloro-ethyl group or intramolecular cyclization between the nitro group and 1-positionof the N-propyl moiety to give benzimidazole derivatives together with the un-usual formation of the quinoxaline derivative (Nilles and Zabik 1974). Thistype of reductive cyclization seems common to dinitroaniline herbicides, as alsodemonstrated by photodegradation of pendimethalin (238) on glass (Dureja andWalia 1989). Rapid photodegradation of isoprothiolane (204) on silica gel in-volved a dithiolane ring cleavage, ester hydrolysis, decarboxylation, heterocy-cles formation such as dithietane and trithiolane and sulfur liberation, and finallythe accumulation of S8 was observed (Chou et al. 1980). 14C-Methoprene (246)quickly dissipated on glass by photolysis and volatilization (Quinstad et al.1975). The main photoreaction was E/Z isomerization at 2-ene position to give50 : 50 mixture of (2E,4E) and (2Z,4E) isomers. 7-Methoxycitronellal was iden-tified as one of the main volatiles and considered to be formed via oxidation at5-position. Sethoxydim (223) was found very unstable, and N-deethoxylatedwas the only derivative identified (Campbell and Penner 1985a). Soeda et al.(1979) investigated the photodegradation of 14C-alloxydim (224) on silica geland found that the main pathway was N-deallyloxylation similar to (223), and(224) also underwent Beckmann rearrangement to give two types of oxo-tetra-hydrobenzoxazole derivatives but in lesser amounts.
Bentazone (200) possessing fairly strong absorption at around 300 nm under-goes direct photolysis (Nilles and Zabik 1975). 14C-(200) was lost from a silicagel surface mainly due to volatilization, whereas photoinduced oxidation of theNH moiety proceeded on glass followed by elimination of SO2 to give N-isopro-pyl-o-nitrosobenzoylamine and the successive oxidation to the nitro derivative.For buprofezin (222) on glass, the few types of ring opening were caused bysunlight, resulting in formation of ureas and thioureas (Datta and Walia 1997).Thiabendazole (212) showed very slow sunlight photodegradation on glass viaopening of the thiazole ring to benzimidazole-2-carboxamide and benzimidazole(Jacob et al. 1975). Photooxidative breakdown of one phenyl ring was observedfor diquat (226) on silica gel, leading to formation of 1,2,3,4-tetrahydro-1-oxo-
Photodegradation of Pesticides 47
pyrido[1,2-a]-5-pyradinium salt and picolinamide (Smith and Grove 1969). Thephotodegradation of fipronil (220) on silica gel, glass, and paper gave the desul-finyl derivative with trace amounts of sulfone and sulfide derivatives, possiblyvia photoinduced oxidation and reduction (Hainzl and Casida 1996). The desul-finylation was assumed to occur from the hydrogen-bonded six-membered inter-mediate formed between NH2 and SOCF3 groups (Fig. 17). Perfluidone (206),having sufficient UV absorption at 330 nm, underwent direct photolysis proba-bly via photochemical breakdown of the CF3SO2NH moiety (Ketchersid andMerkle 1975). The hydrolytic degradation of 14C-chlordimeform (207) to N-formyl-4-chloro-o-toluidine was accelerated by sunlight exposure on silica gel(Knowles and Sen Gupta 1969). 14C-Guazatine (245) gave a very odd photo-product on glass having a carbonyl moiety with a molecular weight greater by28 than (245) (Sato et al. 1985b). The degradate was considered to be formedby photooxidation of the methylene group at 4-position to the central NH moi-ety, followed by methylation at the adjacent methylene carbon. Stepwise de-phenylation was observed for fentin acetate (241) on silica gel when exposed toUV light, finally to an inorganic tin (Barnes et al. 1973). Photooxidation to thebenzoyl derivative was the predominant photodegradation pathway of cinmethy-lin (249) (Grayson et al. 1987). Imazaquin (230) and imazethapyr (231) photo-decomposed on glass and silica gel, probably via decarboxylation or ring de-composition through stepwise oxidation (Basham and Lavy 1987; Goetz et al.1990; Schroeder 1997).
Azadirachtin-A (253) underwent rapid photoisomerization at the (E)-2-meth-ylbut-2-enoate moiety to the Z-isomer on glass (Dureja and Johnson 2000). Atleast 10 primary degradates were formed from avermectin B1a (250) on glassthrough sunlight irradiation, but direct photolysis was unlikely due to lack ofUV absorption at >290 nm (Crouch et al. 1991). The main pathway was inser-tion of oxygen at the 14- or 15-position of the macrocycle with accompanyingdouble-bond shift, probably via formation of an allylic hydroperoxide from 1O2
by the ene-type reaction. Oxidation at the 8α-position, possibly by reaction withO2 to form the intermediate hydroperoxide, was also observed. For avermectinB1a analogue MAB1a (251), photolysis on glass was slightly accelerated com-pared to (250), but no oxidation at the most photosensitive 14- and 15-positionswas observed (Feely et al. 1992). Alternatively, photoinduced isomerization at8- and 9-positions, oxidative N-dealkylation, and cleavage of the ether linkagein the sugar region were observed.
D. Photodegradation of Pesticides in Organic Solventsand Plant Model Systems
Photodegradation profiles of pesticides in organic solvents and thin films offatty acids as plant surface models are summarized in Table 8 (see table on page101). Examples of photodegradation in more complex media such as thin filmsprepared from the extracted epicuticular waxes or enzymatically isolated cuticlesare listed in Table 9 (see table on page 104).
48 T. Katagi
Fig.
17.
Var
ious
phot
odeg
rada
tion
path
way
sof
fipr
onil
(220
).
Photodegradation of Pesticides 49
Organochlorines Photolysis of DDT (130) and methoxychlor (134) was con-ducted in methyl oleate as a representative of octadecanoic acids in plant cuti-cles (Schwack 1988). The radicals produced via homolytic dechlorination re-acted at the C=C double bond of methyl oleate as well as a chlorine radical toform stearic acid derivatives and also abstracted hydrogen from methyl oleateto form the corresponding dichloromethyl derivatives. Dechlorination also oc-curs at the aryl moiety of anilazine (211) in cyclohexene with irradiation, andthe radicals produced reacted with either solvent molecules or methyl oleate(Breithaupt and Schwack 2000). Jahn et al. (1999) confirmed the bound forma-tion of chlorothalonil (117) on the enzymatically isolated tomato cuticles underirradiation by using enzyme-linked immunosorbent assay. Dioxin, 2,3,7,8-TCDD(129), underwent either dechlorination at 8-position by exposure to UV light orrearrangement to biphenyl derivative in isooctane (Kieatiwong et al. 1990).Schuler et al. (1998) reported the photoinduced dechlorination of (129) in a thinwax film of laurel cherry leaves. Photoinduced homolytic dechlorination fol-lowed by reaction with unsaturated C=C bonds was most likely to occur onplant cuticles. Endosulfan (125) exhibited photoinduced isomerization in hexanefrom the α-isomer to the β-isomer but with loss of two chlorine atoms at thebridged carbon (Dureja and Mukerjee 1982). Heptachlor (127) gave 1-exo-hydroxychlordene via substitution of Cl with a hydroxyl group, which under-went either (2π + 2π) cycloaddition to the full-cage isomer or intramolecularene-reaction, finally forming the cyclic ketone (Parlar et al. 1978).
Organophosphorus Esters Photochemistry of this chemical class has been ex-tensively reviewed by Floßer-Muller and Schwack (2001). Schwack (1987) andSchwack et al. (1994) examined the effect of a reaction medium on photodegra-dation profiles of parathion (135). UV irradiation of (135) in cyclohexenecaused reduction of the nitro group followed by addition of cyclohexene to thenitroso group via ene-type reaction. Detection of azo and azoxy dimers of (135)indicated involvement of stepwise photoreduction of the nitro group to aminovia nitroso and hydroxyamino groups (Fig. 18). The main product in 2-propanolwas the azoxy dimer, part of which rearranged to the 2-hydroxyazo derivativewith no detection of the azo dimer. The amounts of these dimers greatly de-creased in cyclohexane containing methyl 12-hydroxystearate (ester of a cutinacid) with predominant formation of the oxon. These findings imply that thereaction medium is one of the most important factors controlling the photopro-cess of (135), and the proton-donating ability of the solvent molecule may playa large role. These processes were confirmed by Schynowski and Schwack(1996) on the enzymatically isolated fruit cuticle of tomato, paprika, apple, andgrape. In the early stage of photolysis, the unstable nitroso derivative of (135)was dominant, but the 2-hydroxyazo derivative finally gradually accumulated.The oxon derivative and 4-nitrophenol were minor products. Dissipation ratesof (135) increased with iodine number of the fruit cuticle, showing that theolefinic portion of cuticles plays an important role in the reaction. In contrast,oxidation to give sulfoxide and sulfone proceeded for fenthion (143) (Leuch and
50 T. Katagi
Fig.
18.
Succ
essi
veph
otor
educ
tion
ofpa
rath
ion
(135
)fo
llow
edby
dim
eriz
atio
n.
Photodegradation of Pesticides 51
Bowman 1968; Minelli et al. 1996). In the thin film of fruit wax from orange,nectarine, and olive, (143) gave the sulfoxide under sunlight with a trace amountof the sulfone (Cabras et al. 1997b; Pirisi et al. 2001). With an increase of waxthickness, dissipation rates slightly increased for orange and nectarine, whereasthe thickest olive wax gave the slowest degradation. These results suggest thatthe component rather than the amount of wax film is one of the important factorscontrolling the photodegradation. Fenitrothion (138) mainly underwent photoox-idation at the aryl methyl group and the P=S moiety in methanol, hexane, andacetone (Ohkawa et al. 1974b; Greenhalgh and Marshall 1976). Thiono-thiolorearrangement (see Fig. 2, reaction 9a) and denitration were minor pathways.The difference in reaction profiles between (135) and (138) most likely origi-nates from the adjacent orientation of nitro and methyl groups in (138) that areknown to take an aci-nitro structure via photoexcitation (Katagi 1989). Thehomolytic cleavage of a C-I or C-Cl bond together with formation of the oxonand cleavage of a P-Oaryl or P-S bond was reported for iodofenphos (141)(Walia et al. 1989b), chlorpyrifos (145) (Walia et al. 1988), and phosalone (170)(Walia et al. 1989a). The cis/trans isomerization could be detected for tetrach-lovinphos (154) in hexane by exposure to UV light (Dureja et al. 1987b). Isofen-phos (175) having a different coordination at phosphorus similarly underwentP=S oxidation to the oxon by UV irradiation in hexane (Dureja et al. 1989).
Pyrethroids Regarding the photolabile chrysanthemic acid moiety, Ruzo andCasida (1980) examined the excited states involved by using methyl esters ofdichloro- and dibromo-vinyl derivatives. The main reactions in methanol werecis/trans isomerization via homolytic cleavage of C1−C3 bond of the cyclopro-pane ring to give a biradical followed by recombination together with the reduc-tive dehalogenation in the vinyl moiety. The isomerization is considered to arisefrom carbonyl excitation to the excited triplet state, as explained by molecularorbital calculations (Katagi et al. 1988). By energy transfer experiments usingvarious sensitizers, the triplet state energy for these chrysanthemates was esti-mated to be �60 kcal mol−1. Insignificant reduction of debromination in thepresence of triplet quenchers (ET = 50–53 kcal mol−1) showed no involvementof the triplet state in this process. They also examined the effect of the alcoholmoiety on photochemistry in benzene at 300 nm under sunlight by using severalpyrethroids possessing a 3-phenoxybenzyl, 3-phenylbenzyl, or 3-benzoylbenzylgroup. Intramolecular energy transfer causing enhanced cis/trans isomerizationwas likely to be involved (Ruzo and Casida 1982). Photoinduced cis/trans iso-merization via triplet excited state was observed for permethrin (17) in organicsolvents, finally giving the cis/trans ratio of �30/70 (Holmstead et al. 1978a).This type of pyrethroid usually exhibits weak UV absorption around 275 nm,essentially in n-π* character, resulting from the combined transition of the car-bonyl system and the lower energy band of the aromatic rings. The ester cleavagewas also the major process forming 3-phenoxybenzyl alcohol and the dichlor-ovinyl chrysanthemic acid. In addition to the efficient cis/trans isomerization,cypermethrin (19) in alcohols or aqueous acetonitrile underwent photoinduced
52 T. Katagi
decarboxylation (Ruzo 1983). The cis-isomer in an argon atmosphere simplygave the corresponding acid and benzyl cyanide while the presence of O2 signifi-cantly gave the ketolactone derivative (50%–60%; in the case of the trans-isomer, the caronic acid instead (Fig. 19). Because Rose Bengal in methanolcould not sensitize this oxidative reaction, O3 was likely to participate insteadof 1O2. The profiles of isomerization of deltamethrin (22) was examined in hex-ane by Maguire (1990), and detailed analysis of the photoproducts in organicsolvents was reported by Ruzo et al. (1977). The higher photoreactivity in meth-anol than (17) and (19) was considered to stem from more efficient intersystemcrossing by the heavy atom effect of bromine. Photoinduced homolytic cleavageof the ester linkage was found to occur at either the C(=O)−O or O−C(CN)bond. Epimerization at the benzyl carbon occurred in alcohols as a dark reactionvia proton exchange with a solvent molecule. Tralomethrin (25) and tralocythrin(26) in organic solvents showed similar photodegradation profiles to those onglass (Ruzo and Casida 1981). Z-cis-Cyhalothrin (21) underwent both E/Z andcis/trans isomerizations in hexane (Ruzo et al. 1987). The decarboxylated deriv-ative and the corresponding acid and alcohol moieties were the primary productsdetected in addition to hexadienes derived from opening of the cyclopropyl ring.In the case of allethrin (10), di-π-methane rearrangement via triplet state in thealcohol moiety (Bullivant and Pattenden 1973, 1976) and epoxidation and ω-oxidation in the acid moiety (Ruzo et al. 1980) proceeded more favorably thanthe usual ester cleavage.
Photochemistry of fenvalerate (27) is characterized by a higher efficiency ofdecarboxylation (Holmstead et al. 1978b). Mikami et al. (1985a) applied thespin-trap method in ESR and demonstrated involvement of the two radical spe-cies originating from acid and alcohol moieties of (27). For photodegradationin hexane, no energy transfer from isobutyrophenone and quenching by 1,3-cyclohexadiene showed involvement of the long-lived excited singlet state. Al-most identical photodegradation profiles have been reported for flucythrinate(29) in methanol or hexane with maximum degradation at 271 nm, indicatingthe involvement of n-π* excitation (Chattopadhyaya and Dureja 1991). Etofen-prox (32) underwent either photooxidation at the benzyl carbon or photoinducedhomolytic cleavage of the central ether linkage followed by radical recombina-tion to give the derivative with loss of CH2O from (32) (Class et al. 1989; Tsaoand Eto 1990b).
Carbamates The main photodegradation products of xylylcarb (63) and tri-methacarb (64) were phenols via cleavage of the O−C(=O) bond in ethanoland cyclohexane (Addison et al. 1974; Kumar et al. 1974). In the case of (63),the photo-Fries reaction proceeded only in ethanol under irradiation at >265 nmtogether with a trace cleavage at the C(aryl)-O bond leading to formation ofxylene. For propoxur (65), photoinduced cleavage of the C(aryl)-O bond oc-curred in 2-propanol, cyclohexane, and cyclohexene without photo-Fries re-arrangement. Contribution from the O−C(=O) bond cleavage was less than 1%.The main product of ethiofencarb (69) in cyclohexane and 2-propanol was the
Photodegradation of Pesticides 53
Fig.
19.
Phot
odeg
rada
tion
ofcy
perm
ethr
in(1
9).
54 T. Katagi
corresponding sulfoxide with a trace amount of the sulfone (in 2-propanol) (Kopfand Schwack 1995). A unique reaction, but as a minor pathway, was oxidationof the benzyl carbon followed by nucleophilic substitution of the thionyl moietyby the carbamate nitrogen to form 3,4-dihydro-3-methyl-1,3-benzoxazine-2,4-dione. Although the simple photoinduced cleavage of the O−C(=O) bond wasobserved for aminocarb (66) in organic solvents (Addison et al. 1974; Kumaret al. 1974), oxidative N-demthylation via the N-CHO intermediate proceededon glass. However, this oxidation product disappeared in the presence of waxfrom nectarine fruits, showing that some wax components may act as scavengersof radicals (Pirisi et al. 2001). Similar photoreactions were detected for pirimi-carb (78) at >280 nm (Schwack and Kopf 1993). In cyclohexane, the intermedi-ate N-CHO derivative of (78) underwent either decarbonylation to the N-de-methylated derivative or oxidation of the aryl methyl group at the 6-position.Stepwise oxidation at the two aryl methyl groups at 5- and 6-positions gave theunique 5,7-dihydro-5-oxo-furo[3,4-d]pyrimidinyl ring in cyclohexane. Nectarine(N) and orange (Or) waxes were found to retard the photodegradation of (78)while the mandarin orange (M) wax accelerated the reaction (Pirisi et al. 1998).The rate of photolysis could not be correlated with UV absorbance of waxes orto their amounts, and thus it was considered dependent on the nature of wax.Because OH� would be the promotor of formylation and N-demethylation,waxes from N and Or should play the role of radical scavengers. In contrast,the component of M wax was considered to act as a sensitizer. Similar to fen-thion (143), the S-methyl sulfur was stepwise oxidized to the correspondingsulfoxide and sulfone in the thin wax film from nectarine (Pirisi et al. 2001).These results indicate that wax chemistry is very important in understanding thephotolytic behavior of pesticides after foliar application.
Dicarboximides Direct photolysis is likely to proceed for this class of fungi-cides having a weak shoulder of UV absorption at >290 nm due to n-π* transi-tions. The most probable reaction is hydrogen abstraction intramolecularly (Nor-rish type II) or from a solvent molecule by the excited carbonyl oxygen. Theformer case is known for N-phthaloylvaline methyl ester (Griesbeck and Gorner1999) but not for dicarboximide fungicides. The latter reaction has been reportedfor photolysis of folpet (107) in cyclohexene (Schwack 1990). The main reac-tion was the allylic addition of cyclohexene to one of the carbonyl groups toform the corresponding carbinol with an oxetane formation via the Paterno–Buchi reaction as a minor pathway. As a unique photoreaction, the (4π + 2π)-1,4-cycloadition at the phenyl moiety to form the benzazepindione derivativewas detected. These reactions with the olefinic carbons indicate photoreactivityin plant cuticles when (107) is foliarly applied. However, captan (106) exhibiteda different photoreactivity, that is, homolytic cleavage of a C-Cl bond followedby release of the SCHCl2 group to tetrahydrophthalimide (Schwack and Floßer-Muller 1990). Procymidone (108), iprodione (109), and vinclozolin (110) com-monly underwent photoinduced cleavage of a C-Cl bond. Successive dechlorina-tion of (109) proceeded in 2-propanol (Schwack et al. 1995a). The addition of
Photodegradation of Pesticides 55
a solvent molecule was predominant in cyclohexene whereas mono-dechlorina-tion was the major change in cyclohexane. Procymidone (108) exhibited almostthe same photolytic profiles as (109) (Schwack et al. 1995b). In (110), solventaddition mainly occurred at the vinyl side chain and successive dechlorinationwas observed (Schwack et al. 1995c). This evidence from photodegradation inorganic solvents suggests the possible photoaddition of this class of fungicidesto wax components of plant cuticles.
Azoles Da Silva et al. (2001) revealed through flash photolysis of triadimefon(188) in cyclohexane, together with analysis of emission spectra, that the firstexcited state is n-π* localized at the carbonyl group via fast conversion from π-π* state at the 4-chlorophenoxy moiety and detected a 4-chlorophenoxy radicalat 25 nsec after a laser pulse. Product analysis showed involvement of threemain photoreactions (Nag and Dureja 1997). First was cleavage of the PhO-Cbond to give 4-chlorophenol and the corresponding triazole derivative. Eithercleavage of CH−C(=O) or C-triazole bond was also observed. The third wasphotoreduction of the carbonyl group to form triadimenol (189). Similar profilesthrough photolysis in methanol were reported by Clark et al. (1978). Triadim-enol (189) having a π-π* character in the first excited state also underwentdechlorination and cleavage of CH-C(OH) or C-triazole bond (Clark and Wat-kins 1986). Although not detected in solution photolysis of (188), the diazirinderivative via release of the N-CH moiety from 1,2,4-triazolyl ring was formedfrom propiconazole (191) in hexane by UV irradiation (Dureja et al. 1987a).Hexaconazole (192), fluotrimazole (195), and penconazole (193), not having thecarbonyl group are considered to undergo photolysis via π-π* transition at thearomatic moieties. Photoliability of (192) was demonstrated in hexane and ace-tonitrile but without detailed information on degradation (Santoro et al. 2000).Photoinduced cleavage of the C-triazole bond followed by addition of methanolmolecule was reported for (195) (Clark et al. 1983). Penconazole (193) under-went photocyclization in 2-propanol or cyclohexane between o-position of the4-chlorophenyl ring and 5-position of the 1,2,4-triazolyl ring to form the 5H,6H-(1,2,4-triazole)-[5,1a]-isoquinoline derivative (Schwack and Hartmann 1994).Similar photocyclization of diniconazole-M (190) was reported by Sharma andChibber (1997). Katagi (2002a) examined this photoprocess for the racemicmixtures of (190) by NMR and molecular orbital calculations and demonstratedthat the reaction proceeds via excited singlet state in a similar manner as re-ported for cis-stilbene.
Ureas In addition to the usual photoinduced cleavage of an N−C(=O) bondvia carbonyl excitation to form the corresponding aniline, oxidative N-demethyl-ation successively proceeded for isoproturon (56) in organic solvents with re-lease of formaldehyde (Kulshrestha and Mukerjee 1986). UV irradiation ofdiflubenzuron (59) in methanol caused the cleavage of the central C(=O)−NHC(=O) bond, mainly leading to formation of N-phenyl methylcarbamate and2,6-difluorobenzamide (Ruzo et al. 1974). Chlorsulfuron (96) and metsulfuron-
56 T. Katagi
methyl (98), which have insignificant UV absorption at >290 nm, are consideredunlikely to undergo direct photolysis in the environment (Yang et al. 1999). Incontrast, chlorimuron-ethyl (102), with UV absorption at 275 nm, was rapidlyphotodegraded in methanol and hexane via cleavage of either the N-C ureic orS-N bond (Choudhury and Dureja 1997b). Contraction of the sulfonylurea bridgewas considered to follow a concerted elimination of SO2 with formation of inter-mediate radicals being recombined (Fig. 20). In contrast, photolysis in benzenedid not produce this derivative (Choudhury and Dureja 1997c), showing the im-portance of solvent polarity. Bhattacharjee and Dureja (1999) reported UV photol-ysis of tribenuron-methyl (99) in organic solvents proceeding via bond cleavagearound the sulfonylurea bridge including its contraction, similar to (102).
Miscellaneous Sunlight photodegradation of pendimethalin (238) was studiedin several organic solvents (Halder et al. 1989). Dureja and Walia (1989) inves-tigated its sunlight photolysis in methanol and found 2,6-dinitro- and 2-amino-6-nitro-3,4-xylidene as principal products via N-dealkylation and photoreduc-tion, but no benzimidazole derivatives formed in aqueous photolysis could bedetected. The effect of unsaturated fatty acids and surfactants coexisting in for-mulation on photolysis of chinomethionat (228) was studied on glass (Nutaharaand Murai 1984). Oleic acid is one of the major fatty acids in leaf extracts ofeggplant and cucumber and accelerated photolysis of (228) as with its self-decomposition. Similar photoacceleration was observed by addition of the vari-ous unsaturated fatty acids or polyoxylene sorbitan oleates (Tween 60, 80, 85).Because oleic acid by itself was stable under irradiation, some photoreactionbetween (228) and the C=C bond of oleic acid similar to the responses of (130),(134), and (211) might account for these results. Draper and Casida (1985)reported the ene-reaction of the nitroso derivative photochemically formed inthin films from nitrofen (216) and CNP (217). The nitroso derivatives reactedwith the C=C bond of various chemicals including methyl oleate to form thecorresponding nitroxides via alkenylarylhydroxyamines being detected by ESR.The weak ESR signal was observed for beet leaves when treated with (216) inan extremely high level, showing the ambiguity of this reaction occurring in theenvironment. The ESR signal was detected for irradiated methyl oleate filmcontaining (135) but not for (138), which coincides with dominant formation ofnitroso and its related derivatives from (135) but major detection of the oxidizedderivatives of (138) instead. As a model cuticle instead of organic solvents orthin film on glass, Caboni et al. (2002) utilized cellulose membrane coated withepicuticular waxes from olives to evaluate the extent of evaporation, codistilla-tion, and thermodegradation of azadirachtin. In the absence of waxes, codistilla-tion with water proceeded but dissipation of azadirachtin from wax-treated cel-lulose was not detected.
VIII. Photodegradation of Pesticides on Soil and Clay Surfaces
The photodegradation profiles of pesticides in/on soil and clay, based on the re-sults of the literature survey, are summarized in Table 10 (see table on page 105).
Photodegradation of Pesticides 57
Fig.
20.
Phot
oind
uced
rear
rang
emen
t(b
ridg
eco
ntra
ctio
n)of
chlo
rim
uron
-eth
yl(1
02).
58 T. Katagi
Organochlorines Dichlobenil (116) and chlorothalonil (117) were reported toundergo photoinduced substitution of Cl with OH or hydration of cyano groupsin aqueous phase although they were rather resistant to photolysis in or onsoils (EPA OPPTS 1998c, 1999c). In contrast, some photodegradation has beenobserved for dicamba (118) and chloramben (119). Misra et al. (1997) examinedphotodegradation of 14C-(119) by varying conditions of loam soil and found that3,5-dihydroxy- and 3-chloro-6-hydroxy-benzoic acids are detected in the intactsoil at 75% field moisture while only the deaminated derivative is formed onair-dried soil. Moisture content might affect the extent of reactive speciesformed such as OH�, resulting in different product profiles. When (118) coatedon synthetic clay laponite was irradiated with UV light, decarboxylation pro-ceeded in addition to dechlorination and hydroxylation (Aguer et al. 2000). Thephotoinduced charge transfer from (118) to clay via interaction of the carbonylgroup with the clay surface was proposed as the reaction mechanism, and resid-ual water molecules on clay were considered to play a role in inducing dechlori-nation and hydroxylation by polarizing either the O-CH3 or C-Cl bond. Penta-chlorophenol (121) rapidly dissipated on soil thin layer by UV irradiation toform octachlorodibenzo-p-dioxin (Liu et al. 2002). Because detailed examina-tion of photoproducts from (121) as solution or solid has revealed that the photo-induced dechlorination primarily results in formation of free radicals whose suc-cessive reactions give dioxins (Piccinini et al. 1998), a similar radical processewould also operate on irradiated soil surfaces. This mechanism may be ac-counted for with less formation of dioxins by addition of fulvic acids to soilsthat can act as a scavenger of radicals. When 2,3,7,8-TCDD (129) applied tosoils was exposed to sunlight, the degradation, possibly via dechlorination, ap-peared only in the first 5 days but the coexistence of 1%–5% hexadecane main-tained constant photodegradation up to 15 d (Kieatiwong et al. 1990). Theseresults coincided with possible photodegradation near the soil surface and im-plied that hexadecane might act as a hydrocarbon film allowing solubilizationand migration of (129) from the deeper region of soil to the irradiated surface.Detection of a trace amount of photodieldrin (124) by soil application of 14C-aldrin (122) showed a possible contribution of photodegradation on the soilsurface (Klein et al. 1973). Involvement of photolysis in field dissipation oforganochlorine pesticides including (122) and (123) was demonstrated by moni-toring studies in 99 fields (Suzuki and Yamato 1974). DDT (130) in/on soil wasphotodegraded under sunlight to DDE (131) via dechlorination (Zayed et al.1994). Less photoreactivity of dicofol (133) was briefly reported on soil (EPAOPPTS 1998d).
Organophosphorus Esters Hautala (1978) reported that the apparent quantumyield of parathion (135) was reduced on soils compared to a solution phase andthat no factors except the amount of soil appeared to correlate with the photoly-sis rate, indicating the importance of the screening effect by soil. As a mainproduct of parathion methyl (136), 4-nitrophenol was reported in an outdoorsunlight photodegradation study (EPA OPPTS 1999e). UV irradiation alone was
Photodegradation of Pesticides 59
ineffective for conversion of (135) to the oxon on soil dusts and clays, but theexistence of O3 at 50–300 ppb increased its rate by a factor of 2–3 (Spencer etal. 1980). Greater formation of the oxon on soil dusts having less organic matterclearly demonstrated that the catalytic activity of clay played a large role inphotooxidation. These reaction profiles have been recently confirmed on soilfor 14C-(136) by Kromer et al. (1999). Cyanophos (137) and fenitrothion (138)were photodegraded on soil thin layers mainly to 4-cyano- or 3-methyl-4-nitro-phenol via cleavage of the P-O aryl bond, respectively (Mikami et al. 1976,1985b). Either the corresponding oxon or O-demethylated derivative was a mi-nor photoproduct from (137) and only the former product was identified for(138). Fenthion (143) was photodegraded on soil thin layers to 40%–80% after4 days, and insignificant degradation was observed on glass (Gohre and Miller1986). No information on degradates was available, but product analysis ondisulfoton (163) and methiocarb (68) suggested formation of the correspondingsulfoxide, most likely via reaction with 1O2 produced on soil surfaces by irradia-tion. The fastest photodegradation in the soil with the least organic matter con-tent might imply the involvement of clay surface.
Degradation of bromophos (140) and iodofenphos (141) on soil was slightlyenhanced by sunlight irradiation via cleavage of the P-O aryl bonds (Allmaierand Schmid 1985; Allmaier et al. 1984). Walia et al. (1989b) reported oxidationof the P=S moiety to oxon and stepwise dehalogenation for (141). 14C-Tol-clofos-methyl (142) was photodegraded on soil via either photoinduced oxida-tion of the P=S moiety to the oxon followed by O-demethylation or cleavageof the P-O aryl bond to give 2,6-dichloro-4-methylphenol (Mikami et al. 1984b).More of the oxon was detected for soils with lesser organic matter content,showing contribution of clay surfaces in oxidation as similarily reported for(135) and (136). From this aspect, Katagi (1990) investigated the photoinducedoxidation of (142) in/on clay surfaces. The UV reflectance spectrum of (142)on kaolinite film exhibited almost the same pattern as that in 10% acetonitrilewith no reflectance above 300 nm. UV light exposure at 320 nm resulted inrapid degradation of (142) especially for the kaolinite surface where significantamounts of oxon were formed, clearly demonstrating involvement of indirectphotolysis. Less formation of the oxon was observed when clay was air-driedor the study was conducted under nitrogen. MS analysis of the oxon formed inkaolinite treated with H2
18O showed about 40% incorporation of 18O into theP=O moiety. Formation of H2O2 was confirmed spectrophotometrically, but thelack of detection of trans-diacetylacetylene from 2,5-dimethylfuran by HPLCanalysis showed the absence of 1O2 on the irradiated clays. Based on these obser-vations, formation of the oxon could be well explained by reaction with OH�that was produced from the successive reaction with residual water molecules,with the superoxide anion radical formed probably via photoinduced electrontransfer from clay to O2.
Photodegradation of chlorpyrifos (145) on soil at 254 nm gave the oxon and3,5,6-trichloropyridinol as main degradates with lesser amounts of dechlorinatedderivatives (Walia et al. 1988). Burkhard and Guth (1979) have shown that
60 T. Katagi
diazinon (144) undergoes photoinduced cleavage of the P-O aryl bond on soil.Similar results have been reported for sunlight photolysis on sandy loam soil(EPA OPPTS 2000). Because the aqueous photolysis was of insignificant contri-bution in its dissipation, some kind of indirect photolysis would operate onthe soil surface. Sunlight photodegradation of quinalphos (148) on soil gavediquinoxalin-2-thiol, diquinoxalin-2-yl sulfide, and disulfide in addition to quin-oxalin-2-ol formed via the usual photoinduced cleavage of the P-O aryl bondwithout formation of the oxon (Dureja et al. 1988). The photoinduced thiono-thiolo rearrangement of (148) followed by cleavage of the P-S aryl bond wasmost probable, as reported for photodegradation on clays (Banerjee and Dureja1999). The photolytic profiles of 14C-dioxabenzofos (183) on soil were found tobe common to other phosphorothioates (Mikami et al. 1977b). Photodegradationof profenofos (160) on soil gave 4-bromo-2-chlorophenol and O-(4-bromo-2-chlorophenyl) O-ethyl O-hydrogen phosphate (Burkhard and Guth 1979). Thelatter compound was most likely to be formed by photoinduced hydrolysis, incontrast to the O-dealkylation of other phosphorothioates.
Qualitatively, the extent of photodegradation of 14C-azinphos-methyl (169)on soil was found to be reduced with an increase of soil depth and organicmatter (Liang and Lichtenstein 1976). Phosalone (170) mainly underwent cleav-age of the SCH2-N bond and was either dechlorinated or oxon derivatives weredetected in trace amounts (Walia et al. 1989a). A similar SCH2-N bond cleavagewas reported for methidathion (171) at >290 nm but at trace amounts (Burkhardand Guth 1979). On exposure to sunlight, 14C-phenthoate (168) was photode-graded via oxidation, cleavage of P-S or S-C bond, and hydrolysis of carboxylicester with formation of the α-carboxybenzyl thiol (Mikami et al. 1977b). O,O,S-Trialkyl derivatives not possessing a chromophore are considered to be degradedby indirect mechanism if photolysis occurs. Phorate (162) was rapidly degradedin the field to give its sulfoxide and sulfone (Lichtenstein et al. 1973). Disulfo-ton (163) showed rapid photodegradation on soil with formation of the corre-sponding sulfoxide (Gohre and Miller 1986). Based on no effect by sterilization,reactions of (162) and (163) with 1O2 being formed by sunlight irradiation onsoil were considered most likely. Formation of the corresponding sulfone wasreported for (163) under sunlight (EPA OPPTS 1999d). The photoinduced oxi-dation of the P=S moiety to the oxon was observed only for ethion (184) (EPAOPPTS 1995c).
Bensulide (164) exhibited simple photoinduced oxidation of the P=S moietyby UV irradiation (EPA OPPTS 1999a). Monocrotophos (156) and dicrotophos(157) are unlikely to undergo photochemical reactions on soil due to lack ofchromophores in their molecules (Lee et al. 1989, 1990). Tetrachlovinphos(154) was expected to undergo E/Z isomerization, but the main reactions wereO-demthylation and cleavage of the P-O vinyl linkage (Beynon and Wright1969; Dureja et al. 1987b). Isofenphos (175) underwent photoinduced P=S oxi-dation to the oxon with cleavage of the P-O aryl bond, but no effect on the P-N linkage was observed (Dureja et al. 1989). The same degradation profiles asaerobic soil metabolism but with a much faster rate were reported on soil (EPA
Photodegradation of Pesticides 61
OPPTS 1998f). Allmaier et al. (1984) reported via soil photolysis of ditalimfos(178) that the main product was O,O-diethyl phosphoramidothioate, probablyby stepwise hydrolysis of the imide ring, but photoinduced cleavage of the P-Nbond as observed in aqueous photolysis was not detected. The P-C bond ofcyanofenphos (180) remained unaffected by irradiation (Mikami et al. 1976).Although examples are limited, either the P-N or P-C bond is considered to beresistant to photolysis on soil.
Phenoxyalkanoates and Esters The apparent quantum yield of methyl ester of2,4-D (1) on soil was found to be 30 times lower than that in aqueous solution,which might be accounted for by screening and/or quenching effects of soil(Hautala 1978). The coarser the soil, the faster the sunlight photodegradation ofmecoprop (4) and its 2,4-dichlorophenyl derivative, which suggests that thedeeper penetration of light into soil facilitated their degradation (Romero et al.1998). Their declines followed the Hoerl function (y = aebxxc) rather than theusual first-order kinetics, and increase in moisture content enhanced the photo-degradation. Therefore, the transport of these pesticides to the photic zone alongwith water movement may control their photodegradation profiles. Norris et al.(1987) reported that triclopyr (7) was degraded in pastures to give 2-methoxy-3,5,6-trichloropyridine and 3,5,6-trichloropyridin-2-ol via successive decarbox-ylation and O-demethylation.
Pyrethroids Photoinduced isomerization was a minor pathway for soil photol-ysis of cis- or trans-permethrin (17) (Holmstead et al. 1978a). Sunlight irradia-tion had no effect on ester cleavage for both isomers, and either dechlorinationor cleavage of the cyclopropyl ring to give dimethylacrylate derivative was alsoa minor pathway. Photoinduced isomerization of trans- and cis-cypermethrin(19) was also found insignificant on soil (Takahashi et al. 1985a). The mainreaction was stepwise hydration of the α-cyano group to CONH2 and COOHand was clearly accelerated by sunlight irradiation, although this hydration wasnot affected by irradiation in the other study (EPA FIFRA 1999). Photodegrada-tion of deltamethrin (22) was briefly reported with slight contribution of photol-ysis on soil, and the main degradation product was the corresponding dibromo-vinyl chrysanthemic acid (EPA FIFRA 1999). Sunlight photodegradation wasfound to be also of less importance for Z-cis-cyhalothrin (21) on soil (Ruzo etal. 1987). In another 14C study using artificial light, formation of the α-CONH2
derivative was reported (EPA FIFRA 1999). In the case of cis-tefluthrin (18),cis/trans isomerization was reported on soil by UV irradiation although its pho-todegradation was rather slow (EPA FIFRA 1999). Rapid sunlight photodeg-radation was reported for 14C-cyfluthrin (20) with formation of 4-fluoro-3-phenoxybenzaldehyde via ester hydrolysis and release of cyanide ion from thecorresponding cyanohydrin (EPA FIFRA 1999). Similar to (19), hydration ofthe α-cyano group to CONH2 predominantly occurred for 14C-fenpropathrin (24)with more formation under sunlight on soil (Takahashi et al. 1985b).
62 T. Katagi
To clarify the reaction mechanism of photoinduced hydration common tothese pyrethroids, Katagi (1993b) examined effects of moisture content and clayon photolysis of 14C-(24) using UV light at >290 nm. The degradation rate of(24) was found to be highly dependent on soil moisture, and UV irradiationonly slightly enhanced the hydration. The amount of α-CONH2 derivative sig-nificantly increased with decreasing soil moisture, and this reaction was en-hanced when clay was used. The shift of C=O vibration in IR spectra to ahigher wavenumber in soil and clay as compared with that in KBr implied someinteraction of the cyano group but not the carbonyl oxygen with these surfaces.Because clay surface is known to exhibit an extremely high acidity when dried,the observed hydration of the α-cyano group was considered most likely to beacid catalyzed on clay surfaces. The inconsistency observed for the amount ofα-CONH2 derivative of (19) between laboratory and outdoor studies can beelucidated by the difference of soil moisture; less moisture in soil thin layerskept outdoors would enhance the hydration.
Fenvalerate (27) dominantly underwent hydration of the α-cyano group onsoil with a trace formation of decarboxylated derivative (Mikami et al. 1980).Katagi (1991) reported hydration of the α-cyano group and O-dephenylation of14C-esfenvalerate (28) on soil and clays, which was enhanced on exposure toUV light at >300 nm. It was demonstrated by MS analysis that about half of18O was incorporated into the O-dephenylated derivative when photolysis wasconducted on clay prepared from H2
18O suspension. Because Fenton’s reagentwas found to give the O-dephenylated derivative of (28), OH� photochemicallyproduced on clay surfaces was most likely to directly react with (28). Further-more, kaolinite clay was found to catalyze hydration of (28) in the presence ofH2O2, acting as a nucleophile against the cyano carbon to finally give the α-CONH2 derivative. Flucythrinate (29) and fluvalinate (30) similarly underwenthydration of the α-cyano group and cleavage of the ester (Quinstad and Staiger1984; Dureja and Chattopadhyay 1995). Most of these pyrethroids have the 3-phenoxybenzyl moiety, which is usually released through photodegradation asPBacid (243). The significant red shift in reflectance spectrum of (243) on ka-olinite clay showed possible interaction with the surface. The insignificant spec-tral overlap the artificial light (>300 nm) implied indirect photolysis; the mainphotodegradate on soil and clay was 3-hydroxybenzoic acid (3-HB). The pho-tonucleophilic reaction by OH− was unlikely because there was no reaction withmore nucleophilic cyanide ion in aqueous photolysis, and 18O incorporation into3-HB was demonstrated by MS analysis when aqueous photolysis was carriedout in 50% H2
18O. Incidentally, Fenton’s reagent gave 3-HB as a main degradate.These results indicated that OH� photochemically produced on these surfacesattacked the 3-position of (243) and this ipso substitution resulted in formationof 3-HB.
Carbamates Contribution of photolysis in dissipation of propoxur (65) on soilwas considered less than that from binding to soil and volatilization (EPA OP-PTS 1997b). Methiocarb (68) has a 4-methylthio moiety reactive to 1O2, and the
Photodegradation of Pesticides 63
main photodegradation product was the sulfoxide on soils under sunlight (Gohreand Miller 1986). UV irradiation of carbaryl (71) at >290 nm on soil showedless photoreactivity than aqueous photolysis (Hautala 1978). The disappearanceof fluorescence of (71) on soil implied the efficient quenching by soil constit-uents, which at least in part accounted for reduction of photolysis. The photoly-sis profiles of carbofuran (72) were briefly examined on field plots as a maindegradate of carbosulfan (88) (Nigg et al. 1984). After an outdoor application,(88) quickly dissipated on soil to give (72), which was rapidly degraded to givea trace amount of the 3-keto derivative. Benfuracarb (89) was reported to besimilarly converted to (72) via cleavage of the N(CH3)-S bond on soil by UVirradiation (Dureja et al. 1990). When 14C-benthiocarb (86) was exposed to sun-light on soil taken from a rice-growing area, the photoinduced S-oxidation togive the sulfoxide and sulfone was observed similarly as (68) possibly via reac-tion with 1O2 (Cheng and Hwang 1996). A similar photooxidation of sulfur bysunlight was reported for butyrate (87) on soil (EPA OPPTS 1993). Molinate(90) is considered to undergo S-oxidation on soil, but faster degradation undersunlight was reported without any information on degradation products (Kons-tantinou et al. 2001). The usual cleavage of carbamate linkage proceeded forasulam (82) to give sulfanilamide as a main photodegradate on soil (EPA OP-PTS 1995a). Desmedipham (83) and phenmedipham (84) have two carbamatelinkages in molecules but the C(=O)−O aryl bond was found to be primarilycleaved. The main pathway of 14C-(83) on soil was formation of ethyl (3-hydrox-yphenyl)carbamate, and degradates via photo-Fries rearrangement in aqueousphotolysis could not be detected (EPA OPPTS 1996b). Maneb (94) was quicklydegraded to ETU (95) on soil (Rhodes 1977). After application of 14C-(94) and14C-(95) to the ground, the recovered radioactivity from soil rapidly decreasedto form ethyleneurea via S-oxidation of (95). Thiophanate-methyl (92) showeda similar S-oxidation at one of two C=S moieties on soil exposed to sunlighttogether with formation of MBC (93) (EPA OPPTS 2001). Almost quantitaiveformation of (93) was reported for benomyl (81) on soil with 2-aminobenzimid-azole as a minor degradate (EPA OPPTS 2001).
Amides, Anilides, and Dicarboximides Soil organic matter was found to accel-erate photolysis of propachlor (33) by sunlight irradiation (Konstantinou et al.2001). For alachlor (34), the rate of photodegradation was enhanced by low soilorganic matter, low pH, or high water content (Fang 1977; Chesters et al. 1989).Alachlor (34) underwent cleavage of either the N−CH2 or N−C(=O) bond fol-lowed by further degradation to 2,6-diethylaniline and reductive dechlorination(Fig. 21). As a unique reaction, the intramolecular cyclization occurred betweennitrogen and o-ethyl group to give N-chloroacetyl-7-ethylindoline. Somich et al.(1988) examined the effect of photolytic ozonation on dissipation of 14C-(34) insoil and found that O3 caused release of more carbon dioxide from the irradiatedsoil. Photolysis of metolachlor (35) on soil by artificial sunlight gave N-chloro-acetyl-N-(hydroxyprop-1-en-2-yl)-2-ethyl-6-methylaniline as a main degradate(see Fig. 21) (Chesters et al. 1989). This product was considered to be formed
64 T. Katagi
Fig.
21.
Com
para
tive
phot
odeg
rada
tion
path
way
sof
alac
hlor
(34)
and
met
olac
hlor
(35)
.
Photodegradation of Pesticides 65
via photoinduced cleavage of the O-CH3 bond. Metalaxyl (37) was slowly pho-todegraded on soil, but its degradation was found to be also controlled by eithermicrobial degradation or abiotic factors other than light (Sukul and Spiteller2001). The slower rate of degradation was observed for soil having a larger claycontent, and light screening by adsorption of (37) into the interlayer of claymight reduce the effect of irradiation. On air-dried soil, (37) was reported toundergo cleavage of either the CH2-OCH3 or N−C(=O) bond (Saha and Sukul1997). Under simulated sunlight, carboxin (42) was photodegraded to give thecorresponding sulfoxide, and increased moisture content accelerated photolysis(Murthy et al. 1998). Because insignificant photodegradation of oxycarboxin(43) was observed under the same conditions, the main degradation pathway of(42) was most likely to be photoinduced S-oxidation. Further photodegradationof the sulfoxide was examined in soil suspension, and oxanilic and malonicacids were additionally identified (Hustert et al. 1999).
Effects of soil properties such as moisture content and soil depth have beeninvestigated in conjunction with photolytic profiles of 14C-nicloamide (40)(Frank et al. 2002; Graebing et al. 2002). The reactive site of (40) was the 4-nitro group, which was either reduced to an amino group or substituted withOH, and these products were finally degraded to 3-chloro-6-hydroxybenzoicacid. NO−
3 added as a fertilizer, iron oxide, or humic acid was found to causeinsignificant effects on photodegradation of (40) in moistened soil, but reduceddegradation was observed in air-dried soil. Although the photodegradation path-way was not available, the importance of pesticide transport to soil surface hasbeen extensively studied for napropamide (47) (Miller and Donaldson 1994;Donaldson and Miller 1996). The main metabolic pathway of florasulam (48)in soil was O-demethylation, whose formation was accelerated by sunlight expo-sure, and this product was further photodegraded via stepwise opening of thetriazolopyrimidine ring (Krieger et al. 2000). Microbial degradation of 14C-(48)was considered to dominate its dissipation in soil, but one product ASTP (8-fluoro-5-methoxy[1,2,4]triazolo-[1,5c]pyrimidine-2-sulfonamide) characteristicof soil photolysis was formed via cleavage of the NH-aryl bond. Degradationof captan (106) was slightly enhanced by sunlight exposure on moist soil withmajor degradates identified as tetrahydrophthalimide and cyclohex-4-ene-2-cyano-1-carboxylic acid (EPA OPPTS 1999b). The former product was consid-ered to be formed via cleavage of the N-S bond, whereas opening of the imidering followed by reduction of the amide moiety would also proceed in soil. 14C-Iprodione (109) exhibited a slightly rapid degradation on soil with formation of3,5-dichloroaniline and 3-(3,5-dichlorophenyl)-2,4-dioxaimidazolinone (Fig. 22)(EPA OPPTS 1999b). As a unique degradate, 3-(1-methyl-ethyl)-N-(3,5-dichlo-rophenyl)-2,4-dioxo-1-imidazolidinecarboxamide was identified, and photoin-duced cleavage of the amide linkage in the ring followed by recombination ofthe carbonyl radical with the N-isopropyl nitrogen was most likely to be in-volved. The photochemistry of famoxadone (111) on soil was briefly reportedbut the characteristic reaction induced by light exposure was not clarified (Jern-berg and Lee 1999).
66 T. Katagi
Fig. 22. Photoinduced rearrangement of iprodione (109).
Ureas Jirkovsky et al. (1997) reported that diuron (53) was photodegraded onsand via N-demethylation and oxidation to the N-formyl-N-methyl derivativewith a trace formation of monuron (52). As N-demethylation of (53) was dem-onstrated not to require O2, it was considered that the photoinduced rearrange-ment of an N-methyl group to carbonyl oxygen gave the corresponding isoureaderivative, which was further hydrolyzed to the NHCH3 derivative. For the N-formyl-N-methyl derivative, the excited carbonyl group was likely to initiatehydrogen abstraction from the N-methyl group followed by reaction with O2.Photodegradation of linuron (54) on soil gave NHOCH3, NH2 derivatives, and3,4-dichloroaniline (EPA OPPTS 1995d). By comparing the results in aerobicsoil metabolism, photolysis was likely to be of minor importance for (54). Inthe case of isoproturon (56), the same photoreactions as (53) were observed butwith a slower degradation rate (Kulshrestha and Mukerjee 1986). The photoin-duced ring rearrangement was reported for 14C-thidiazuron (58) on soil thinlayer, leading to formation of 1-phenyl-3-(1,2,5-thiadiazol-3-yl)urea (Klehr etal. 1983). Information on benzoylurea pesticides is very limited, but the resultsfor photodegradation of diflubenzuron (59) on soil showed an insignificant con-tribution of photolysis (EPA OPPTS 1997a). Chlorsulfuron (96) was slowlyphotodegraded on soil via either O-demethylation or cleavage of the sulfonyl-urea linkage, but acetylbiuret was not detected (Strek 1998). Similar photodegra-dation under sunlight was reported for chlorimuron-ethyl (102) together withunique contraction of the sulfonylurea bridge (see Fig. 20) (Choudhury andDureja 1997a). Tribenuron-methyl (99) was photodegraded under sunlight viaN-demethylation with cleavage of either the S-N bond or urea moiety, but anydegradates via bridge contraction were not detected (Bhattacharjee and Dureja2002). In contrast, photodegradation of 14C-rimsulfuron (103) on soil gave twomajor degradates via bridge contraction but no acceleration of degradation by
Photodegradation of Pesticides 67
sunlight exposure was observed (Schneiders et al. 1993). One of the degradateswas N-(pyrimidin-2-yl)-N-(pyridin-2-yl)urea derivative, which was consideredto be degraded to the second by release of the carbamoyl group. Involvementof direct photolysis on sterilized soil was confirmed for triasulfuron (100) andthifensulfuron-methyl (105) (Albanis et al. 2002).
Azoles and Triazines Triadimefon (188) underwent photoinduced cleavage ofeither O-CH or CH−C(=O) bond and reduction of the carbonyl group on soilunder sunlight with the decarbonylated derivative as a minor product (Nag andDureja 1996). Judging from its UV absorption, direct photolysis was likely toproceed and the increase of soil moisture enhanced photodegradation (Murthyet al. 1998). Propiconazole (191) was photodegraded on soil via cleavage of theC-triazole bond, liberating 1,2,4-triazole. The unique ring opening was reportedfor photodegradation of 14C-prochloraz (240) in both laboratory and field studies(Hollrigl-Rosta et al. 1999). Prochloraz (240) was gradually photodegraded onsoil to give primarily the formylurea derivative of (240) followed by deformyla-tion (Fig. 23). Atrazine (185) was found resistant to photolysis on air-driedsoils (Curran et al. 1992), although slight sunlight photodegradation of an extentproportional to the content of soil organic matter was reported (Konstantinou etal. 2001). Gong et al. (2001) showed that in coarser soil where light can pene-trate more deeply, or upon addition of humic acid, or in moistened soil wheremovement of the pesticide molecule is facilitated, an increased rate of photodeg-radation can occur.
Miscellaneous Photolysis seems to be of minor importance for dinitroanilineherbicides relative to volatilization loss and thermal degradation (Wright andWarren 1965; Parochetti and Hein 1973; Parochetti and Dec 1978). Although adetailed photodegradation pathway on soil was not available, photolysis of tri-fluralin (232) on kaolinite clay was conducted to theoretically investigate theimportance of photic depth in clay and its transport within the layer (Balmer etal. 2000). On exposure to UV light, (232) on clay was slowly decomposed withformation of two benzimidazole derivatives. Either photoinduced cyclization be-tween nitro nitrogen and the 1-position of an N-propyl group to give the benzim-idazole or N-depropylation was most likely to occur. Cyclization was precededby photoinduced reduction of the nitro group to a nitroso derivative whose ex-cited state extracted hydrogen from the C1 position of the N-alkyl group. Photo-degradation of fluchloralin (236) on soil gave three benzimidazole derivativesvia similar reactions observed for (232) (Nilles and Zabik 1974). The releaseof the chloroethyl moiety was observed with a unique formation of 5-nitro-7-trifluoromethyl-1,4-quinoxaline. In photodegradation of ethalfluralin (237), 1H-benzimidazole-3-oxide was additionally detected (EPA OPPTS 1995b). The ex-istence of this product supported a reaction mechanism where the photoexcitednitro group extracted hydrogen at the C1 position of the N-alkyl group and radi-cal recombination followed by release of hydroxide resulted in benzimidazole-N-oxide. Insignificant degradation by exposure to sunlight was observed for
68 T. Katagi
Fig.
23.
Phot
oind
uced
ring
open
ing
ofpr
ochl
oraz
(240
).
Photodegradation of Pesticides 69
butralin (234) on soil (EPA OPPTS 1998b). Halder et al. (1989) reported thephotoinduced N-deethylation of pendimethalin (238) on sunlight-exposed soil;other reactions such as photoreduction were predominant when exposed to UVlight (Dureja and Walia 1989). In contrast to these dinitroaniline herbicides,oryzalin (235) was found to be photolabile on soil, forming many unknowns,and bound 14C via cleavage of the C-N(C3H7)2 bond, hydrolysis of sulfonamide,and formation of the benzimidazole derivative (EPA OPPTS 1994).
Amitrole (196) was moderately resistant to sunlight photolysis on soil butunderwent C-N bond cleavage to give 1,2,4-triazole (EPA OPPTS 1996a). An-other type of photoinduced deamination via cleavage of the N-N bond was re-ported for metribuzin (201) in an outdoor photolysis study on soil (EPA OPPTS1998g). Terbacil (197) underwent cleavage of the N-C(CH3)3 bond to give 5-chloro-6-methyluracil (EPA OPPTS 1998h). Bentazon (200) underwent oxida-tive opening of the thiadiazinone ring to give N-isopropyl-2-nitrosobenzamide,followed by oxidation to the corresponding nitro derivative (Nilles and Zabik1975). The primary photoprocess was considered to be hydrogen abstraction atthe NH moiety to form the radical whose center would also be located at the 5-and 7-position of the benzothiadiazinone ring (o- and p-position toward thecarbonyl moiety) via resonance. Norflurazon (214) showed moderate sunlightphotolysis on soil with N-demethylation being the dominant process (SchroederKvien and Banks 1985). Fipronil (220) exhibited a unique photoreaction to givethe desulfinyl derivative (Bobe et al. 1998b), and the sulfone derivative wasalso detected in two field dissipation studies (Bobe et al. 1998a; Fenet et al.2001). 14C-DTP (221), the herbicidal entity of pyrazolate, mainly underwentoxidative N-demethylation on paddy soils (Yamaoka et al. 1988).
IX. Photodegradation of Pesticides on Plants
Photodegradation profiles of pesticides on plant surfaces were reviewed basedon surface-wash analysis in plant metabolism studies, unless described other-wise, to distinguish the photochemical conversion from biotic processes. Theplant species and some experimental conditions are summarized in Table 11(see table on page 120) for each pesticide with its half-life.
Organochlorines Each formulation of DDT (130), aldrin (122), dieldrin (123),and endrin (126) was sprayed on apple trees in the field and the hexane rinsatesof leaves were analyzed (Harrison et al. 1967). DDT was photodegraded toDDD (132) and 4,4′-dichlorobenzophenone. Aldrin was degraded with concomi-tant formation of (123). The cage-type ketone and aldehyde derived from reac-tions at the bridged carbons were detected for (126). When (122), (123), and(126) were applied to leaves of young bean plant or glass plates under sunlight,similar photodegradation profiles were identified (Ivie and Casida 1971b; Ivieet al. 1972). In the same study using apple trees, the β-isomer of endosulfan(125) was found to be a little more persistent than the α-isomer with formationof its sulfate. After application to cotton leaves in the field, the α-isomer mainly
70 T. Katagi
underwent dechlorination at the bridge carbon with trace amounts of β-isomerand ring-opening products, whereas the β-isomer only gave the latter (Durejaand Mukerjee 1982). These results agreed with those seen with solution photoly-sis in hexane. Similar solution photochemistry was also reported for chlordane(128) applied to cabbage leaves (Parlar et al. 1978). As shown in Fig. 24, N-(α-trichloromethyl-p-methoxybenzyl)-p-methoxyaniline principally underwentphotoinduced rearrangement on lettuce and bean leaves to N-phenyl-α-hydroxy-benzylamide, which was the common photoproduct in water and on glass orsilica gel (Miller et al. 1974). Direct absorption of light caused a charge transferfrom nitrogen to the CCl3 moiety, followed by the successive release of chlorideion and recombination to the unstable three-membered intermediate, which washydrolyzed to the corresponding amide.
Organophosphorus Esters This class of pesticides undergoes various transfor-mations in plant metabolism, as reviewed by Katagi and Mikami (2000). El-Refai and Hopkins (1966) compared dissipation of parathion (135) topicallyapplied to garden beans or glass plates. The biphasic decay in contrast to thesimple first-order dissipation on glass implied penetration of (135) into cuticleand tissue. A similar biphasic foliar decay was observed in residue trials inorange groves with concomitant formation of the oxon (Popendorf and Leffing-well 1978). Formation and decay of the oxon was found to strongly correlatewith dry and stable weather, and effects of foliar dust and airborne oxidantswere suspected. Spear et al. (1978) conducted residue trials of (135) on dwarfEureka lemon trees in the presence or absence of O3 and soil dusts (<50 µm).They showed that the a photoinduced dust-catalyzed process is one of the mostimportant routes for the foliar P=S oxidation of (135). However, the presenceof soil dust on foliage might retard the decay of the oxon by its stronger adsorp-tion to dust (Adams et al. 1977). Joiner and Baetcke (1973) scrutinized thedegradates from 14C-(135) on cotton. Although the degradates were extracted byhomogenization, the S-ethyl isomer was detected with a trace amount of the S-phenyl isomer, indicating the contribution of photolysis.
Plant metabolism studies using 14C- or 32P-labeled fenitrothion (138) in rice(Miyamoto and Sato 1965), sugar beet, (Ohkawa et al. 1974b), and apples (Ho-sokawa and Miyamoto 1974) have been reported. 32P-(138) rapidly penetratedinto tissues of rice plants but information on degradation was not provided.Analysis of methanol rinses of bean leaves showed that (138) was rapidly de-graded via similar pathways as (135), but oxidation of the aryl methyl group toCOOH was characteristically detected. In the case of apple fruits, the oxon and3-methyl-4-nitrophenol were identified as major degradates in the acetone wash,the former of which was not detected in the homogenates. In the rinsate, thecorresponding S-isomer was also confirmed. Therefore, both oxon and S-isomerwere most likely to be photochemically produced on the surface of apple fruits,as was also demonstrated by Fukushima et al. (2003) on tomato fruits. For 14C-cyanophos (137) on bean plants, photolysis was of minor importance (Chiba etal. 1976). The degradation of bromophos (140) on tomato leaves was also found
Photodegradation of Pesticides 71
Fig.
24.
Phot
odeg
rada
tion
ofN
-(α-
tric
hlor
omet
hyl-
p-m
etho
xybe
nzyl
)-p-
met
hoxy
anili
ne.
72 T. Katagi
to be less important than metabolism in tissues (Stiasni et al. 1969). In contrast,fenthion (143) was very rapidly degraded on coastal bermudagrass or cornplants with successive oxidation of the S-methyl sulfur to form the correspond-ing sulfoxide and sulfone (Leuch and Bowman 1968). Residue analysis of (143)and its degradates was conducted for a citrus grove, and both sulfoxide andsulfone were detected only in the orange peel, showing that these oxidations aresurface reactions on fruits (Minelli et al. 1996). Dechlorination of chlorpyrifos(145) was confirmed by a trace amount through its photodegradation on thedorsal leaves of soft shield fern by irradiation, but the main degradates were3,5,6-trichloropyridinol and the oxon (Walia et al. 1988). Formation of the oxonfrom isoxathion (151) on foliage was found insignificant, as demonstrated inmetabolism of 14C-(151) (Ando et al. 1975) and residue trials (Endo et al. 1985).When phoxim (152) was applied outdoors to tomato plants, the surface rinse ofleaves with acetone was found to contain two unknown photoproducts morepolar than (152) (Makary et al. 1981). The corresponding oxon was confirmedby GC analysis of corn forage treated with emulsifiable concentrate formulationof (152) but its route of formation was ambiguous due to the harsh Soxhletextraction (Bowman and Leuck 1971). Ivie and Bull (1976) conducted photo-degradation studies of 14C-sulprofos (161) on cotton leaves and confirmed thepredominant formation of sulfoxide and sulfone in the methanol rinse. Metabo-lism of 14C- and 32P-phenthoate (168) in Valencia orange leaves and fruit showedthat the main degradation pathways on the surface were P=S oxidation to theoxon, stepwise hydrolysis at the S-C bond and carboxylate moiety to mandelicacid, and hydrolysis of the P-S bond followed by formation of disulfide (Takadeet al. 1976). The other minor reaction, O-demethylation, was detected mostly onorange tree leaves. Similar degradation profiles were observed for 14C-azinphos-methyl (169) in corn and bean metabolism. Extraction by homogenization onlymade a site of conversion difficult to identify, but similar profiles on glass underirradiation showed possible photodegradation on plant surfaces (Liang and Kich-tenstein 1976).
32P- and 14C-Dimethoate (165) was gradually degraded on leaves via P=Soxidation followed by conversion of the amide moiety finally to the carboxylderivative of the oxon, including oxidative N-dealkylation (Dauterman et al.1960; Lucier and Menzer 1968). Due to lack of a chromophore in (165), indirectphotolysis may account for a part of these conversions. Formothion (166) under-went rapid conversion to (165) on bean leaves but contribution of photolysis isunclear (Sauer 1972). Malathion (167) is considered to be also resistant to directphotolysis, and only hydrolysis of ester linkages is a dominant pathway (Awadet al. 1967; El-Refai and Hopkins 1972; Mostafa et al. 1974). 14C-Edifenphos(173) was slowly degraded on rice leaves, presumably via hydrolysis, and thusthe contribution of photolysis also was unlikely (Ishizuka et al. 1973). Photoin-duced cis/trans isomerization was expected for mevinphos (155), but its highvolatility made it difficult to confirm this possibility (Casida et al. 1956). Hydrol-ysis of monocrotophos (156) and dicrotophos (157) was found only predominanton plant surfaces without any contribution from photolysis (Lindquist and Bull
Photodegradation of Pesticides 73
1967; Beynon and Wright 1972; Bull and Lindquist 1964). Bull et al. (1967)conducted a metabolism study in cotton using the cis- and trans-isomers of 14C-and 32P-phosphamidon (158) and reported faster degradation of the cis-isomeron foliage, which would be due to its easier hydrolysis. In contrast, photoin-duced E/Z isomerization was observed for 14C-tetrachlorovinphos (154) onleaves of cabbage, apple, bean, and rice (Beynon and Wright 1969; Dureja etal. 1987b). Acephate (174), cyanofenphos (180), leptophos (181), and butonate(182), having P-C and P-N bonds in their molecules, underwent either O-deal-kylation or ester hydrolysis, and photolysis on plant surfaces seemed to be ofminor importance (Chiba et al. 1976; Zayed et al. 1978; Bull 1979: Derek et al.1979).
Pyrethroids The trans- and cis-isomers of 14C-phenothrin (13) were rapidlydegraded on kidney bean and rice plants via unique ozonization of the isobu-tenyl side chain successively to the corresponding aldehyde and carboxylic acid(Nambu et al. 1980); this seems to be a typical example of reaction of pesticideswith active oxygen species in air. Measurable isomerization was observed forthe aldehyde and carboxylic acid derivatives, at least in part showing involve-ment of photoprocess. Instead of oxidation, the cis-isomer of 14C-cypermethrin(19) predominantly underwent cis/trans isomerization on cotton and bean leavesgrown outdoors (Cole et al. 1982). A similar phototransformation was observedfor deltamethrin (22) (Ruzo and Casida 1979; Maguire 1990). Rapid conversionof tralomethrin (25) and tralocythrin (26) to (22) and (19) followed by isomer-ization to the trans-isomers was observed together with a slight epimerizationat the benzyl carbon, possibly as a dark reaction (Cole et al. 1982). Dissipationof fenpropathrin (24) on leaves of mandarin orange was mostly due to penetra-tion into leaf tissues (Takahashi et al. 1985b). The insignificant contribution byphotolysis was accounted for by the very slight differences in half-lives when(24) was applied to green beans and tomatoes in winter and spring when sun-light intensity to (24) was different (Martinez Galera et al. 1997). Decarboxyl-ation proceeded for fenvalerate (27) on cotton (Holmstead et al. 1978b) andbean leaves (Ohkawa et al. 1980). Similar profiles have been separately reportedfor metabolism in spring wheat, and the analysis of hexane rinse of leavesclearly demonstrated that decarboxylation is a photoreaction (Lee et al. 1988).Similar photoinduced decarboxylation via radical processes was detected forflucythrinate (29) on French bean leaves with degradates formed via cleavageat the O-CH bond (Chattopadhyaya and Dureja 1991).
Carbamates Metolcarb (61), xylylcarb (63), and trimethacarb (64) likely dissi-pated from plant foliage mainly by volatilization, with photochemical reactionsplaying a minor role (Slade and Casida 1970; Ohkawa et al. 1974a). Althoughthe hydroxylated derivative at the methylene carbon of the isobutyl group wasconfirmed for 14C-fenobucarb (62) applied to rice leaves, the trace amount de-tected implied that photolysis was of minor importance (Ogawa et al. 1976).For propoxur (65), Abdel-Wahab et al. (1966) reported that its foliar application
74 T. Katagi
to garden snapbean resulted in rapid dissipation, but the degradation profileswere not clear. They also showed stepwise sulfur oxidation at the thiomethylgroup of methiocarb (68) to its sulfoxide and sulfone. On the leaves treated withaminocarb (66) and mexacarbate (67), the stepwise oxidation proceeded out-doors at the N,N-dimethylamino moiety, evidenced by analysis of chloroformrinsates (Abdel-Wahab and Casida 1967). Because similar reactions were identi-fied when silica gel was used, the oxidation reactions were likely to be photoin-duced processes. Carbaryl (71) underwent hydroxylation at the 4- or 5-positionof the naphthyl moiety and N-methyl group by stem injection (Mumma et al.1971), but its photolytic behavior on plant surfaces was unclear (Abdel-Wahabet al. 1966). The contribution of photodegradation was not clear for carbofuran(72), but either hydrolysis of the carbamate linkage or stepwise oxidation atthe 3-position of the 2,3-dihydrobenzofuranyl moiety proceeded on strawberry(Archer et al. 1977). When 14C-benfuracarb (89) was applied to leaves of bushbean, cotton, and corn, (89) was gradually degraded to (72) on leaf surfaces viacleavage of the N(CH3)-SNRR′ bond (Tanaka et al. 1985). Cleavage was consid-ered to also occur at the N(CH3)S-NRR′ bond, resulting in formation of thedimer derivatives of (72) possessing Sn (n > 1) or derivatives having the chemi-cal structure of (89) but with Sn (n > 1) linkage. Because these products weredetected predominantly on the leaf surface, photodegradation most likely ac-counted for this conversion. From 14C-carbosulfan (88), similar derivatives hav-ing the Sn linkage were detected only in surface rinse of leaves and fruits ofValencia orange trees (Clay and Fukuto 1984). In addition, S-oxidation to formthe sulfone derivative of (88) occurred mainly on leaf surfaces.
Hydrolysis was the main degradation pathway in plants for oxamyl (74), andno clear explanation about the extent of photodegradation was given (Harvey etal. 1978). In contrast, pirimicarb (78) was known to rapidly dissipate from let-tuce leaves, not only by volatilization but also by stepwise oxidation of theN,N-dimethyl group of the pyrimidyl ring, but the extent of the photochemicalcontribution was not clear (Cabras et al. 1990). Similar oxidation of the N-methyl group was reported for fenothiocarb (85) on mandarin orange trees to-gether with S-oxidation to the sulfoxide (Unai et al. 1986). Benomyl (81) andthiophanate-methyl (92) are known to give the same degradate, MBC (93). MBC(93) was only formed from (81) on leaves of several plants via release of theN-butylcarbamoyl group (Baude et al. 1973). 14C-(92) on leaves of apple andgrape trees gave (93) as a main degradate together with the degaradate wherethe two C=S groups were oxidized to carbonyls (Soeda et al. 1972). Buchenaueret al. (1973) examined the photoreactivity of (92) in solid and aqueous phasesusing UV light and found that (92) was stable as a solid but rapidly degradedto (93) in water. Therefore, the photodegradation of (92) on plant foliage seemsto proceed in an aqueous microenvironment, probably originating from morningdew. MBC (93) was found to be mostly photostable but degradable in the pres-ence of a photosensitizer such as riboflavin (Fleeker and Lacy 1977). Maneb(94) was rapidly degraded to ETU (95) on leaves of tomato and snapbean plants,followed by further transformation to either ethyleneurea via C=S oxidation to
Photodegradation of Pesticides 75
C=O or dimerization to Jaffe’s base (1-(2-imidazoline-2-yl)-2-imidazolinethi-one) (Rhodes 1977). Similar degradates were identified in aqueous photolysis,showing that these reactions were likely to proceed via photolysis.
Amides, Imides, and Ureas Flutolanil (39) showed slow dissipation on cucum-ber leaves via deisopropylation at the phenyl ring followed by methylation orhydroxylation at the 4-position of the aniline ring (Uchida et al. 1983). Conver-sion on plant surfaces was minimum for carboxin (42) (Buchenauer 1975). Pro-pyzamide (45) was cyclized via reaction between carbonyl oxygen and ethynylcarbon to form the oxazoline ring followed by its opening to N-(1,1-dimethyla-cetonyl)benzamide (Yih and Swithenbank 1971). Because this conversion isknown in its hydrolysis (Katagi 2002b), contribution of photolysis was question-able. Opening of its imide ring was observed for procymidone (108) on cucum-ber leaves but only in trace amounts (Mikami et al. 1984a). Methazole (112)underwent either opening of the 1,2,4-oxadiazoline-3,5-dione ring to the 3-methyl-1-phenylurea derivative or decarboxylation to the 2-oxo-benzimidazolederivative, with greater amounts detected on the surface of cotton leaves (Do-rough et al. 1973). The latter degradate at least was considered to be formed byphotoreaction because it was also detected in aqueous photolysis. Photoreactionscarcely proceeded for lenacil (199) on sugar beet (Zhang et al. 1999). Diflube-nzuron (59) on cotton leaves was resistant to photolysis with insignificant trans-location (Bull and Ivie 1976; Mansager et al. 1979). Rodriguez et al. (2001)identified 2,6-difluorobenzamide as a sole degradate through residue trials onpine needles. As cumulative solar irradiation was found to correlate highly withdissipation of (59), and 4-chloroaniline formed via hydrolysis was not detected,photodegradation forming the corresponding benzamide and isocyanate wasconsidered most likely. The lack of detection of the latter degradate may beaccounted for by its high volatility. In contrast, diafenthiuron (57) exhibitedrapid photodegradation on cotton leaves (Drabek et al. 1992) and Chinese cab-bage (Keum et al. 2002) via reaction of the thiourea moiety with 1O2 to carbodii-mide. Tribenuron methyl (99) underwent cleavage of each bond in the sulfonyl-urea bridge with its contraction on wheat leaves. These processes were mostlikely photoreactions because similar degradates were identified on glass platesexposed to sunlight (Bhattacharjee and Dureja 2002). In contrast, most of 14C-thifensulfuron (104) remained unchanged in the surface rinse of soybean plants,with trace amounts of thiophene-2-methoxycarbonyl-3-sulfonamide and the 2-amino-1,3,5-triazine derivative (Brown et al. 1993).
Azoles On the leaves of marrow plants, triadimefon (188) was converted totwo diastereomers of triadimenol (189) via reduction of carbonyl group toCHOH, but the contribution of photolysis was unclear (Clark et al. 1978). Deg-radation of (189) was briefly investigated on apple leaves with 1-(4-chlorophen-oxy)-3,3-dimethylbutan-2-one being detected as the sole metabolite (Clark andWatkins 1986). Because the same degradate was identified through photolysisin methanol, its formation on foliage was likely to be a photoprocess. Although
76 T. Katagi
dissipation profiles of the other azole fungicides on grape have been investi-gated, their degradation pathways are not available (Cabras et al. 1997a, 1998;Peacock et al. 1994). For fluotrimazole (195), the substitution of the 1,2,4-trai-zole moiety with the hydroxyl group was confirmed on leaves of barley, withthe photo-induced cleavage of C-N bond being proposed (Clark et al. 1983).
Miscellaneous Although 2,4-D (1) does not possess UV absorption >290 nm,more of (1) was lost from Zea mays leaves by exposure to UV light >290 nmthan the dark control, and thus the possible photosensitization of either somecomponents in epicuticular waxes or a coexisting oxysorbic surfactant mightoccur (Venkatesh and Harrison 1999). The degradation pathway was not clearbut may be estimated by the results of residue trials for triclopyr (7). When (7)was sprayed on grasses, it was rapidly degraded to give 3,5,6-trichloro-2-pyridi-nol with a trace amount of 2-methoxy-3,5,6-trichloropyridine (Norris et al.1987); this suggests the possible cleavage of O-CH2 and the following decarbox-ylation are involved in degradation. The photostability of 2,3,7,8-TCDD (129)was examined on excised leaves of rubber plant under sunlight (Crosby andWong 1976). TCDD (129) was degraded possibly via direct photolysis becauseits UV absorption maximum was at �300 nm. Although its degradation pathwaywas not available, dechlorination was most probable based on the latter photo-degradation studies (Schuler et al. 1998). Both dinoseb (202) and dinobuton(203) were rapidly degraded to several unknown compounds on garden snap-bean seedlings, and 5%–6% of (203) was found to be converted to (202) (Mat-suo and Casida 1970). In the presence of a photosensitizer such as rotenone,these pesticides were more rapidly decomposed via oxidation, ester cleavage,and reduction of the nitro group (Bandal and Casida 1972).
Sethoxydim (223) was degraded on grasses to eight unknown products andthe O-deethylated derivative, which were also detected in photolytic and thermaltransformation (Campbell and Penner 1985b). For alloxidim (224), the contribu-tion of photolysis to its dissipation on sugar beet leaves was examined by Soedaet al. (1979). Alloxidim was degraded via cleavage of the N-O bond to formthe amine derivative and Beckmann rearrangement to the two cyclized deriva-tives. The former main degradate was also formed either by UV photolysis onsilica gel or by catalytic reduction of (224) with 10% Pd/C in a hydrogen atmo-sphere, indicating photoinduced reductive dissociation was most probable on theleaf surface. 14C-Imidacloprid (215) on tomato leaves dissipated under sunlightvia oxidation of the imidazolidinimine ring and stepwise loss of the nitroiminogroup to finally form the imidazolidin-2-one derivative (Scholz and Reinhard1999). As the dark control resulted in minimum degradation, these degradatesoriginated from photolysis. For fipronil (220), photochemical conversion of thetrifluoromethylsulfinyl moiety via homolytic cleavage of the S-CF3 or S-C(pyr-azolyl) bond was confirmed on leaves of corn, sweet pea, and pear (Hainzl andCasida 1996). In contrast, the main degradate in field residue trials was thesulfone derivative with a trace of the desulfinyl derivative (Fenet et al. 2001).The well-aerated leaf surface with higher levels of water under tropical condi-
Photodegradation of Pesticides 77
tions might result in favorable photoinduced S-oxidation. Thiabendazole (212)was photodecomposed on sugar beet, possibly via oxidation to benzimidazole-2-carboxamide and benzimidazole, but only in trace amounts (Jacob et al. 1975).Photoinduced oxidation of an alkyl chain was reported for guazatine (245) ondwarf apple trees (Sato et al. 1985a). Oxidation to ketone at the 4-position tothe NH moiety followed by methylation at the 3- or 5-position was proposedto proceed via reaction with the hydroxyl radical or some sensitizer in waxcomponents.
Moye et al. (1990) investigated the degradation of 3H-, 14C-avermectin B1a
(250) in celery seedlings. By HPLC analysis of homogenization acetone ex-tracts, the ∆8,9 isomer formed via photoinduced geometric isomerization at 8-and 9-positions of the macrocycle was detected as a main degradate. Analysisof methanol rinsates from cabbage plant treated with 14C-4″-(epi-methylamino)-4′-deoxyavermectin B1a benzoate [MAB; (251)] showed that surface degradationwas mainly due to photolysis; isomerization of the 8,9-double bond, stepwiseoxidation of the N-methyl group via N-formyl to the amino group, hydroxylationat the 8α-position, and loss of the outer sugar by cleavage of the ether bond(Wrzesinski et al. 1996). The other example is Spinosad consisting of spinosynA and D. Saunders and Bret (1997) utilized 14C-spinosyn A (252) for foliar ortopical application to cotton, turnip, cabbage, and apple fruits. Although noinformation on the degradation pathway is available, by analogy with (251),oxidation at double bonds, N-demthylation, and ether cleavage may occur.
Summary
Photodegradation is an abiotic process in the dissipation of pesticides wheremolecular excitation by absorption of light energy results in various organicreactions, or reactive oxygen species such as OH�, O3, and 1O2 specifically ornonspecifically oxidize the functional groups in a pesticide molecule. In the caseof soil photolysis, the heterogeneity of soil together with soil properties varyingwith meteorological conditions makes photolytic processes difficult to under-stand. In contrast to solution photolysis, where light is attenuated by solid parti-cles, both absorption and emission profiles of a pesticide are modified throughinteraction with soil components such as adsorption to clay minerals or solu-bilization to humic substances. Diffusion of a pesticide molecule results in het-erogeneous concentration in soil, and either steric constraint or photoinducedgeneration of reactive species under the limited mobility sometimes modifiesdegradation mechanisms. Extensive investigations of meteorological effects onsoil moisture and temperature as well as development of an elaborate testingchamber controlling these factors seems to provide better conditions for re-searchers to examine the photodegradation of pesticides on soil under conditionssimilar to the real environment. However, the mechanistic analysis of photodeg-radation has just begun, and there still remain many issues to be clarified. Forexample, how photoprocesses affect the electronic states of pesticide moleculeson soil or how the reactive oxygen species are generated on soil via interaction
78 T. Katagi
with clay minerals and humic substances should be investigated in greater detail.From this standpoint, the application of diffuse reflectance spectroscopy andusage or development of various probes to trap intermediate species is highlydesired. Furthermore, only limited information is yet available on the reactionsof pesticides on soil with atmospheric chemical species. For photodegradationon plants, the importance of an emission spectrum of the light source near itssurface was clarified. Most photochemical information comes from photolysisin organic solvents or on glass surfaces and/or plant metabolism studies. Epicu-ticular waxes may be approximated by long-chain hydrocarbons as a very vis-cous liquid or solid, but the existing form of pesticide molecules in waxes isstill obscure. Either coexistence of formulation agents or steric constraint in therigid medium would cause a change of molecular excitation, deactivation, andphotodegradation mechanisms, which should be further investigated to under-stand the dissipation profiles of a pesticide in or on crops in the field. A thin-layer system with a coat of epicuticular waxes extracted from leaves or isolatedcuticles has been utilized as a model, but its application has been very limited.There appear to be gaps in our knowledge about the surface chemistry andphotochemistry of pesticides in both rigid media and plant metabolism. Photo-degradation studies, for example, by using these models to eliminate contribu-tion from metabolic conversion as much as possible, should be extensively con-ducted in conjunction with wax chemistry, with the controlling factors beingclarified. As with soil surfaces, the effects of atmospheric oxidants should alsobe investigated. Based on this knowledge, new methods of kinetic analysis or adevice simulating the fate of pesticides on these surfaces could be more ratio-nally developed. Concerning soil photolysis, detailed mechanistic analysis ofthe mobility and fate of pesticides together with volatilization from soil surfaceshas been initiated and its spatial distribution with time has been simulated withreasonable precision on a laboratory scale. Although mechanistic analyses havebeen conducted on penetration of pesticides through cuticular waxes, its combi-nation with photodegradation to simulate the real environment is awaiting fur-ther investigation.
Photodegradation of Pesticides 79
Table Listing
Table 1. ............................................................................................................ 80–84Table 2. ............................................................................................................ 85Table 3. ............................................................................................................ 86–87Table 4. ............................................................................................................ 88Table 5. ............................................................................................................ 89–91Table 6. ............................................................................................................ 92–93Table 7. ............................................................................................................ 94–100Table 8. ............................................................................................................ 101–103Table 9. ............................................................................................................ 104Table 10. ............................................................................................................ 105–119Table 11. ............................................................................................................ 120–128
80 T. Katagi
Tab
le1.
Wav
elen
gth
offl
uore
scen
cean
dph
osph
ores
cenc
esp
ectr
aof
pest
icid
es.
Fluo
resc
ence
Phos
phor
esce
nce
No.
Pest
icid
eE
m.
Ex.
Sola
τbT
cE
m.
Ex.
Sol
τT
Ref
eren
ce
12,
4-D
——
510
280
EPA
LSo
glie
roet
al.
1985
495
290
E<0
.2s
LM
oye
and
Win
efor
dner
1965
22,
4,5-
T48
030
0E
<0.2
sL
Moy
ean
dW
inef
ordn
er19
653
MC
PA30
923
0A
rM
uelle
ret
al.
1992
6Fl
uazi
fopb
utyl
450
267
Ar
Mue
ller
etal
.19
929
Pyre
thru
m-I
338
292
E25
431
279
EL
Bow
man
and
Ber
oza
1967
a10
Alle
thri
n33
229
2E
2543
728
2E
LB
owm
anan
dB
eroz
a19
67a
19C
yper
met
hrin
321
296
EPA
L48
127
3E
PAL
Tak
ahas
hiet
al.
1985
a28
Esf
enva
lera
te42
527
7A
LK
atag
i19
9134
Ala
chlo
r34
925
5A
rM
uelle
ret
al.
1992
35M
etol
achl
or34
525
0A
rM
uelle
ret
al.
1992
42C
arbo
xin
462
311
EW
LA
aron
etal
.19
7944
Nap
tala
m42
732
8A
Wr
Kra
use
1983
515
300
SSW
Van
nelli
and
Schu
lman
1984
47N
apro
pam
ide
340
282
Sr
528
282
S0.
2m
sr
Mur
illo
Pulg
arin
and
Gar
cıa
Ber
mej
o20
0233
529
3M
rA
rgau
er19
8034
229
6A
Wr
Kra
use
1983
520
310
SSW
Van
nelli
and
Schu
lman
1984
53D
iuro
n31
625
5E
PAL
498
255
EPA
LSo
glie
roet
al.
1985
55Fl
umet
uron
329
294
Ar
Mue
ller
etal
.19
9260
Phen
mec
283
261
EPA
r37
526
1E
PA2.
7s
LA
ddis
onet
al.
1977
61M
etol
carb
283
264
EPA
r37
926
4E
PA3.
4s
LA
ddis
onet
al.
1977
64T
rim
etha
carb
287
268
EPA
r39
326
8E
PA2.
9s
LA
ddis
onet
al.
1977
65Pr
opox
ur32
427
6E
2540
028
0E
0.8
sL
Bow
man
and
Ber
oza
1967
b
Photodegradation of Pesticides 81
Tab
le1.
(Con
tinue
d).
Fluo
resc
ence
Phos
phor
esce
nce
No.
Pest
icid
eE
m.
Ex.
Sola
τbT
cE
m.
Ex.
Sol
τT
Ref
eren
ce
66A
min
ocar
b37
526
2E
2546
025
3E
0.6
sL
Bow
man
and
Ber
oza
1967
b35
824
8E
PAr
459
248
EPA
1.2
sL
Add
ison
etal
.19
7746
029
0E
0.6
sL
Moy
ean
dW
inef
ordn
er19
6567
Mex
acar
bate
373
272
E25
430
267
E0.
6s
LB
owm
anan
dB
eroz
a19
67b
360
262
EPA
r42
326
2E
PA0.
7s
LA
ddis
onet
al.
1977
440
285
E0.
5s
LM
oye
and
Win
efor
dner
1965
68M
ethi
ocar
b—
—E
2543
027
0E
0.2
sL
Bow
man
and
Ber
oza
1967
b43
527
5E
<0.2
sL
Moy
ean
dW
inef
ordn
er19
6571
Car
bary
l34
028
5E
2551
828
8E
2.1
sL
Bow
man
and
Ber
oza
1967
b32
628
1E
PAr
467,
503
281
EPA
2.2
sL
Add
ison
etal
.19
7733
228
0M
rA
rgau
er19
8033
828
6A
Wr
Kra
use
1983
334
285
EPA
LSo
glie
roet
al.
1985
495,
530
295
SSW
rV
anne
llian
dSc
hulm
an19
8448
5,51
030
0E
2.0
sL
Moy
ean
dW
inef
ordn
er19
6572
Car
bofu
ran
325
281
E25
400
282
E1.
7s
LB
owm
anan
dB
eroz
a19
67b
304
280
Mr
Arg
auer
1980
306
278
AW
rK
raus
e19
8340
028
5E
1.6
sL
Moy
ean
dW
inef
ordn
er19
6573
Mob
am32
026
6A
Wr
Kra
use
1983
460
290
SSW
rV
anne
llian
dSc
hulm
an19
8475
Dim
etila
n37
530
4E
2542
224
3E
0.6
sL
Bow
man
and
Ber
oza
1967
b76
Pyro
lan
400
266
E25
400
257
E1.
6s
LB
owm
anan
dB
eroz
a19
67b
77Is
olan
365
270
E25
421
260
E0.
7s
LB
owm
anan
dB
eroz
a19
67b
82 T. Katagi
Tab
le1.
(Con
tinue
d).
Fluo
resc
ence
Phos
phor
esce
nce
No.
Pest
icid
eE
m.
Ex.
Sola
τbT
cE
m.
Ex.
Sol
τT
Ref
eren
ce
78Pi
rim
icar
b38
031
0M
rA
rgau
er19
8079
Prop
ham
306
242
AW
rK
raus
e19
8380
Chl
orpr
opha
m—
—E
2540
024
7E
0.3
sL
Bow
man
and
Ber
oza
1967
b81
Ben
omyl
300
286
Mr
Arg
auer
1980
402
295
SSW
rV
anne
llian
dSc
hulm
an19
8438
628
6E
W2.
6s
LA
aron
etal
.19
7948
030
8SS
S25
Aar
onet
al.
1979
107
Folp
et44
030
5E
WL
Aar
onet
al.
1979
489
306
SSS
25A
aron
etal
.19
7911
6D
ichl
orob
enil
313
285
EPA
L41
228
5E
PAL
Sogl
iero
etal
.19
8511
9C
hlor
ambe
n40
532
5A
rM
uelle
ret
al.
1992
120
Picl
oram
425
320
Ar
450
320
EPA
40m
sL
Gla
ss19
7513
0D
DT
420
270
E0.
2s
LM
oye
and
Win
efor
dner
1965
131
DD
E42
527
0E
0.2
sL
Moy
ean
dW
inef
ordn
er19
6513
2D
DD
298
245
EPA
L42
624
5E
PAL
Sogl
iero
etal
.19
8541
526
5E
0.2
sL
Moy
ean
dW
inef
ordn
er19
6513
3D
icof
ol51
528
5E
0.2
sL
Moy
ean
dW
inef
ordn
er19
6513
4M
etho
xych
lor
386
270
EPA
LSo
glie
roet
al.
1985
380
275
E0.
7s
LM
oye
and
Win
efor
dner
1965
135
Para
thio
n51
536
0E
<0.2
sL
Moy
ean
dW
inef
ordn
er19
6513
9Fe
nchl
orph
os47
530
0E
<0.1
sL
Moy
ean
dW
inef
ordn
er19
6514
4D
iazi
non
395
275
E5.
0s
LM
oye
and
Win
efor
dner
1965
145
Chl
orpy
rifo
s—
—48
428
0E
PAL
Sogl
iero
etal
.19
85
Photodegradation of Pesticides 83
Tab
le1.
(Con
tinue
d).
Fluo
resc
ence
Phos
phor
esce
nce
No.
Pest
icid
eE
m.
Ex.
Sola
τbT
cE
m.
Ex.
Sol
τT
Ref
eren
ce
147
Cou
map
hos
380
320
Mr
Arg
auer
1980
380
320
AW
rK
raus
e19
8335
932
0E
PAL
Sogl
iero
etal
.19
8551
532
5SS
WV
anne
llian
dSc
hulm
an19
8451
033
5E
<0.2
sL
Moy
ean
dW
inef
ordn
er19
6514
9Py
razo
phos
420
252
Mr
Arg
auer
1980
169
Azi
npho
smet
hyl
340
290
Mr
Arg
auer
1980
457
280
EPA
LSo
glie
roet
al.
1985
420
325
E0.
6s
LM
oye
and
Win
efor
dner
1965
170
Phos
alon
e31
028
2M
rA
rgau
er19
8032
028
7A
Wr
Kra
use
1983
172
Phos
met
440
305
E0.
8s
LM
oye
and
Win
efor
dner
1965
188
Tri
adim
efon
420
310
C0.
3ps
21D
aSi
lva
etal
.20
0118
9T
riad
imen
ol32
028
5C
0.7p
s21
Da
Silv
aet
al.
2001
200
Ben
tazo
ne45
034
0M
rA
rgau
er19
8043
326
0A
rM
uelle
ret
al.
1992
212
Thi
aben
dazo
le34
031
0M
rA
rgau
er19
8021
4N
orfl
uraz
on39
829
4A
rM
uelle
ret
al.
1992
218
Oxy
fluo
rfen
350
323
A18
nsr
411
330
EPA
LSc
rano
etal
.19
9921
9E
thox
yqui
n44
036
0M
rA
rgau
er19
8044
635
8A
Wr
Kra
use
1983
225
Para
quat
360
282
Ar
Mue
ller
etal
.19
9234
528
5A
rV
illem
ure
etal
.19
8622
6D
iqua
t34
531
0A
rM
uelle
ret
al.
1992
84 T. Katagi
Tab
le1.
(Con
tinue
d).
Fluo
resc
ence
Phos
phor
esce
nce
No.
Pest
icid
eE
m.
Ex.
Sola
τbT
cE
m.
Ex.
Sol
τT
Ref
eren
ce
228
Qui
nom
ethi
onat
e38
036
0M
rA
rgau
er19
8039
536
2A
Wr
Kra
use
1983
535
360
SSW
rV
anne
llian
dSc
hulm
an19
8423
0Im
azaq
uin
453
259
Ar
Mue
ller
etal
.19
9223
9Fe
nari
mol
360
295
E0.
2ns
2541
829
5D
LC
once
icao
etal
.19
9724
7N
AA
324
290
Mr
Arg
auer
1980
248
War
fari
ne39
031
0M
rA
rgau
er19
8047
532
0SS
Wr
Van
nelli
and
Schu
lman
1984
Em
.&
Ex.
,em
issi
onan
dex
cita
tion
wav
elen
gths
innm
.—
,N
otde
tect
ed.
a Solv
ent:
A(a
ceto
nitr
ile),
AW
(ace
toni
trile
-wat
er,
1/1)
,C
(cyc
lohe
xane
),D
(die
thyl
ethe
r),
E(e
than
ol),
EW
(eth
anol
-wat
er,
1/9)
,H
(hex
ane)
,M
(met
hano
l),
S(s
odiu
mdo
decy
lsu
lfat
em
icel
le),
EPA
(die
thyl
ethe
r-pe
ntan
e-et
hyl
alco
hol,
5/5/
2),
SSW
(sol
idst
ate,
Wha
tman
No.
42pa
per)
,SS
S(s
olid
stat
e,S&
S904
filte
rpa
per)
.b τ,
lifet
ime.
c Tem
pera
ture
:r:
room
tem
pera
ture
;L
:77
K;
valu
esin
°C.
Photodegradation of Pesticides 85
Tab
le2.
Max
imum
wav
elen
gths
ofab
sorp
tion
orre
flec
tanc
esp
ectr
aof
chem
ical
sin
clud
ing
pest
icid
es.
Abs
orpt
ion
Ref
lect
ion
No.
Pest
icid
eSo
lven
tλ m
ax(n
m)
Med
ium
λ max
(nm
)R
efer
ence
12,
4-D
N.R
.24
0Si
lica
gel
282
Parl
ar19
9024
Fenp
ropa
thri
nA
ceto
nitr
ile27
8T
hree
Japa
nese
soils
280
Kat
agi
1993
b28
Esf
enva
lera
teA
q.ac
eton
itrile
277
Kao
linite
276
Kat
agi
1991
115
Hex
achl
orob
enze
neH
exan
e21
8,23
1(s
h)Si
lica
gel
241,
255,
288
Gab
etal
.19
75b
121
Pent
achl
orop
heno
lH
exan
e21
8,23
1(s
h),
305
(br)
Silic
age
l/ads
orbe
d24
7,31
0G
abet
al.
1975
b12
4Ph
oto-
diel
drin
Hex
ane
193
Silic
age
l/ads
orbe
d26
4Pa
rlar
1980
130
DD
TH
exan
e23
5,26
5(b
r)Si
lica
gel/a
dsor
bed
240,
270
(br)
Parl
ar19
8013
5Pa
rath
ion
N.R
.26
6Si
lica
gel
291
Parl
ar19
9014
2T
olcl
ofos
-met
hyl
Aq.
acet
onitr
ile27
5,28
2K
aolin
ite27
5,28
3K
atag
i19
9018
5A
traz
ine
Met
hano
l22
6,26
8Si
lica
gel
233,
268
Frei
and
Nom
ura
1968
225
Para
quat
Aqu
eous
255
5%N
a-he
ctri
tesu
spen
sion
263
Bai
ley
and
Kar
ickh
off
1973
242
NM
HA
queo
us34
6N
a-m
ontm
orill
onite
Swy-
136
0M
argu
lies
etal
.19
8824
3PB
acid
pH2
&7
buff
er29
2;27
9Si
lica
gel
orka
olin
ite29
0;30
5K
atag
i19
92—
Nitr
oben
zene
Cyc
lohe
xane
257
+Si
lica
gel/s
lurr
y27
3L
eerm
aker
set
al.
1966
—N
,N-D
imet
hyla
nilin
eC
yclo
hexa
ne25
7,29
7+
Silic
age
l/slu
rry
238,
276
Lee
rmak
ers
etal
.19
66—
Eth
ylpy
ruva
teC
yclo
hexa
ne33
8+
Silic
age
l/slu
rry
323
Lee
rmak
ers
etal
.19
66—
PBB
Hex
ane
253
Silic
age
l28
5,32
58s
h9P
ere
etal
.20
01—
Thi
athr
ene
Cyc
lohe
xane
275
Na-
lapo
nite
265,
290
(sh)
,M
aoan
dT
hom
as19
9345
0–60
0(b
r)—
Cry
stal
viol
etA
queo
us59
5N
a-be
nton
ite54
5–54
7G
hosa
lan
dM
ukhe
rjee
1972
N.R
.:no
tre
port
ed;
sh:
shou
lder
;br
:br
oad;
PBB
:N
-pro
pyl
p-be
nzoy
lben
zam
ide.
86 T. Katagi
Table 3. Emission profiles of photosensitizers.
Sensitizer λmax ES ET ΦISC Reference
Acetone 300 85 78.9 0.90 � 0.98 Carmichael and Hug1989; Tsao andEto 1994
Acetophenone 330 79 73.9 1.00 Carmichael and Hug1989; Tsao andEto 1994
Xanthone 610 77.6 73.9 1.00 Carmichael and Hug1989; Ivie andCasida 1971a
Tsao and Eto 1994
Rotenone 290, 340 63 65 — Mallet and Surette1974; Rau andHormann 1981;Ke et al. 1940
Tryptophan 460 88 64.4 � 65.8 — Carmichael and Hug1989; Segura-Carretero et al.2000; Nag-Chaudhuri andAugenstein 1964
Anthraquinone 390 — 62.4 0.90 Carmichael and Hug1989; Ivie andCasida 1971a
Humic substances — — 60 � 62 — Zepp 1985; VanNoort et al. 1988
TOP-9EO 53 � 54 Tanaka et al. 1991
Riboflavin 440, 470 57.8 50 — Tsao and Eto 1994;Nag-Chaudhuriand Augenstein1964; Chambersand Kearns 1969
Eosin 580 — 45.4 0.43 Carmichael and Hug1989
Eosin Y 520 52.5 45.5 — Chambers andKearns 1969
Rose bengal — — 44.6 0.8 Tsao and Eto 1994
Rhodamine 6G 620 — 43.0 0.002 Carmichael and Hug1989
Rhodamine B 560 49.3 43.0 — Chambers andKearns 1969
Methylene blue 420 — 33.0 0.52 Carmichael and Hug1989
Photodegradation of Pesticides 87
Table 3. (Continued).
Sensitizer λmax ES ET ΦISC Reference
Chlorophyll b 316, 450 — 31.1 0.81 Carmichael and Hug1989
Chlorophyll a 460 — 29.4 0.53 Carmichael and Hug1989
λmax: absorption maximum in nm; ES & ET: energies of excited singlet and triplet states in kcalmole−1; ΦISC: quantum yield of intersystem crossing; —: not applicable; TOP-9EO: nonaethoxy-lated p-(1,1,3,3-tetramethylbutyl)phenol.
88 T. Katagi
Table 4. Reactions of pesticides with active oxygen species.
Source ofNo. Pesticide active oxygen species Reference
Singlet oxygen,1O212 S-Bioallethrin Bengal red B in ethanol, O2, at Ruzo et al. 1980
360 nm
13 Phenothrin Rose bengal in acetonitrile, O2, Ruzo et al. 1982with sunlamp
17 Permethrin Rose bengal in methanol, O2, with Holmstead et al. 1978a40 W GE lamp Ruzo 1983
23 Tetramethrin Rose bengal in acetonitrile, O2, Ruzo et al. 1982with sunlamp
49 Chlorthiamid Riboflavin or methylene blue in Rajasekharan Pillai 1977methanol with sunlight
86 Benthiocarb Eosin in methanol with F40BL Draper and Crosby 1981fluorescent lamp
145 Chlorpyrifos Rose bengal in methanol, air with Walia et al. 1988600 W tungsten lamp
138 Fenitrothion Methylene blue in methanol with Verma et al. 1991200 W tungsten lamp
141 Iodofenphos Rose bengal in methanol, air with Walia et al. 1989b600 W tungsten lamp
146 Potasan Methylene blue in methanol at Abdou et al. 1988>313 nm
Hydroxyl radical, HO�51 Fenuron Aqueous humic acid suspension at Aguer and Richard 1996b
253.7 nm
86 Benthiocarb Aqueous H2O2 at >285 nm or Fen- Draper and Crosby 1981ton’s reagent Draper and Crosby 1984
90 Molinate Aqueous H2O2 at >285 nm Draper and Crosby 1984
122 Aldrin Aqueous H2O2 at >285 nm Draper and Crosby 1984
136 Parathion-methyl O3 (85–200 ppb) at >290 nm Kromer et al. 1999
142 Tolclofos-methyl Clay aqueous suspension at >320 Katagi 1990nm
185 Atrazine Aqueous H2O2 at >290 nm Sanlaville et al. 1996Aqueous Fe(ClO4)3 with sunlight Larson et al. 1991Aqueous semiconductor suspen- Pelizzetti et al. 1993
sion at >340 nm
243 PBacid Fenton’s reagent, N2 Katagi 1992
Ozone, O313 Phenothrin Electric discharge, hexane Ruzo et al. 1982
23 Tetramethrin Electric discharge, hexane Ruzo et al. 1982
135 Parathion Laboratory ozonizer (30–300 ppb) Spencer et al. 1980
Micro-ozonizer Gunther et al. 1970
136 Parathion-methyl Laboratory ozonizer (85–200 ppb) Kromer et al. 1999
Photodegradation of Pesticides 89
Tab
le5.
Com
posi
tion
ofso
lubl
ecu
ticul
arw
axes
offr
uits
and
leav
es.
Com
posi
tion
(%of
wax
)(m
ajor
hom
olog
ue)
Plan
tsp
ecie
sQ
uant
itya /
Ext
ract
bH
CA
LC
AL
DA
CE
SO
ther
sR
efer
ence
<Fru
its>
Mar
shgr
apef
ruit
McD
onal
det
al.
1993
-/C
HC
l 318
.23.
234
.7—
—43
.9(t
erpe
noid
)
App
leB
eldi
nget
al.
1998
989/
CH
Cl 3
18.9
10.2
—69
.8—
0.8
(ket
ones
)[C
29]
[C28
][u
rsol
ic]
Ora
nge
Bak
eret
al.
1975
30�
50/C
HC
l 340
.112
.028
.519
.3—
—[C
27,2
9,31
][C
24,2
6,28
][C
24,2
6,28
][C
26,2
8,30
,32]
Lem
onB
aker
etal
.19
7520�
40/C
HC
l 322
.915
.043
.418
.7—
—[C
29,3
1][C
24,2
6,28
][C
24,2
6,28
,30]
[C24
,28,
30,3
2]
Gra
peR
adle
ran
dH
orn
1965
N.R
./lig
ht1
4012
718
—pe
trol
eum
[C25
,27,
29,3
1][C
24,2
6,28
][C
24,2
6,28
][C
20,2
4,26
][C
46]
Tom
ato
Bak
eret
al.
1982
16�
21/C
HC
l 330
–50
——
<0.5
—30�
50(a
myr
in)
[C29
,31]
5�
30(n
arin
geni
n)
Egg
plan
tB
aker
etal
.19
75N
.R.
53—
—47
——
90 T. Katagi
Tab
le5.
(Con
tinue
d).
Com
posi
tion
(%of
wax
)(m
ajor
hom
olog
ue)
Plan
tsp
ecie
sQ
uant
itya /
Ext
ract
bH
CA
LC
AL
DA
CE
SO
ther
sR
efer
ence
<Lea
ves>
Bitt
eror
ange
Haa
san
dSc
honh
err
1979
9.8/
CH
Cl 3
6�
2731�
55—
18�
3113�
35—
[C29
,31,
33]
[C26
,32,
34]
[C16
,18]
[C40
,42]
Peac
hB
ukov
acet
al.
1979
40�
69/C
HC
l 3�
10�
20—
�20
20�
3010�
20(s
tero
l)B
aker
etal
.19
79[C
25,2
7,29
,31]
[C26
,28,
30,3
2][u
rsol
ic]
[C48
,50,
52]
Tea
crab
appl
eB
aker
and
Hun
t19
8138
/CH
Cl 3−
�30
�20
—�
30�
5�
10(β
-am
yrin
)et
her
(1/1
)[C
29,3
1][C
26,2
8,30
][u
rsol
ic]
[C40
,42,
44]
Che
rry
Bak
eran
dH
unt
1981
24/C
HC
l 3−�
5�
10—
�70
<5—
ethe
r(1
/1)
[C29
,31]
[C26
,28]
[urs
olic
][C
42,4
4,46
]
Gra
peB
aker
and
Hun
t19
8112
/CH
Cl 3−
�10
�80
—<5
�5
Tra
ceet
her
(1/1
)[C
29,3
1][C
26,2
8][C
16,1
8][C
42,4
4,46
,48,
50]
(C29
,31
keto
nes)
Ric
eO
’Too
leet
al.
1979
0.42
6/C
HC
l 3�
60—
——
——
[C33
]
Oat
Ben
gsto
net
al.
1978
9�
21/C
HC
l 30.
3�
6.6
39�
65—
2.9�
4.9
——
[C26
]
Bar
ley
Lar
sson
and
Sven
ning
s-16
.1/C
HC
l 31.
082
7.0
1.7
6.1
�7
son
1986
[C29
,31,
33]
[C26
][C
26]
[C16
,18,
26]
[C42
,44,
46,4
8](β
-dik
eton
es)
Sven
ning
sson
1988
Photodegradation of Pesticides 91
Tab
le5.
(Con
tinue
d).
Com
posi
tion
(%of
wax
)(m
ajor
hom
olog
ue)
Plan
tsp
ecie
sQ
uant
itya /
Ext
ract
bH
CA
LC
AL
DA
CE
SO
ther
sR
efer
ence
Cor
nB
arta
and
Kom
ives
1984
N.R
./CH
Cl 3
3.5
59.4
19.5
4.8
12.8
—[C
31]
[C32
][C
32]
[C24
][C
56]
Mai
zeA
vato
etal
.19
90N
.R./C
HC
l 317
149
1442
4(s
tero
ls)
[C29
,31,
33]
[C26
,28,
30,3
2][C
28,3
0,32
][C
26,2
8,30
][C
44,4
6]
Dw
arf
bean
Bak
eran
dH
unt
1981
0.9/
CH
Cl 3−
�5
�80
—<5
�10
Tra
ceet
her
(1/1
)[C
29,3
1,33
][C
26]
[C16
][C
44,5
0](t
rite
rpen
oids
)
Suga
rbe
etB
aker
and
Hun
t19
813.
9/C
HC
l 3−<5
�70
——
�10
�5
ethe
r(1
/1)
[C29
,31,
33]
[C22
,24,
26]
[C38
,40,
42,4
4](β
-sito
ster
ols)
Spin
ach
Bak
er19
825�
10/N
.R.
—>6
0—
——
—
Pota
toSe
n19
875.
4/C
HC
l 339
.024
.58.
62.
219
.65.
9(C
23,2
5ke
tone
s)[C
27,2
9,31
][C
18–3
4][C
22–2
8][C
18–3
4][C
42,4
4]
Whi
tecl
over
Bak
eran
dH
unt
1981
16/C
HC
l 3−�
5�
50�
5<5
�20
—et
her
(1/1
)[C
29,3
1][C
30]
[C26
,28,
30]
[C42
,44,
46,4
8]
ain
µgcm
−2.
b Org
anic
solv
ent
used
for
extr
actio
n.“—
”or
N.R
.:no
tre
port
ed.
Com
posi
tion:
HC
:hy
droc
arbo
n;A
LC
:al
coho
l;A
LD
:al
dehy
de;
AC
:ac
id;
ES:
este
r.
92 T. Katagi
Table 6. Diffusion coefficients.
No. Chemicals Mediuma MCb pH OMb °C Db Reference
Soil and clay1 2,4-D Silt loam 32.5 6.4 7.1 23 6.33 Scott and Phillips
(3/69/28) 1973
33 Propachlor Silt loam 23 7.3 2 27 2.28 Ritter et al. 1973(15/70/15)
50 Diphenamid Silt loam 38 6.4 7.1 24 2.59 Scott and Phillips(3/69/28) 1972
55 Flumeturon Silt loam 32.5 6.4 7.1 23 2.17 Scott and Phillips(3/69/28) 1973
80 Chlorpropham Silt loam 25 6.4 7.1 24 6.22 Scott and Phillips(3/69/28) 1972
114 Lindane Silt loam 10 — 0.58 30 1.57 Ehlers et al. 1969a(–/–/18)
123 Dieldrin Clay loam 53RH 7.8 0.2 20 0.051 Farmer and Jensen(14/19/67) 1970
135 Parathion Silt loam — — 0.5 25 0.6–2.9 Gerstl et al. 1979(–/–/20)
144 Diazinon Silt loam 23 7.3 2 27 0.48 Ritter et al. 1973(15/70/15)
163 Disulfoton Silt loam 32.8 7.8 2.7* 20 0.13 Graham-Bryce(–/–/18) 1969
165 Dimethoate Silt loam 32.8 7.8 2.7* 20 4.94 Graham-Bryce(–/–/18) 1969
185 Atrazine Silt loam 23 7.3 2 27 1.37 Ritter et al. 1973(15/70/15)
Silt loam 38 6.4 7.1 24 3.70 Scott and Phillips(3/69/28) 1972
186 Simazine Silt loam 38 6.4 7.1 24 3.28 Scott and Phillips(3/69/28) 1972
187 Prometone Silt loam 38 6.4 7.1 24 7.69 Scott and Phillips(3/69/28) 1972
194 Triticonazole Loam clay — 8.2 1.0 22 3.0 Beigel et al. 1997(15/54/29)
232 Trifluralin Silt loam 30.4 6.7 4.8 22 0.20 Jacques and(17/66/17) Harvey 1979
Silt loam 38 6.4 7.1 24 0.52 Scott and Phillips(3/69/28) 1972
Kaolinite clay 28 0.003 Balmer et al. 2000
235 Oryzalin Silt loam 30.4 6.7 4.8 22 0.05 Jacques and(17/66/17) Harvey 1979
— Urea (9–41/16– 7–27 — — 25 0.8–7 Sadeghi et al.67/10–51) 1989
Photodegradation of Pesticides 93
Table 6. (Continued).
No. Chemicals Mediuma MCb pH OMb °C Db Reference
— PEG4000 Sandy loam 30–50 — 2.5 25 0.3–1.6 Barraclough and(38/47/15) Nye 1979
— p-Nitroanisole Kaolinite 28 0.0069 Balmer et al. 2000
Waxes and cuticles1 2,4-D Barley waxes 25 1 × 10−6 Schreiber and
Schonherr 1993Isolated citrus 3 × 10−4 Schonherr and
cuticles Riederer 1989
121 Pentachloro- Barley waxes 25 2 × 10−6 Schreiber andpenol Schonherr 1993
185 Atrazine Isolated citrus 9 × 10−5 Schonherr andcuticles Riederer 1989
189 Triadimenol Barley waxes 25 4 × 10−7 Schreiber andSchonherr 1993
Water— Eight Water 23 51.8 Scott and Phillips
pesticides 1973
aMedium: values in the parentheses are weight % of sand, silt, and clay in soil.bMC: soil moisture content in %; RH: relative humidity; OM: soil organic matter content in % (*,soil organic carbon content); D: apparent diffusion coefficient in mm2 day−1.
94 T. Katagi
Table 7. Photodegradation of pesticides on glass and silica gel surfaces.
Carrier (Label), Light sourceApp DT50 (wavelength or
No. Pesticide (light/dark) season, filter) Reference
1 2,4-D GL(14C) UV fluorescent lamp Venkatesh andN.R. (max. 356 nm) Harrison 1999
3 MCPA GL, 6 × 103 Sunlight (summer) Crosby and Bow-2.5 d/N.R. ers 1985
10 Allethrin GL (14C), 2.6 275W G.E. sunlamp Chen and Casida<5 hr/>32 hr 1969GL, 300 RPR 3500 UV lamp Kimmel et al. 1982N.R. (> 290 nm, Pyrex
glass)GL, 4 × 103 15W Fluorescence Isobe et al. 1984N.R. lamp
13 Phenothrin GL, 100–300 Sunlight (Sept.) Ruzo et al. 1982N.R.GL (10EC), 30– Sunlight (summer) Samsonov and
1000 Makarov 1996�3 hr/N.R.
14 Cyphenothrin SG (14C) RPR 3500A UV lamp Dureja et al. 1984�2 hr/N.R. (max. 360 nm)
15 Resmethrin SG (14C), 10–17 Sunlight Ueda et al. 1974N.R.
16 Kadethrin GL (14C), 35 Sunlight Ohsawa andN.R. Casida 1979
22 Deltamethrin GL (14C), 40 Sunlight Ruzo et al. 1977N.R.
23 Tetramethrin GL (14C), 2.6 275W G.E. sunlamp Chen and Casida<5 hr/>32 hr 1969GL, 100–300 Sunlight (Sept.) Ruzo et al. 1982N.R.
25 Tralomethrin GL (14C), 100 Sunlight Ruzo and CasidaN.R. 1981
26 Tralocythrin GL (14C), 100 Sunlight Ruzo and CasidaN.R. 1981
27 Fenvalerate GL, 127 Sunlight (July–Aug., Holmstead et al.4 d Pyrex glass) 1978b
29 Flucythrinate GL UV light in a Rayonet Chattopadhyaya11.8 hr/N.R. reactor and Dureja 1991
30 Fulvalinate GL (14C), 2–4 Sunlight, outdoors Quinstad and1 d/N.R. Staiger 1984
Photodegradation of Pesticides 95
Table 7. (Continued).
Carrier (Label), Light sourceApp DT50 (wavelength or
No. Pesticide (light/dark) season, filter) Reference
31 Acrinathrin GL, 0.3–10 500 W high-pressure Samsonov andHg lamp Pokrovskii 2001
2.7 hr/N.R. (313 nm, glass filter)
32 Etofenprox GL, 1–4 RPR 3000 UV lamp Class et al. 19891.7 d (290–320 nm, Pyrex
glass)GL, 140 GL10 UV lamp (254 Tsao and Eto1.94 hr nm) 1990b
34 Alachlor GL Sunlight (Mar.–Apr.) Fang 19776 hr/N.R.
36 Butachlor GL Germicidal lamp (254 Chen and Chen1.5 hr/N.R. nm) 1978
38 Mepronil SG (14C) Sunlight (Sept.–Dec.) Yumita and Yama-36 d/N.R. moto 1982SG, 25 400W high-pressure Yumita et al. 1984N.R. Hg lamp (max. 365
nm)
39 Flutolanil GL, 2.5 × 103 Germicidal UV lamp Tsao and Eto 1991N.R. (254 nm)
40 Niclosamide SG (14C) Long-wave lamp Schultz and Har-20.5 hr/>7 d (290–405 nm) man 1978
41 Naproanilide GL UV germicidal GL10 Tsao and EtoN.R. lamp (>254 nm) 1990a
42 Carboxin GL Sunlight Buchenauer 1975�10 hr/N.R.
46 Isoxaben SG Xenon lamp (Hereaus Mamouni et al.N.R. Suntest) 1992
57 Diafenthiuron TF UV light Drabek et al. 19921 hr/N.R.
59 Diflubenzuron GL, SG RUL 3000 lamp (max. Ruzo et al. 1974N.R. 300 nm)SG(14C), 4.0 Sunlight (summer) Bull and Ivie 1976�4 wk/N.R.
66 Aminocarb SG (14C), 400 UV light at 253.7 nm Abdel-Wahab andN.R. Casida 1967
67 Mexacarbate SG (14C, 3H), 400 UV light at 253.7 nm Abdel-Wahab andN.R. Casida 1967
96 T. Katagi
Table 7. (Continued).
Carrier (Label), Light sourceApp DT50 (wavelength or
No. Pesticide (light/dark) season, filter) Reference
78 Pirimicarb GL 125W high-pressure Pirisi et al. 199664 min Hg lamp (> 290
nm, Pyrex glass)CE, 0.03 Sunlight (Feb.), out-19 min doors
84 Phenmedi- SG UV light from Xe Schafmeier et al.pham 15 d/144 d lamp (Heraeus sun- 1998
test)
85 Fenothiocarb SG (14C) Sunlight (Sept.–Oct.) Unai and Tomi-45 hr/N.R. zawa 1986
86 Benthiocarb GL (14C) High-pressure Hg Ishikawa et al.1.7 hr/N.R. lamp (max. 365 1977
nm)GL (14C), 1 × 104 Sunlight (3.5–4.5 mW Cheng and HwangN.R. cm−2) 1996
89 Benfuracarb GL Low-pressure Hg Dureja et al. 1990N.R. lamp (254 nm)
91 Cartap GL, 12.7 Germicidal lamp (373 Tsao and Eto 1989N.R. nm)
92 Thiophanate- GL (14C), 33 Sunlight (May–Aug.), Soeda et al. 1972methyl 2.8 d/N.R. outdoors
93 MBC SG (3T,14C), 5.5 Sunlight (July) Fleeker and LacyN.R. 1977
96 Chlorsulfuron SG 125W high-pressure Herrmann et al.60 hr/N.R. Hg lamp (>290 nm, 1985
borosilicate glass)
99 Tribenuron- GL Sunlight (May) or UV Bhattacharjee andmethyl 7 d or 11 hr/N.R. light (max. 254 nm) Dureja 2002
113 DDOD GL (14C), 6.6 500 W Xenon arc Sumida et al. 1973lamp
8 d/>20 d
121 Pentachloro- GL, 1 × 103 125 W high-pressure Piccinini et al.phenol N.R. Hg lamp (>290 nm, 1998
water filter)
122 Aldrin GL Sunlight (June–July) Rosen and Suther-N.R. land 1967SG 125 W high-pressure Gab et al. 1975aN.R. Hg lamp (>290 nm,
Pyrex glass)
Photodegradation of Pesticides 97
Table 7. (Continued).
Carrier (Label), Light sourceApp DT50 (wavelength or
No. Pesticide (light/dark) season, filter) Reference
123 Dieldrin GL GE G30T8 germicidal Benson 19711 hr/N.R. lamp
125 Endosulfan GL Sunlight (Mar.) Dureja and Muker-N.R. jee 1982
128 Chlordane GL, 890 Sunlight (summer) Benson et al. 1971N.R.SG 125 W high-pressure Gab et al. 1975aN.R. Hg lamp (>290 nm,
Pyrex glass)
130 DDT GL (14C) 15W germicidal lamp Mosier et al. 1969N.R. (254 nm)
136 Parathion- GL (14C), 0.84 Xe lamp in Suntest Kromer et al. 1999methyl �1 d/>1 d CPS+ (>290 nm,
volatility chamber)
137 Cyanophos SG (14C) Sunlight (Sept.–Oct.), Mikami et al. 19764 d/N.R. outdoors
138 Fenitrothion SG (14C) 172.5 W high-pressure Ohkawa et al.15 min–6 d/N.R. Hg lamp or sunlight 1974b
(Nov.)
141 Iodofenphos GL 1 kW metal halide Walia et al. 1989bN.R. lamp (Applied Pho-
tophysics 9500)
143 Fenthion GL Fluorescent lamp Hirahara et al.0.02–1.34 hr/N.R. (380–750 nm), UV 2001
light (UV-A, UV-B,UV-C)
145 Chlorpyrifos GL Low-pressure Hg Walia et al. 198818.7 d/N.R. lamp (254 nm)FP (14C), 1.18 UV light (Pyrex glass) Meikle et al. 19833.2 d/N.R.
148 Quinalphos GL Low-pressure UV Dureja et al. 1988N.R. lamp (254 nm)
150 Pyridafenthion GL, 6.4 Black light fluores- Tsao et al. 1989N.R. cence lamp (>300
nm)
152 Phoxim GL UV light (254 nm & Makary et al. 19814–19 hr/N.R. 350 nm, uncovered
Petri dish)
98 T. Katagi
Table 7. (Continued).
Carrier (Label), Light sourceApp DT50 (wavelength or
No. Pesticide (light/dark) season, filter) Reference
156 Monocroto- GL (32P) Sunlight in a green- Lindquist and Bullphos 5.5 d/N.R. house. 1967
GL, 1.6 15W germicidal lamp Dureja 1989N.R. (253.7 nm) or sun-
light (Apr.–May)
159 Propaphos SG, GL (14C) Sunlight (Apr.–Aug.) Fujii et al. 19791.2 hr/>72 hr
161 Sulprofos GL (14C), 53 Sunlight (summer) Ivie and Bull 19761.1 d/N.R.
162 Phorate GL Germicidal lamp (254 Sharma and Gupta5 hr/>13 hr nm) 1994
163 Disulfoton GL Fluorescent lamp Hirahara et al.0.41–43.3 hr/N.R. (380–750 nm), UV 2001
light (UV-A, UV-B,UV-C)
165 Dimethoate GL (32P) Sunlight in a green- Dauterman et al.N.R. house. 1960
167 Malathion GL (F) UV (253.7 nm) or Awad et al. 1967N.R. fluorescent (366
nm) light
168 Phenthoate GL (14C,32P) Sunlight (Mar. & Takade et al. 1976<3 d/N.R. Sept.)SG (14C) Sunlight (Sept.–Oct.), Mikami et al.4 d/>8 d outdoors 1977b
170 Phosalone GL 1 kW high-pressure Walia et al. 1989a8.5 d/>15 d metal-halide lamp
(>300 nm)
173 Edifenphos GL (32P), 5.0 UV light Ishizuka et al.�10 d/N.R. 1973
175 Isofenphos GL Low-pressure Hg Dureja et al. 1989N.R. lamp
176 S-2571 SG (3T), 300 172.5W high-pressure Mikami et al.N.R. Hg lamp 1977a
180 Cyanofenphos SG (14C) Sunlight (Sept.–Oct.), Mikami et al.19762 d/N.R. outdoors
181 Leptophos SG (32P) UV light (310 nm) Zayed et al. 19783.4 d/N.R.GL, 100 Sunlight Riskallah et al.20 d/N.R. 1979
Photodegradation of Pesticides 99
Table 7. (Continued).
Carrier (Label), Light sourceApp DT50 (wavelength or
No. Pesticide (light/dark) season, filter) Reference
183 Dioxaben- SG (14C) Sunlight (Sept.–Oct.), Mikami et al.zofos 2 d/>8 d outdoors 1977b
188 Triadimefon GL, 32 UV light (254 nm) or Nag and Dureja1.3–2.8 hr/N.R. sunlight (Sept.) 1996
189 Triadimenol GL, 51 400 W medium-pres- Clark and WatkinsN.R. sure Hg lamp (boro- 1986
silicate glass)
190 Diniconazole- GL, 50 Sunlight (June) Sharma and Chib-M N.R. ber 1997
191 Propiconazole GL, 147 Sunlight Dureja et al. 1987aN.R.
195 Fluotrimazole GL, 13-50 100 W medium-pres- Clark et al. 1983N.R. sure Hg lamp (boro-
silicate) or summersunlight
200 Bentazone GL (14C) UV lamps (300 & 350 Nilles and Zabik>5 d/N.R. nm) 1975
204 Isoprothiolane SG 10 W germicidal lamp Chou et al. 19803 hr/N.R. (254 nm)
206 Perfluidone GL, 33.6 UV light (254 or 365 Ketchersid and3–6 wk/N.R. nm) Merkle 1975
207 Chlordime- SG (14C) Sunlight Knowles and Senform N.R. Gupta 1969
212 Thiabendazole GL (14C), 19 Sunlight in a green- Jacob et al. 1975>4 mon/N.R. house
220 Fipronil SG, GL, FP Sunlight Hainzl and CasidaN.R. 1996
222 Buprofezin GL Sunlight (Feb.–Mar.) Datta and Walia15 d/N.R. 1997
223 Sethoxydim GL (14C) Sunlight in a green- Campbell and Pen-<1 hr/N.R. house (350 µE m−2 ner 1985a
sec−1)
224 Alloxydim SG (14C) 12W UV light (253.7 Soeda et al. 19790.7, 4.4 hr/ N.R. or 365 nm)
226 Diquat SG (14C) Sunlight (May –June), Smith and GroveN.R. outdoors 1969
232 Trifluralin GL Sunlight (June–July) Wright and WarrenN.R. 1965
100 T. Katagi
Table 7. (Continued).
Carrier (Label), Light sourceApp DT50 (wavelength or
No. Pesticide (light/dark) season, filter) Reference
236 Fluchloralin GL (14C) RPR UV light (300 & Nilles and Zabik48 hr/N.R. 350 nm, Pyrex 1974
glass)
SG (14C) Sunlight (Aug.–Oct.)N.R.
238 Pendimethalin GL Low-pressure Hg Dureja and WaliaN.R. lamp (254 nm) 1989
241 Fentin acetate SG (14C) 125W high-pressure Barns et al. 1973N.R. Hg lamp (max. 365
nm)
245 Guazatine GL (14C), 0.5 Sunlight lamp (950 Sato et al. 1985b36 hr/N.R. µE m−2 sec−1)
246 Methoprene GL (14C), 11 Sunlight (Oct.) Quinstad et al.6 hr/N.R. 1975
249 Cinmethylin GL, 2 × 103 1 kW Xe lamp (Oriel Grayson et al.N.R. solar simulator, 1987
AM1 filter)
250 Avermectin GL, 0.7 Sunlight Crouch et al. 1991B1a 2–3 hr/N.R.
251 MAB1a GL, 0.7 275 W Suntanner RS Feely et al. 19926.2 hr/N.R. bulb (60–70 mW
cm−2 h−1)
253 Azadirachtin- GL UV light (254 nm) Dureja and John-A 48 min/N.R. son 2000
Medium: Thin film of a pesticide is basically prepared from its organic solution followed by vapor-ization of solvent. When unspecified, nonradiolabeled pesticide was used.“F,” formulation. Materials of carrier are glass (GL), silica gel (SG), filter paper (FP), cellulosesheet (CE), and Teflon sheet (TF). Label, radiolabel; App, application rate in µg cm−2 if describedin the literature; N.R., not reported.
Photodegradation of Pesticides 101
Table 8. Photodegradation of pesticides in organic solvent as model plant cuticles.
Light sourceMedium (wavelength or
No. Pesticide DT50 season, UV filter) Reference
17 Permethrin Methanol RPR 3000 lamp Holmstead et al.1–1.5 hr (290–320 nm) 1978a
21 Cyhalothrin Cyclohexane RPR 3000 UV lamp Ruzo et al. 1987N.R. (290–320 nm,
Pyrex glass)
22 Deltamethrin Hexane Summer sunlight Maguire 1990�2 days (Pyrex glass, out-
doors)Hexane Sunlight Ruzo et al. 1977N.R.
27 Fenvalerate Hexane RPR 3000 UV lamp Holmstead et al.18 min (290–320 nm, 1978b
Pyrex glass)
32 Etofenprox Methanol RPR 3000 UV lamp Class et al. 19895.8 days (290–320 nm,
Pyrex glass)
59 Diflubenzuron Methanol RUL 3000 lamp Ruzo et al. 1974N.R. (>285 nm, borosili-
cate glass)
63 Xylylcarb Ethanol UV light (>265 nm) Kumar et al. 197422.6 hr
64 Trimethacarb Cyclohexane 1 kW Xe-Hg lamp Addison et al.N.R. (>300 nm, Corning 1974
0-54 filter)
65 Propoxur Organic solvents 150 W Hg lamp Schwack and Kopf12–39 hr (>280 nm, WG295 1992
filter)
66 Aminocarb Cyclohexane 1 kW Xe-Hg lamp Addison et al.N.R. (>300 nm, Corning 1974
0-54 filter)Ethanol UV light (>265 nm) Kumar et al. 197416.4 hr
69 Ethiofencarb Organic solvents 150 W Hg lamp Kopf and Schwack1.3–5.5 hr (>280 nm, WG295 1995
filter)
78 Pirimicarb Organic solvents 150 W Hg lamp Schwack and Kopf60–140 min (>280 nm, WG295 1993
filter)
96 Chlorsulfuron Methanol 20W low-pressure Yang et al. 19996.3 hr Hg lamp
102 T. Katagi
Table 8. (Continued).
Light sourceMedium (wavelength or
No. Pesticide DT50 season, UV filter) Reference
98 Metsulfuron Methanol 20W low-pressure Yang et al. 1999methyl 1.8 hr Hg lamp
99 Tribenuron 2-Propanol 125W medium- Bhattacharjee andmethyl 1.7 hr pressure Hg lamp Dureja 1999
102 Chlorimuron- Hexane 125W Medium- Choudhury andethyl 55.8 min pressure Hg lamp Dureja 1997b
(Pyrex glass)
106 Captan Organic solvents 150W Hg lamp Schwack and37–420 min (>280nm, WG295 Floßer-Muller
filter) 1990
107 Folpet Cyclohexene 150W Hg lamp Schwack 1990N.R. (WG295, 305, 320,
335 & 345 filters)
108 Procymidone Organic solvents 150W Hg lamp Schwack et al.N.R. (>280nm, WG295 1995b
filter)
109 Iprodione Organic solvents 150W Hg lamp Schwack et al.N.R. (>280nm, WG295 1995a
filter)
110 Vinclozolin Organic solvents 150W Hg lamp Schwack et al.N.R. (>280nm, WG295 1995c
filter)
125 Endosulfan Hexane High-pressure Hg Dureja and Muker-N.R. lamp (>300 nm) jee 1982
130 DDT Methyl oleate 150W Hg lamp Schwack 1988N.R. (>280 nm)
134 Methoxychlor Methyl oleate 150W Hg lamp Schwack 1988N.R. (>280 nm)
135 Parathion 12-Hydroxy- UV-B Fluorescent Schwack et al.stearate/TL sunlamp (max, 315 1994
N.R. nm)2-Propanol 1kW Tungsten-N.R. halogen lamp
(>280 nm)Cyclohexene 150W Hg lamp Schwack 1987N.R. (>280 nm, WG295
filter)
138 Fenitrothion Hexane Low-pressure u.v. Greenhalgh and85 min Pen Ray lamp Marshall 1976
(253.7 nm)
Photodegradation of Pesticides 103
Table 8. (Continued).
Light sourceMedium (wavelength or
No. Pesticide DT50 season, UV filter) Reference
Methanol Low-pressure u.v.120 min Pen Ray lamp
(253.7 nm)
141 Iodofenphos Hexane 1 kW Metal halide Walia et al. 1989bN.R. lamp (Applied
Photophysics9500)
145 Chlorpyrifos Hexane High-pressure Hg Walia et al. 1988N.R. lamp
154 Tetrachlovinphos Hexane Medium-pressure Hg Dureja et al. 1987b4.5 hr lamp
170 Phosalone Hexane 125 W High-pressure Walia et al. 1989aN.R. Hg lamp (254–360
nm)
188 Triadimefon Methanol 400 W Medium- Clark et al. 1978N.R. pressure Hg lamp
(borosilicate glass)Hexane, methanol 125 W medium- Nag and Dureja2.5–2.8 hr pressure Hg lamp 1997
192 Hexaconazole Hexane 125 W Hg lamp, Santoro et al. 200023.1 hr Pyrex
193 Penconazole Organic solvents Tungsten halogen Schwack and Hart-5–23 hr lamp (WG305 or mann 1994
WG320 filter)
195 Fluotrimazole Methanol 100 W medium- Clark et al. 1983N.R. pressure Hg lamp
(borosilicate glass)
211 Anilazine Methyl oleate Metal halogen lamp Breithaupt andN.R. (WG295 filter) Schwack 2000Cyclohexene Metal halogen lamp8.0 or 15.0 min (WG295 or WG
320 filter)
220 Fipronil Methanol UV light (max. 300 Hainzl and CasidaN.R. nm, cutoff of 280– 1996
290 nm)
228 Chinomethionat Unsat. fatty acids/ Fluorescent black Nutahara andTL light Murai 1984
N.R.
N.R.: not reported; TL, as a thin layer.
104 T. Katagi
Table 9. Photodegradation of pesticides in plant waxes and cuticles.
Wax (W),Cuticle (C) Light source
No. Pesticide DT50 (wavelength, filter) Reference
66 Aminocarb Nectarine fruits W. 125 W Hg lamp (>290 Pirisi et al. 200159 min nm, borosilicate glass)
68 Methiocarb Nectarine fruits W. 125 W Hg lamp (>290 Pirisi et al. 2001436 min nm, borosilicate glass)
78 Primicarb Nectarine fruits W. 125 W Hg lamp (>290 Pirisi et al. 2001222 min nm, borosilicate glass)Fruits W. 125 W Hg lamp (>290 Pirisi et al. 199835–449 min nm, borosilicate glass)Fruits W. Sunlight15–331 min (May–June, 39 °N)
117 Chlorothalonil Tomato fruits C. Simulated sunlight Jahn et al. 1999N.R. (Suntest CPS+)
129 2,3,7,8-TCDD Laurel cherry W. Sunlight and 300 W Schuler et al.4–9 hr high-pressure Hg 1998
lamps
135 Parathion Fruits C. UV-fluorescent sunlamp Schynowski and2.1–13.5 hr (max, 315 nm) Schwack 1996
143 Fenthion Nectarine fruits W. 125 W Hg lamp (>290 Pirisi et al. 2001204 min nm, borosilicate glass)
Fruits W. Sunlight Cabras et al.2.4–11.9 hr 1997b
N.R., not reported.
Photodegradation of Pesticides 105
Tab
le10
.Ph
otod
egra
datio
nof
pest
icid
esin
and
onso
il(c
lay)
thin
-lay
ersu
rfac
es.
Soil
prop
erti
esan
dap
plic
atio
nra
tea)
App
licat
ion
med
ium
b)L
ight
sour
ce(w
avel
engt
hor
#Pe
stic
ide
DT
50(l
ight
/dar
k)se
ason
,fi
lter)
,te
mp
(°C
)R
efer
ence
12,
4-D
Fou
rso
ils(-
/4.4�
7.6/
-),3
0�
m,3
3�
gcm
−2H
auta
la19
78A
ceto
neso
ln.
450W
Med
ium
-pre
ssur
e3.
3�
7.8
d/N
.R.
Hg
lam
p(P
yrex
glas
s)
4M
ecop
rop
Thr
eeso
ils(1
.4�
2.1/
-/-)
,1m
m,0
.125�
gcm
−2R
omer
oet
al.
1998
Met
hano
lso
ln.
Sunl
ight
(Oct
.),
outd
oors
10�
15d/
N.R
.
7T
ricl
opyr
Silt
ycl
aylo
amso
ils,f
ield
(1�
5/-/
-),-
,34�
gcm
−2N
orri
set
al.
1987
Form
ulat
ion
Sunl
ight
75�
81d/
N.R
.
17Pe
rmet
hrin
Dun
kirk
silt
loam
soil
(2.6
/6.0
/-),
0.25
mm
,0.0
2�
gcm
−2H
olm
stea
det
al.
1978
a14
C,
N.R
.Su
nlig
htN
.R.
18T
eflu
thri
nL
oam
soil
(5.0
/6.5
/-),
-,60
0g
ha−1
EPA
FIFR
A19
9914
C,
N.R
.X
ela
mp
(4.5
hrd−1
)>3
1d/
N.R
.25
°C19
Cyp
erm
ethr
inT
hree
Japa
nese
soils
(2�
15/5�
6/1�
12),
0.5m
m,1
.1�
gcm
−2T
akah
ashi
etal
.19
85a
14C
,di
ethy
let
her
soln
.Su
nlig
ht(A
ug.)
,ou
tdoo
rs0.
6�
1.9
d/>7
dSa
ndy
loam
soil
(1.8
/6.9
/-),
-,-
EPA
FIFR
A19
9914
C,
N.R
.Su
nlig
ht�
56d/
76�
100
d
106 T. Katagi
Tab
le10
.(C
ontin
ued)
.
Soil
prop
erti
esan
dap
plic
atio
nra
tea)
App
licat
ion
med
ium
b)L
ight
sour
ce(w
avel
engt
hor
#Pe
stic
ide
DT
50(l
ight
/dar
k)se
ason
,fi
lter)
,te
mp
(°C
)R
efer
ence
20C
yflu
thri
nSa
ndy
loam
soil
(2.2
/5.4
/-),
-,-
EPA
FIFR
A19
9914
C,
N.R
.Su
nlig
ht5.
3d/
97.9
d
21C
yhal
othr
inR
ichv
ale,
MSF
and
Kra
caw
sty
pes
(N.R
.),-
,50�
gcm
−2R
uzo
etal
.19
87H
exan
eso
ln.
Sunl
ight
(Jun
.)N
.R.
Loa
mso
il(5
.0/6
.5/-
),-,
40g
ha−1
EPA
FIFR
A19
9914
C,
N.R
.A
rtif
icia
llig
ht,
25°C
>166
hr/N
.R.
22D
elta
met
hrin
N.R
.E
PAFI
FRA
1999
14C
,N
.R.
Xe
lam
p,co
ntin
uous
�9
d/10�
11d
24Fe
npro
path
rin
Kod
aira
light
clay
soil
(15/
5.5/
11),
0.5
mm
,1.1�
gcm
−2T
akah
ashi
etal
.19
85b
14C
,di
ethy
let
her
soln
.Su
nlig
ht(S
ept.)
,ou
tdoo
rs1
d/>2
wk
Thr
eeJa
pane
seso
ils(2�
8/5.
7�
6.6/
4�
17),
1m
m,1
0pp
mK
atag
i19
93b
14C
,ac
eton
itrile
soln
.50
0WX
ela
mp
(>29
0nm
,3�
51d/
4�
160
dPy
rex
glas
s),
25°C
27Fe
nval
erat
eT
hree
Japa
nese
soils
(2�
15/5�
6/4�
12),
0.5m
m,0
.6�
gcm
−2M
ikam
iet
al.
1980
14C
,di
ethy
let
her
Sunl
ight
(Sep
t.),
outd
oors
1.8�
18d/
>20
d
28E
sfen
vale
rate
Noi
chi
sand
ycl
aylo
amso
il(1
.4/5
.7/3
.7),
2m
m,1
0pp
mK
atag
i19
9114
C,
1,2-
dich
loro
etha
ne50
0WX
ela
mp
(>30
0nm
,10
0d/
138
dPy
rex
glas
s),
25°C
Photodegradation of Pesticides 107
Tab
le10
.(C
ontin
ued)
.
Soil
prop
erti
esan
dap
plic
atio
nra
tea)
App
licat
ion
med
ium
b)L
ight
sour
ce(w
avel
engt
hor
#Pe
stic
ide
DT
50(l
ight
/dar
k)se
ason
,fi
lter)
,te
mp
(°C
)R
efer
ence
29Fl
ucyt
hrin
ate
Fou
rso
ils(0
.3�
0.5/
6�
8.4/
-),5
mm
,7m
gcm
−2D
urej
aan
dC
hatto
padh
yay
1995
Die
thyl
ethe
rso
ln.
Sunl
ight
(at
300�
400
nm,
1�
2d/
>5d
1.6m
W)
30Fl
uval
inat
eSt
erili
zed
sand
ylo
amso
il(N
.R.)
,3�
5m
m,1
.3�
gcm
−2Q
uins
tad
and
Stai
ger
1984
14C
,N
.R.
Sunl
ight
,ou
tdoo
rs1
d/N
.R.
33Pr
opac
hlor
Thr
eeso
ils(0
.9�
3.5/
7.0�
7.5/
-),1
mm
,5�
20pp
mK
onst
antin
ouet
al.
2001
Met
hano
lso
ln.
Sunl
ight
(Jul
.)14�
32d/
N.R
.
34A
lach
lor
Thr
eeT
aiw
anso
ils(1
.5�
2.6/
5.0�
6.4/
-),-
,100
ppm
Fang
1977
Ace
tone
soln
.Su
nlig
ht(M
ar.�
Apr
.),
>8hr
/N.R
.30�
35°C
35M
etol
achl
orSi
ltlo
amso
il(N
.R.)
,-,5
.15
hgha
−1C
hest
ers
etal
.19
89N
.R.
Sunl
ight
,50�
55°C
8d/
N.R
.
37M
etal
axyl
Fou
rso
ils(0
.2�
4.6/
5�
7/60
%M
WH
C),
5m
m,0
.5�
gcm
−2Su
kul
and
Spite
ller
2001
Aqu
eous
soln
.X
enon
lam
p(>
285
nm)
,25°
C8�
21d/
36�
73d
Tw
oso
ils(0
.86�
1.0/
6.1�
7.4/
-),-
,500
ppm
Saha
and
Suku
l19
97N
.R.
Sunl
ight
7.7
d/N
.R.
40N
iclo
sam
ide
Loa
my
sand
soil
(-/5
.4/d
ryor
75%
FM
C),
2mm
,2.5
ppm
Fran
ket
al.
2002
14C
,ac
eton
itrile
soln
.X
ela
mp
(>29
0nm
,G
raeb
ing
etal
.20
027�
14d/
18d
Her
aeus
sunt
est)
,25
°C
108 T. Katagi
Tab
le10
.(C
ontin
ued)
.
Soil
prop
erti
esan
dap
plic
atio
nra
tea)
App
licat
ion
med
ium
b)L
ight
sour
ce(w
avel
engt
hor
#Pe
stic
ide
DT
50(l
ight
/dar
k)se
ason
,fi
lter)
,te
mp
(°C
)R
efer
ence
42C
arbo
xin
Sche
yern
soil
(N.R
.),2
mm
,5pp
mM
urth
yet
al.
1998
N.R
.X
ela
mp
(>29
0nm
,29
hr/N
.R.
Her
aeus
sunt
est)
,18°
C
47N
apro
pam
ide
Tw
oso
ils(0
.3�
1.7/
7.3�
7.9/
-),-
,-D
onal
dson
and
Mill
er19
96C
H2C
l 2so
ln.
Sunl
ight
3�
7d/
N.R
.
48Fl
oras
ulam
Cal
tin
silt
loam
soil
(2.9
/6.8
/dry
),-,
0.13�
0.32
ppm
Kri
eger
etal
.20
0014
C,
N.R
.Su
nlig
ht(M
ay�
Jun.
)30
d/79
d
52M
onur
onSa
nd/m
ontm
orill
onit
ean
dka
olin
ite
clay
s,-,
-Ji
rkov
sky
etal
.19
97D
ieth
ylet
her
soln
.G
L20
fluo
resc
ent
lam
pN
.R.
(>30
0nm
,gl
ass
filte
r)
53D
iuro
nSa
nd/m
ontm
orill
onit
ean
dka
olin
ite
clay
s,-,
-Ji
rkov
sky
etal
.19
97D
ieth
ylet
her
soln
.G
L20
fluo
resc
ent
lam
p20�
100
hr/N
.R.
(>30
0nm
,gl
ass
filte
r)
54L
inur
onSi
ltlo
amso
il(N
.R.)
,-,-
EPA
OPP
TS
1995
d14
C,
N.R
.X
ela
mp
(Pyr
exgl
ass)
,>1
5d/
N.R
.25
°C56
Isop
rotu
ron
Sand
ylo
amso
il(0
.35/
7.2/
-),-
,2.5
mg/
gof
soil
Kul
shre
stha
and
Muk
erje
e19
86N
.R.
Low
-pre
ssur
eH
gla
mp
N.R
.
58T
hidi
azur
onSp
eyer
soil
2.3
(1.2
/5.5
/1.5
),0.
5m
m,1
.5�
gcm
−2K
lehr
etal
.19
8314
C,
met
hano
lso
ln.
2.5k
WX
ela
mp
(>29
0nm
,0.
5hr
/51
hrW
G29
5+D
uran
filte
r),
<30°
C
Photodegradation of Pesticides 109
Tab
le10
.(C
ontin
ued)
.
Soil
prop
erti
esan
dap
plic
atio
nra
tea)
App
licat
ion
med
ium
b)L
ight
sour
ce(w
avel
engt
hor
#Pe
stic
ide
DT
50(l
ight
/dar
k)se
ason
,fi
lter)
,te
mp
(°C
)R
efer
ence
59D
iflu
benz
uron
N.R
.E
PAO
PPT
S19
97a
14C
,N
.R.
Art
ific
ial
light
11.3
d/3.
7d
65Pr
opox
urT
wo
soils
(1.0�
1.5/
5.3�
7.1/
-),-
,0.4�
0.6
ppm
EPA
OPP
TS
1997
b14
C,
met
hano
lM
ediu
m-p
ress
ure
Hg
lam
p>1
d/�
200d
(>29
0nm
,T
Q15
0fi
lter)
68M
ethi
ocar
bF
our
soils
(4.5�
7.5/
5.8�
6.3/
dry)
,-,-
Goh
rean
dM
iller
1986
CH
2Cl 2
soln
.Su
nlig
ht(J
un.�
Aug
.,7�
14d/
N.R
.K
imax
glas
s),
outd
oors
72C
arbo
fura
nO
rang
egl
ove
soil
(N.R
.),-
,44.
8�
gcm
−2N
igg
etal
.19
842.
5EC
as(4
9)Su
nlig
htN
.R.
81B
enom
ylSi
ltlo
amso
il(N
.R.)
,-,1
lbac
re−1
EPA
OPP
TS
2001
14C
,N
.R.
Sunl
ight
at25
°C<
4d/
N.R
.
82A
sula
mSa
ndy
loam
soil
(N.R
.),-
,-E
PAO
PPT
S19
95a
14C
,N
.R.
Xe
lam
p,25
�28
°C.
1.5
hr/8
3hr
83D
esm
edip
ham
Sand
ylo
amso
il(N
.R.)
,-,-
EPA
OPP
TS
1996
b14
C,
N.R
.X
ela
mp
(3-f
old
irra
diat
ion
110�
160
hr/>
500
hrof
sum
mer
noon
sunl
ight
)
84Ph
enm
edip
ham
Met
apun
toso
il(4
.8/7
.4/-
),-,
-Sc
hafm
eier
etal
.19
98A
ceto
nitr
ileso
ln.
Xe
lam
p12
d/15
d(H
erae
ussu
ntes
t)
110 T. Katagi
Tab
le10
.(C
ontin
ued)
.
Soil
prop
erti
esan
dap
plic
atio
nra
tea)
App
licat
ion
med
ium
b)L
ight
sour
ce(w
avel
engt
hor
#Pe
stic
ide
DT
50(l
ight
/dar
k)se
ason
,fi
lter)
,te
mp
(°C
)R
efer
ence
86B
enth
ioca
rbR
ice-
grow
ing
area
clay
soil
(1.9
5/4.
6/-)
,-,-
Che
ngan
dH
wan
g19
9614
C,
acet
one
soln
.Su
nlig
htN
.R.
(3.5�
4.5
mW
cm−2
)
87B
utyr
ate
Loa
mso
il(N
.R.)
,-,-
EPA
OPP
TS
1993
14C
,N
.R.
Sunl
ight
,ou
tdoo
rs,
25°C
N.R
.
88C
arbo
sulf
anO
rang
egl
ove
soil
(N.R
.),-
,44.
8�
gcm
−2N
igg
etal
.19
842.
5E
CSu
nlig
ht5.
9d/
N.R
89B
enfu
raca
rbSa
ndy
loam
soil
(N.R
.),-
,125�
gcm
−2D
urej
aet
al.
1990
N.R
.L
ow-p
ress
ure
Hg
lam
pN
.R.
(254
nm)
90M
olin
ate
Thr
eeso
ils(0
.9�
3.5/
7.0�
7.5/
-),1
mm
,5�
20pp
mK
onst
antin
ouet
al.
2001
Met
hano
lso
ln.
Sunl
ight
(Jul
.)13�
34d/
N.R
.
92T
hiop
hana
te-
Sand
ylo
amso
il(1
.7/7
.4/-
),-,
-E
PAO
PPT
S20
01m
ethy
l14
C,
N.R
.Su
nlig
ht2.
9�
5.5
d/10�
19d
94M
aneb
Del
awar
eso
il(N
.R.)
,-,2
2.4�
gcm
−2R
hode
s19
7714
C,
aque
ous
soln
.Su
nlig
ht(s
prin
g)<1
wk/
N.R
.
96C
hlor
sulf
uron
Nor
asi
lty
clay
loam
soil
(2/8
.0/-
),1
mm
,1.7�
gcm
−2St
rek
1998
14C
,pH
7bu
ffer
soln
.X
ela
mp
(>29
0nm
),25
°C50
d/13
0d
Photodegradation of Pesticides 111
Tab
le10
.(C
ontin
ued)
.
Soil
prop
erti
esan
dap
plic
atio
nra
tea)
App
licat
ion
med
ium
b)L
ight
sour
ce(w
avel
engt
hor
#Pe
stic
ide
DT
50(l
ight
/dar
k)se
ason
,fi
lter)
,te
mp
(°C
)R
efer
ence
99T
ribe
nuro
n-A
lluvi
al(1
.2/7
.5/-
),2
mm
,-B
hatta
char
jee
and
Dur
eja
2002
met
hyl
14C
,ac
eton
eso
ln.
Sunl
ight
(May
)or
u.v.
11d
or11
hr/N
.R.
light
(max
.25
4nm
)
100
Tri
asul
furo
nT
wo
soils
(0.9�
2.3/
7.0�
7.1/
dry)
,1m
m,6�
7pp
mA
lban
iset
al.
2002
Met
hano
lso
ln.
1.1k
WX
ela
mp
(Sun
test
6�
15hr
/26�
198
hrC
PS+,
>300
nm),
20°C
102
Chl
orim
uron
-T
hree
soils
(0.7�
1.2/
6.2�
8.1/
-),2
mm
,50
ppm
Cho
udhu
ryan
dD
urej
a199
7aet
hyl
N.R
.Su
nlig
ht(A
pr.�
May
),11�
21d/
N.R
.30�
35°C
103
Rim
sulf
uron
Sass
afra
ssa
ndy
loam
soil
(1.0
/6.3
/-),
1mm
,0.5�
gcm
−2Sc
hnei
ders
etal
.19
9314
C,
acet
onitr
ileso
ln.
Sunl
ight
(Jun
.�
Jul.)
,25
°C11
d/11
d
105
Thi
fens
ulfu
ron-
Tw
oso
ils(0
.9�
2.3/
7.0�
7.1/
dry)
,1m
m,6�
7pp
mA
lban
iset
al.
2002
met
hyl
Met
hano
lso
ln.
1.1k
WX
ela
mp
(Sun
test
�7
hr/2
4�
34hr
CPS
+,>3
00nm
),20
°C10
6C
apta
nSa
ndy
loam
soil
(-/-
/moi
st),
-,-
EPA
OPP
TS
1999
b14
C,
N.R
.Su
nlig
ht5�
15d/
10�
21d
109
Ipro
dion
eSa
ndy
loam
soil
(N.R
.),-
,-E
PAO
PPT
S19
98e
14C
,N
.R.
Xe
lam
p7�
14d/
14�
21d
111
Fam
oxad
one
N.R
.Je
rnbe
rgan
dL
ee19
99N
.R.
N.R
.12
d/28
d
112 T. Katagi
Tab
le10
.(C
ontin
ued)
.
Soil
prop
erti
esan
dap
plic
atio
nra
tea)
App
licat
ion
med
ium
b)L
ight
sour
ce(w
avel
engt
hor
#Pe
stic
ide
DT
50(l
ight
/dar
k)se
ason
,fi
lter)
,te
mp
(°C
)R
efer
ence
118
Dic
amba
Lap
onit
e,-,
-A
guer
etal
.20
00N
.R.
125W
high
-pre
ssur
eH
gla
mp
N.R
.(>
290
nm,
2.2-
cmw
ater
filte
r)
119
Chl
oram
ben
Pen
nsyl
vani
alo
amso
il(2
.0/5
–6/-
),2
mm
,3pp
mM
isra
etal
.19
9714
C,
acet
onitr
ileX
enon
lam
p(H
erae
us29�
109d
/2�
500d
Sunt
est
CPS
),25
°C12
1Pe
ntac
hlor
o-T
hree
soils
(0.3�
1.5/
4.4�
7.7/
dry)
,0.0
8m
m,1
000
ppm
Liu
etal
.20
02ph
enol
Hex
ane
soln
.30
0Wm
ediu
m-p
ress
ure
20�
60m
in/N
.R.
Hg
lam
p(w
ater
filte
r)
122
Ald
rin
UK
and
Ger
man
soils
(2�
3.5/
7.4�
8.1/
-),-
,�
30�
gcm
−2K
lein
etal
.19
7314
C,
EC
form
ulat
ion
Sunl
ight
(Apr
il),
outd
oors
N.R
.
123
Die
ldri
nJa
pane
seso
ils(N
.R.)
,-,-
Suzu
kian
dY
amam
oto
1974
Form
ulat
ion
Sunl
ight
,fi
led
N.R
.
130
DD
TC
lay
loam
soil
(2.5
/7.5
/fie
ld),
-,-
Zay
edet
al.
1994
14C
,N
.R.
Sunl
ight
,ou
tdoo
rs55
d/N
.R.
133
Dic
ofol
Silt
loam
soil
(N.R
.),-
,-E
PAO
PPT
S19
98d
14C
,N
.R.
Art
ific
ial
light
21�
30d/
N.R
.
Photodegradation of Pesticides 113
Tab
le10
.(C
ontin
ued)
.
Soil
prop
erti
esan
dap
plic
atio
nra
tea)
App
licat
ion
med
ium
b)L
ight
sour
ce(w
avel
engt
hor
#Pe
stic
ide
DT
50(l
ight
/dar
k)se
ason
,fi
lter)
,te
mp
(°C
)R
efer
ence
136
Para
thio
n-O
rthi
cliv
isol
(1.9
/7.2
/-),
0.1
mm
,-K
rom
eret
al.
1999
met
hyl
Met
hano
lso
ln.
Xe
lam
pin
Sunt
est
CPS
+�
1d/
>1d
20.5
°CSa
ndy
loam
soil
(N.R
.),-
,>14�
gcm
−2E
PAO
PPT
S19
99e
14C
,N
.R.
Sunl
ight
(Jul
y),
outd
oors
61d/
106
dca
.25
°C13
7C
yano
phos
Tw
oJa
pane
seso
ils(3�
19/5
.2�
6.4/
5�
12),
0.5
mm
,-M
ikam
iet
al.
1976
14C
,N
.R.
Sunl
ight
(Sep
t.�
Oct
.),
2d/
>12
dou
tdoo
rs
138
Feni
trot
hion
Tw
oJa
pane
seso
ils(2
.5�
19/-
/5�
12),
50�
m,1
0�
gcm
−2M
ikam
iet
al.
1985
b14
C,
CH
Cl 3
soln
.Su
nlig
ht(J
un.)
,ou
tdoo
rs�
1d/
>12
d
140
Bro
mop
hos
Spey
erst
anda
rdso
il2.
2(2
.6/5
.8/1
2),-
,180
ppm
Allm
aier
etal
.19
84M
etha
nol
soln
.D
aylig
ht+
UV
-A&
-Bla
mps
Allm
aier
and
Schm
id19
8548
d/80
d(>
290
nm),
25°C
141
Iodo
fenp
hos
Fin
ely
pow
dere
dso
il(N
.R.)
,-,-
Wal
iaet
al.
1989
bA
ceto
neso
ln.
1kW
met
alha
lide
lam
pA
llmai
eran
dSc
hmid
1985
N.R
.(A
pplie
dPh
otop
hysi
cs95
00)
Spey
erst
anda
rdso
il2.
22(2
.6/5
.8/1
2),-
,180
ppm
Allm
aier
etal
.19
84M
etha
nol
soln
.D
aylig
ht+
UV
-A&
-Bla
mps
71d/
85d
(>29
0nm
),25
°C14
2T
olcl
ofos
-F
our
Japa
nese
soils
(3�
15/5�
7/5�
16)
,50�
m,7�
gcm
−2M
ikam
iet
al.
1984
bm
ethy
l14
C,
CH
Cl 3
soln
.Su
nlig
ht(M
ay�
Jun.
),1�
2d/
2�
>15
dou
tdoo
rs
114 T. Katagi
Tab
le10
.(C
ontin
ued)
.
Soil
prop
erti
esan
dap
plic
atio
nra
tea)
App
licat
ion
med
ium
b)L
ight
sour
ce(w
avel
engt
hor
#Pe
stic
ide
DT
50(l
ight
/dar
k)se
ason
,fi
lter)
,te
mp
(°C
)R
efer
ence
143
Fent
hion
Fiv
eU
.S.s
oils
(0.8�
6.3/
4.5�
7.5/
-),-
,50�
200
ppm
Goh
rean
dM
iller
1986
CH
2Cl 2
soln
.Su
nlig
ht(M
ay�
Aug
.),
N.R
.ou
tdoo
rs
144
Dia
zino
nSw
itze
rlan
dsi
lty
loam
(3.6
/6.1
/dry
or12
%),
-,10
ppm
Bur
khar
dan
dG
uth
1979
14C
,N
.R.
Xe
lam
p(>
290
nm,
u.v.
filte
r<1
d/<1
d+
IRre
flec
ting
glas
s),�
45°C
Sand
ylo
amso
il(N
.R.)
,-,-
EPA
OPP
TS
2000
14C
,N
.R.
Sunl
ight
20hr
/14
.7d
145
Chl
orpy
rifo
sF
inel
ypo
wde
red
soil
(N.R
.),2
mm
,-W
alia
etal
.19
880.
5%ac
eton
eso
ln.
Low
-pre
ssur
eH
gla
mp
17.3
d/N
.R.
(254
nm)
148
Qui
nalp
hos
Fou
rIn
dian
soils
(-/5
.6�
8.4/
-),5
0�
m,7�
gcm
−2D
urej
aet
al.
1988
Chl
orof
orm
soln
.Su
nlig
ht(M
ay�
Jun.
)2�
5d/
14�
>25
d
154
Tet
rach
lo-
Eas
tA
nglia
med
ium
loam
(-/8
.0/1
9),-
,13
ppm
Bey
non
and
Wri
ght
1969
vinp
hos
14C
,ac
eton
eso
ln.
Subd
ued
dayl
ight
4�
5d/
N.R
.Sa
ndy
loam
soil
(0.3
5/7.
2/-)
,-,2
.5m
g/g
ofso
ilD
urej
aet
al.
1987
bN
.R.
Med
ium
-pre
ssur
eH
gla
mp
N.R
./>10
d
156
Mon
ocro
toph
osSt
erili
zed
sand
ylo
am(1
.3/6
.4/-
)so
il,<1
mm
,5pp
mL
eeet
al.
1989
14C
,m
etha
nol
soln
.Su
nlig
ht(J
ul.�
Aug
.)3
d/30
d
Photodegradation of Pesticides 115
Tab
le10
.(C
ontin
ued)
.
Soil
prop
erti
esan
dap
plic
atio
nra
tea)
App
licat
ion
med
ium
b)L
ight
sour
ce(w
avel
engt
hor
#Pe
stic
ide
DT
50(l
ight
/dar
k)se
ason
,fi
lter)
,te
mp
(°C
)R
efer
ence
157
Dic
roto
phos
Fou
rU
.S.s
oils
(-/5
.7�
6.7/
-),<
1m
m,2
5pp
mL
eeet
al.
1989
14C
,ac
eton
eso
ln.
Fluo
resc
ent
lam
psN
.R.
(GE
P40B
L,
BL
B),
35°C
160
Prof
enof
osSw
itze
rlan
dsi
lty
loam
(3.6
/6.1
/dry
or12
%),
-,10
ppm
Bur
khar
dan
dG
uth
1979
14C
,N
.R.
Xe
lam
p(>
290
nm,
u.v.
filte
r<1
d/�
1d
+IR
refl
ectin
ggl
ass)
,�
45°C
162
Phor
ate
Pla
nosi
ltlo
amso
il(N
.R.)
,fie
ld,1
12�
gcm
−2L
icht
enst
ein
etal
.19
73Fo
rmul
atio
nSu
nlig
ht(M
ay),
fiel
d<1
wk/
N.R
.
163
Dis
ulfo
ton
Sand
ylo
amso
il(N
.R.)
,-,-
EPA
OPP
TS
1999
d14
C,
N.R
.Su
nlig
ht2.
4d/
N.R
.F
our
soils
(4.5�
7.5/
0.8�
6.3/
dry)
,-,-
Goh
rean
dM
iller
1986
Dic
hlor
omet
hane
soln
.Su
nlig
ht(A
ug.
orO
ct.,
�3
d/>5
dK
imax
glas
s),
outd
oors
164
Ben
sulid
eSo
rent
olo
amso
il(N
.R.)
,-,-
EPA
OPP
TS
1999
a14
C,
N.R
.X
ela
mp
90d/
N.R
.
168
Phen
thoa
teT
wo
Japa
nese
soils
(3�
19/5�
6/5�
12),
0.5
mm
,10�
gcm
−2M
ikam
iet
al.
1977
b14
C,
diet
hyl
ethe
rso
ln.
Sunl
ight
(Sep
t.�
Oct
.),
3d/
>6d
outd
oors
169
Azi
npho
s-Sa
ndy
loam
soil
(-/5
.1/-
),-,
-E
PAO
PPT
S19
98a
met
hyl
14C
,N
.R.
Sunl
ight
(Apr
il)18
0d/
N.R
.
116 T. Katagi
Tab
le10
.(C
ontin
ued)
.
Soil
prop
erti
esan
dap
plic
atio
nra
tea)
App
licat
ion
med
ium
b)L
ight
sour
ce(w
avel
engt
hor
#Pe
stic
ide
DT
50(l
ight
/dar
k)se
ason
,fi
lter)
,te
mp
(°C
)R
efer
ence
170
Phos
alon
eF
inel
ypo
wde
red
soil
(N.R
.),-
,-W
alia
etal
.19
89a
Ace
tone
soln
.1k
Whi
gh-p
ress
ure
met
al-
5d/
>15
dha
lide
lam
p(>
300
nm)
171
Met
hida
thio
nSw
itze
rlan
dsi
lty
loam
(3.6
/6.1
/dry
or12
%),
-,10
ppm
Bur
khar
dan
dG
uth
1979
14C
,N
.R.
Xe
lam
p(>
290
nm,
u.v.
filte
r<1
d/<1
d+
IRre
flec
ting
glas
s),�
45°C
175
Isof
enph
osSa
ndy
loam
soil
(0.3
5/7.
2/-)
,-,1
25�
gcm
−2D
urej
aet
al.
1989
N.R
.L
ow-p
ress
ure
Hg
lam
pN
.R.
178
Dita
limfo
sSp
eyer
stan
dard
soil
2.2
(2.6
/5.8
/12)
,-,3
10pp
mA
llmai
eret
al.
1984
Met
hano
lso
ln.
Day
light
+U
V-A
&-B
�18
d/N
.R.
lam
ps(>
290
nm),
25°C
180
Cya
nofe
npho
sT
wo
Japa
nese
soils
(3�
19/5
.2�
6.4/
5�
12),
0.5
mm
,-M
ikam
iet
al.
1976
14C
,N
.R.
Sunl
ight
(Sep
t.�
Oct
.),
2d/
>12
dou
tdoo
rs
183
Dio
xabe
nzof
osT
wo
Japa
nese
soils
(3�
19/5�
6/5�
12),
0.5
mm
,10�
gcm
−2M
ikam
iet
al.
1977
b14
C,
diet
hyl
ethe
rso
ln.
Sunl
ight
(Sep
t.�
Oct
.),
<1d/
>6d
outd
oors
184
Eth
ion
Ster
ilize
dsa
ndy
loam
soil
(N.R
.),-
,8.6
ppm
EPA
OPP
TS
1995
c14
C,
N.R
.Su
nlig
ht61
.6d/
175.
9d
185
Atr
azin
eE
ight
soils
(0.9�
1.6/
7.8�
8.0/
vari
ous)
,0.2�
0.5
mm
,-G
ong
etal
.20
01M
etha
nol
soln
.1k
Wm
ediu
m-p
ress
ure
4�
8m
in/N
.R.
Hg
lam
p
Photodegradation of Pesticides 117
Tab
le10
.(C
ontin
ued)
.
Soil
prop
erti
esan
dap
plic
atio
nra
tea)
App
licat
ion
med
ium
b)L
ight
sour
ce(w
avel
engt
hor
#Pe
stic
ide
DT
50(l
ight
/dar
k)se
ason
,fi
lter)
,te
mp
(°C
)R
efer
ence
188
Tri
adim
efon
Tw
oso
ils(0
.4�
0.8/
5.3�
7.4/
-),2
mm
,31.
8�
gcm
−2N
agan
dD
urej
a19
96A
ceto
neso
ln.
u.v.
light
(254
nm)
or9.
5�
22hr
/N.R
.su
nlig
ht(S
ept.)
Sche
yern
soil
(N.R
.),2
mm
,5pp
mM
urth
yet
al.
1998
N.R
.X
ela
mp
(>29
0nm
,16
6hr
/N.R
.H
erae
ussu
ntes
t),
18°C
191
Prop
icon
azol
eSa
ndy
loam
soil
(N.R
.),3
.5m
m,0
.3�
gcm
−2D
urej
aet
al.
1987
aA
ceto
neso
ln.
Sunl
ight
12d/
>26
d
196
Am
itrol
eSa
ndy
loam
soil
(N.R
.),-
,-E
PAO
PPT
S19
96a
14C
,N
.R.
Xe
lam
p,25
°C<7
3d/
N.R
.
197
Ter
baci
lD
rum
mer
silt
ycl
aylo
amso
il(N
.R.)
,-,1
.2lb
acre
−1E
PAO
PPT
S19
98h
14C
,N
.R.
Xe
lam
p,25
°C61
d/N
.R.
200
Ben
tazo
nM
ontc
alm
sand
ylo
amso
il(N
.R.)
,0.5
mm
,100�
gcm
−2N
illes
and
Zab
ik19
7514
C,
CH
2Cl 2
soln
.R
PRu.
v.lig
ht(3
00&
>5d/
N.R
.35
0nm
)
201
Met
ribu
zin
Sand
ylo
amso
il(N
.R.)
,-,-
EPA
OPP
TS
1998
g14
C,
N.R
.Su
nlig
ht,
outd
oors
,31
°C2.
5d/
N./R
.
118 T. Katagi
Tab
le10
.(C
ontin
ued)
.
Soil
prop
erti
esan
dap
plic
atio
nra
tea)
App
licat
ion
med
ium
b)L
ight
sour
ce(w
avel
engt
hor
#Pe
stic
ide
DT
50(l
ight
/dar
k)se
ason
,fi
lter)
,te
mp
(°C
)R
efer
ence
214
Nor
flur
azon
Rom
elo
amso
il(2
.0/6
.2/-
),-,
0.6�
gcm
−2Sc
hroe
der
Kvi
enan
dB
anks
1985
N.R
.Su
nlig
ht,
outd
oors
,25�
70°C
8d/
N.R
.
220
Fipr
onil
Nor
ther
nSe
nega
lso
il(0
.3/7
.6/-
),fi
eld,
0.05�
0.1�
gcm
−2Fe
net
etal
.20
01Fo
rmul
atio
nSu
nlig
ht,
fiel
d4–
5d/
N.R
.T
wo
Nig
erso
ils(0
.1�
0.3/
5.3�
5.8/
-),-
,0.0
8�
gcm
−2B
obe
etal
.19
98a
Form
ulat
ion
Sunl
ight
(Sep
t.�
Oct
.),
fiel
d1.
5d/
N.R
.B
aniz
oum
bou
soil
(6.5
/8.3
/dry
)so
ils,-
,2.5
ppm
Bob
eet
al.
1998
bM
etha
nol
soln
.1.
8kW
Xe
lam
p(S
unte
st,
6–9
d/N
.R.
>290
nm,
u.v.
filte
r)
221
DT
PT
wo
Japa
nese
soils
(3�
9/5.
6�
5.8/
-),0
.5m
m,3
.8�
gcm
−2Y
amao
kaet
al.
1988
14C
,aq
ueou
sso
ln.
Sunl
ight
(May�
Jun.
)31�
34d/
N.R
.
232
Tri
flur
alin
Sand
ylo
amso
il(N
.R.)
,-,-
EPA
OPP
TS
1996
c14
C,
N.R
.N
.R.
41d/
66d
234
But
ralin
Sand
ylo
amso
il(N
.R.)
,-,3
74pp
mE
PAO
PPT
S19
98b
14C
,N
.R.
Sunl
ight
99.6
d/11
2.7
d
235
Ory
zalin
Sand
ylo
amso
il(N
.R.)
,-,-
EPA
OPP
TS
1994
14C
,N
.R.
Xe
lam
p22
.4hr
/N.R
.
Photodegradation of Pesticides 119
Table10.(Continued).
Soil
prop
erti
esan
dap
plic
atio
nra
tea)
App
licat
ion
med
ium
b)L
ight
sour
ce(w
avel
engt
hor
#Pe
stic
ide
DT
50(l
ight
/dar
k)se
ason
,fi
lter)
,te
mp
(°C
)R
efer
ence
236
Fluc
hlor
alin
Mon
tcal
msa
ndy
loam
soil
(N.R
.),0
.5m
m,1
00�
gcm
−2N
illes
and
Zab
ik19
7414
C,
CH
2Cl 2
soln
.R
PRu.
v.lig
ht(3
00&
N.R
.35
0nm
)
237
Eth
alfl
ural
inSa
ndy
loam
soil
(N.R
.),-
,-E
PAO
PPT
S19
95b
14C
,N
.R.
N.R
.14
.2d/
N.R
.
238
Pend
imet
halin
Kal
yani
allu
vial
soil
(1.7
/7.2
/dry
),2m
m,2
8�g/
gof
soil
Had
ler
etal
.19
89H
exan
eso
ln.
Sunl
ight
N.R
.N
ewD
elhi
sand
ylo
amso
il(3
.6/6
.1/-
),50�
m,7�
gcm
−2D
urej
aan
dW
alia
1989
Met
hano
lso
ln.
Low
-pre
ssur
eH
gla
mp
N.R
.(2
54nm
)
240
Proc
hlor
azT
wo
soils
(1.0�
1.5/
5.3�
7.1/
-),-
,0.4�
0.6
ppm
Hol
lrig
l-R
osta
etal
.19
9914
C,
met
hano
lM
ediu
m-p
ress
ure
Hg
lam
p>1
d/�
200d
(>29
0nm
,T
Q15
0fi
lter)
a Soil
prop
ertie
san
dap
plic
atio
nra
tear
elis
ted
inth
efo
llow
ing
orde
ras
bold
face
:soi
lnam
e(o
rgan
icm
atte
rco
nten
t%/p
H/m
oist
ure
cont
ent%
),so
illa
yer
thic
knes
s,ap
plic
atio
nra
te.
b Non
radi
olab
eled
pest
icid
ew
hen
unsp
ecif
ied.
“-”
orN
.R.:
not
repo
rted
.M
HW
C,
max
imum
wat
erho
ldin
gca
paci
ty;
FMC
,fi
eld
moi
stur
eco
nten
t
120 T. Katagi
Tab
le11
.Su
rfac
ede
grad
atio
nof
pest
icid
esin
folia
ror
topi
cal
appl
icat
ion.
Plan
tsp
ecie
sA
pplic
atio
nm
ediu
mN
o.Pe
stic
ide
DT
50L
ight
sour
ce(s
easo
n),
cond
ition
sR
efer
ence
s
12,
4-D
Cor
nle
af14
C,
0.25
%ox
ysor
bic
surf
acta
ntV
enka
tesh
and
Har
riso
n19
9914
.6hr
Fluo
resc
ent
lam
ps
13Ph
enot
hrin
Bea
n&
rice
leaf
14C
,m
etha
nol
soln
.N
ambu
etal
.19
80<1
dSu
nlig
ht(N
ov.)
,gr
eenh
ouse
19C
yper
met
hrin
Cot
ton
&be
anle
af14
C,
diet
hyl
ethe
rso
ln.
Col
eet
al.
1982
2–4
dSu
nlig
ht(J
uly–
Sept
.),
outd
oors
22D
elta
met
hrin
Cot
ton
leaf
14C
,di
ethy
let
her
soln
.R
uzo
and
Cas
ida
1979
1.1
wk
Sunl
ight
,gr
eenh
ouse
Bea
nle
af14
C,
diet
hyl
ethe
rso
ln.
Col
eet
al.
1982
�4
dSu
nlig
ht(J
uly–
Sept
.),
outd
oors
Pota
tole
af2.
5%E
CM
agui
re19
901–
2d
Sunl
ight
(sum
mer
),fi
eld
24Fe
npro
path
rin
Man
dari
nor
ange
leaf
14C
,m
etha
nol
soln
.T
akah
ashi
etal
.19
85b
4d
Sunl
ight
(Sep
t.),
gree
nhou
se
27Fe
nval
erat
eK
idne
ybe
anle
af14
C,
met
hano
lso
ln.
Ohk
awa
etal
.19
8014
dSu
nlig
ht(O
ct.)
,gr
eenh
ouse
Spri
ngw
heat
leaf
14C
,0.
1%E
CL
eeet
al.
1988
2–4
dSu
nlig
ht(S
ept.
–Dec
.),
outd
oors
Cot
ton
leaf
2.4
lb/g
alE
Cfo
rmul
atio
nH
olm
stea
det
al.
1978
b8
dSu
nlig
ht(m
id-J
uly)
29Fl
ucyt
hrin
ate
Fren
chbe
anle
afM
etha
nol
soln
.C
hatto
padh
yaya
and
Dur
eja
1991
3d
Sunl
ight
(Apr
.),
gree
nhou
se
Photodegradation of Pesticides 121
Tab
le11
.(C
ontin
ued)
.
Plan
tsp
ecie
sA
pplic
atio
nm
ediu
mN
o.Pe
stic
ide
DT
50L
ight
sour
ce(s
easo
n),
cond
ition
sR
efer
ence
s
39Fl
utol
anil
Cuc
umbe
rle
af14
C,
diet
hyl
ethe
rso
ln.
Uch
ida
etal
.19
8329
.3d
Sunl
ight
,gr
eenh
ouse
42C
arbo
xin
Bea
nle
afSu
spen
sion
Buc
hena
uer
1975
<10
hrSu
nlig
ht
45Pr
opyz
amid
eA
lfal
fale
af14
C,
acet
one
soln
.Y
ihan
dSw
ithen
bank
1971
63.8
dSu
nlig
ht,
fiel
d
57D
iafe
nthi
uron
Chi
nese
cabb
age
leaf
25E
CK
eum
etal
.20
024
dSu
nlig
ht,
fiel
dC
otto
nle
afSC
400
form
ulat
ion
Dra
bek
etal
.19
92<3
hrSu
nlig
ht,
fiel
d
59D
iflu
benz
uron
Cot
ton
leaf
14C
,25
%W
PB
ull
and
Ivie
1976
31.9
dSu
nlig
ht(s
umm
er),
outd
oors
Con
ifer
pine
need
le45
%oi
lfo
rmul
atio
nR
odri
guez
etal
.20
012–
3w
kSu
nlig
ht(A
ug.–
Oct
.),
fiel
d
61M
etol
carb
Bea
nle
af14
C,
met
hano
lso
ln.
Ohk
awa
etal
.19
74a
<1d
Sunl
ight
,gr
eenh
ouse
62Fe
nobu
carb
Ric
ele
af14
C,
met
hano
l-w
ater
(1/3
)so
ln.
Oga
wa
etal
.19
76N
.R.
Sunl
ight
,gr
eenh
ouse
63X
ylyl
carb
Bea
nle
af14
C,
met
hano
lso
ln.
Ohk
awa
etal
.19
74a
<1d
Sunl
ight
,gr
eenh
ouse
64T
rim
etha
carb
Pint
obe
anle
af14
C,
etha
nol
soln
.Sl
ade
and
Cas
ida
1970
N.R
.Su
nlig
ht(J
une–
July
),ou
tdoo
rs
122 T. Katagi
Tab
le11
.(C
ontin
ued)
.
Plan
tsp
ecie
sA
pplic
atio
nm
ediu
mN
o.Pe
stic
ide
DT
50L
ight
sour
ce(s
easo
n),
cond
ition
sR
efer
ence
s
65Pr
opox
urG
arde
nsn
apbe
anle
af14
C,
etha
nol
soln
.A
bdel
-Wah
abet
al.
1966
8hr
Sunl
ight
(Aug
.–Se
pt.)
,ou
tdoo
rs
66A
min
ocar
bG
arde
nsn
apbe
anle
af14
C,
etha
nol
soln
.A
bdel
-Wah
aban
dC
asid
a19
674
hrSu
nlig
ht(A
ug.–
Sept
.),
outd
oors
67M
exac
arba
teG
arde
nsn
apbe
anle
af3 H
,14
C;
etha
nol
soln
.A
bdel
-Wah
aban
dC
asid
a19
672–
3hr
Sunl
ight
(Aug
.–Se
pt.)
,ou
tdoo
rs
68M
ethi
ocar
bG
arde
nsn
apbe
anle
af14
C,
etha
nol
soln
.A
bdel
-Wah
abet
al.
1966
>3d
Sunl
ight
(Aug
.–Se
pt.)
,ou
tdoo
rs
71C
arba
ryl
Gar
den
snap
bean
leaf
14C
,et
hano
lso
ln.
Abd
el-W
ahab
etal
.19
662.
8d
Sunl
ight
(Aug
.–Se
pt.)
,ou
tdoo
rs
72C
arbo
fura
nSt
raw
berr
y43
.8%
FLA
rche
ret
al.
1977
1–3
dSu
nlig
ht,
fiel
d
74O
xam
ylT
obac
cole
af14
C,
0.2%
Tw
een
20aq
ueou
sso
ln.
Har
vey
etal
.19
78�
15d
Plan
tgr
owth
cham
ber
78Pi
rim
icar
bL
ettu
cele
af25
%liq
uid
form
ulat
ion
Cab
ras
etal
.19
90�
2d
Sunl
ight
(May
),fi
eld
81B
enom
ylPi
nto
bean
leaf
14C
,52
%W
PB
aude
etal
.19
73N
.R.
Sunl
ight
,gr
eenh
ouse
85Fe
noth
ioca
rbM
anda
rin
oran
ge14
C,
30%
EC
Una
iet
al.
1986
1.6–
12d
Sunl
ight
(Sep
t.),
gree
nhou
se
88C
arbo
sulf
anV
alen
cia
oran
ge14
C,
EC
Cla
yan
dFu
kuto
1984
3–6
dSu
nlig
ht(s
umm
er),
fiel
d
Photodegradation of Pesticides 123
Tab
le11
.(C
ontin
ued)
.
Plan
tsp
ecie
sA
pplic
atio
nm
ediu
mN
o.Pe
stic
ide
DT
50L
ight
sour
ce(s
easo
n),
cond
ition
sR
efer
ence
s
89B
enfu
raca
rbC
otto
nle
af14
C,
acet
one-
wat
er(1
/1)
Tan
aka
etal
.19
85N
.R.
Sunl
ight
,gr
eenh
ouse
92T
hiop
hana
te-m
ethy
lC
otto
nle
af70
%W
PB
uche
naue
ret
al.
1973
N.R
.Su
nlig
ht,
outd
oors
App
letr
eele
af14
C,
70%
WP
Soed
aet
al.
1972
15d
Sunl
ight
(May
–Aug
.)
93M
BC
Cor
nle
af3 H
,14
C;
10m
MH
Cl
in50
%et
hano
l.Fl
eeke
ran
dL
acy
1977
N.R
.Su
nlig
ht(J
uly)
,ou
tdoo
rs
95E
TU
Tom
ato
leaf
14C
,80
%W
PR
hode
s19
772.
1d
Sunl
ight
,ou
tdoo
rs
99T
ribe
nuro
nm
ethy
lW
heat
leaf
Ace
tone
soln
.B
hatta
char
jee
and
Dur
eja
2002
N.R
.Su
nlig
ht,
gree
nhou
se
104
Thi
fen-
sulf
uron
Soyb
ean
leaf
14C
,aq
ueou
sso
ln.±
surf
acta
ntB
row
net
al.
1993
4–20
dSu
nlig
ht,
gree
nhou
se
108
Proc
ymid
one
Bea
n&
cucu
mbe
rle
af14
C,
diet
hyl
ethe
rso
ln.
Mik
ami
etal
.19
84a
2–3
wk
Sunl
ight
,gr
eenh
ouse
112
Met
hazo
leC
otto
nle
af14
C,
aque
ous
soln
.D
orou
ghet
al.
1973
<1d
Sunl
ight
(Jun
e),
outd
oors
122
Ald
rin
App
letr
eele
afA
ldre
x30
Har
riso
net
al.
1967
<1w
kSu
nlig
ht(J
une)
,fi
eld
123
Die
ldri
nA
pple
tree
leaf
50%
disp
ersi
ble
pow
der
Har
riso
net
al.
1967
<1w
kSu
nlig
ht(J
une)
,fi
eld
124 T. Katagi
Tab
le11
.(C
ontin
ued)
.
Plan
tsp
ecie
sA
pplic
atio
nm
ediu
mN
o.Pe
stic
ide
DT
50L
ight
sour
ce(s
easo
n),
cond
ition
sR
efer
ence
s
125
End
osul
fan
App
letr
eele
af20
%co
ncen
trat
eH
arri
son
etal
.19
67<1
wk
Sunl
ight
(Jun
e),
fiel
dC
otto
nle
af0.
1%he
xane
soln
.D
urej
aan
dM
uker
jee
1982
N.R
.Su
nlig
ht(J
une)
126
End
rin
App
letr
eele
afE
ndre
x20
Har
riso
net
al.
1967
<1w
kSu
nlig
ht(J
une)
,fi
eld
130
DD
TA
pple
tree
leaf
25%
EC
or50
%di
sper
sibl
epo
wde
rH
arri
son
etal
.19
67<1
–2w
kSu
nlig
ht(J
une)
,fi
eld
135
Para
thio
nG
arde
nbe
anle
af0.
2%T
rito
nX
-155
+B
-195
6(1/
1)E
l-R
efai
and
Hop
kins
1966
�1
dFl
uore
scen
tla
mps
,gr
eenh
ouse
Cot
ton
leaf
14C
,m
etha
nol
soln
.Jo
iner
and
Bae
tcke
1973
N.R
.Su
nlig
ht,
fiel
d
137
Cya
noph
osK
idne
ybe
anle
af14
C,
benz
ene-
hexa
ne(4
/1)
+su
rfac
tant
Chi
baet
al.
1976
0.54
dSu
nlig
ht,
gree
nhou
se
138
Feni
trot
hion
App
letr
eele
af0.
5%em
ulsi
onH
osok
awa
and
Miy
amot
o19
741.
2d
Sunl
ight
(Oct
.–N
ov.)
Bea
nle
af14
C,
etha
nol
soln
.O
hkaw
aet
al.
1974
b<1
dSu
nlig
ht(N
ov.)
,ou
tdoo
rs
140
Bro
mop
hos
Tom
ato
leaf
32P
&3 T
,em
ulsi
onSt
iasn
iet
al.
1969
<8
hr40
0W
dayl
ight
lam
psin
cham
ber
143
Fent
hion
Ora
nge
frui
t,pe
elC
omm
erci
alfo
rmul
atio
n(2
4.2%
a.i.)
Min
elli
etal
.19
963.
9–4.
8d
Sunl
ight
(Apr
.),
outd
oors
Cor
nle
af50
%E
CL
euch
and
Bow
man
1968
�1
dSu
nlig
ht,
fiel
d
Photodegradation of Pesticides 125
Tab
le11
.(C
ontin
ued)
.
Plan
tsp
ecie
sA
pplic
atio
nm
ediu
mN
o.Pe
stic
ide
DT
50L
ight
sour
ce(s
easo
n),
cond
ition
sR
efer
ence
s
145
Chl
orpy
rifo
sSo
ftsh
ield
fern
leaf
14C
,0.
1%ac
eton
eso
ln.
Wal
iaet
al.
1988
54.3
dSo
lar
sim
ulat
or(1
kWm
etal
-hal
ide
lam
p)
151
Isox
athi
onC
abba
gele
af14
C,
0.03
%T
wee
n20
aque
ous
soln
.A
ndo
etal
.19
752–
3d
Sunl
ight
,gr
eenh
ouse
152
Phox
imT
omat
ole
af5%
form
ulat
ion
Mak
ary
etal
.19
81�
1d
Sunl
ight
,fi
eld
Cor
nle
afE
CB
owm
anan
dL
euck
1971
<1d
Sunl
ight
,fi
eld
154
Tet
rach
lo-v
inph
osA
pple
tree
leaf
14C
,ac
eton
eso
ln.
Bey
non
and
Wri
ght
1969
�2
dSu
nlig
ht,
gree
nhou
seB
ean
leaf
Ace
tone
soln
.D
urej
aet
al.
1987
b6
dSu
nlig
ht
156
Mon
ocro
to-p
hos
Cot
ton
leaf
32P,
aque
ous
soln
.L
indq
uist
and
Bul
l19
67<2
dSu
nlig
ht,
gree
nhou
seB
ush
appl
efr
uit
14C
,ac
eton
eso
ln.
Bey
non
and
Wri
ght
1972
N.R
.Su
nlig
ht,
gree
nhou
se
157
Dic
roto
phos
Cot
ton
leaf
32P,
aque
ous
soln
.B
ull
and
Lin
dqui
st19
64<1
dL
abor
ator
y
158
Phos
pham
i-do
nC
otto
nle
af32
P,aq
ueou
sso
ln.
Bul
let
al.
1967
<1d
Sunl
ight
,gr
eenh
ouse
161
Sulp
rofo
sC
otto
nle
af14
C,
50%
EC
Ivie
and
Bul
l19
761
dSu
nlig
ht(A
ug.)
,ou
tdoo
rs
126 T. Katagi
Tab
le11
.(C
ontin
ued)
.
Plan
tsp
ecie
sA
pplic
atio
nm
ediu
mN
o.Pe
stic
ide
DT
50L
ight
sour
ce(s
easo
n),
cond
ition
sR
efer
ence
s
165
Dim
etho
ate
Cor
nle
af32
P,em
ulsi
onD
aute
rman
etal
.19
60N
.R.
Sunl
ight
,gr
eenh
ouse
Bea
nle
af14
C&
32P,
aque
ous
soln
.L
ucie
ran
dM
enze
r19
68�
4d
Sunl
ight
(Apr
.),
gree
nhou
seB
ean
leaf
14C
,aq
ueou
sso
ln.
Luc
ier
and
Men
zer
1970
1.7
dSu
nlig
ht,
gree
nhou
se
166
Form
othi
onB
ean
leaf
14C
,20
%E
CSa
uer
1972
1.2
dA
rtif
icia
llig
ht,
gree
nhou
se
167
Mal
athi
onB
road
bean
leaf
32P,
acet
one
soln
.M
osta
faet
al.
1974
N.R
.Su
nlig
ht,
fiel
dB
ean
leaf
Em
ulsi
onE
l-R
efai
and
Hop
kins
1972
2d
Sunl
ight
,fi
eld
Cot
ton
leaf
14C
,U
LV
or57
%E
CA
wad
etal
.19
671.
2–3.
8d
Sunl
ight
,gr
eenh
ouse
168
Phen
thoa
teV
alen
cia
oran
ge32
P&
14C
,0.
06%
emul
sion
Tak
ade
etal
.19
763–
7d
Sunl
ight
(Mar
.&
Sept
.)
169
Azi
npho
s-m
ethy
lB
ean
&co
rnle
af14
C,
acet
one
soln
.L
iang
and
Lic
hten
stei
n19
76�
1d
Sunl
ight
(Jun
e–A
ug.)
173
Edi
fenp
hos
Ric
ele
af32
P,em
ulsi
onIs
hizu
kaet
al.
1973
�5
dSu
nlig
ht,
gree
nhou
se
174
Ace
phat
eC
otto
nle
af14
C,
0.1%
Tri
ton
X-1
00B
ull
1979
5.9
hrSu
nlig
ht,
fiel
dT
obac
cole
af50
%W
PY
amaz
aki
etal
.19
825–
8d
Sunl
ight
,gr
eenh
ouse
Photodegradation of Pesticides 127
Tab
le11
.(C
ontin
ued)
.
Plan
tsp
ecie
sA
pplic
atio
nm
ediu
mN
o.Pe
stic
ide
DT
50L
ight
sour
ce(s
easo
n),
cond
ition
sR
efer
ence
s
180
Cya
nofe
npho
sK
idne
ybe
anle
af14
C,
benz
ene-
hexa
ne(4
/1)
+su
rfac
tant
Chi
baet
al.
1976
2.25
wk
Sunl
ight
,gr
eenh
ouse
181
Lep
toph
osC
otto
nle
af32
P,50
%aq
ueou
sac
eton
eZ
ayed
etal
.19
78N
.R.
Sunl
ight
182
But
onat
eB
ean
leaf
32P,
aque
ous
soln
.D
erek
etal
.19
798.
3hr
Sunl
ight
188
Tri
adim
efon
Mar
row
,1s
ttr
uele
af1
mM
,W
PC
lark
etal
.19
78N
.R.
Sunl
ight
,gr
eenh
ouse
189
Tri
adim
enol
App
letr
eele
afA
ceto
ne-w
ater
(3/7
)so
ln.
Cla
rkan
dW
atki
ns19
86N
.R.
Sunl
ight
(Jul
y),
outd
oors
195
Fluo
trim
azol
eB
arle
yle
afA
ceto
ne-w
ater
(1/1
)so
ln.
Cla
rket
al.
1983
N.R
.40
0WH
gla
mp,
gree
nhou
se
199
Len
acil
Suga
rbe
etle
af14
C,
50%
WP
Zha
nget
al.
1999
N.R
.Su
nlig
ht,
gree
nhou
se
202
Din
oseb
Gar
den
snap
bean
leaf
14C
,et
hano
lso
ln.
Mat
suo
and
Cas
ida
1970
0.9
hrSu
nlig
ht(A
ug.)
,gr
eenh
ouse
203
Din
obut
onG
arde
nsn
apbe
anle
af14
C,
etha
nol
soln
.B
anda
lan
dC
asid
a19
720.
3hr
Sunl
ight
(Aug
.),
gree
nhou
se
215
Imid
aclo
prid
Tom
ato
leaf
14C
+20
SLfo
rmul
atio
nSc
holz
and
Rei
nhar
d19
990.
7–1.
4d
Sunl
ight
(51
°N),
gree
nhou
se
220
Fipr
onil
Cor
nle
afA
ceto
neso
ln.
Hai
nzl
and
Cas
ida
1996
�20
hrSu
nlig
ht(N
ov.)
Fene
tet
al.
2001
128 T. Katagi
Tab
le11
.(C
ontin
ued)
.
Plan
tsp
ecie
sA
pplic
atio
nm
ediu
mN
o.Pe
stic
ide
DT
50L
ight
sour
ce(s
easo
n),
cond
ition
sR
efer
ence
s
223
Seth
oxyd
imN
avy
bean
leaf
14C
,aq
ueou
sem
ulsi
on.
Cam
pbel
lan
dPe
nner
1985
b�
1hr
Fluo
resc
ence
light
,gr
eenh
ouse
224
Allo
xydi
mSu
gar
beet
leaf
14C
,aq
ueou
sem
ulsi
onSo
eda
etal
.19
793
dSu
nlig
ht(J
an.–
Mar
.),
outd
oors
245
Gua
zatin
eD
war
fap
ple
leaf
14C
,+
200
ppm
noni
onic
surf
acta
ntSa
toet
al.
1985
a67
wk
Sunl
amps
,gr
owth
cham
ber
250
Ave
rmec
tinB
1aC
eler
y14
C&
3 H,
EC
form
ulat
ion
Moy
eet
al.
1990
5–9
dSu
nlig
ht(J
une–
Mar
.),
outd
oors
251
MA
B1a
Cab
bage
leaf
14C
,E
CW
rzes
insk
iet
al.
1996
N.R
.Su
nlig
ht,
fiel
d
252
Spin
osyn
A4
plan
tsp
ecie
sC
omm
erci
alfo
rmul
atio
nSa
unde
rsan
dB
ret
1997
1.6–
16d
Sunl
ight
N.R
.:no
tre
port
ed.
Form
ulat
ion:
UL
V:
ultr
a-lo
w-v
olum
efo
rmul
atio
n;E
C:
emul
sifi
able
conc
entr
ate;
WP:
wet
tabl
epo
wde
r;FL
:fl
owab
le.
Photodegradation of Pesticides 129
Appendices Listing
Appendix Number Page1 ................................................................................................................................ 1362 ................................................................................................................................ 1373 ................................................................................................................................ 1394 ................................................................................................................................ 1405 ................................................................................................................................ 1416 ................................................................................................................................ 1447 ................................................................................................................................ 1458 ................................................................................................................................ 1469 ................................................................................................................................ 148
10 ................................................................................................................................ 15111 ................................................................................................................................ 152
130 T. Katagi
Directory of pesticide chemical structures.
Pesticide Identification number Appendix number
Acephate 174 9Acrinathrin 31 2Alachlor 34 3Aldrin 122 8Allethrin 10 2Alloxydim 224 11Aminocarb 66 5Amitrole 196 11Anilazine 211 11Asulam 82 5Atrazine 185 10Avermectin B1a 250 11Azadirachtin-A 253 11Azinphos-methyl 169 9Azoxystrobin 244 11Benfuracarb 89 5Benomyl 81 5Bensulide 164 9Bentazone 200 11Benthiocarb 86 5Bioallethrin 11 2Bromacil 198 11Bromophos 140 9Buprofezine 222 11Butachlor 36 3Butamifos 177 9Butonate 182 9Butralin 234 11Butylate 87 5Captan 106 7Carbaryl 71 5Carbofuran 72 5Carbosulfan 88 5Carboxin 42 3Cartap 91 5Chinomethionat 228 11Chloramben 119 8Chlordane 128 8Chlordimeform 207 11Chlorimuron 101 6Chlorimuron ethyl 102 6Chlorothalonil 117 8Chlorpropham 80 5Chlorpyrifos 145 9
Photodegradation of Pesticides 131
Directory of pesticide chemical structures (Continued).
Pesticide Identification number Appendix number
Chlorsulfuron 96 6Chlorthiamid 49 3Cinmethylin 249 11CNP (Chlornitrofen) 217 11Coumaphos 147 9Cyanofenphos 180 9Cyanophos 137 9Cyfluthrin 20 2Cyhalothrin 21 2Cypermethrin 19 2Cyphenothrin 14 2Cyprodinil 210 112,4-D 1 1DDD 132 8DDE 131 8DDOD 113 7DDT 130 8DTP 221 11Deltamethrin 22 2Desmedipham 83 5Diafenthiuron 57 4Diazinon 144 9Dicamba 118 8Dichlobenil 116 8Dichlofluanid 205 11Dichlorvos 153 9Diclofop-methyl 5 1Dicofol 133 8Dicrotophos 157 9Dieldrin 123 8Diflubenzuron 59 4Dimethoate 165 9Dimetilam 75 5Diniconazole-M 190 10Dinobuton 203 11Dinoseb 202 11Dioxabenzofos 183 9Diphenamid 50 3Diquat 226 11Disulfoton 163 9Ditalimfos 178 9Diuron 53 4ETU 95 5Edifenphos 173 9Endosulfan 125 8
132 T. Katagi
Directory of pesticide chemical structures (Continued).
Pesticide Identification number Appendix number
Endrin 126 8Esfenvalerate 28 2Ethalfluralin 237 11Ethiofencarb 69 5Ethion 184 9Ethirimol 213 11Ethoxyquin 219 11Etofenprox 32 2Famoxadone 111 7Fenarimol 239 11Fenchlorphos 139 9Fenitrothion 138 9Fenobucarb 62 5Fenothiocarb 85 5Fenpropathrin 24 2Fenpropimorph 227 11Fenthion 143 9Fentin acetate 241 11Fenuron 51 4Fenvalerate 27 2Fipronil 220 11Florasulam 48 3Fluazifop-butyl 6 1Fluchloralin 236 11Flucythrinate 29 2Fludioxinil 208 11Flumetralin 233 11Flumeturon 55 4Fluotrimazole 195 10Flutolanil 39 3Fluvalinate 30 2Folpet 107 7Formothion 166 9Guazatine 245 11Haloxyfop 8 1Heptachlor 127 8Hexachlorobenzene 115 8Hexaconazole 192 10Imazapyr 229 11Imazaquin 230 11Imazethapyr 231 11Imidacloprid 215 11Iodofenphos 141 9Iprodione 109 7Isofenphos 175 9
Photodegradation of Pesticides 133
Directory of pesticide chemical structures (Continued).
Pesticide Identification number Appendix number
Isolan 77 5Isoprothiolane 204 11Isoproturon 56 4Isoxaben 46 3Isoxathion 151 9Kadethrin 16 2Lenacil 199 11Leptophos 181 9Lindane 114 8Linuron 54 4MAB1a 251 11MBC 93 5MCPA 3 1Malathion 167 9Maneb 94 5Mecoprop 4 1Mepronil 38 3Metalaxyl 37 3Methazole 112 7Methidathion 171 9Methiocarb 68 5Methomyl 70 5Methoprene 246 11Methoxychlor 134 8Metolachlor 35 3Metolcarb 61 5Metribuzin 201 11Metsulfuron 97 6Metsulfuron methyl 98 6Mevinphos 155 9Mexacarbate 67 5Mobam 73 5Molinate 90 5Monocrotophos 156 9Monuron 52 4NAA 247 11NMH 242 11Naproanilide 41 3Napropamide 47 3Naptalam 44 3Niclosamide 40 3Nitrofen 216 11Norflurazon 214 11Oryzalin 235 11Oxamyl 74 5
134 T. Katagi
Directory of pesticide chemical structures (Continued).
Pesticide Identification number Appendix number
Oxycarboxin 43 3Oxyfluorfen 218 11PBacid 243 11Paraquat 225 11Parathion 135 9Parathion-methyl 136 9Penconazole 193 10Pendimethalin 238 11Pentachlorophenol 121 8Perfluidone 206 11Permethrin 17 2Phenmec 60 5Phenmedipham 84 5Phenothrin 13 2Phenthoate 168 9Phorate 162 9Phosalone 170 9Phosmet 172 9Phosphamidon 158 9Photo-dieldrin 124 8Phoxim 152 9Picloram 120 8Pirimicarb 78 5Potasan 146 9Prochloraz 240 11Procymidone 108 7Profenofos 160 9Prometone 187 10Propachlor 33 3Propaphos 159 9Propham 79 5Propiconazole 191 10Propoxur 65 5Propyzamide 45 3Pyrazophos 149 9Pyrethrin-I 9 2Pyridaphenthion 150 9Pyrimethanil 209 11Pyrolan 76 5Quinalophos 148 9Resmethrin 15 2Rimsulfuron 103 6S-2571 176 9S-Bioallethrin 12 2Sethoxydim 223 11
Photodegradation of Pesticides 135
Directory of pesticide chemical structures (Continued).
Pesticide Identification number Appendix number
Simazine 186 10Spinosyn A 252 11Sulprofos 161 92,4,5-T 2 12,3,7,8-TCDD 129 8Tefluthrin 18 2Terbacil 197 11Tetrachlovinphos 154 9Tetramethrin 23 2Thiabendazole 212 11Thiadiazuron 58 4Thifensulfuron 104 6Thifensulfuron methyl 105 6Thiophanate-methyl 92 5Tolclofos-methyl 142 9Tralocythrin 26 2Tralomethrin 25 2Triadimefon 188 10Triadimenol 189 10Triasulfuron 100 6Tribenuron methyl 99 6Trichlorfon 179 9Triclopyr 7 1Trifluralin 232 11Trimethacarb 64 5Triticonazole 194 10Vinclozoline 110 7Warfarine 248 11Xylylcarb 63 5
136 T. Katagi
App
endi
x1.
Che
mic
alst
ruct
ures
ofar
ylox
yalk
anoa
tes.
No.
Pest
icid
eX
R1
R2
R3
12,
4-D
C2,
4-C
l 2H
H2
2,4,
5-T
C2,
4,5-
Cl 3
HH
3M
CPA
C4-
Cl-
2-C
H3
HH
4M
ecop
rop
C4-
Cl-
2-C
H3
CH
3H
5D
iclo
fop-
met
hyl
C4-
(2,4
-Cl 2-
Phen
oxy)
CH
3C
H3
6Fl
uazi
fop-
buty
lC
5-C
F 3-2
-Pyr
idyl
oxy
CH
3n-
C4H
9
7T
ricl
opyr
2-N
3,5,
6-C
l 3H
H8
Hal
oxyf
opC
3-C
l-5-
CF 3
-2-P
yrid
ylox
yC
H3
H
Photodegradation of Pesticides 137
App
endi
x2.
Che
mic
alst
ruct
ures
ofpy
reth
roid
s.
No.
Inse
ctic
ide
R1
XY
Con
figu
ratio
nR
2Z
Con
figu
ratio
nR
3
9Py
reth
rin-
IA
1C
H3
CH
31R
-tra
nsB
1—
Z-S
CH=C
H2
10A
lleth
rin
A1
CH
3C
H3
1RS-
cis,
tran
sB
1—
RS
H11
Bio
alle
thri
nA
1C
H3
CH
31R
-tra
nsB
1—
RS
H12
S-B
ioal
leth
rin
A1
CH
3C
H3
1R-t
rans
B1
—S
H13
Phen
othr
inA
1C
H3
CH
31R
S-ci
s,tr
ans
B2
H—
3-Ph
enox
y14
Cyp
heno
thri
nA
1C
H3
CH
31R
S-ci
s,tr
ans
B2
CN
RS
3-Ph
enox
y15
Res
met
hrin
A1
CH
3C
H3
1RS-
cis,
tran
sB
3—
——
16K
adet
hrin
A2
——
E-1
R-c
isB
3—
——
17Pe
rmet
hrin
A1
Cl
Cl
1RS-
cis,
tran
sB
2H
—3-
Phen
oxy
18T
eflu
thri
nA
1C
lC
F 3Z
-1R
S-ci
sB
2H
—2,
3,5,
6-T
etra
fluo
ro-4
-met
hyl
19C
yper
met
hrin
A1
Cl
Cl
1RS-
cis,
tran
sB
2C
NR
S3-
Phen
oxy
20C
yflu
thri
nA
1C
lC
l1R
S-ci
s,tr
ans
B2
CN
RS
4-Fl
uoro
-3-p
heno
xy21
Cyh
alot
hrin
A1
Cl
CF 3
Z-1
RS-
cis
B2
CN
RS
3-Ph
enox
y22
Del
tam
ethr
inA
1B
rB
r1R
-cis
B2
CN
S3-
Phen
oxy
23T
etra
met
hrin
A1
CH
3C
H3
1RS-
cis,
tran
sB
4—
——
138 T. Katagi
App
endi
x2.
(Con
tinue
d).
No.
Inse
ctic
ide
R1
XY
Con
figu
ratio
nR
2Z
Con
figu
ratio
nR
3
24Fe
npro
path
rin
A3
——
—B
2C
NR
S3-
Phen
oxy
25T
ralo
met
hrin
A4
Br
—1R
-cis
B2
CN
S3-
Phen
oxy
26T
ralo
cyth
rin
A4
Cl
—1R
-cis
B2
CN
S3-
Phen
oxy
(28)
/27
(Es)
fenv
aler
ate
A5
—4-
Cl
(2S)
2RS
B2
CN
(S)
RS
3-Ph
enox
y29
Fluc
ythr
inat
eA
5—
4-O
CH
F 22S
B2
CN
RS
3-Ph
enox
y30
Fluv
alin
ate
A5
NH
2-C
l-4-
CF 3
2RB
2C
NR
S3-
Phen
oxy
31A
crin
athr
inA
1H
CO
OC
H(C
F 3) 2
Z-1
R-c
isB
2C
NS
3-Ph
enox
y
Photodegradation of Pesticides 139
App
endi
x3.
Che
mic
alst
ruct
ures
ofan
ilide
san
dam
ides
.
No.
Pest
icid
eR
1R
2R
3
33Pr
opac
hlor
HC
H2C
lC
H(C
H3)
2
34A
lach
lor
2,6-
(C2H
5)2
CH
2Cl
CH
2OC
H3
35M
etol
achl
or2-
C2H
5-6-
CH
3C
H2C
lC
H(C
H3)
CH
2OC
H3
36B
utac
hlor
2,6-
(C2H
5)2
CH
2Cl
CH
2O(C
H2)
3CH
3
37M
etal
axyl
2,6-
(CH
3)2
CH
2OC
H3
CH
(CH
3)C
OO
CH
3
38M
epro
nil
3-O
-iso
-C3H
72-
CH
3Ph
H39
Flut
olan
il3-
O-i
so-C
3H7
2-C
F 3Ph
H40
Nic
losa
mid
e2-
Cl-
4-N
O2
3-C
l-6-
OH
PhH
41N
apro
anili
deH
CH
(CH
3)O
-2-N
apht
hyl
H42
Car
boxi
nH
A1
H43
Oxy
carb
oxin
HA
2H
140 T. Katagi
App
endi
x4.
Che
mic
alst
ruct
ures
ofur
eas
and
benz
oylu
reas
.
No.
Pest
icid
eX
R1
R2
R3
51Fe
nuro
nO
HC
H3
CH
3
52M
onur
onO
4-C
lC
H3
CH
3
53D
iuro
nO
3,4-
Cl 2
CH
3C
H3
54L
inur
onO
3,4-
Cl 2
OC
H3
CH
3
55Fl
umet
uron
O3-
CF 3
CH
3C
H3
56Is
opro
turo
nO
4-is
o-C
3H7
CH
3C
H3
57D
iafe
nthi
uron
S2,
6-(i
so-C
3H7)
2-4-
OPh
tert
-C4H
9H
Photodegradation of Pesticides 141
App
endi
x5.
Che
mic
alst
ruct
ures
ofca
rbam
ates
.
No.
Pest
icid
eR
1R
2R
3X
Y
60Ph
enm
ecC
H3
HPh
OO
61M
etol
carb
CH
3H
3-C
H3P
hO
O62
Feno
buca
rbC
H3
H2-
sec-
C4H
9Ph
OO
63X
ylyl
carb
CH
3H
3,4-
(CH
3)2P
hO
O64
Tri
met
haca
rbC
H3
H3,
4,5
(or
2,3,
5)-(
CH
3)3P
hO
O65
Prop
oxur
CH
3H
2-O
-iso
-C3H
7Ph
OO
66A
min
ocar
bC
H3
H3-
CH
3-4-
N(C
H3)
2Ph
OO
67M
exac
arba
teC
H3
H3,
5-(C
H3)
2-4-
N(C
H3)
2Ph
OO
68M
ethi
ocar
bC
H3
H3,
5-(C
H3)
2-4-
SCH
3Ph
OO
69E
thio
fenc
arb
CH
3H
2-C
H2S
C2H
5-Ph
OO
70M
etho
myl
CH
3H
N=C
(CH
3)SC
H3
OO
71C
arba
ryl
CH
3H
Nap
hth-
1-yl
OO
72C
arbo
fura
nC
H3
HA
1O
O73
Mob
amC
H3
HA
2O
O74
Oxa
myl
CH
3H
N=C
(SC
H3)
C(O
)N(C
H3)
2O
O75
Dim
etila
mC
H3
CH
3A
3O
O76
Pyro
lan
CH
3C
H3
A4
OO
77Is
olan
CH
3C
H3
A5
OO
78Pi
rim
icar
bC
H3
CH
3A
6O
O79
Prop
ham
PhH
iso-
C3H
7O
O80
Chl
orpr
opha
m3-
ClP
hH
iso-
C3H
7O
O81
Ben
omyl
A7
HC
H3
OO
82A
sula
mA
8H
CH
3O
O83
Des
med
ipha
mPh
H3-
NH
CO
2C2H
5Ph
OO
84Ph
enm
edip
ham
3-C
H3P
hH
3-N
HC
O2C
H3P
hO
O
142 T. Katagi
App
endi
x5.
(Con
tinue
d).
No.
Pest
icid
eR
1R
2R
3X
Y
85Fe
noth
ioca
rbC
H3
CH
3(C
H2)
4OPh
OS
86B
enth
ioca
rbC
2H5
C2H
5C
H2-
4-C
lPh
OS
87B
utyl
ate
(CH
3)2C
HC
H2
(CH
3)2C
HC
H2
C2H
5O
S
Photodegradation of Pesticides 143
App
endi
x5.
(Con
tinue
d).
144 T. Katagi
App
endi
x6.
Che
mic
alst
ruct
ures
ofsu
lfon
ylur
eas.
Ary
l
No.
Her
bici
deX
YR
1R
2Z
R3
R4
R5
96C
hlor
sulf
uron
CC
—C
lN
HO
CH
3C
H3
97M
etsu
lfur
onC
C—
CO
OH
NH
OC
H3
CH
3
98M
etsu
lfur
onm
ethy
lC
C—
CO
OC
H3
NH
OC
H3
CH
3
99T
ribe
nuro
nm
ethy
lC
C—
CO
OC
H3
NC
H3
OC
H3
CH
3
100
Tri
asul
furo
nC
C—
OC
H2C
H2C
lN
HO
CH
3C
H3
101
Chl
orim
uron
CC
—C
OO
HC
HC
lO
CH
3
102
Chl
orim
uron
ethy
lC
C—
CO
OC
2H5
CH
Cl
OC
H3
103
Rim
sulf
uron
CN
—SO
2C2H
5C
HO
CH
3O
CH
3
104
Thi
fens
ulfu
ron
A1
——
NH
OC
H3
CH
3
105
Thi
fens
ulfu
ron
met
hyl
A2
——
NH
OC
H3
CH
3
Photodegradation of Pesticides 145
App
endi
x7.
Che
mic
alst
ruct
ures
ofcy
clic
dica
rbox
imid
esan
dre
late
dpe
stic
ides
.
146 T. Katagi
App
endi
x8.
Che
mic
alst
ruct
ures
ofor
gano
chlo
rine
pest
icid
es.
Photodegradation of Pesticides 147
App
endi
x8.
(Con
tinue
d).
148 T. Katagi
App
endi
x9.
Che
mic
alst
ruct
ures
ofor
gano
phos
phor
uspe
stic
ides
.
No.
Pest
icid
eR
1R
2R
3X
135
Para
thio
nO
C2H
5O
C2H
5O
(4-N
O2P
h)S
136
Para
thio
n-m
ethy
lO
CH
3O
CH
3O
(4-N
O2P
h)S
137
Cya
noph
osO
CH
3O
CH
3O
(4-C
NPh
)S
138
Feni
trot
hion
OC
H3
OC
H3
O(3
-CH
3-4-
NO
2Ph)
S13
9Fe
nchl
orph
osO
CH
3O
CH
3O
(2,4
,5-C
l 3Ph)
S14
0B
rom
opho
sO
CH
3O
CH
3O
(2,5
-Cl 2-
4-B
rPh)
S14
1Io
dofe
npho
sO
CH
3O
CH
3O
(2,5
-Cl 2-
4-IP
h)S
142
Tol
clof
os-m
ethy
lO
CH
3O
CH
3O
(2,6
-Cl 2-
4-C
H3P
h)S
143
Fent
hion
OC
H3
OC
H3
O(3
-CH
3-4-
SCH
3Ph)
S14
4D
iazi
non
OC
2H5
OC
2H5
A1
S14
5C
hlor
pyri
fos
OC
2H5
OC
2H5
O(3
,5,6
-Cl 3-
pyri
din-
2-yl
)S
146
Pota
san
OC
2H5
OC
2H5
A2
S14
7C
oum
apho
sO
C2H
5O
C2H
5A
3S
148
Qui
nalo
phos
OC
2H5
OC
2H5
A4
S14
9Py
razo
phos
OC
2H5
OC
2H5
A5
S15
0Py
rida
phen
thio
nO
C2H
5O
C2H
5A
6S
151
Isox
athi
onO
C2H
5O
C2H
5A
7S
152
Phox
imO
C2H
5O
C2H
5O
N=C
(CN
)Ph
S15
3D
ichl
orvo
sO
CH
3O
CH
3O
CH=C
Cl 2
O15
4T
etra
chlo
vinp
hos
OC
H3
OC
H3
OC
(=C
HC
l)(2
,4,5
-Cl 3P
h)O
155
Mev
inph
osO
CH
3O
CH
3O
C(C
H3)=C
HC
OO
CH
3O
156
Mon
ocro
toph
osO
CH
3O
CH
3O
C(C
H3)=C
HC
(O)N
HC
H3
O15
7D
icro
toph
osO
CH
3O
CH
3O
C(C
H3)=C
HC
(O)N
(CH
3)2
O15
8Ph
osph
amid
onO
CH
3O
CH
3O
C(C
H3)=C
ClC
(O)N
(C2H
5)2
O15
9Pr
opap
hos
O-n
C3H
7O
-nC
3H7
O(4
-SC
H3P
h)O
Photodegradation of Pesticides 149
App
endi
x9.
(Con
tinue
d).
No.
Pest
icid
eR
1R
2R
3X
160
Prof
enof
osO
C2H
5S-
nC3H
7O
(4-B
r-2-
ClP
h)O
161
Sulp
rofo
sO
C2H
5S-
nC3H
7O
(4-S
CH
3)Ph
S16
2Ph
orat
eO
C2H
5O
C2H
5SC
H2S
C2H
5S
163
Dis
ulfo
ton
OC
2H5
OC
2H5
SCH
2CH
2SC
2H5
S16
4B
ensu
lide
O-i
so-C
3H7
O-i
so-C
3H7
SCH
2CH
2NH
S(O
) 2Ph
S16
5D
imet
hoat
eO
CH
3O
CH
3SC
H2C
(O)N
HC
H3
S16
6Fo
rmot
hion
OC
H3
OC
H3
SCH
2C(O
)N(C
HO
)CH
3S
167
Mal
athi
onO
CH
3O
CH
3SC
H(C
OO
C2H
5)C
H2C
OO
C2H
5S
168
Phen
thoa
teO
CH
3O
CH
3SC
H(C
OO
C2H
5)Ph
S16
9A
zinp
hos-
met
hyl
OC
H3
OC
H3
A8
S17
0Ph
osal
one
OC
2H5
OC
2H5
A9
S17
1M
ethi
dath
ion
OC
H3
OC
H3
A10
S17
2Ph
osm
etO
CH
3O
CH
3A
11S
173
Edi
fenp
hos
OC
2H5
SPh
SPh
O17
4A
ceph
ate
OC
H3
NH
C(O
)CH
3SC
H3
O17
5Is
ofen
phos
OC
2H5
NH
-iso
-C3H
7O
(2-C
(O)O
-iso
-C3H
7Ph)
S17
6S-
2571
OC
2H5
NH
-iso
-C3H
7O
(3-C
H3-
6-N
O2P
h)S
177
But
amif
osO
C2H
5N
H-s
ec-C
4H9
O(3
-CH
3-6-
NO
2Ph)
S17
8D
italim
fos
OC
2H5
OC
2H5
A12
S17
9T
rich
lorf
onO
CH
3O
CH
3C
H(O
H)C
Cl 3
O18
0C
yano
fenp
hos
OC
2H5
O(4
-CN
Ph)
PhS
181
Lep
toph
osO
CH
3O
(2,5
-Cl 2-
4-B
rPh)
PhS
182
But
onat
eO
CH
3O
CH
3C
H(C
Cl 3)
OC
(=O
)C3H
7O
150 T. Katagi
App
endi
x9.
(Con
tinue
d).
Photodegradation of Pesticides 151
App
endi
x10
.C
hem
ical
stru
ctur
esof
tria
zine
san
daz
oles
.
No.
Pest
icid
eR
1R
2R
3
185
Atr
azin
eC
lC
H(C
H3)
2C
H2C
H3
186
Sim
azin
eC
lC
H2C
H3
CH
2CH
3
187
Prom
eton
eO
CH
3C
H(C
H3)
2C
H(C
H3)
2
152 T. Katagi
App
endi
x11
.C
hem
ical
stru
ctur
esof
mis
cella
neou
spe
stic
ides
.
Photodegradation of Pesticides 153
App
endi
x11
.(C
ontin
ued)
.
154 T. Katagi
App
endi
x11
.(C
ontin
ued)
.
Photodegradation of Pesticides 155
App
endi
x11
.(C
ontin
ued)
.
156 T. Katagi
App
endi
x11
.(C
ontin
ued)
.
Photodegradation of Pesticides 157
References
Aaron JJ, Kaleel EM, Winefordner JD (1979) Comparative study of low-temperature androom-temperature phosphorescence characteristics of several pesticides. J Agric FoodChem 27:1233–1237.
Abbott CK, Sorensen DL, Sims RC (1992) Use and efficiency of ethylene glycol mono-methyl ether and monoethanolamine to trap volatilized [7-14C]naphthalene and 14CO2.Environ Toxicol Chem 11:181–185.
Abdel-Malik MM, de Mayo P (1984) Surface photochemistry: the amide photo-Friesrearrangement. Can J Chem 62:1275–1278.
Abdel-Wahab AM, Casida JE (1967) Photooxidation of two 4-dimethylaminoaryl meth-ylcarbamate insecticides (zectran and matacil) on bean foliage and of alkylaminophe-nyl methylcarbamates on silica gel chromatoplates. J Agric Food Chem 15:479–487.
Abdel-Wahab AM, Kuhr RJ, Casida JE (1966) Fate of 14C-carbonyl-labeled aryl methyl-carbamate insecticide chemicals in and on bean plants. J Agric Food Chem 14:290–298.
Abdou WM, Mahran MR, Sidky MM, Wamhoff H (1988) Photochemistry of pesticides.13. Some photoreactions of O,O-diethyl O-(4-methyl-2-oxo-2H-1-benzopyran-7-yl)phosphorothioate (Potasan). Phosphorus Sulfur Relat Elem 39:199–203.
Abe Y, Tsuda K, Fujita Y (1972) Studies on pyrethroidal compounds. Part III. Photosta-bility of pyrethroidal compounds. Botyu-Kagaku 37:102–111.
Adams JD, Iwata Y, Gunther FA (1977) Worker environment research. V. Effect of soildusts on dissipation of paraoxon dislodgeable residues on citrus foliage. Bull EnvironContam Toxicol 18:445–451.
Addison JB, Silk PJ, Unger I (1974) The photochemical reactions of carbamates. II. Thesolution photochemistry of matacil (4-dimethylamino-m-tolyl-N-methylcarbamate)and landrin (3,4,5-trimethylphenyl-N-methylcarbamate). Bull Environ Contam Tox-icol 11:250–255.
Addison JB, Semeluk GP, Unger I (1977) The luminescence properties of pesticides.I. Fluorescencing and phosphorescing carbamates. J Lumin 15:323–339.
Aguer JP, Richard C (1996a) Reactive species produced on irrdiation at 365 nm ofaqueous solutions of humic acids. J Photochem Photobiol A Chem 93:193–198.
Aguer JP, Richard C (1996b) Transformation of fenuron induced by photochemical excit-tion of humic acids. Pestic Sci 46:151–155.
Aguer JP, Richard C (1999) Influence of the excitation wavelength on the photoinductiveproperties of humic substances. Chemosphere 38:2293–2301.
Aguer JP, Richard C, Andreux F (1997) Comparison of the photoinductive properties ofcommercial, synthetic and soil-extracted humic substances. J Photochem Photobiol AChem 103:163–168.
Aguer JP, Blachere F, Boule P, Garaudee S, Guillard C (2000) Photolysis of dicamba(3,6-dichloro-2-methoxybenzoic acid) in aqueous solution and dispersed on solid sup-ports. Int J Photoenergy 2:81–86.
Aguer JP, Trubetskaya O, Trubetskoj O, Richard C (2001) Photoinductive properties ofsoil humic acids and their fractions obtained by tandem size exclusion chromatography-polyacrylamide gel electrophoresis. Chemosphere 44:205–209.
Aguer JP, Richard C, Trubetskaya O, Trubetskoj O, Levegue J, Andreux F (2002) Photo-inductive efficiency of soil extracted humic and fulvic acids. Chemosphere 49:259–262.
158 T. Katagi
Albanis TA, Bochicchio D, Bufo SA, Cospito I, D’Auria M, Lekka M, Scrano L (2002)Surface adsorption and photo-reactivity of sulfonylurea herbicides. Int J Anal Chem82:561–569.
Alenius CM, Vogelmann TC, Bornman JF (1995) A three-dimensional representation ofthe relationship between penetration of UV-B radiation and UV-screening pigmentsin leaves of Brassica napus. New Phytol 131:297–302.
Allebone JE, Hamilton RJ, Bryce TA, Kelly W (1971) Anthraquinone in plant surfacewaxes. Experientia (Basel) 27:13–14.
Allmaier GM, Schmid ER (1985) Effects of light on the organophosphorus pesticidesbromophos and iodofenphos and their main degradation products examined in rainwater and on soil surface in a long-term study. J Agric Food Chem 33:90–92.
Allmaier GM, Fogy I, Heinisch G, Schmid ER (1984) Photolysis of three organophos-phorus pesticides in rain water and soil surface. In: Frigerio A, Milon H (eds) Chro-matography and Mass Spectrometry in Nutrition Science and Food Safety. Elsevier,Amsterdam, pp 115–125.
Ando M, Iwasaki Y, Nakagawa M (1975) Metabolism of isoxathion, O,O-dimethyl O-(5-phenyl-3-isoxazolyl) phosphorothioate in plants. Agric Biol Chem 39:2137–2143.
Archer TE, Stokes JD, Bringhurst RS (1977) Fate of carbofuran and its metabolites onstrawberries in the environment. J Agric Food Chem 25:536–541.
Argauer RJ (1980) Fluorescence and ultraviolet absorbance of pesticides and naturallyoccurring chemicals in agricultural products after HPLC separation on a bonded-CNpolar phase. In: Harvey J Jr, Zweig G (eds) Pesticide Analytical Methodology. ACSSymposium Series 136. American Chemical Society, Washington, DC, pp 103–126.
Avato P, Bianchi G, Pogna N (1990) Chemosystematics of surface lipids from maizeand some related species. Phytochemistry (Oxf) 29:1571–1576.
Avnir D, Johnston LJ, DeMayo P, Wong SK (1981) Surface photochemistry: radical paircombination on a silica gel surface and in micelles. J Chem Soc Chem Commun958–959.
Awad TM, Vinson SB, Brazzel JR (1967) Effect of environmental and biological factorson persistence of malathion applied as ultra-low-volume or emulsifiable concentrateto cotton plants. J Agric Food Chem 15:1009–1013.
Bailey GW, Karickhoff SW (1973) UV-VIS spectroscopy in the characterization of claymineral surfaces. Anal Lett 6:43–49.
Baker EA (1982) Chemistry and morphology of plant epicuticular waxes. In: Cutler DF,Alvin KL, Price CE (eds) The Plant Cuticles. Linnean Society Symposium Series 10(Plant Cuticle). Academic Press, New York, pp 139–165.
Baker EA, Hunt G (1981) Developmental changes in leaf epicuticular waxes in relationto foliar penetration. New Phytol 88:731–747.
Baker EA, Bukovac MJ, Flore JA (1979) Ontogenic variations in the composition ofpeach leaf wax. Phytochemistry (Oxf) 18:781–784.
Baker EA, Bukovac MJ, Hunt GM (1982) Compositions of tomato fruit cuticle as relatedto fruit growth and development. In: Cutler DF, Alvin KL, Price CE (eds) The PlantCuticles. Linnean Society Symposium Series 10 (Plant Cuticle). Academic Press,New York, pp 33–44.
Baker EA, Hunt GM, Stevens PJG (1983) Studies of plant cuticle and spray dropletinteractions: a fresh approach. Pestic Sci 14:645–658.
Baker EA, Procopiou J, Hunt GM (1998) The cuticles of citrus species. Composition ofleaf and fruit waxes. J Sci Food Agric 26:1093–1101.
Photodegradation of Pesticides 159
Balkaya N (2003) Photocatalytic degradation technology for pesticide elimination fromaquatic media available. Energy Educ Sci Technol 10:73–80.
Balmer ME, Sulzberger B (1999) Atrazine degradation in irradiated iron/oxalate systems:effects of pH and oxalate. Environ Sci Technol 33:2418–2424.
Balmer ME, Goss KU, Schwarzenbach (2000) Photolytic transformation of organic pol-lutants on soil surfaces: an experimental approach. Environ Sci Technol 34:1240–1245.
Bandal SK, Casida JE (1972) Metabolism and photoalteration of 2-sec-butyl-4,6-dinitro-phenol (DNBP herbicide) and its isopropyl carbonate derivative (dinobuton acari-cide). J Agric Food Chem 20:1235–1245.
Banerjee K, Dureja P (1999) Phototransformation of quinalphos on clay surfaces. Tox-icol Environ Chem 68:475–480.
Barnes RD, Bull AT, Poller RC (1973) Studies on persistence of the organotin fungicidefentin acetate (triphenyltin acetate) in the soil and on surfaces exposed to light. PesticSci 4:305–317.
Barraclough D, Nye PH (1979) The effect of molecular size on diffusion characteristicsin soil. J Soil Sci 30:29–42.
Barta IC, Komives T (1984) Gas-liquid chromatographic method for the rapid analysisof the epicuticular wax composition of plants. J Chromatogr 287:438–441.
Basham GW, Lavy TL (1987) Microbial and photolytic dissipation of imazaquin in soil.Weed Sci 35:865–870.
Baude FJ, Gardiner JA, Han JCY (1973) Characterization of residues on plants followingfoliar spray applications of benomyl. J Agric Food Chem 21:1084–1090.
Bauer H, Schonherr J (1992) Determination of mobilities of organic compounds in plantcuticles and correlation with molar volumes. Pestic Sci 35:1–11.
Beigel C, Barriaso E, Di Pietro L (1997) Time dependency of triticonazole fungicidesorption and consequences for diffusion in soil. J Environ Qual 26:1503–1510.
Belding RD, Blankenship SM, Young E, Leidy RB (1998) Composition and variabilityof epicuticular waxes in apple cultivars. J Am Soc Hortic Sci 123:348–356.
Bengston C, Larsson S, Liljenberg C (1978) Effects of water stress on cuticular transpira-tion rate and amount and composition of epicuticular wax in seedlings of six oatvarieties. Physiol Plant 44:319–324.
Benson WR (1971) Photolysis of solid and dissolved dieldrin. J Agric Food Chem 19:66–72.
Benson WR, Lombardo P, Egry IJ, Ross IJ Jr, Barron RP, Mastbrook DW, Hansen EA(1971) Chlordane photoalteration products: their preparations and identification.J Agric Food Chem 19:857–862.
Bentson KP (1990) Fate of xenobiotics in foliar pesticide deposits. Rev Environ ContamToxicol 114:125–161.
Berenbaum MR, Larson RA (1988) Flux of singlet oxygen from leaves of phototoxicplants. Experientia (Basel) 44:1030–1032.
Bertino DJ, Zepp RG (1991) Effects of solar radiation on manganese oxide reactionswith selected organic compounds. Environ Sci Technol 25:1267–1273.
Beynon KI, Wright AN (1969) Breakdown of the insecticide ‘Gardona’ on plants and insoils. J Sci Food Agric 20:250–256.
Beynon KI, Wright AN (1972) The breakdown of [14C] monocrotophos insecticide onmaize, cabbage and apple. Pestic Sci 3:277–292.
Bhattacharjee AK, Dureja P (1999) Light induced transformation of tribenuron-methyl.Chemosphere 38:741–749.
160 T. Katagi
Bhattacharjee AK, Dureja P (2002) Light-induced transformation of tribenuron-methylon glass, soil and plant surfaces. J Environ Sci Health B37:131–140.
Bianchi G (1995) Plant waxes. In: Hamilton RJ (ed) Waxes: Chemistry, Molecular Biol-ogy and Functions, vol 6. The Oily Press, Dundee, pp 175–222.
Bobe A, Cooper JF, Coste CM, Muller MA (1998a) Behavior of fipronil in soil underSahelian plain field conditions. Pestic Sci 52:275–281.
Bobe A, Meallier P, Cooper JF, Coste CM (1998b) Kinetics and mechanisms of abioticdegradation of fipronil (hydrolysis and photolysis). J Agric Food Chem 46:2834–2839.
Bornman JF, Vogelman TC (1991) Effect of UV-B radiation on leaf optical propertiesmeasured with fiber optics. J Exp Bot 42:547–554.
Bowman MC, Beroza M (1967a) Spectra and analysis of insecticide synergists and re-lated compounds containing the methylenedioxyphenyl group by spectrophotofluoro-metry (SPF) and spectrophotophosphorimetry (SPF). Residue Rev 17:1–22.
Bowman MC, Beroza M (1967b) Spectrophotofluorescent and spectrophotophosphores-cent data on insecticidal carbamates and the analysis of five carbamates in milk byspectrophotofluorometry. Residue Rev 17:23–34.
Bowman MC, Leuck DB (1971) Determination and persistence of phoxim and its oxygenanalog in forage corn and grass. J Agric Food Chem 19:1215–1218.
Breithaupt DE, Schwack W (2000) Photoinduced addition of the fungicide anilazine tocyclohexene and methyl oleate as model compounds of plant cuticle constituents.Chemosphere 41:1401–1406.
Breugem P, van Noort P, Velberg S, Wondergem E, Zijlstra J (1986) Steady-state con-centrations of the phototransient hydrated electron in natural waters. Chemosphere15:717–724.
Brown HM, Brattsten LB, Lilly DE, Hanna PJ (1993) Metabolic pathways and residuelevels of thifensulfuron methyl in soybeans. J Agric Food Chem 41:1724–1730.
Buchenauer H (1975) Differences in light stability of some carboxylic acid anilide fungi-cides in relation to their applicability for seed and foliar treatment. Pestic Sci 6:525–535.
Buchenauer H, Edington LV, Grossmann F (1973) Photochemical transformation of thio-phanate-methyl and thiophanate to alkyl benzimidazol-2-yl carbamates. Pestic Sci 4:343–348.
Bukovac MJ, Flore JA, Baker EA (1979) Peach leaf surfaces: changes in wettability,retention, cuticular permeability, and epicuticular wax chemistry during expansionwith special reference to spray application. J Am Soc Hortic Sci 104:611–617.
Bull DL (1979) Fate and efficacy of acephate after application to plants and insects.J Agric Food Chem 27:268–272.
Bull DL, Ivie GW (1976) Fate of diflubenzuron in cotton, soil and rotational crops.J Agric Food Chem 26:515–520.
Bull DL, Lindquist DA (1964) Metabolism of 3-hydroxy-N,N-dimethylcrotonamide di-methyl phosphate by cotton plants, insects and rats. J Agric Food Chem 12:310–317.
Bull DL, Lindquist DA, Grabbe RR (1967) Comparative fate of the geometric isomersof phosphamidon in plants and animals. J Econ Entomol 60:332–241.
Bullivant MJ, Pattenden G (1973) Photolysis of bio-allethrin. Tetrahedron Lett 3679–3680.
Bullivant MJ, Pattenden G (1976) Photochemistry of 2-(prop-2-enyl)cyclopent-2-enones.J Chem Soc Perkin Trans I:249–256.
Photodegradation of Pesticides 161
Burghardt M, Schreiber L, Riederer M (1998) Enhancement of the diffusion of activeingredients in barley leaf cuticular wax by monodisperse alcohol ethoxylates. J AgricFood Chem 46:1593–1602.
Burkhard N, Guth JA (1979) Photolysis of organophosphorus insecticides on soil sur-faces. Pestic Sci 10:313–319.
Burrows HD, Canle M, Santaballa JA, Steenken S (2002) Reaction pathways and mecha-nisms of photodegradation of pesticides. J Photochem Photobiol B Biol 67:71–108
Busch MA, Franklin TC (1979) Nature of the copper(I) carbonyl formed by acid cuprouschloride in the presence of carbon monoxide. Inorg Chem 18:521–524.
Caboni P, Cabras M, Angioni A, Russo M, Cabras P (2002) Persistence of azadirachtinresidues on olives after field treatment. J Agric Food Chem 50:3491–3494.
Cabras P, Spanedda L, Cabitza F, Cubeddu M, Martini MG, Brandolini V (1990) Pirimi-carb and its metabolite residues in lettuce. Influence of cultural environment. J AgricFood Chem 38:879–882.
Cabras P, Angioni A, Garau VL, Melis M, Pirisi FM, Minelli EV, Cabitza F, CubedduM (1997a) Fate of some new fungicides (cyprodinil, fludioxinil, pyrimethanil andtebuconazole) from vine to wine. J Agric Food Chem 45:2708–2710.
Cabras P, Angioni A, Garau VL, Melis M, Pirisi FM, Minelli EV (1997b) Effect ofepicuticular waxes of fruits on the photodegradation of fenthion. J Agric Food Chem45:3681–3683.
Cabras P, Angioni A, Garau VL, Melis M, Pirisi FM, Espinoza J, Mendoza A, CabitzaF, Pala M, Brandolini V (1998) Fate of azoxystrobin, fluazinam, kresoxim-methyl,mepanipyrim, and tetraconazole from vine to wine. J Agric Food Chem 46:3249–3251.
Caine M, Dyer G, Holder JV, Osborne BN, Matear WA, McCabe RW, Mobbs D, Rich-ardson S, Wang L (1999) The use of clays as sorbents and catalysts. In: MisaelidesP, Macasek F, Pinnavaia TJ, Colella C (eds) Natural Microporous Materials in Envi-ronmental Technology. Kluwer, Dordrecht, pp 49–69.
Calumpang SMF, Tejada AW, Magallona ED (1984) Photodecomposition on silica gelplates of nine selected organophosphorus insecticide formulations. Philipp Entomol6:191–204.
Campbell JR, Penner D (1985a) Abiotic transformations of sethoxydim. Weed Sci 33:435–439.
Campbell JR, Penner D (1985b) Sethoxydim metabolism in monocotyledonous and di-cotyledonus plants. Weed Sci 33:771–773.
Canonica S, Jans U, Stemmler K, Hoigne (1995) Transformation kinetics of phenols inwater: photosensitization by dissolved natural organic material and aromatic ketones.Environ Sci Technol 29:1822–1831.
Cape JN (1997) Photochemical oxidants—what else is in the atmosphere besides ozone?Phyton (Austria) 37:45–58.
Carmichael I, Hug GL (1989) Spectroscopy and intramolecular photophysics of tripletstates. In: Scaiano JCD (ed) CRC Handbook of Organic Photochemistry, vol 1. CRCPress, Boca Raton, FL, pp 369–403.
Carruthers W, Johnstone RAW (1959) Composition of a paraffin wax fraction fromtobacco leaf and tobacco smoke. Nature (Lond) 184:1131–1132.
Casida JE, Gatterdam PE, Getzin Jr LW, Chapman RK (1956) Residual properties of thesystemic insecticide O,O-dimethyl 1-carbomethoxy-1-propen-2-yl phosphate. J AgricFood Chem 4:236–243.
162 T. Katagi
Cen YP, Bornman JF (1993) The effect of exposure to enhanced UV-B radiation on thepenetration of monochromatic and polychromatic UV-B radiation in leaves of Bras-sica napus. Physiol Plant 87:249–255.
Cessna AJ, Muir DCG (1991) Photochemical transformations. In: Grover R, Cessna AJ(eds) Environmental Chemistry of Herbicides, vol 2. CRC Press, Boca Raton, FL, pp199–263.
Chambers RW, Kearns DR (1969) Triplet states of some common photosensitizing dyes.Photochem Photobiol 10:215–219.
Chameides WL (1989) The chemistry of ozone deposition to plant leaves: Role ofascorbic acid. Environ Sci Technol 23:595–600.
Chattopadhyaya S, Dureja P (1991) Photolysis of flucythrinate. Pestic Sci 31:163–173.Chen J, Quan X, Yang F, Peijnenburg WJGM (2001) Quantitative structure-property
relationships on photodegradation of PCDD/Fs in cuticular waxes of laurel cherry(Prunus laurocerasus). Sci Total Environ 269:163–170.
Chen PH, Watts RJ (2000) Determination of rates of hydroxyl radical generation inmineral-catalyzed Fenton-like oxidation. J Chin Inst Environ Eng 10:201–208.
Chen YL, Casida JE (1969) Photodecomposition of pyrethrin I, allethrin, phthalthrin,and dimethrin. J Agric Food Chem 17:208–215.
Chen YL, Chen CC (1978) Photodecomposition of a herbicide, butachlor. J Pestic Sci 3:143–148.
Chen ZM, Zabik MJ, Leavitt RA (1984) Comparative study of thin film photodegradativerates for 36 pesticides. Indian Eng Chem Prod Res Dev 23:5–11.
Cheng HM, Hwang DF (1996) Photodegradation of benthiocarb. Chem Ecol 12:91–101.Chesters G, Simsiman GV, Levy J, Alhajjar BJ, Fathulla RN, Harkin JM (1989) Environ-
mental fate of alachlor and metolachlor. Rev Environ Contam Toxicol 110:1–74.Chiba M, Kato S, Yamamoto I (1976) Metabolism of cyanox and surecide in bean
plants and degradation in soil. J Pestic Sci 1:179–191.Chou SS, Taniguchi E, Eto M (1980) Photodegradation of dialkyl 1,3-dithiolan-2-ylide-
nemalonates and some other pesticides on solid particles. Agric Biol Chem 44:1169–2177.
Choudhry GG (1981) Humic substances. Part II: Photophysical, photochemical and freeradical characterization. Toxicol Environ Chem 4:261–295.
Choudhry GG (1984a) Photophysical and photochemical properties of soil and aquatichumic materials. Residue Rev 92:59–112.
Choudhry GG (1984b) Humic substances. Structural aspects, and photophysical, photo-chemical and free radical characteristics. In: Hutzinger O (ed) The Handbook of Envi-ronmental Chemistry, vol 1, part C. Springer-Verlag, Berlin, pp 1–24.
Choudhry GG, Webster GRB (1985) Protocol guidelines for the investigations of photo-chemical fate of pesticides in water, air, and soils. Residue Rev 96:80–136.
Choudhury PP, Dureja P (1997a) Studies on photodegradation of chlorimuron-ethyl insoil. Pestic Sci 51:201–205.
Choudhury PP, Dureja P (1997b) Photolysis of chlorimuron-methyl. Toxicol EnvironChem 63:71–81.
Choudhury PP, Dureja P (1997c) Photolysis of chlorimuron-ethyl in benzene. ToxicolEnviron Chem 61:187–193.
Chukwudebe A, March RB, Othman M, Fukuto TR (1989) Formation of trialkyl phos-phorothioate esters from organophosphorus insecticides after exposure to either ultra-violet light or sunlight. J Agric Food Chem 37:539–545.
Photodegradation of Pesticides 163
Cieslik S, Labatut A (1997) Ozone deposition on various surface types. Transp ChemTransform Pollut Troposphere 4:225–243.
Clark T, Watkins DAM (1986) Photolysis of triadimenol. Chemosphere 15:765–770.Clark T, Clifford DR, Deas AHB, Gendle P, Watkins DAM (1978) Photolysis, metabo-
lism and other factors influencing the performance of triadimefon as a powdery mil-dew fungicide. Pestic Sci 9:497–506.
Clark T, Watkins DAM, Weerasinghe DK (1983) Photolysis of fluotrimazole. Pestic Sci14:449–452.
Class TJ, Casida JE, Ruzo LO (1989) Photochemistry of etofenprox and three relatedpyrethroids with ether, alkane, and alkene central linkage. J Agric Food Chem 37:216–222.
Clay VE, Fukuto TR (1984) Metabolism of carbosulfan in Valencia orange tree leavesand fruits. Arch Environ Contam Toxicol 13:53–62.
Clements P, Wells CHJ (1992) Soil sensitized generation of singlet oxygen in the photo-degradation of bioresmethrin. Pestic Sci 34:163–166.
Coats JR, Metcalf RL, Kapoor IP, Chio LC, Boyle PA (1979) Physical-chemical andbiological degradation studies on DDT analogues with altered aliphatic moieties.J Agric Food Chem 27:1016–1022.
Cockell CS, Knowland J (1999) Ultraviolet radiation screening compounds. Biol Rev74:311–345.
Cole LM, Casida JE, Ruzo LO (1982) Comparative degradation of the pyrethroids tralo-methrin, tralocythrin, deltamethrin, and cypermethrin on cotton and bean foliage.J Agric Food Chem 30:916–920.
Conceicao M, Mateus DA, da Silva AM, Burrows HD (1997) UV-visible absorptionspectra and luminescence of the pesticide fenarimol. Spectrochim Acta Part A MolBiomol Spectrosc 53:2679–2684.
Cookson RC, Dandegaonker SH (1955) Absorption spectra of ketones. Part III. Thelong-wavelength band of αβ-unsaturated ketones. J Chem Soc 1651–1654.
Cooper WJ (1989) Sunlight-induced photochemistry of humic substances in natural wa-ters: major reactive species. In: Suffet IH, MacCarthy PM (eds) Aquatic Humic Sub-stances—Influence on Fate and Treatment of Pollutants. Advances in Chemistry Se-ries 219. American Chemical Society, Washington, DC, pp 333–362.
Crosby DG (1983) Atmospheric reactions of pesticides. In: Miyamoto J, Kearney PC(eds) Human Welfare and the Environment. Proceedings, 5th International Congresson Pesticide Chemistry, vol 3. Pergamon Press, Oxford, pp 327–332.
Crosby DG, Bowers JB (1985) Composition and photochemical reactions of a dimethyl-amine salt formulation of (4-chloro-2-methylphenoxy)acetic acid (MCPA). J AgricFood Chem 33:569–573.
Crosby DG, Wong AS (1976) Environmental degradation of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD). Science 195:1337–1338.
Crosley DR (1995) The measurement of OH and HO2 in the atmosphere. J Atmos Sci52:3299–3314.
Crouch LS, Feely WF, Arison BH, VandenHeuvel WJA, Colwell LF, Stearns RA, KlineWF, Wislocki PG (1991) Photodegradation of avermectin B1a thin films on glass.J Agric Food Chem 39:1310–1319.
Crutzen PJ (1982) The global distribution of hydroxyl. In: Goldberg ED (ed) Atmo-spheric Chemistry. Springer-Verlag, Berlin, pp 313–328.
Curran WS, Loux MM, Liebl RA, Simmons FW (1992) Photolysis of imidazolinoneherbicides in aqueous solutions and on soil. Weed Sci 40:143–148.
164 T. Katagi
Da Silva JP, Da Silva AM, Khmelinskii IV, Martinho JMG, Vieira Ferreira LF (2001)Photophysics and photochemistry of azole fungicides: triadimefon and triadomenol.J Photochem Photobiol A Chem 142:31–37.
Datta S, Walia S (1997) Photodegradation of buprofezin. Toxicol Environ Chem 60:1–11.
Dauterman WC, Viado GB, Casida JE, O’Brien RD (1960) Persistence of dimethoateand metabolites following foliar application to plants. J Agric Food Chem 8:115–119.
Day TA, Howells BW, Rice WJ (1994) Ultraviolet absorption and epidermal-transmit-tance spectra in foliage. Physiol Plant 92:207–218.
Derek W, Georgi W, Grahl R (1979) Comparative degradation and metabolism of 32P-labeled butonate, trichlorfone and dichlorvos in crop plants. Biochem Physiol Pflanz174:707–722.
Dixon SR, Wells CHJ (1983) Dye-sensitized photo-oxidation of 2-dimethylamino-5,6-dimethylpyrimidin-4-ol in aqueous solution. Pestic Sci 14:444–448.
Dixon SR, Wells CHJ (1987) Chlorophyll sensitized photodegradation of 2-dimethyl-amino-5,6-dimethylpyrimidin-4-ol. Pestic Sci 21:155–163.
Dodge AD, Knox JP (1986) Photosensitizers from plants. Pestic Sci 17:579–586.Donaldson SG, Miller GC (1996) Coupled transport and photodegradation of napropa-
mide in soils undergoing evaporation from a shallow water table. Environ Sci Technol30:924–930.
Dorough HW, Witacre DM, Cardona RA (1973) Metabolism of the herbicide methazolein cotton and beans, and fate of certain of its polar metabolites in rats. J Agric FoodChem 21:797–803.
Dorn HP, Brandenburger U, Brauers T, Hausmann M (1995) A new in situ laser long-path absorption instrument for the measurement of tropospheric OH radicals. J AtmosSci 52:3373–3380.
Drabek J, Boger M, Ehrenfreund J, Stamm E, Steinemann A, Alder A, Burckhardt U(1992) New thioureas as insecticides. In: Crombie L (ed) Recent Advances in theChemistry of Insect Control, vol II. Special publication 79. Royal Society of Chemis-try, Cambridge, pp 170–183.
Draper WM, Casida JE (1985) Nitroxide radical adducts of nitrodiphenyl ether herbicidesand other nitroaryl pesticides with unsaturated cellular lipids. J Agric Food Chem 33:103–108.
Draper WM, Crosby DG (1981) Hydrogen peroxide and hydroxyl radical: intermediatesin indirect photolysis reactions in water. J Agric Food Chem 29:699–702.
Draper WM, Crosby DG (1983) The photochemical generation of hydrogen peroxide innatural waters. Arch Environ Contam Toxicol 12:121–126.
Draper WM, Crosby DG (1984) Solar photooxidation of pesticides in dilute hydrogenperoxides. J Agric Food Chem 32:231–237.
Dureja P (1989) Photodecomposition of monocrotophos in soil, on plant foliage, and inwater. Bull Environ Contam Toxicol 43:239–245.
Dureja P, Chattopadhyay S (1995) Photodegradation of pyrethroid insecticide flucythri-nate in water and on soil surface. Toxicol Environ Chem 52:97–102.
Dureja P, Johnson S (2000) Photodegradation of azadirachtin-A: a neam-based pesticide.Curr Sci 79:1700–1703.
Dureja P, Mukerjee SK (1982) Photoinduced reactions: part IV. Studies on photochem-ical fate of 6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,4,3-benzo[e]dioxathiepin-3-oxide (Endosulphan), an important insecticide. Indian J Chem21B:411–413.
Photodegradation of Pesticides 165
Dureja P, Walia S (1989) Photodecomposition of pendimetalin. Pestic Sci 25:105–114.Dureja P, Casida JE, Ruzo LO (1984) Dinitroanilines as photostabilizers for pyrethroids.
J Agric Food Chem 32:246–250.Dureja P, Walia S, Mukerjee SK (1987a) Photolysis of propiconazole. Toxicol Environ
Chem 16:61–67.Dureja P, Khazanchi R, Mukerjee SK (1987b) Photochemical decomposition of tetra-
chlorovinphos. Toxicol Environ Chem 15:293–300.Dureja P, Walia S, Mukerjee SK (1988) Multiphase photodegradation of quinalphos.
Pestic Sci 22:287–295.Dureja P, Walia S, Mukerjee SK (1989) Photodecomposition of isofenphos (O-ethyl
O-(2-isopropoxycarbonyl)phenyl isopropyl phosphoramidothioate). Toxicol EnvironChem 19:187–192.
Dureja P, Walia S, Prasad D (1990) Photolysis of benfuracarb. Toxicol Environ Chem28:239–244.
Eastman JA, Wesely ML, Stedman DH (1981) On the mechanisms that control verticalozone flux to vegetative surfaces. Proc Quad Int Ozone Symp 1:462–470.
Ebing W, Schuphan I (1979) Studies on the behavior of environmental chemicals inplants and soil quantitatively investigated in closed cultivating systems. EcotoxicolEnviron Saf 3:133–143.
Ehlers W, Letey J, Spencer WF, Farmer WJ (1969a) Lindane diffusion in soils: I. Theo-retical considerations and mechanism of movement. Soil Sci Soc Am Proc 33:501–504.
Ehlers W, Spencer WF, Farmer WJ, Letey J (1969b) Lindane diffusion in soils: II. Watercontent, bulk density, and temperature effects. Soil Sci Soc Am Proc 33:505–508.
Elazzouzi M, Bensaoud A, Bouhaouss A, Guittonneau S, Dahchour A, Meallier P, Pic-colo A (1999) Photodegradation of imazapyr in the presence of humic substances.Fresenius Environ Bull 8:478–485.
El-Nahhal Y, Nir S, Margulies L, Rubin B (1999) Reduction of photodegradation andvolatilization of herbicides in organo-clay formulation. Appl Clay Sci 14:105–119.
El-Nahhal Y, Undabeytia T, Polubesova T, Mishael YG, Nir S, Rubin B (2001) Organo-clay formulations of pesticides: reduced leaching and photodegradation. Appl ClaySci 18:309–326.
El-Refai A, Hopkins TL (1966) Parathion absorption, translocation, and conversion toparaoxon in bean plants. J Agric Food Chem 14:588–592.
El-Refai A, Hopkins TL (1972) Malathion absorption, translocation, and conversion tomalaoxon in bean plants. J Assoc Offic Anal Chem 55:526–531.
Emmelin C, Guittonneau S, Lamartine R, Meallier P (1993) Photodegradation of pesti-cides on adsorbed phases. Photodegradation of carbetamid. Chemosphere 27:757–763.
Emmelin C, Knudsen F, Guittonneau S, Meallier P (1998) Choice of silica as standard-ized matrix for photodegradation studies of the pesticide phenmedipham on adsorbedphase. Fresenius Environ Bull 7:673–680.
Endo S, Mintarsih TH, Kazano H (1985) Disappearance of diazinon, isoxathion andcartap applied to rice plant. Proc Assoc Plant Prot Kyushu 31:115–118.
EPA FIFRA (1999) In: Environmental fate assessment for the synthetic pyrethroids. FIFRAScientific Advisory Panel Meeting, Background Documents. Environmental ProtectionAgency, Washington, D.C. http://www.epa.gov/scipoly/sap/1999/index.htm.
166 T. Katagi
EPA OPPTS (1993) Butyrate. In: Reregistration Eligibility Decision (RED) Butyrate.EPA 738-R-93-014. U.S. Environmental Protection Agency, Office of Prevention,Pesticides and Toxic Substances, Washington, DC.
EPA OPPTS (1994) Oryzalin. In: Reregistration Eligibility Decision (RED) Oryzalin.EPA 738-R-94-016. U.S. Environmental Protection Agency, Office of Prevention,Pesticides and Toxic Substances, Washington, DC.
EPA OPPTS (1995a) Asulam. In: Reregistration Eligibility Decision (RED) Asulam.EPA 738-R-95-024. U.S. Environmental Protection Agency, Office of Prevention,Pesticides and Toxic Substances, Washington, DC.
EPA OPPTS (1995b) Ethalfluralin. In: Reregistration Eligibility Decision (RED) Ethal-fluralin. EPA 738-R-95-001. U.S. Environmental Protection Agency, Office of Pre-vention, Pesticides and Toxic Substances, Washington, DC.
EPA OPPTS (1995c) Ethion. In: Pesticide Reregistration Status (REDs, IREDS andTREDs). U.S. Environmental Protection Agency, Washington, DC. Documents forEthion. Environmental fate and effects, preliminary assessment, pp 1–35. http://www.epa.gov/pesticides/reregistration/status.htm
EPA OPPTS (1995d) Linuron. In: Reregistration Eligibility Decision (RED) Linuron.EPA 738-R-95-003. U.S. Environmental Protection Agency, Office of Prevention,Pesticides and Toxic Substances, Washington, DC.
EPA OPPTS (1996a) Amitrole. In: Reregistration Eligibility Decision (RED) Amitrole.List A, case 0095. U.S. Environmental Protection Agency, Office of Prevention, Pes-ticides and Toxic Substances, Washington, DC.
EPA OPPTS (1996b) Desmedipham. In: Reregistration Eligibility Decision (RED) De-smedipham. EPA 738-R-96-004. U.S. Environmental Protection Agency, Office ofPrevention, Pesticides and Toxic Substances, Washington, DC.
EPA OPPTS (1996c) Trifluralin. In: Reregistration Eligibility Decision (RED) Desmedi-pham. EPA 738-R-95-040. U.S. Environmental Protection Agency, Office of Preven-tion, Pesticides and Toxic Substances, Washington, DC.
EPA OPPTS (1997a) Diflubenzuron. In: Reregistration Eligibility Decision (RED) Diflu-benzuron. EPA 738-R-97-008. U.S. Environmental Protection Agency, Office of Pre-vention, Pesticides and Toxic Substances, Washington, DC.
EPA OPPTS (1997b) Propoxur. In: Reregistration Eligibility Decision (RED) Propoxur.EPA 738-R-97-009. U.S. Environmental Protection Agency, Office of Prevention,Pesticides and Toxic Substances, Washington, DC.
EPA OPPTS (1998a) Azinphos-methyl. In: Pesticide Reregistration Status (REDs, IREDSand TREDs). U.S. Environmental Protection Agency, Washington, D.C. Documentsfor Azinphos-methyl. Environmental fate and effects, preliminary assessment, pp 1–162. http://www.epa.gov/pesticides/reregistration/status.htm.
EPA OPPTS (1998b) Butralin. In: Reregistration Eligibility Decision (RED) Butralin.EPA 738-R-97-09. U.S. Environmental Protection Agency, Office of Prevention, Pes-ticides and Toxic Substances, Washington, DC.
EPA OPPTS (1998c) Dichlobenil. In: Reregistration Eligibility Decision (RED) Dichlo-benil. EPA 738-R-98-003. U.S. Environmental Protection Agency, Office of Preven-tion, Pesticides and Toxic Substances, Washington, DC.
EPA OPPTS (1998d) Dicofol. In: Reregistration Eligibility Decision (RED) Dicofol.EPA 738-R-98-018. U.S. Environmental Protection Agency, Office of Prevention,Pesticides and Toxic Substances, Washington, DC.
Photodegradation of Pesticides 167
EPA OPPTS (1998e) Iprodione. In: Reregistration Eligibility Decision (RED) Iprodione.EPA 738-R-98-019. U.S. Environmental Protection Agency, Office of Prevention,Pesticides and Toxic Substances, Washington, DC.
EPA OPPTS (1998f) Isofenphos. In: Pesticide Reregistration Status (REDs, IREDS andTREDs). U.S. Environmental Protection Agency, Washington, DC. Documents forIsofenphos. Environmental fate and effects, preliminary assessment, pp 1–47. http://www.epa.gov/pesticides/reregistration/status.htm.
EPA OPPTS (1998g) Metribuzin. In: Reregistration Eligibility Decision (RED) Metri-buzin. EPA 738-R-97-006. U.S. Environmental Protection Agency, Office of Preven-tion, Pesticides and Toxic Substances, Washington, DC.
EPA OPPTS (1998h) Terbacil. In: Reregistration Eligibility Decision (RED) Terbacil.EPA 738-R-97-011. U.S. Environmental Protection Agency, Office of Prevention,Pesticides and Toxic Substances, Washington, DC.
EPA OPPTS (1999a) Bensulide. In: Pesticide Reregistration Status (REDs, IREDS andTREDs). U.S. Environmental Protection Agency, Washington, DC. Documents forBensulide. Revised environmental fate and effects assessment, pp 1–102. http://www.epa.gov/pesticides/reregistration/status.htm.
EPA OPPTS (1999b) Captan. In: Reregistration Eligibility Decision (RED) Captan. EPA738-R-99-015. U.S. Environmental Protection Agency, Office of Prevention, Pesti-cides and Toxic Substances, Washington, DC.
EPA OPPTS (1999c) Chlorothalonil. In: Reregistration Eligibility Decision (RED) Chlo-rothalonil. EPA 738-R-99-004. U.S. Environmental Protection Agency, Office of Pre-vention, Pesticides and Toxic Substances, Washington, DC.
EPA OPPTS (1999d) Disulfoton. In: Pesticide Reregistration Status (REDs, IREDS andTREDs). U.S. Environmental Protection Agency, Washington, DC. Documents forDisulfoton. Revised environmental fate and effects assessment, pp 1–102. http://www.epa.gov/pesticides/reregistration/status.htm.
EPA OPPTS (1999e) Methyl parathion. In: Pesticide Reregistration Status (REDs, IREDSand TREDs). U.S. Environmental Protection Agency, Washington, DC. Documentsfor Methyl Parathion. Revised environmental fate and effects assessment, pp 1–87.http://www.epa.gov/pesticides/reregistration/status.htm.
EPA OPPTS (2000) Diazinon. In: Pesticide Reregistration Status (REDs, IREDS andTREDs). U.S. Environmental Protection Agency, Washington, DC. Documents for Di-azinon. Revised science chapter, pp 1–171. http://www.epa.gov/pesticides/reregistration/status.htm.
EPA OPPTS (2001) Thiophanate-methyl. In: Pesticide Reregistration Status (REDs, IREDSand TREDs). U.S. Environmental Protection Agency, Washington, DC. Documentsfor Thiophanate-methyl. Preliminary risk Assessments, pp 1–124. http://www.epa.gov/pesticides/reregistration/status.htm.
Fang CH (1977) Effects of soils on the degradation of herbicide alachlor under the light.J Chin Agric Chem Soc 15:53–59.
Farmer WJ, Jensen CR (1970) Diffusion and analysis of carbon-14 labeled dieldrin insoils. Soil Sci Soc Am Proc 34:28–31.
Feely WF, Crouch LS, Arison BH, VandenHeuvel WJA, Colwell LF, Wislocki PG(1992) Photodegradation of 4″-(epi-methylamino)-4″-deoxyavermectin B1a thin filmson glass. J Agric Food Chem 40:691–696.
Fenet H, Beltran E, Gadji B, Cooper JF, Coste CM (2001) Fate of a phenylpyrazole invegetation and soil under tropical field conditions. J Agric Food Chem 49:1293–1297.
168 T. Katagi
Feng W, Nansheng D (2000) Photochemistry of hydrolytic iron (III) species and photoin-duced degradation of organic compounds. A minireview. Chemosphere 41:1137–1147.
Fischer AM, Kliger DS, Winterle JS, Mill T (1985) Direct observation of phototransientsin natural waters. Chemosphere 14:1299–1306.
Fischer AM, Winterle JS, Mill T (1987) Primary photochemical processes in photolysismediated by humic substances. In: Zika RG, Cooper WJ (eds) Photochemistry ofEnvironmental Aquatic Systems. ACS Symposium Series 327. American ChemicalSociety, Washington, DC, pp 141–156.
Fleeker JR, Lacy HM (1977) Photolysis of methyl 2-benzimidaolecarbamate. J AgricFood Chem 25:51–55.
Floßer-Muller H, Schwack W (2001) Photochemistry of organophosphorus insecticides.Rev Environ Contam Toxicol 172:129–228.
Fontan J, Minga A, Lopez A, Druilhet A (1992) Vertical ozone profiles in a pine forest.Atmos Environ 26A:863–869.
Foote CS (1968a) Mechanism of photosensitized oxidation. Science 162:963–970.Foote CS (1968b) Photosensitized oxygenations and the role of singlet oxygen. Acc
Chem Res 1:104–110.Fowler D, Flechard C, Cape JN, Storeton-West RL, Coyle M (2001) Measurements of
ozone deposition to vegetation quantifying the flux, the stomatal and non-stomatalcomponents. Water Air Soil Pollut 130:63–74.
Frank MP, Graebing PG, Chib JS (2002) Effect of soil moisture and sample depth onpesticide photolysis. J Agric Food Chem 50:2607–2614.
Frei RW, Nomura NS (1968) A comparison of new techniques for the detection andquantitative determination of triazine herbicides separated by thin-layer chromatogra-phy. II. Reflectance spectroscopy. Mikrochim Acta (Wien) 3:565–573.
Frimmel FH (1994) Photochemical aspects related to humic substances. Environ Int 20:373–385.
Fruekilde P, Hjorth J, Jensen NR, Kotzias D, Larson B (1998) Ozonolysis at vegetationsurfaces: a source of acetone, 4-oxopentanal, 6-methyl-5-hepten-2-one, and geranylacetone in the troposphere. Atmos Environ 32:1893–1902.
Fujii Y, Asaka S, Misato T (1979) Photodegradation of dipropyl 4-(methylthio)phenylphosphate (propaphos, Kayaphos). J Pestic Sci 4:361–366.
Fukushima M, Tatsumi K (1999) Photocatalytic reaction by iron (III)-humate complexand its effect on the removal of organic pollutant. Toxicol Environ Chem 73:103–116.
Fukushima M, Tatsumi K (2001) Degradation pathways of pentachlorophenol by photo-Fenton systems in the presence of iron (III), humic acid, and hydrogen peroxide.Environ Sci Technol 35:1771–1778.
Fukushima M, Tatsumi K, Morimoto K (2000) The fate of aniline after a photo-Fentonreaction in an aqueous system containing iron (III), humic acid, and hydrogen perox-ide. Environ Sci Technol 34:2006–2013.
Fukushima M, Tatsumi K, Nagao S (2001) Degradation characteristics of humic acidduring photo-Fenton processes. Environ Sci Technol 35:3683–3690.
Fukushima M, Fujisawa T, Katagi T, Takimoto Y (2003) Metabolism of fenitrothion andconjugation of 3-methyl-4-nitrophenol in tomato plant (Lycopersicon esculentum).J Agric Food Chem 51:5016–5023.
Gab S, Saravanja V, Korte F (1975a) Irradiation studies of aldrin and chlordane adsorbedon a silica gel surfaces. Bull Environ Contam Toxicol 13:301–306.
Photodegradation of Pesticides 169
Gab S, Nitz S, Parlar H, Korte F (1975b) Photomineralization of certain aromatic xenobi-otica. Chemosphere 4:251–256.
Garau V, Angioni A, Real AAD, Russo M, Cabras P (2002) Disappearance of azoxy-strobin, pyrimethanil, cyprodinil and fludioxinil on tomatoes in a greenhouse. J AgricFood Chem 50:1929–1932.
Gates DM, Keegan HJ, Schleter JC, Weidner VR (1965) Spectral properties of plants.Appl Opt 4:11–20.
Gerecke AC, Canonica S, Muller SR, Scharer M, Schwarzenbach RP (2001) Quantifica-tion of dissolved natural organic matter (DOM) mediated phototransformation of phe-nylurea herbicides in lakes. Environ Sci Technol 35:3915–3923.
Gerstl Z, Yaron B, Nye PH (1979) Diffusion of a biodegradable pesticide: I. In a biologi-cally inactive soil. Soil Sci Soc Am J 43:839–842.
Ghosal DN, Mukherjee SK (1972) A spectrophotometric study of dye aggregation onclay surfaces. Indian J Chem 10:835–837.
Gil Garcia MD, Martinez Vidal JL, Martinez Galera M, Rodriguez Torreblanca C, Gon-zalez C (1997) Determination and degradation of methomyl in tomatoes and greenbeans grown in greenhouses. J Assoc Offic Anal Chem Int 80:633–638.
Glass B (1975) Photosensitization and luminescence of picloram. J Agric Food Chem23:1109–1112.
Goetz AJ, Lavy TL, Gbur Jr EE (1990) Degradation and field persistence of imazethapyr.Weed Sci 38:421–428.
Gohre K, Miller GC (1983) Singlet oxygen generation on soil surfaces. J Agric FoodChem 31:1104–1108.
Gohre K, Miller GC (1985) Photochemical generation of singlet oxygen on non-transi-tion-metal oxide surfaces. J Chem Soc Faraday Trans 1 81:793–800.
Gohre K, Miller GC (1986) Photooxidation of thioether pesticides on soil surfaces.J Agric Food Chem 34:709–713.
Gohre K, Scholl R, Miller GC (1986) Singlet oxygen reaction on irradiated soil surfaces.Environ Sci Technol 20:934–938.
Gong A, Ye C, Wang X, Lei Z, Liu J (2001) Dynamics and mechanism of ultravioletphotolysis of atrazine on soil surface. Pest Manag Sci 57:380–385.
Gould IR (1989a) Conventional light sources. In: Scaiano JC (ed) CRC Handbook ofOrganic Photochemistry, vol 1. CRC Press, Boca Raton, FL, pp 3–17.
Gould IR (1989b) Conventional light sources. In: Scaiano JC (ed) CRC Handbook ofOrganic Photochemistry, vol 1. CRC Press, Boca Raton, FL, pp 155–196.
Graebing P, Frank M, Chib JS (2002) Effects of fertilizer and soil components on pesti-cide photolysis. J Agric Food Chem 50:7332–7339.
Graebing P, Frank M, Chib JS (2003) Soil photolysis of herbicides in a moisture- andtemperature-controlled environment. J Agric Food Chem 51:4331–4337.
Graham-Bryce IJ (1969) Diffusion of organophosphorus insecticides in soils. J Sci FoodAgric 20:489–494.
Grayson BT, Williams KS, Freehauf PA, Pease RR, Ziesel WT, Sereno RL, ReinsfelderRE (1987) The physical and chemical properties of the herbicide cinmethylin (SD95481). Pestic Sci 21:143–153.
Greenhalgh R, Marshall WD (1976) Ultraviolet irradiation of fenitrothion and the synthe-sis of the photolytic oxidation products. J Agric Food Chem 24:708–713.
Griesbeck AG, Gorner H (1999) Laser flash photolysis study of N-alkylated phthali-mides. J Photochem Photobiol A Chem 129:111–119.
170 T. Katagi
Gunther FA (1969) Insecticide residues in California citrus fruits and products. ResidueRev 28:1–119.
Gunther FA, Ott DE, Ittig M (1970) The oxidation of prathion to paraoxon. II. By useof ozone. Bull Environ Contam Toxicol 5:87–94.
Gustafson DI, Holden LR (1990) Nonlinear pesticide dissipation in soil: a new modelbased on spatial variability. Environ Sci Technol 24:1032–1038.
Guth JA (1981) Experimental approaches to studying the fate of pesticides in soil. In:Hutson DH, Roberts TR (eds) Progress in Pesticide Biochemistry, vol 1. Wiley, NewYork, pp 85–114.
Haag WR, Hoigne J (1986) Singlet oxygen in surface waters. 3. Photochemical formationand steady-state concentrations in various types of waters. Environ Sci Technol 20:341–348.
Haas K, Schonherr J (1979) Composition of soluble cuticular lipids and water permeabil-ity of cuticular membranes from citrus leaves. Planta (Berl) 146:399–403.
Hainzl D, Casida JE (1996) Fipronil insecticide: novel photochemical desulfinylationwith retention of neurotoxocity. Proc Natl Acad Sci USA 93:12764–12767.
Halder P, Barua AS, Raha P, Biswas B, Pal S, Bhattacharys A, Bedi S, Chowdhury A(1989) Studies on the photodegradation of pendimethalin in solutions and in Kalyanisoil. Chemosphere 18:1611–1619.
Harrison RB, Holmes DC, Roburn J, Tatton JOG (1967) The fate of some organochlorinepesticides on leaves. J Sci Food Agric 18:10–15.
Harrison SK, Thomas SM (1990) Interaction of surfactants and reaction media on photol-ysis of chlorimuron and metsulfuron. Weed Sci 38:620–624.
Harrison SK, Wax LM (1985) The effect of adjuvants and oil carriers on photodecompo-sition of 2,4-D, bentazon and haloxyfop. Weed Sci 34:81–87.
Harvey J Jr, Han JCY, Reiser RW (1978) Metbolism of oxamyl in plants. J Agric FoodChem 26:529–536.
Hautala RR (1978) Surfactant effects on pesticide photochemistry in water and soil.EPA Technical Report Data. EPA-600/3-78-060 (PB-285175). U.S. EnvironmentalProtection Agency, Washington, DC, pp 1–83.
Hazen JL (2000) Adjuvants: terminology, classification, and chemistry. Weed Technol14:773–784.
Herbert VR, Miller GC (1990) Depth dependence of direct and indirect photolysis onsoil surfaces. J Agric Food Chem 38:913–918.
Herrmann M, Kotzias D, Korte F (1985) Photochemical behavior of chlorsulfuron inwater and in adsorbed phase. Chemosphere 14:3–8.
Hess FD, Foy CL (2000) Interaction of surfactants with plant cuticles. Weed Technol14:807–813.
Hirahara Y, Ueno H, Nakamuro K (2001) Comparative photodegradation study of fen-thion and disulfoton under irradiation of different light sources in liquid- and solid-phases. J Health Sci 47:129–135.
Hirahara Y, Okuno T, Ueno H, Nakamuro K (2003) Photooxidation mechanism of fen-thion by singlet oxygen: evidence by ESR analysis with a selective spin trappingagent. J Health Sci 49:34–39.
Hirayama Y, Sayato Y, Nakamuro K (1998) Studies on photochemical behaviors ofpesticides in environment. Jpn J Toxicol Environ Health 44:451–461.
Hirt RC, Schmitt RG, Searle ND, Sullivan AP (1960) Ultraviolet spectral energy distri-bution of natural sunlight and accelerated test light sources. J Opt Soc Am 50:706–713.
Photodegradation of Pesticides 171
Hoigne J, Faust BC, Haag WR, Scully FE Jr, Zepp RG (1989) Aquatic humic substancesas sources and sinks of photochemically produced transient reactants. In: Suffet IH,MacCarthy PM (eds) Aquatic Humic Substances: Influence on Fate and Treatment ofPollutants. Advances in Chemistry Series 219. American Chemical Society, Washing-ton, DC, pp 363–381.
Holland F, Hessling M, Hofzumahaus A (1995) In situ measurement of tropospheric OHradicals by laser-induced fluorescence: a description of the KFA instrument. J AtmosSci 52:3393–3401.
Hollrigl-Rosta A, Kreuzig R, Bahadir M (1999) Investigation on the metabolic fate ofprochloraz in soil under field and laboratory conditions. Pestic Sci 55:531–538.
Holmes MG, Keiller DR (2002) Effects of pubescence and waxes on the reflectance ofleaves in the ultraviolet and photosynthetic wavebands: a comparison of a range ofspecies. Plant Cell Environ 25:85–93.
Holmstead RL, Casida JE, Ruzo LO, Fullmer DG (1978a) Pyrethroid photodecomposi-tion: permethrin. J Agric Food Chem 26:590–595.
Holmstead RL, Fullmer DG, Ruzo LO (1978b) Pyrethroid photodecomposition: pydrin.J Agric Food Chem 26:954–959.
Horn DHS, Lamberton JA (1962) Long-chain β-diketones from plant waxes. Chem Ind(Lond) 2036–2037.
Hosokawa S, Miyamoto J (1974) Metabolism of 14C-labeled sumithion, O,O-dimethyl O-(3-methyl-4-nitrophenyl) phosphorothioate in apples. Botyu-Kagaku 39:49–53.
Hubbs CW, Lavy TL (1990) Dissipation of norflurazon and other persistent herbicidesin soil. Weed Sci 38:81–88.
Huling SG, Arnold RG, Sierka RA, Miller MR (1998) Measurement of hydroxyl radicalactivity in a soil slurry using the spin trap α-(4-pyridyl-1-oxide)-N-tert-butylnitrone.Environ Sci Technol 32:3436–3441.
Hulpke H, Stegh R, Wilmes R (1983) Light-induced transformations of pesticides onsilica gel as a model system for photodegradation on soil. In: Miyamoto J, KearneyPC (eds) Human Welfare and the Environment. Proceedings 5th International Con-gress on Pesticide Chemistry, vol 3. Pergamon Press, Oxford, pp 323–326.
Hustert K, Moza PN (1994) Photocatalytic degradation of azo dyes by semiconductingiron compounds. Fresenius Environ Bull 3:762–767.
Hustert K, Moza PN (1997) Photochemical degaradtion of dicarboxiimide fungicides inthe presence of soil constituents. Chemosphere 35:33–37.
Hustert K, Moza PN, Kettrup A (1999) Photochemical degradation of carboxin and oxy-carboxin in the presence of humic substances and soil. Chemosphere 38:3423–3429.
Ishikawa K, Nakamura Y, Niki Y, Kuwatsuka S (1977) Photodegradation of benthiocarbherbicide. J Pestic Sci 2:17–25.
Ishizuka K, Takase I, Ei-Tan K, Mitsui S (1973) Absorption and translocation of O-ethyl S,S-diphenyl phosphorodithioate (Hinosan) in rice plants. Agric Biol Chem 37:1307–1316.
Isobe N, Matsuo M, Miyamoto J (1984) Novel photoproducts of allethrin. TetrahedronLett 25:861–864.
Ivie GW, Bull DL (1976) Photodegradation of O-ethyl O-[4-(methylthio)phenyl] S-pro-pyl phosphorodithioate (BAY NTN9306). J Agric Food Chem 24:1053–1057.
Ivie GW, Casida JE (1970) Enhancement of photoalteration of cyclodiene insecticidechemical residues by rotenone. Science 167:1620–1622.
172 T. Katagi
Ivie GW, Casida JE (1971a) Sensitized photodecomposition and photosensitizer activityof pesticide chemicals exposed to sunlight on silica gel chromatoplates. J Agric FoodChem 19:405–409.
Ivie GW, Casida JE (1971b) Photosensitizers for accelerated degradation of chlorinatedcyclodienes and other insecticide chemicals exposed to sunlight on bean leaves.J Agric Food Chem 19:410–416.
Ivie GW, Knox JR, Khalifa S, Yamamoto I, Casida JE (1972) Novel photoproducts ofheptachlor epoxide, trans-chlordane and trans-nonachlor. Bull Environ Contam Tox-icol 76:376–382.
Jacques GL, Harvey RG (1979) Adsorption and diffusion of dinitroaniline herbicides insoils. Weed Sci 27:450–455.
Jacob TA, Carlin JR, Walker RW, Wolf FJ, Vanden Heuvel JA (1975) Photolysis ofthiobendazole. J Agric Food Chem 23:704–709.
Jacques GL, Harvey RG (1979) Adsorption and diffusion of dinitroaniline herbicides insoils. Weed Sci 27:450–455.
Jaffe HH, Orchin M (1962) Theory and Applications of Ultraviolet Spectroscopy. Wiley,Sons, New York.
Jahn C, Zorn H, Petersen A, Schwack W (1999) Structure-specific detection of plantcuticle bound residues of chlorothalonil by ELISA. Pestic Sci 55:1167–1176.
Jensen-Korte U, Anderson C Spiteller M (1987) Photodegradation of pesticides in thepresence of humic substances. Sci Total Environ 62:335–340.
Jernberg KM, Lee PW (1999) Fate of famoxadone in the environment. Pestic Sci 55:587–589.
Jirkovsky J, Faure V, Boule P (1997) Photolysis of diuron. Pestic Sci 50:42–52.Joiner RL, Baetcke KP (1973) Parathion: persistence on cotton and identification of its
photoalteration products. J Agric Food Chem 21:391–396.Johnston LJ, DeMayo P, Wong SK (1984) Surface photochemistry: decomposition of
azobis(isobutyronitrile) on dry silica gel. J Org Chem 49:20–26.Kanofsky JR (2000) Assay for singlet oxygen generation by peroxidases using 1270-nm
chemiluminescence. In: Packer L, Sies H (eds) Singlet Oxygen, UV-A, and Ozone.Methods in Enzymology, vol 319. Academic Press, New York, pp 59–67.
Kanofsky JR, Sima PD (2000) Assay for singlet oxygen generation by plant leaves ex-posed to ozone. In: Packer L, Sies H (eds) Singlet Oxygen, UV-A, and Ozone. Meth-ods in Enzymology, vol 319. Academic Press, New York, pp 512–520.
Katagi T (1989) Molecular orbital approaches to the photolysis of organophosphorusinsecticide fenitrothion. J Agric Food Chem 37:1124–1130.
Katagi T (1990) Photoinduced oxidation of the organophosphorus fungicide tolclofos-methyl on clay minerals. J Agric Food Chem 38:1595–1600.
Katagi T (1991) Photodegradation of the pyrethroid insecticide esfenvalerate on soil,clay minerals, and humic acid surfaces. J Agric Food Chem 39:1351–1356.
Katagi T (1992) Photodegradation of 3-phenoxybenzoic acid in water and on solid sur-faces. J Agric Food Chem 40:1269–1274.
Katagi T (1993a) Photochemistry of organophosphorus herbicide butamifos. J AgricFood Chem 41:496–501.
Katagi T (1993b) Effect of moisture content and UV irradiation on degradation of fen-propathrin on soil surfaces. J Pestic Sci 18:333–341.
Katagi T (2002a) Experimental and theoretical studies on photodegradation of fungicidediniconazole. J Pestic Sci 27:111–117.
Photodegradation of Pesticides 173
Katagi T (2002b) Abiotic hydrolysis of pesticides in the aquatic environment. Rev Envi-ron Contam Toxicol 175:79–261.
Katagi T, Mikami N (2000) Primary metabolism of agrochemicals in plants. In: RobertsT (ed) Metabolism of Agrochemicals in Plants. Wiley, New York, pp 43–106.
Katagi T, Kikuzono Y, Mikami N, Matsuda T, Miyamoto J (1988) A theoretical ap-proach to photochemistry of pyrethroids possessing the cyclopropane ring. J PesticSci 13:129–132.
Ke TS, Hsieh YM, Ts’ai LS, Wang Y (1940) The ultraviolet absorption spectrum ofrotenone. J Chin Chem Soc 6:40–43.
Kerstiens G, Lendzion K (1989) Interactions between ozone and plant cuticles. I. Ozonedeposition and permeability. New Phytol 112:13–19.
Ketchersid ML, Merkle MG (1975) Persistence and movement of perfluidone in soil.Weed Sci 23:344–348.
Keum YS, Liu KH, Seo JS, Kim JH, Kim K, Kim YH, Kim PJ (2002) Dissipation offoliar residues of diafenthiuron and its metabolites. Bull Environ Contam Toxicol 68:845–851.
Kieatiwong S, Miller GC (1992) Photolysis of aryl ketones with varying vapor pressureson soil. Environ Toxicol Chem 11:173–179.
Kieatiwong S, Nguyen LV, Herbert VR, Hackett M, Miller GC, Miille MJ, Mitzel R(1990) Photolysis of chlorinated dioxins in organic solvents and on soils. Environ SciTechnol 24:1575–1580.
Kieber DJ, Blough NV (1990) Determination of carbon-centered radicals in aqueoussolution by liquid chromatography with fluorescence detection. Anal Chem 62:2275–2283.
Kimmel EC, Casida JE, Ruzo LO (1982) Identification of mutagenic photoproducts ofthe pyrethroids allethrin and terallethrin. J Agric Food Chem 30:623–626.
Kitchener JA (1946) The photochemistry of solids. Sci J R Colloid Sci 19:1–14.Klehr M, Iwan J, Riemann J (1983) An experimental approach to the photolysis of pesti-
cides adsorbed on soil: thiadiazuron. Pestic Sci 14:359–366.Kleier DA (1994) Environmental effects on the photodegradation of pesticides. In: Com-
paring Glasshouse & Field Pesticide Performance, vol II. BCPC Monograph No. 59.The Brighton Crop Protection Council, Farnham, Surrey (UK), pp 97–109.
Klein W, Kohli J, Weisgerber I, Korte F (1973) Fate of aldrin-14C in potatoes and soilunder outdoor conditions. J Agric Food Chem 21:152–156.
Knowles CO, Sen Gupta AK (1969) Photodecomposition of the acaricide N′-(4-chloro-o-tolyl)-N,N-dimethylformamidine. J Econ Entomol 62:344–348.
Kofler M, Langemann A, Ruegg R, Chopard-dit-Jean LH, Rayroud A, Isler O (1959)Structure of a plant quinone with isopremoid side chain. Helv Chim Acta 42:1283–1292.
Kolb CA, Kazer MA, Kopecky J, Zotz G, Riederer M, Pfundel EE (2001) Effects ofnatural intensities of visible and ultraviolet radiation on epidermal ultraviolet screen-ing and photosynthesis in grape leaves. Plant Physiol 127:863–875.
Konstantinou IK, Zarkadis AK, Albanis TA (2001) Photodegradation of selected herbi-cides in various natural waters and soils under environmental conditions. J EnvironQual 30:121–130.
Kopf G, Schwack W (1995) Photodegradation of the carbamate insecticide ethiofencarb.Pestic Sci 43:303–309.
174 T. Katagi
Koshy KT, Burdick MD, Knuth DW (1983) Multiphase photodegradation of methyl N-[[[[[(1,1-dimethylethyl) (5,5-dimethyl-2-thioxo-1,3,2-dioxaphosphorinan-2-yl)-amino]thio]methylamino] carbonyl]oxy]ethanimidothiolate. J Agric Food Chem 31:625–629.
Kotzias D, Herrmann M, Zsolnay A, Russi H, Korte F (1986) Photochemical reactivityof humic materials. Naturwissenschaften 73:35–36.
Krause RT (1983) Determination of fluorescent pesticides and metabolites by reversed-phase high-performance liquid chromatography. J Chromatogr 255:497–510.
Krieger MS, Yoder RN, Gibson R (2000) Photolytic degradation of florasulam on soiland in water. J Agric Food Chem 48:3710–3717.
Kromer T, Ophoff H, Fuhr F, Stork A (1999) Photodegradation and volatilization ofparathion-methyl on glass and soil dust under laboratory conditions. In: Human Envi-ronmental Exposure to Xenobiotics. Proceedings, 11th Symposium on PesticideChemistry. Goliardica Pavese, Pavia, Italy, pp 363–374.
Kulshrestha G, Mukerjee SK (1986) The photochemical decomposition of the herbicideisoproturon. Pestic Sci 17:489–494.
Kumar Y, Semeluk GP, Silk PJ, Unger I (1974) The photochemistry of carbamates. VI:The photodecomposition of meobal (3,4-xylyl-N-methylcarbamate) and mesurol(4-methylthio-3,5-xylyl-N-methylcarbamate). Chemosphere 3:23–27.
Lackhoff M, Niessner R (2002) Photocatalytic atrazine degradation by synthetic miner-als, atmospheric aerosols, and soil particles. Environ Sci Technol 36:5342–5347.
Larson RA, Schlauch MB, Marley KA (1991) Ferric ion promoted photodecompositionof triazines. J Agric Food Chem 39:2057–2062.
Larson RA, Marley KA (1999) Singlet oxygen in the environment. In: Boule P (ed) TheHandbook of Environmental Chemistry, vol 2, part L. Springer-Verlag, Berlin, pp123–137.
Larsson S, Svenningsson M (1986) Cuticular transpiration and epicuticular lipids of pri-mary leaves of barley (Hordeum vulgare). Physiol Plant 68:13–19.
Lee JSK, Huang PM (1995) Photochemical effects on the abiotic transformations ofpolyphenolics as catalyzed by Mn(II) oxide. In: Huang PM, Berthelin J, Bollag JM,McGill WB (eds) Environmental Impacts of Soil Component Interactions: Land Qual-ity, Natural and Anthropogenic Organics, vol 1. Lewis, Boca Raton, FL, pp 177–189.
Lee PW, Srearns SM, Powell WR (1988) Metabolic fate of fenvalerate in wheat plants.J Agric Food Chem 36:189–193.
Lee PW, Stearns SM, Hernandez H, Powell WR, Naidu MV (1989) Fate of dicrotophosin the soil environment. J Agric Food Chem 37:1169–1174.
Lee PW, Fukuto JM, Hernandez H, Stearns SM (1990) Fate of monocrotophos in theenvironment. J Agric Food Chem 38:567–573.
Leermakers PA, Thomas HT, Weis LD, James FC (1966) Spectra and photochemistryof molecules adsorbed on silica gel. IV. J Am Chem Soc 88:5075–5083.
Leifer A (1988) The Kinetics of Environmental Aquatic Photochemistry. Theory andPractice. ACS Professional Reference Book. American Chemical Society, Washing-ton, DC.
Lendzian KJ, Kerstiens G (1991) Sorption and transport of gases and vapors in plantcuticles. Rev Environ Contam Toxicol 121:65–128.
Leuch DB, Bowman MC (1968) Residues of fenthion and five of its metabolites: theirpersistence in corn and grape forages. J Econ Entomol 61:1594–1597.
Lewis RG (1976) Sampling and analysis of airborne pesticides. In: Lee RE Jr (ed) AirPollution from Pesticides and Agricultural Processes. CRC Press, Cleveland, OH, pp51–94.
Photodegradation of Pesticides 175
Liang TT, Lichtenstein EP (1976) Effects of soils and leaf surfaces on the photodecom-position of [14C]Azinphosmethyl. J Agric Food Chem 24:1205–1210.
Lichtenstein EP, Fuhrmann TW, Schulz KR, Liang TT (1973) Effects of field applicationmethods on the persistence and metabolism of phorate in soils and its translocationinto crops. J Econ Entomol 66:863–866.
Linders J, Mensink H, Stephenson G, Wauchope D, Racke K (2000) Foliar interceptionand retention values after pesticide application. A proposal for standardized valuesfor environmental risk assessment. Pure Appl Chem 72:2199–2218.
Lindquist DA, Bull DL (1967) Fate of 3-hydroxy-N-methyl-cis-crotonamide dimethylphosphate in cotton plants. J Agric Food Chem 15:267–272.
Liu PY, Zheng MH, Xu XB (2002) Phototransformation of polychlorinated dibenzo-p-dioxins from photolysis of pentachlorophenol on soil surface. Chemosphere 46:1191–1193.
Liu X, Iu KK, Mao Y, Thomas JK (1994) Photoinduced reactions on clay and modelsurfaces. In: Helz GR, Zepp RG, Crosby DG (eds) Aquatic Surface Photochemistry.Lewis, Boca Raton, FL, pp 187–195.
Logan JA (1999) An analysis of ozonesonde data for the troposphere: recommendationsfor testing 3-D models and development of a gridded climatology for troposphericozone. J Geophys Res 104:16115–16149.
Lucier GW, Menzer RE (1968) Metabolism of dimethoate in bean plants in relation toits mode of application. J Agric Food Chem 16:936–945.
Lucier GW, Menzer RE (1970) Nature of oxidative metabolites of dimethoate formed inrats, liver microsomes, and bean plants. J Agric Food Chem 18:698–704.
Maguire RJ (1990) Chemical and photochemical isomerization of deltamethrin. J AgricFood Chem 38:1613–1617.
Mahnken GE, Weber JB (1988) Capillary movement of triasulfuron and chlorsulfuron inRion sandy loam soil. Proc South Weed Sci Soc 41:332–336.
Makary MH, Riskallah MR, Hegazy ME, Belal MH (1981) Photolysis of phoxim onglass and on tomato leaves. Bull Environ Contam Toxicol 26:413–419.
Mallet V, Surette DP (1974) Fluorescence of pesticides by treatment with heat, acid orbase. J Chromatogr 95:243–246.
Mamouni A, Schmitt P, Mansour M, Schiavon M (1992) Abiotic degradation pathwaysof isoxaben in the environment. Pestic Sci 35:13–20.
Manahan SE (1994) The geosphere and geochemistry. In: Manahan SE (ed) Environmen-tal Chemistry, 6th Ed. Lewis, Boca Raton, FL, pp 433–456.
Mansager ER, Still GG, Frear DS (1979) Fate of [14C]diflubenzuron on cotton and insoil. Pestic Biochem Physiol 12:172–182.
Mansour M, Feicht EA, Behechti A, Scheunert I (1997) Experimental approaches tostudying the photostability of selected pesticides in water and soil. Chemosphere 35:39–50.
Mao Y, Thomas JK (1993) Photoinduced electron transfer and subsequent chemical reac-tions of adsorbed thianthrene on clay surfaces. J Org Chem 58:6641–6649.
Marcheterre L, Choudhry GG, Webster GRB (1988) Environmental photochemistry ofherbicides. Rev Environ Contam Toxicol 103:61–126.
Margulies L, Rozen H, Cohen E (1985) Energy transfer at the surface of clays andprotection of pesticides from photodegradation. Nature (Lond) 315:658–659.
Margulies L, Cohen E, Rozen H (1987) Photostabilization of bioresmethrin by organiccations on a clay surface. Pestic Sci 18:79–87.
176 T. Katagi
Margulies L, Rozen H, Cohen E (1988) Photostabilization of a nitromethylene heterocy-cle insecticide on the surface of montmorillonite. Clays Clay Miner 36:159–164.
Margulies L, Stern T, Rubin B, Ruzo LO (1992) Photostabilization of trifluralin adsorbedon a clay matrix. J Agric Food Chem 40:152–155.
Margulies L, Rozen H, Stern T, Rytwo G, Rubin B, Ruzo LO, Nir S, Cohen E (1993)Photostabilization of pesticides by clays and chromophores. Arch Insect BiochemPhysiol 22:467–486.
Martınez Galera M, Martınez Vidal JL, Egea Gonzalez FJ, Gil Garcıa MD (1997) Astudy of fenpropathrin residues in tomatoes and green beans grown in greenhouses inSpain. Pestic Sci 50:127–134.
Martınez Vidal JL, Egea Gonzalez FJ, Martınez Galera M, Castro Cano ML (1998)Diminution of chlorpyrifos and chlorpyrifos oxon in tomatoes and green beans grownin greenhouses. J Agric Food Chem 46:1440–1444.
Matsuo H, Casida JE (1970) Photodegradation of two dinitrophenolic pesticide chemi-cals, dinobuton and dinoseb, applied to bean leaves. Bull Environ Contam Toxicol 5:72–78.
Mazellier P, Bolte M (2000) Heterogeneous light-induced transformation of 2,6-dimeth-ylphenol in aqueous suspensions containing goethite. J Photochem Photobiol A Chem132:129–135.
McDonald RE, Nordby HE, McCollum TG (1993) Epicuticular wax morphology andcomposition are related to grapefruit chilling injury. Hortic Sci 28:311–312.
McFarlane JC (1995) Anatomy and physiology of plant conductive systems. In: TrappS, McFarlane JC (eds) Plant Contamination: Modeling and Simulation of OrganicChemical Processes. Lewis, Boca Raton, FL, pp 13–34.
McPhail DB, Hartley RD, Gardner PT, Duthie GG (2003) Kinetic and stoichiometricassessment of the antioxidant activity of flavonoids by electron spin resonance spec-troscopy. J Agric Food Chem 51:1684–1690.
Meallier P (1999) Phototransformation of pesticides in aqueous solution. In: The Hand-book of Environmental Chemistry, vol 2, part L. Springer-Verlag, Berlin, pp 241–261.
Megahed HS, Steurbaut W, Dejonckheere W (1987) Influence of the presence of soybeanoil–surfactant combinations on the rainfastness and the photodegradation of insecti-cide deposits. Meded Fac Landbouwwet Rijkuniv Gent 52:713–719.
Meikle RW, Kurihara NH, DeVries DH (1983) Chlorpyrifos: the photodecompositionrates in dilute aqueous solution and on a surface, and the volatilization rates from asurface. Arch Environ Contam Toxicol 12:189–193.
Mikami N, Ohkawa H, Miyamoto J (1976) Photodecomposition of surecide (O-ethylO-4-cyanophenyl phenylphosphonothioate) and cyanox (O,O-dimethyl O-4-cyano-phenyl phosphorothioate). J Pestic Sci 1:273–281.
Mikami N, Ohkawa H, Miyamoto J (1977a) Stereospecificity in oxidation of the opticalisomers of O-ethyl O-2-nitro-5-methylphenyl N-isopropyl phosphoramidothioate(S-2571) by liver mixed function oxidase and UV light. J Pestic Sci 2:119–126.
Mikami N, Ohkawa H, Miyamoto J (1977b) Photodecomposition of salithion (2-methoxy-4H-1,3,2-benzodioxaphosphorin-2-sulfide) and phenthoate (O,O-dimethyl S-α-etho-xycarbonylbenzyl phosphorodithioate). J Pestic Sci 2:279–290.
Mikami N, Takahashi N, Hayashi K, Miyamoto J (1980) Photodegradation of fenvalerate(Sumicidin) in water and on soil surfaces. J Pestic Sci 5:225–236.
Mikami N, Yoshimura J, Yamada H, Miyamoto J (1984a) Translocation and metabolismof procymidone in cucumber and bean plants. J Pestic Sci 9:131–136.
Photodegradation of Pesticides 177
Mikami N, Imanishi K, Yamada H, Miyamoto J (1984b) Photodegradation of the fungi-cide tolclofos-methyl in water and on soil surfaces. J Pestic Sci 9:215–222.
Mikami N, Takahashi N, Yamada H, Miyamoto J (1985a) Separation and identificationof short-lived free radicals formed by photolysis of the pyrethroid insecticide fenval-erate. J Pestic Sci 16:101–112.
Mikami N, Imanishi K, Yamada H, Miyamoto J (1985b) Photodegradation of fenitro-thion in water and on soil surface, and its hydrolysis in water. J Pestic Sci 10:263–272.
Miller GC, Donaldson SG (1994) Factors affecting photolysis of organic compounds onsoils. In: Helz GR, Zepp RG, Crosby DG (eds) Aquatic and Surface Photochemistry.Lewis, Boca Raton, FL, pp 97–109.
Miller GC, Zepp RG (1979) Photoreactivity of aquatic pollutants sorbed on suspendedsediments. Environ Sci Technol 13:860–863.
Miller GC, Zepp RG (1983) Extrapolating photolysis rates from the laboratory to theenvironment. Residue Rev 85:89–110.
Miller GC, Herbert VR, Miller WW (1989) Effect of sunlight on organic contaminantsat the atmosphere-soil interface. In: Reactions and Movement of Organic Chemicalsin Soils. Special Publication No. 622. Soil Science Society of America, Madison, WI,pp 99–110.
Miller LL, Nordblom GD, Yost GA (1974) Photochemistry of N-(α-trichloromethyl-p-methoxybenzyl)-p-methoxyaniline. J Agric Food Chem 22:853–855.
Minelli EV, Cabras P, Angioni A, Garau VL, Meils M, Pirisi FM, Cabitza F, CubedduM (1996) Persistence and metabolism of fenthion in orange fruit. J Agric Food Chem44:936–939.
Misra B, Graebing PW, Chib JS (1997) Photodegradation of chloramben on a soil sur-face: a laboratory-controlled study. J Agric Food Chem 45:1464–1467.
Miyamoto J, Sato Y (1965) Determination of insecticide residue in animal and planttissues. Botyu-Kagaku 30:45–49.
Moore WM, DuPont RR, McLean JE (1989) Soil phase photodegradation of toxic organ-ics at contaminated disposal sites for soil renovation and groundwater quality protec-tion. USGS/G-1304, No. PB89-237267. NTIS, Springfield, VA.
Mosier AR, Guenzi WD, Miller LL (1969) Photochemical decomposition of DDT by afree-radical mechanism. Science 164:1083–1085.
Mostafa IY, Fakhr IMI, El-Zawahry YA (1974) Metabolism of organophosphorus insec-ticides. XV. Translocation and degradation of 32P-malathion in bean and cotton plants.In: Proceedings, Comparative Studies on Food and Environmental Contamination.IAEA, Vienna, pp 385–392.
Moye HA, Winefordner JD (1965) Phosphorimetric study of some common pesticides.J Agric Food Chem 13:516–518.
Moye HA, Malagodi MH, Yoh J, Deyrup CL, Chang SM, Leibee GL, Ku CC, WislockiPG (1990) Avermectin B1a metabolism in celery: a residue study. J Agric Food Chem38:290–297.
Mueller TC, Moorman TB, Locke MA (1992) Detection of herbicides using fluorescencespectroscopy. Weed Sci 40:270–274.
Muller T, Maurer T, Kubiak R (1995) Metabolism and volatilization of parathion-methylunder simulated outdoor conditions. Meded Fac Landbouww Univ Gent 60:541–547.
Mumma RO, Khalifa S, Hamilton RH (1971) Spectroscopic identification of metabolitesof carbaryl in plants. J Agric Food Chem 19:445–451.
178 T. Katagi
Murillo Pulgarin JA, Garcıa Bermejo LF (2002) Determination of the pesticide napro-pamide in soil, pepper, tomato by micelle-stabilized room-temperature phosphores-cence. J Agric Food Chem 50:1002–1008.
Murthy NBK, Hustert K, Moza PN, Kettrup A (1998) Photodegradation of selected fun-gicides on soil. Fresenius Environ Bull 7:112–117.
Nag SK, Dureja P (1996) Phototransformation of triadimefon on glass and soil surfaces.Pestic Sci 48:247–252.
Nag SK, Dureja P (1997) Photodegradation of azole fungicide triadomefon. J Agric FoodChem 45:294–298.
Nag-Chaudhuri J, Augenstein L (1964) Effect of physical environment on excited statesof amino acids and proteins. Targeted Diagnosis and Therapy (1964) 13:441–452.
Nakajima A, Hidaka H (1993) Photosensitized oxidation of oleic acid, methyl oleate,and olive oil using visible light. J Photochem Photobiol A Chem 74:189–194.
Nambu K, Ohkawa H, Miyamoto J (1980) Metabolic fate of phenothrin in plants andsoils. J Pestic Sci 5:177–197.
Nicholls CH, Leermakers PA (1971) Photochemical and spectroscopic properties of or-ganic molecules in adsorbed or other perturbing polar environments. In: Pitts JN Jr,Hammond GS, Noyes WA (eds) Advances in Photochemistry, vol 8. Wiley-Intersci-ence, New York, pp 315–336.
Nigg HN, Stamper JH, Knaak JB (1984) Leaf, fruit, and soil surface residues of carbosul-fan and its metabolites in Florida citrus groves. J Agric Food Chem 32:80–85.
Nilles GP, Zabik MJ (1974) Photochemistry of bioactive compounds. Multiphase photo-degradation of basalin. J Agric Food Chem 22:684–688.
Nilles GP, Zabik MJ (1975) Photochemistry of bioactive compounds. Multiphase photo-degradation and mass spectral analysis of basagran. J Agric Food Chem 23:410–415.
Nir S, Undabeytia T, Yaron-Marcovich D, El-Nahhal Y, Polubesova T, Serban C, RytwoG, Lagaly G, Rubin B (2000) Optimization of adsorption of hydrophobic herbicideson montmorillonite preadsorbed by monovalent organic cations: interaction betweenphenyl rings. Environ Sci Technol 34:1269–1274.
Niu J, Chen J, Henkelmann B, Quan X, Yang F, Kettrup A, Schramm KW (2003) Photo-degradation of PCDD/Fs adsorbed on spruce (Picea abies (L.) Karst.) needles undersunlight irradiation. Chemosphere 50:1217–1225.
Norris LA, Montgomery ML, Warren LE (1987) Triclopyr persistence in western Oregonhill pastures. Bull Environ Contam Toxicol 39:134–141.
Nutahara M, Murai T (1984) Accelerating effect of natural unsaturated fatty acids onphotodecomposition of chinomethionat (Morestan). J Pestic Sci 9:667–674.
Ogawa K, Tsuda M, Yamaguchi F, Yamaguchi I, Misato T (1976) Metabolism of 2-sec-butylphenyl N-methylcarbamate (Bassa, BPMC) in rice plants and its degradation insoils. J Pestic Sci 1:219–229.
Ohkawa H, Yoshihara R, Kohara T, Miyamoto J (1974a) Metabolism of m-tolyl N-methylcarbamate (Tsumacide) in rats, houseflies and bean plants. Agric Biol Chem38:1035–1044.
Ohkawa H, Mikami N, Miyamoto J (1974b) Photodecomposition of sumithion (O,O-dimethyl-O-(3-methyl-4-nitrophenyl)phosphorothioate). Agric Biol Chem 38:2247–2255.
Ohkawa H, Nambu K, Miyamoto J (1980) Metabolic fate of fenvalerate (sumicidin) inbean plants. J Pestic Sci 5:215–223.
Ohsawa K, Casida JE (1979) Photochemistry of the potent knockdown pyrethroid kade-thrin. J Agric Food Chem 27:1112–1120.
Photodegradation of Pesticides 179
Oliver BG, Cosgrove EG, Carey JH (1979) Effect of suspended sediments on the photol-ysis of organics in water. Environ Sci Technol 13:1075–1077.
Oltmans SJ (1981) Surface ozone measurements in clean air. J Geophys Res 86:1174–1180.
Oltmans SJ, Levy H II (1992) Seasonal cycle of surface ozone over the western NorthAtlantic. Nature (Lond) 358:392–394.
Ophoff FF, Stork A, Smelt J (1999) Volatilization of fenpropimorph under simulatedfield conditions after application onto different plants. In: Human Environmental Ex-posure to Xenobiotics. Proceedings, 11th Symposium on Pesticide Chemistry. Goliar-dica Pavese, Pavia, Italy, pp 199–209.
Osawa T (1994) Novel natural antioxidants for utilization in food and biological systems.In: Uritani I, Garcia VV, Mendoza EMT (eds) Postharvest Biochemistry of PlantFood: Materials in the Topics. Japan Science Society Press, Tokyo, pp 241–251.
O’Toole JC, Cruz RT, Seiber JN (1979) Epicuticular wax and cuticular resistance in rice.Physiol Plant 47:239–244.
Paciolla MD, Davies G, Jansen SA (1999) Generation of hydroxyl radicals from metal-loaded humic acids. Environ Sci Technol 33:1814–1818.
Parlar H (1980) Photochemistry at surfaces and interfaces. In: Hutzinger O (ed) TheHandbook of Environmental Chemistry. vol 2, part A. Springer-Verlag, Berlin, pp145–159.
Parlar H (1984) Geochemical induced degradation of environmental chemicals. FreseniusZ Anal Chem 319:114–118.
Parlar H (1990) The role of photolysis in the fate of pesticides. In: Hutson DH, RobertsTR (eds) Progress in Pesticide Biochemistry and Toxicology, vol 7. Wiley, NewYork, pp 245–276.
Parlar H, Mansour M, Baumann R (1978) Photoreactions of hydroxychlordane in solu-tion, as solids, and on surface of leaves. J Agric Food Chem 26:1321–1324.
Parochetti JV, Hein ER (1973) Volatility and photodecomposition of trifluralin, benefinand nitralin. Weed Sci 21:469–473.
Parochetti JV, Dec GW Jr (1978) Photodecomposition of eleven dinitroaniline herbi-cides. Weed Sci 26:153–156.
Peacock GA, Riches MN, Wood S (1994) A new method for the evaluation of the photo-stability of crop protection compounds: the prediction of photostability in the field.BCPC Monogr 59:251–256.
Pelizzetti E, Carlin V, Maurino V, Minero C, Dolci M, Marchesini A (1990) Degradationof atrazine in soil through induced photocatalytic processes. Soil Sci 150:523–526.
Pelizzetti E, Minero C, Carlin V (1993) Photoinduced degradation of atrazine over differ-ent metal oxides. New J Chem 17:315–319.
Pere E, Cardy H, Cairon O, Simon M, Lacombe S (2001) Quantitative assessment oforganic compounds adsorbed on silica gel by FT-IR and UV-VIS spectroscopies: thecontribution of diffuse reflectance spectroscopy. Vib Spectrosc 25:163–175.
Petigara BR, Blough NV, Mignerey AC (2002) Mechanisms of hydrogen peroxide de-composition in soils. Environ Sci Technol 36:639–645.
Piccinini P, Pichat P, Guillard C (1998) Phototransformations of solid pentachlorophenol.J Photochem Photobiol A Chem 119:137–142.
Pirisi FM, Cabras P, Garau VL, Melis M, Secchi E (1996) Photodegradation of pesti-cides. Photolysis rates and half-life of pirimicarb and its metabolites in reactions inwater and in solid phase. J Agric Food Chem 44:2417–2422.
180 T. Katagi
Pirisi FM, Angioni A, Cabizza M, Cabras P, Maccioni E (1998) Influence of epicuticularwaxes on the photolysis of pirimicarb in the solid phase. J Agric Food Chem 46:762–765.
Pirisi FM, Angioni A, Cabizza M, Cabras P, Cao CF (2001) Photolysis of pesticides:influence of epicuticular waxes from Persica laevis DC on the photodegradation inthe solid phase of aminocarb, methiocarb and fenthion. Pestic Manag Sci 57:522–526.
Pohlman AA, Mill T (1983) Peroxy radical interaction with soil constituents. Soil SciSoc Am J 47:922–927.
Popendorf WJ, Leffingwell JT (1978) Natural variations in the decay and oxidation ofparathion foliar residues. J Agric Food Chem 26:437–441.
Power JF, Sharma DK, Langford CH, Bonneau R, Joussot-Dubien J (1987) Laser flashphotolysis studies of a well-characterized soil humic substances. In: Zika RG, CooperWJ (eds) Photochemistry of Environmental Aquatic Systems. ACS Symposium Series327. American Chemical Society, Washington, DC, pp 157–173.
Prinn RG (1994) The interactive atmosphere: Global atmospheric-biospheric chemistry.Ambio 23:50–61.
Que Hee SS, Paine SH, Sutherland RG (1979) Photodecomposition of a formulatedmixed butyl ester of 2,4-dichlorophenoxyacetic acid in aqueous and hexane solutions.J Agric Food Chem 27:79–82.
Quinstad GB, Staiger LE (1984) Photodegradation of fluvalinate. J Agric Food Chem32:1134–1138.
Quinstad GB, Staiger LE, Schooley DA (1975) Environmental degradation of the insectgrowth regulator methoprene (isopropyl (2E,4E)-11-methoxy-3,7,11-trimethyl-2,4-dodecadienoate). III. Photodecomposition. J Agric Food Chem 23:299–303.
Racke KD (1993) Environmental fate of chlorpyrifos. Rev Environ Contam Toxicol 131:1–150.
Radler F, Horn DHS (1965) The composition of grape cuticle wax. Aust J Chem 18:1059–1069.
Rajasekharan Pillai VN (1977) Role of singlet oxygen in the environmental degradationof chlorthiamid to dichlobenil. Chemosphere 6:777–782.
Rau H, Hormann M (1981) Kinetic resolution of optically active molecules and asym-metric chemistry: Asynmmetrically sensitized photolysis of trans-3,5-diphenylpyrazo-line. J Photochem 16:231–247.
Reichman R, Wallach R, Mahrer Y (2000a) A combined soil-atmospheric model forevaluating the fate of surface-applied pesticides. 1. Model development and verifica-tion. Environ Sci Technol 34:1313–1320.
Reichman R, Mahren Y, Wallach R (2000b) A combined soil-atmospheric model forevaluating the fate of surface-applied pesticides. 2. The effect of varying environmen-tal conditions. Environ Sci Technol 34:1321–1330.
Reynolds G, Graham N, Perry R, Rice RG (1989) Aqueous ozonation of pesticides: Areview. Ozone Sci Eng 11:339–382.
Rhodes RC (1977) Studies with manganese [14C]ethylenebis(dithiocarbamate) ([14C]maneb)fungicide and [14C]ethylenethiourea ([14C]ETU) in plants, soil and water. J Agric FoodChem 25:528–533.
Richard C, Vialaton D, Aguer JP, Andreux F (1997) Transformation of monuron photo-sensitized by soil extracted humic substances: energy or hydrogen transfer mecha-nism? J Photochem Photobiol A Chem 111:265–271.
Photodegradation of Pesticides 181
Riederer M, Schneider G (1990) The effect of the environment on the permeability andcomposition of citrus leaf cuticles. II. Composition of soluble cuticular lipids andcorrelation with transport properties. Planta (Berl) 180:154–165.
Riskallah MR, Esaac EG, El-Sayed MM (1979) Photodegradation of leptophos. BullEnviron Contam Toxicol 23:636–641.
Riter RE, Adams VD, George DB, Kleine EA (1990) The effects of selected iron com-pounds on the sensitized photooxidation of bromacil. Chemosphere 21:717–728.
Ritter WF, Johnson HP, Lovely WG (1973) Diffusion of atrazine, propachlor and diazi-non in a silt loam soil. Weed Sci 21:381–384.
Robberecht R, Caldwell MM (1980) Leaf ultraviolet optical properties along a latitudinalgradient in the Arctic-alpine life zone. Ecology 61:612–619.
Rodriguez E, Barrio RJ, Goicolea A, Peche R, de Balugera ZG, Sampedro C (2001)Persistence of the insecticide Dimilin 45 ODC on conifer forest foliage in an Atlantic-climate ecosystem. Environ Sci Technol 35:3804–3808.
Rogers MAJ (1987) Singlet oxygen quantum yields. In: Heitz JR, Downum KR (eds)Light-Activated Pesticides. ACS Symposium Series 339. American Chemical Society,Washington, DC, pp 76–97.
Romero E, Dios G, Mingorance MD, Matallo MB, Pena A, Sanchez-Rasero F (1998)Photodegrdation of mecoprop and dichlorprop on dry, moist and amended soil sur-faces exposed to sunlight. Chemosphere 37:577–589.
Roof AAM (1982) Basic principles of environmental photochemistry. In: Hutzinger O(ed) The Handbook of Environmental Chemistry, vol 2, part B. Springer-Verlag, Ber-lin, pp 1–17.
Rosen H, Margulies L (1991) Photostabilization of tetrahydro-2-(nitromethylene)-2H-1,3-thiazine adsorbed on clays. J Agric Food Chem 39:1320–1325.
Rosen JD, Sutherland DJ (1967) The nature and toxicity of the photoconversion productsof aldrin. Bull Environ Contam Toxicol 2:1–9.
Ruggiero P (1999) Abiotic transformation of organic xenobiotics in soils: a compoundingfactor in the assessment of bioavailability. In: NATO Science Series 2. EnvironmentalSecurity 64. Bioavailability of Organic Xenobiotics in the Environment. NATO,Washington, DC, pp 159–205.
Runeckles VC (1992) Uptake of ozone by vegetations. In: Lefohn AS (ed) Surface LevelOzone Exposures and Their Effects on Vegetations. Lewis, Chelsea, MI, pp 157–188.
Ruzo LO (1983) Involvement of oxygen in the photoreactions of cypermethrin and otherhalogenated pyrethroids. J Agric Food Chem 31:1115–1117.
Ruzo LO, Casida JE (1979) Degradation of decamethrin on cotton plants. J Agric FoodChem 27:572–575.
Ruzo LO, Casida JE (1980) Pyrethroid photochemistry: mechanistic aspects in reactionsof the (dihalogenovinyl)cyclopropanecarboxylate substituent. J Chem Soc PerkinTrans I 728–732.
Ruzo LO, Casida JE (1981) Pyrethroid photochemistry: (S)-α-cyano-3-phenoxybenzylcis-(1R,3R,1′R or S)-3-(1′,2′-dibromo-2′,2′-dihaloethyl)-2,2-dimethylcyclopropanecar-boxylates. J Agric Food Chem 29:702–706.
Ruzo LO, Casida JE (1982) Pyrethroid photochemistry: intramolecular sensitization andphotoreactivity of 3-phenoxybenzyl, 3-phenoxybenzoyl, and 3-benzoylbenzyl esters.J Agric Food Chem 30:963–966.
Ruzo LO, Casida JE (1985) Photochemistry of thiocarbamate herbicides: oxidative andfree radical processes of thiobencarb and diallate. J Agric Food Chem 33:272–276.
182 T. Katagi
Ruzo LO, Zabik MJ, Schuetz RD (1974) Photochemistry of bioactive compounds: 1-(4-chlorophenyl)-3-(2,6-dihalobenzoyl)ureas. J Agric Food Chem 22:1106–1108.
Ruzo LO, Holmstead RL, Casida JE (1977) Pyrethroid photochemistry: decamethrin.J Agric Food Chem 25:1385–1394.
Ruzo LO, Gaughan LC, Casida JE (1980) Pyrethroid phorochemistry: S-bioallethrin.J Agric Food Chem 28:246–249.
Ruzo LO, Smith IH, Casida JE (1982) Pyrethroid photochemistry: photooxidation reac-tions of the chrysanthemates phenothrin and tetramethrin. J Agric Food Chem 30:110–115.
Ruzo LO, Krishnamurthy VV, Casida JE, Gohre K (1987) Pyrethroid photochemistry:influence of the chloro(trifluoromethyl)vinyl substituent in cyhalothrin. J Agric FoodChem 35:879–883.
Sadeghi AM, Kissel DE, Cabrera ML (1989) Estimating molecular diffusion coefficientsof urea in unsaturated soil. Soil Sci Soc Am J 53:15–18.
Saha T, Sukul P (1997) Metlaxyl: its persistence and metabolism in soil. Toxicol EnvironChem 58:251–258.
Samsonov YN, Makarov VI (1996) Kinetics and photophysical mechanism of sunlightphotolysis of unstable resmethrin and phenothrin in aerosols and their films. BullEnviron Contam Toxicol 56:903–910.
Samsonov YN, Pokrovskii LM (2001) Sensitized photodecomposition of high dispersepesticide chemicals exposed to sunlight and irradiation from halogen or mercurylamp. Atmos Environ 35:2133–2141.
Sanlaville Y, Guittonneau S, Mansour M, Feicht EA, Meallier P, Lettrup A (1996) Pho-tosensitized degradation of terbutylazine in water. Chemosphere 33:353–362.
Santoro A, Scopa A, Bufo SA, Mansour M, Mountacer H (2000) Photodegradation ofthe triazole fungicide hexaconazole. Bull Environ Contam Toxicol 64:475–480.
Sato K, Kato Y, Maki S, Matano O, Goto S (1985a) Penetration, translocation and me-tabolism of fungicide guazatine in dwarf apple trees. J Pestic Sci 10:81–90.
Sato K, Kato Y, Maki S, Matano O, Goto S (1985b) Photolysis of fungicide guazatineon glass surfaces. J Pestic Sci 10:91–100.
Sauer HH (1972) Fate of formothion on bean plants in the greenhouse. J Agric FoodChem 20:578–583.
Saunders DG, Bret BL (1997) Fate of spinosad in the environment. Down Earth 52:14–20.
Schafmeier A, Emmelin C, Guittonneau S, Meallier P (1998) Influence of humic sub-stances on the phenmedipham photodegradation. Fresenius Environ Bull 7:232–237.
Schneiders GE, Koeppe MK, Naidu MV, Horne P, Brown AM, Mucha CF (1993) Fateof rimsulfuron in the environment. J Agric Food Chem 41:2404–2410.
Scholz K, Reinhard F (1999) Photolysis of imidacloprid (NTN 33893) on the leaf surfaceof tomato plants. Pestic Sci 55:652–654.
Schonherr J, Riederer M (1989) Foliar penetration and accumulation of organic chemi-cals in plant cuticles. Rev Environ Contam Toxicol 108:1–70.
Schreiber L, Schonherr J (1993) Mobilities of organic compounds in reconstituted cuticu-lar wax of barley leaves: determination of diffusion coefficients. Pestic Sci 38:353–361.
Schroeder J (1997) S-215 Regional research project final report. Behavior and fate ofselected sulfonylurea and imidazolinone herbicides in the southern environment.Southern Cooperative Bulletin No. 385, Arkansas Agricultural Experiment Station,Fayetteville, AR.
Photodegradation of Pesticides 183
Schroeder Kvien J, Banks PA (1985) Soil surface degradation of norflurazon. Weed SciSoc Am 25:95 (abstract).
Schuler F, Schmid P, Schlatter C (1998) Photodegradation of polychlorinated dibenzo-p-dioxins and dibenzofurans in cuticular waxes of laurel cherry (Prunus laurocerasus).Chemosphere 36:21–34.
Schultz DP, Harman PD (1978) Hydrolysis and photolysis of the lampricide 2,5′-dichloro-4′-nitrosalicylanilide (Bayer 73). Invest Fish Control 85:1–5.
Schwack W (1987) Photoreduction of parathion ethyl. Toxicol Environ Chem 14:63–72.Schwack W (1988) Photoinduced addition of pesticides to biomolecules. 2. Model reac-
tions of DDT and methoxychlor with methyl oleate. J Agric Food Chem 36:645–648.Schwack W (1990) Photo-induced addition of pesticides to biomolecules. III. Model
reactions of folpet with cyclohexene. Z Lebensm-Unters-Forsch 190:420–424.Schwack W, Floßer-Muller H (1990) Fungicides and photochemistry. Photodehalogena-
tion of captan. Chemosphere 21:905–912.Schwack W, Hartmann M (1994) Fungicides and photochemistry: photodegradation of
the azole fungicide penconazole. Z Lebensm-Unters-Forsch 198:11–14.Schwack W, Kopf G (1992) Photodegradation of the carbamate insecticide propoxur. Z
Lebensm-Unters-Forsch 195:250–253.Schwack W, Kopf G (1993) Photodegradation of the carbamate insecticide pirimicarb.
Z Lebensm-Unters-Forsch 197:264–268.Schwack W, Andlauer W, Armbruster W (1994) Photochemistry of parathion in the plant
cuticle environment: model reaction in the presence of 2-propanol and methyl 12-hydroxystearate. Pestic Sci 40:279–284.
Schwack W, Bourgeois B, Walker F (1995a) Fungicides and photochemistry: photodeg-radation of the dicarboximide fungicide iprodione. Chemosphere 31:2993–3000.
Schwack W, Bourgeois B, Walker F (1995b) Fungicides and photochemistry: photodeg-radation of the dicarboximide fungicide procymidone. Chemosphere 31:4033–4040.
Schwack W, Walker F, Bourgeois B (1995c) Fungicides and photochemistry: photodeg-radation of the dicarboximide fungicide vinclozolin. J Agric Food Chem 43:3088–3092.
Schynowski F, Schwack W (1996) Photochemistry of parathion on plant surfaces: rela-tionship between photodecomposition and iodine number of the plant cuticle. Chemo-sphere 33:2255–2262.
Scott HD, Phillips RE (1972) Diffusion of selected herbicides in soil. Soil Sci Soc AmProc 36:714–719.
Scott HD, Phillips RE (1973) Self-diffusion coefficients of selected herbicides in waterand estimates of their transmission factors in soil. Soil Sci Soc Am Proc 37:965–967.
Scrano L, Bufo SA, D’Auria M, Emmelin C (1999) Photochemical behavior of oxyfluor-fen: a diphenyl-ether herbicide. J Photochem Photobiol A Chem 129:65–70.
Segura-Carretero A, Cruces-Blanco C, Canabate-Diaz B, Fernandez-S´anchez JF,Fernandez-Gutierrez A (2000) Heavy-atom induced room-temperature phosphores-cence: a straightforward methodology for the determination of organic compounds insolution. Anal Chim Acta 417:19–30.
Sen A (1987) Chemical composition and morphology of epicuticular waxes from leavesof Solanum tuberosum. Z Naturforsch 42c:1153–1158.
Senesi N, Loffredo E (1997) Minimizing environmental damage originating from pesti-cide utilization: abiotic photochemical control and remedies. In: Rosen D, Tel-Or E,Hadar Y, Chen Y (eds) Developments in Plant and Soil Sciences. Modern Agricultureand Environment, vol. 71. Kluwer, London, pp 47–73.
184 T. Katagi
Senesi N, Miano TM (1995) The role of abiotic interactions with humic substances onthe environmental impact of organic pollutants. In: Huang PM, Berthelin J, BollagJM, McGill WB (eds) Environmental Impacts of Soil Component Interactions: Natu-ral and Anthropogenic Organics, vol 1. CRC Press, Boca Raton, FL, pp 311–335.
Senesi N, Schnitzer M (1977) Effects of pH, reaction time, chemical reduction and irradi-ation on ESR spectra of fulvic acid. Soil Sci 123:224–234.
Senesi N, Testini C (1984) Theoretical aspects and experimental evidence of the capacityof humic substances to bind herbicides by charge-transfer mechanism. Chemosphere13:461–468.
Senesi N, Miano TM, Provenzano MR, Brunetti G (1989) Spectroscopic and composi-tional comparative characterization of I.H.S.S. reference and standard fulvic and hu-mic acids of various origin. Sci Total Environ 81/82:143–156.
Sharma BK, Gupta N (1994) Photodegradation of the organophosphorus insecticide‘phorate’. Toxicol Environ Chem 41:249–254.
Sharma KK, Chibber SS (1997) Photolysis of diniconazole-M under sunlight. Pestic Sci49:115–118.
Sherman DM (1989) Crystal chemistry, electronic structures, and spectra of Fe sites inclay minerals: application to photochemistry and electron transport. In: Coyne LM,Blake DF, McKeever SWS (eds) Spectroscopic Characterization of Minerals andTheir Surfaces. ACS Symposium Series 415. American Chemical Society, Washing-ton, DC, pp 284–309.
Singh HB, Ludwig FL, Johnson WB (1978) Tropospheric ozone: concentrations andvariabilities in clean remote atmospheres. Atmos Environ 12:2185–2196.
Slade M, Casida JE (1970) Metabolic fate of 3,4,5- and 2,3,5-trimethylphenyl methylcar-bamates, the major constituents in landrin insecticide. J Agric Food Chem 18:467–474.
Smith AE, Grove J (1969) Photochemical degradation of diquat in dilute aqueous solu-tion and on silica gel. J Agric Food Chem 17:609–613.
Smith AM, Mao J, Doane RA, Kovacs MF Jr (1995) Metabolic fate of [14C] acroleinunder aerobic and anaerobic aquatic conditions. J Agric Food Chem 43:2497–2503.
Soeda Y, Kosaka S, Noguchi T (1972) The fate of thiophanate-methyl fungicide and itsmetabolites on plant leaves and glass plates. Agric Biol Chem 36:931–936.
Soeda Y, Ishihara K, Iwataki I, Kamimura H (1979) Fate of a herbicide 14C-alloxydim-sodium in sugar beet. J Pestic Sci 4:121–128.
Sogliero G, Eastwood D, Gilbert J (1985) A concise feature set for the pattern recogni-tion of low-temperature luminescence spectra of hazardous chemicals. ASTM SpecialTechnical Publication 863. Advances in Luminescence Spectroscopy. American Soci-ety for Testing and Materials, Philadelphia, PA, pp 95–115.
Somich CJ, Kearney PC, Muldoon MT, Elsasser S (1988) Enhanced soil degradationof alachlor by treatment with ultraviolet light and ozone. J Agric Food Chem 36:1322–1326.
Spear RC, Lee YS, Leffingwell JT, Jenkins D (1978) Conversion of parathion to para-oxon in foliar residues: effects of dust level and ozone concentration. J Agric FoodChem 26:434–436.
Spencer WF, Adams JD, Shoup TD, Spear RC (1980) Conversion of parathion to para-oxon on soil dusts and clay minerals as affected by ozone and UV light. J Agric FoodChem 28:366–371.
Photodegradation of Pesticides 185
Stamper JH, Nigg HN, Allen JC (1979) Organophosphate insecticide disappearance fromleaf surfaces: an alternative to first-order kinetics. Environ Sci Technol 13:1402–1405.
Stevenson FJ (1976) Organic matter reactions involving pesticides in soil. In: KaufmanDD, Still GG, Paulson GD, Bandal SK (eds) Bound and Conjugated Pesticide Resi-dues. ACS Symposium Series 29. American Chemical Society, Washington, DC, pp180–207.
Stiasni M, Deckers W, Schmidt K, Simon H (1969) Translocation, penetration, and me-tabolism of O-(4-bromo-2,5-dichlorophenyl)-O,O-dimethyl phosphorothioate (bro-mophos) in tomato plants. J Agric Food Chem 17:1017–1020.
Strek HJ (1998) Fate of chlorsulfuron in the environment. 1. Laboratory evaluations.Pestic Sci 53:29–51.
Suflita JM, Loll MJ, Snipes WC, Bollag JM (1981) Electron spin resonance study offree radicals generated by a soil extract. Soil Sci 131:145–150.
Sukul P, Spiteller M (2001) Influence of biotic and abiotic factors on dissipating metal-axyl in soil. Chemosphere 45:941–947.
Sumida S, Yoshihara R, Miyamoto J (1973) Degradation of 3-(3′,5′-dichlorophenyl)-5,5-dimethyloxazolidine-2,4-dione by plants, soil and light. Agric Biol Chem 37:2781–2790.
Suzuki M, Yamamoto Y (1974) Photodieldrin residues in field soils. Bull Environ Con-tam Toxicol 12:275–280.
Svenningsson M (1988) Epi- and intracuticular lipids and cuticular transpiration rates ofprimary leaves of eight barley (Hordeum vulgare) cultivars. Physiol Plant 73:512–517.
Takade DY, Seo MS, Kao TS, Fukuto TR (1976) Alteration of O,O-dimethyl S-[α-(carboethoxy)benzyl] phosphorodithioate (phenthoate) in citrus, water and upon expo-sure to air and sunlight. Arch Environ Contam Toxicol 5:63–86.
Takagi K, Shichi T (2000) Photophysics and photochemistry in clay minerals. Mol Su-pramol Photochem 5:31–110.
Takahashi N, Mikami N, Matsuda T, Miyamoto J (1985a) Photodegradation of the pyre-tyhroid insecticide cypermethrin in water and on soil surface. J Pestic Sci 10:629–642.
Takahashi N, Mikami N, Yamada H, Miyamoto J (1985b) Photodegradation of the pyre-throid insecticide fenpropathrin in water, on soil and on plant foliage. Pestic Sci 16:119–131.
Takahashi N, Ito M, Mikami N, Matsuda T, Miyamoto J (1988) Identification of reactiveoxygen species generated by irradiation of aqueous humic acid solution. J Pestic Sci13:429–435.
Tanaka AK, Umetsu N, Fukuto TR (1985) Metabolism of benfuracarb in young cotton,bean and corn plants. J Agric Food Chem 33:1049–1055.
Tanaka FS, Wien RG, Mansager ER (1979) Effect of nonionic surfactants on the photo-chemistry of 3-(4-chlorophenyl)-1,1-dimethylurea in aqueous solution. J Agric FoodChem 27:774–779.
Tanaka FS, Wien RG, Mansager ER (1981) Survey for surfactant effects on the photo-degradation of herbicides in aqueous media. J Agric Food Chem 29:227–230.
Tanaka FS, Wien RG, Hoffer BL (1986) Photosensitized degradation of a homogeneousnonionic surfactant: hexaethoxylated 2,6,8-trimethyl-4-nonanol. J Agric Food Chem34:547–551.
186 T. Katagi
Tanaka FS, Wien RG, Zaylskie RG (1991) Photolytic degradation of a homogeneousTriton X nonionic syrfactant: nonaethoxylated p-(1,1,3,3-tetramethylbutyl)phenol.J Agric Food Chem 39:2046–2052.
Theng YW, Chang IJ, Wang CM (1997) Direct evidence of clay-mediated charge trans-fer. J Phys Chem B 101:10386–10389.
Thomas JK (1993) Physical aspects of photochemistry and radiation chemistry of mole-cules adsorbed on SiO2, γ-Al2O3, zeolites and clays. Chem Rev 93:301–320.
Thomas SM, Harrison SK (1990) Surfactant-altered rates of chlorimuron and metsul-furon photolysis in sunlight. Weed Sci 38:602–606.
Thomas-Smith TE, Blough NV (2001) Photoproduction of hydrated electron from con-stituents of natural water. Environ Sci Technol 35:2721–2726.
Tsao R, Eto M (1989) Chemical and photochemical transformation of the insecticidecartap hydrochloride into nereistoxin. J Pestic Sci 14:47–51.
Tsao R, Eto M (1990a) Photoreactions of the herbicide naproanilide and the effect ofsome photosensitizers. J Environ Sci Health B 25:569–585.
Tsao R, Eto M (1990b) Photolytic and chemical oxidation reactions of the insecticideetofenprox. J Pestic Sci 15:405–411.
Tsao R, Eto M (1991) Photolysis of flutolanil fungicide and the effect of some photosen-sitizers. Agric Biol Chem 55:763–768.
Tsao R, Eto M (1994) Effect of some natural photosensitizers on photolysis of somepesticides. In: Helz GR, Zepp RG, Crosby DG (eds) Aquatic and Surface Photochem-istry. Lewis, Boca Raton, FL, pp 163–171.
Tsao R, Hirashima A, Eto M (1989) Photolysis of the insecticide pyridafenthion and theeffect of some photosensitizers. J Pestic Sci 14:315–319.
Turner DW (1959) Spectrophotometry in the far-ultraviolet region. Part II. Absorptionspectra of steroids and triterpenoids. J Chem Soc 30–33.
Turner NC, Waggoner PE, Rich S (1974) Removal of ozone from the atmosphere bysoil and vegetation. Nature (Lond) 250:486–489.
Turro NL (1978) Modern Molecular Photochemistry. Benjamin/Cummings, Menlo Park,CA.
Uchida M, Ogawa K, Sugimoto T, Aizawa H (1983) Metabolism of flutolanil in riceplant and cucumber. J Pestic Sci 8:537–544.
Ueda K, Gaughan LC, Casida JE (1974) Photodecomposition of resmethrin and relatedpyrethroids. J Agric Food Chem 22:212–220.
Unai T, Tomizawa C (1986) Photodegradation of fenothiocarb on silica gel plate exposedto sunlight. J Pestic Sci 11:363–367.
Unai T, Tamaru H, Tomizawa C (1986) Translocation and metabolism of the acaricidefenothiocarb in citrus. J Pestic Sci 11:347–356.
Undabeytia T, Nir S, Tel-Or E, Rubin B (2000) Photostbilization of the herbicide norflur-azon by using organoclays. J Agric Food Chem 48:4774–4779.
Van Koot IRY, Dijkhuizen T (1968) Light-transmission of dirty glass and clearing meth-ods. Acta Hortic (ISHS) 6:97–108.
Van Noort P, Lammers R, Verboom H, Wondergem E (1988) Rates of triplet humic acidsensitized photolysis of hydrophobic compounds. Chemosphere 17:35–38.
Vannelli JJ, Schulman EM (1984) Solid surface room-temperature phosphorescence ofpesticides. Anal Chem 56:1030–1033.
Vaugham PP, Blough NV (1998) Photochemical formation of hydroxyl radical by con-stituents of natural waters. Environ Sci Technol 32:2947–2953.
Photodegradation of Pesticides 187
Venkatesh R, Harrison SK (1999) Photolytic degradation of 2,4-D on Zea mays leaves.Weed Sci 47:262–269.
Verma NK, Pitliya RL, Vaidya VK, Ameta SC (1991) Photo-sensitized oxidation ofO,O-dimethyl O-4-nitro-m-tolyl phosphorothioate by singlet oxygen. Asian J Chem3:260–263.
Villemure G, Detellier C, Szabo AG (1986) Fluorescence of clay-intercalated methylvio-logen. J Am Chem Soc 108:4658–4659.
Voelker BM, Morel FMM, Sulzberger B (1997) Iron redox cycling in surface waters:effects of humic substances and light. Environ Sci Technol 31:1004–1011.
Vogelmann TC, Bjorn LO (1984) Measurement of light gradients and spectral regime inplant tissue with a fiber optic probe. Physiol Plant 60:361–368.
Walia S, Dureja P, Mukerjee SK (1988) New photodegradation products of chlorpyrifosand their detection on glass, soil, and leaf surfaces. Arch Environ Contam Toxicol17:183–188.
Walia S, Dureja P, Mukerjee SK (1989a) Photochemical transformation of phosalone.Pestic Sci 25:1–9.
Walia S, Dureja P, Mukerjee SK (1989b) Photodegradation of the organophosphorusinsecticide iodofenphos. Pestic Sci 26:1–9.
Walker A, Crawford DV (1970) Diffusion coefficients for two triazine herbicides in sixsoils. Weed Res 10:126–132.
Walton TJ (1990) Waxes, cutin and suberin. Methods Plant Biochem 4:105–158.Watkins DAM (1974) Some implications of the photochemical decomposition of pesti-
cides. Chem Ind 185–190.Watkins DAK (1987) Effects of leaf surfaces and plant waxes on rates of photodegrada-
tion of fenarimol. Asp Appl Biol 14:335–346.Weizmann A, Mazur Y (1958) Steroids and triterpenoids of citrus fruit. II. Isolation of
citrostadienol. J Org Chem 23:832–834.Wendlandt WWM, Hecht HG (1966) Reflectance Spectroscopy. Wiley-Interscience,
New York.Wheeler OH, Mateos JL (1956) The ultraviolet absorption of isolated double bonds.
J Org Chem 21:1110–1112.Whitaker BD, Schmidt WF, Kirk MC, Barnes S (2001) Novel fatty acid esters of p-
coumaryl alcohol in epicuticular wax of apple fruit. J Agric Food Chem 49:3787–3792.
Willis GH, McDowell LL (1987) Pesticide persistence on foliage. Rev Environ ContamToxicol 100:23–73.
Wilkinson F, Brummer JG (1981) Rate constants for the decay and reactions of thelowest electronically excited singlet state of molecular oxygen in solution. J PhysChem Ref Data 10:809–999.
Wolfe CJM, Halmans MTH, van der Heijde HB (1981) The formation of singlet oxygenin surface waters. Chemosphere 10:59–62.
Wolfe NL, Mingelgrin U, Miller GC (1990) Abiotic transformations in water, sediments,and soils. In: Cheng HH (ed) Pesticides in the Soil Environment: Processes, Impact,and Modeling. SSSA Book Series 2. Soil Science Society of America, Madison, WI,pp 103–168.
Wright WL, Warren GF (1965) Photochemical decomposition of trifluralin. Weeds 13:329–331.
188 T. Katagi
Wrzesinski CL, Arison BH, Smith J, Zinh DL, Vanden Heuvel WJA, Crouch LS (1996)Isolation and identification of residues of 4″-(epi-methylamino-4″-deoxyavermectinB1a benzoate from the surface of cabbage. J Agric Food Chem 44:304–312.
Wuhrmann-Meyer K, Wuhrmann-Meyer M (1941) The absorption of ultraviolet light bycuticular and wax layers of leaves. Planta (Berl) 32:43–50.
Yamaoka K, Tsujino Y, Ando M, Nakagawa M, Ishida M (1988) Photolysis of DTP, theherbicidal entity of pyrazolate, in water and on soil surface. J Pestic Sci 13:29–37.
Yamazaki M, Sakai M, Goto F (1982) Behavior of acephate in tabacco plants treated aswettable powder. J Pestic Sci 7:167–173.
Yang X, Wang X, Kong L, Wang L (1999) Photolysis of chlorsulfuron and metsulfuron-methyl in methanol. Pestic Sci 55:75–754.
Yih RY, Swithenbank C (1971) Identification of metabolites of N-(1,1-dimethylpropy-nyl)-3,5-dichlorobenzamide in soil and alfalfa. J Agric Food Chem 19:314–319.
Yokley RA, Garrison AA, Wehry EL, Mamantov G (1986) Photochemical transforma-tion of pyrene and benzo[a]pyrene vapor-deposited on eight coal stack ashes. EnvironSci Technol 20:86–90.
Yumita T, Yamamoto I (1982) Photodegradation of mepronil. J Pestic Sci 7:125–131.Yumita T, Shimazaki I, Miyamoto T, Yamamoto I (1984) Production of benazamide
and isoindoline type compounds on photodegradation of benzanilides. J Pestic Sci 9:419–423.
Zayed SMAD, Farghaly M, Hassan A (1978) Chemistry and toxicology of pesticidechemicals. VII. Photodecompostion of leptophos. Isotopenpraxis 2:68–70.
Zayed SMAD, Mostafa IY, El-Arab AE (1994) Degradation and fate of 14C-DDT and14C-DDE in Egyptian soil. J Environ Sci Health B 29:47–56.
Zepp RG (1982) Experimental approaches to environmental photochemistry. In: Hut-zinger O (ed) The Handbook of Environmental Chemistry, vol 2, part B. Springer-Verlag, Berlin, pp 19–41.
Zepp RG (1988) Environmental photoprocesses involving natural organic matter. In:Frimmel FH, Christman RF (eds) Humic Substances and Their Role in the Environ-ment. Wiley, New York, pp 193–214.
Zepp RG (1991) Photochemical conversion of solar energy in the environment. In: Peliz-zetti E, Schiavello M (eds) Photochemical Conversion and Storage of Solar Energy.Kluwer, Dordrecht, pp 497–515.
Zepp RG, Cline DM (1977) Rates of direct photolysis in aquatic environment. J AgricFood Chem 11:359–366.
Zepp RG, Schlotzhauer PF (1981) Effects of equilibration time on photoreactivity of thepollutant DDE sorbed on natural sediments. Chemosphere 10:453–460.
Zepp RG, Wolfe NL, Baughman GL, Hollis RC (1977) Singlet oxygen in natural waters.Nature (Lond) 267:421–423.
Zepp RG, Baughman GL, Schlotzhauer PF (1981) Comparison of photochemical behav-ior of various humic substances in water: I. Sunlight induced reactions of aquaticpollutants photosensitized by humic substances. Chemosphere 10:109–117.
Zepp RG, Schlotzhauer PF, Sink RM (1985) Photosensitized transformation involvingelectronic energy transfer in natural waters: role of humic substances. Environ SciTechnol 19:74–81.
Zepp RG, Braun AM, Hoigne J, Leenheer JA (1987) Photoproduction of hydrated elec-trons from natural organic solutes in aquatic environments. Environ Sci Technol 21:485–490.
Photodegradation of Pesticides 189
Zepp RG, Faust BC, Hoigne J (1992) Hydroxyl radical formation in aqueous reactions(pH3–8) of iron (II) with hydrogen peroxide: the photo-Fenton reaction. Environ SciTechnol 26:313–319.
Zhang L, Brook JR, Vet R (2002) On ozone dry deposition—with emphasis on non-stomatal uptake and wet canopies. Atmos Environ 36:4787–4799.
Zhang M, Smyser BP, Shalaby LM, Boucher CR, Berg DS (1999) Lenacil degradationin the environment and its metabolism in the sugar beets. J Agric Food Chem 47:3843–3849.
Zongmao C, Haibin W (1997) Degradation of pesticides on plant surfaces and its predic-tion: a case study on tea plant. Environ Monit Assess 44:303–313.
Manuscript received September 20, accepted October 20, 2003.
http://www.springer.com/978-0-387-20845-9