Spatial and Temporal Gradients ofTriazines in the Baltic Sea o� PolandJ. PEMPKOWIAK *, J. TRONCZY �NSKIà and K. PAZDRO  Department of Marine Chemistry and Biochemistry, Institute of Oceanology, P.O. Box 197, 81-712 Sopot, PolandàIFREMER, P.O. Box 1049, Nantes, France

The herbicides atrazine, simazine and terbuthylazine (andthe degradation product deethylatrazine) were analysed intwo river-to-open-sea transects and two vertical (open-sea)pro®les in the southern Baltic o� Poland. Samples takenin September 1995 and April 1997 contained total triazineconcentrations ranging from 7 to 31 and 4.5 to 13 ng/dm3,respectively. Concentrations of the individual compoundsranged from 0 to 8 ng/dm3. These are generally higherthan levels reported, for example, in the North Sea. Thelargest surface concentrations were found close to theVistula and Odra river mouths, endorsing river run-o� asa primary source of the triazines. Temporal variability canbe related to the late-spring and early-summer agricul-tural applications of the compounds. Variations in ratiosbetween the individual triazines can be explained by usagepatterns and di�ering residence times. O�shore verticalpro®les indicate enrichment of the surface layer throughatmospheric triazines inputs, highest concentrations abovethe halocline associated with colloidal organics and lowestconcentrations in the bottom waters, probably as a resultof particulate scavenging. The in¯uence of the North Seain¯ow to the Baltic is also discussed. Ó 2000 ElsevierScience Ltd. All rights reserved.

Keywords: atrazine; simazine; terbuthylazine; concentra-tions; ratios; origin; residence time.

Introduction

The Baltic Sea is a semi-enclosed brackish water bodywith a drainage basin covering some 700 000 km2. Ofthis 35% is cultivated land, which owing to climaticconditions is mainly adjoining the southern Baltic(HELCOM, 1998). Two main features characterize thehydrology of the sea. The surface waters are substan-tially more brackish than near-bottom waters as a resultof riverine input, and there is a permanent halocline atapproximately 60±80 m depth. Although waters belowthe halocline are periodically fed with in¯ows from the

North Sea, oxygen depletion and anoxia are a perma-nent feature of near-bottom water layers in central ba-sins (Voipio, 1981).

Several hundred organic herbicides are currently usedfor agricultural purposes in the countries surroundingthe Baltic Sea. Some 5% of the total amount applied,are triazine-type herbicides (Hock et al., 1995), a veryconsiderable tonnage, which in Europe consists of atr-azine, simazine, and terbuthylazine (Zhou et al., 1996).The most common degradation product of triazinesfound in the environment is DEA-deethylatrazine(Bester and H�uhnerfuss, 1996). Deethylsimazine,deethylterbuthylazine, deisopropylatrazine have, how-ever also been reported (Tronczy�nski et al., 1993; Besterand H�unnerfuss, 1996; Pereira and Rastad, 1990).

Total triazine concentrations in the North Sea and theMediterranean vary from several tenths of a nanogram(per litre) in the open sea to tens of nanograms in coastalareas and hundreds of nanograms in estuarine watersclose to river mouths (Bester and H�unnerfuss, 1993;Readman et al., 1993; Zhou et al., 1996). Triazines arebelieved to behave conservatively when fresh and salinewaters mix (Tronczy�nski et al., 1993). Their highly dy-namic distribution in estuaries is attributed to theirseasonal application to agricultural lands and to ran-dom wash-out from soils to rivers following heavyrainfall (Tronczy�nski et al., 1993).

Available data on triazines in the Baltic Sea are lim-ited to the western Baltic and the Pomeranian Bay o�Germany. Bester and H�uhnerfuss (1993) measured thefollowing respective concentrations of atrazine, simazineand terbuthylazine in o�-shore/near-shore waters in1991: 2±5=6±8, 3±5=1±13, 1±2=1±11 (ng/dm3). In theearly 1990s a ban on the use of atrazine (1991) andsimazine (1992) was introduced in Germany (Graeveand Wodarg, 1996). Despite this prohibition, atrazineand simazine concentrations in the ranges 3±18/1.5±3and 10±19/8±11 (ng/dm3), respectively were measured incoastal/o�-shore waters of the Pomeranian Bay byGraeve and Wodarg (1996). Only in a few samples,collected in the Greifswalden Boden, did they detectterbuthylazine, in concentrations up to several ng/dm3,and they attributed its presence to intensive sugar-beetfarming in Brandenburg. In a recent study Pazdro et al.

Marine Pollution Bulletin Vol. 40, No. 12, pp. 1082±1089, 2000

Ó 2000 Elsevier Science Ltd. All rights reserved

Printed in Great Britain

0025-326X/00 $ - see front matterPII: S0025-326X(00)00059-X

*Corresponding author. Tel.: +48-58-517281; fax: +48-58-8512130.E-mail address: pempa@iopan.gda.pl (J. Pempkowiak).

1082

(1999) reported total triazines concentrations of up to30.1 ng/dm3 in late summer and 12.7 ng/dm3 in earlyspring. Apart from simazine and atrazine we foundterbuthylazine in all the samples we examined.

The purpose of this study was to achieve an under-standing of the distribution of atrazine, simazine,terbuthylazine, and DEA in the southern Baltic so thatfurther areas with a known pattern of the herbicidescould be mapped. Samples were collected in the Gda�nskBay and the Pomeranian Bay along transects from themouths of the rivers Vistula and Odra out to sea, toassess the in¯uence of river run-o� on the herbicidesdistribution. At two o�shore stations vertical pro®les ofthe concentrations were measured to ®nd the concen-trations above and below the halocline. Sampling cam-paigns were carried out in September (1995) and April(1997) in order to follow temporal changes in the dis-tribution due to seasonal application of the herbicides inagriculture.

Experimental

The water samples (total volume of 40±200 dm3) werecollected with an all-Te¯on pumping system during the``GebieÕ95'' and ``GebieÕ97'' cruises of RV ``Oceania''.The location of the sampling stations is shown in Fig. 1.At two stations located at the Bornholm Deep (no. 16)and the Gda�nsk Deep (no. 11) vertical pro®les were alsosampled. They included from 5 to 8 samples collected atvarious depths. Following collection, the water waspassed through an in-line ®ltering system with pre-combusted (450°C, 4 h) glass ®bre ®lters (Whatman GF/F, 293 mm diameter). Immediately after ®ltering, theinternal standards (pretilachlor and cyprazine) wereadded and the water was allowed to ¯ow at a rate of

50±80 cm3/min through Te¯on columns (/ 2� 25 cm)containing precleaned (overnight extractions in an Soxletapparatus with methanol, followed by acetonitrile, thenby methylene chloride) Amberlite XAD-2 resin. Beforeuse the resin was washed with 150 ml of methanol and300 ml of water. After the water had passed through, theresin was dried and the adsorbed organics were elutedwith methylene chloride. Traces of water were removedwith anhydrous Na2SO4, while methylene chloride wasreplaced with isooctane as solvent.

The triazines were identi®ed and quanti®ed in aVarian 3400 gas chromatograph equipped with a NPDdetector, and a DB5 30 m� 0:32 mm capillary column.The following analytical conditions were used through-out the study: carrier gas ± helium, injection port tem-perature ± 250°C, oven temperature program ± 50°Cheld for 1 min, followed by 15°C/min increase to 150°C,followed by 3°C/min increase to 250°C. Identi®cationwas con®rmed in a GC±MS system consisting of aHewlett-Packard HP 5890A gas-chromatographyequipped with a 5989A mass spectrometer detector andan HP Ultra 2 fused silica capillary column. Separationwas performed in the following temperature regime:injection port temperature 250°C, oven temperatureprogram ± 80°C held for 1 min, followed by 15°C/minincrease to 140°C, followed by 3°C/min increase to270°C. Other details of the identi®cation and quanti®-cation procedures can be found in Tronczy�nski et al.(1993). The detection limit of individual compounds laywithin the 0.03±0.10 ng/dm3 range. The precision ofanalyses as determined from a parallel analysis of aseawater sample (n � 3) yielded the following results(average� standard deviation): atrazine 11:1� 0:6 (ng/dm3); simazine 7:0� 0:2 (ng/dm3); DEA 8:0� 0:4 (ng/dm3); terbuthylazine 5:0� 0:9 (ng/dm3).

Fig. 1 Location of sampling stations and distribution of atrazine,simazine, terbuthylazine, and DEA in surface water of thesouthern Baltic in September 1995 and in April 1997.

1083

Volume 40/Number 12/November 2000

The following parameters were measured in the col-lected water samples: salinity (with a salinometer), ox-ygen (Winkler method), particulate matter (0.45 mmMillipore ®lters), and chlorophyll a according toStrickland and Parsons (1972).

Results and Discussion

Concentrations of herbicides in the water samplescollected in September, 1995 are presented in Table 1,the April, 1997 concentrations are in Table 2.

The average total concentrations (� SD) (ng/dm3) inSeptember 1995 were 20:1��1:7�; 14:5��0:3�, and22:3��4:7� in surface layer of the Pomeranian Bay, opensea, and the Gda�nsk Bay, respectively. The average re-spective concentrations (ng/dm3) of atrazine, simazine,terbuthylazine and DEA were:· Pomeranian Bay ± 6:4��1:1�, 6:5��1:2�, 4:9��2:7�,and 2.5;

· Open sea ± 4:3��0:4�, 4:9��0:1�, 1:9��0:1�, and3:4��0:1�;

· Gda�nsk Bay ± 6:0��2:2�, 6:0��0:4�, 4:5��1:4�, and5:8��1:2�.

In April 1997 the total concentrations in the open seaand the Gda�nsk Bay were 9:2��1:8�, and 10:1��2:3�,respectively. Concentrations of individual herbicideswere:· Open sea: atrazine ± 3:0��0:7�, simazine ± 3:9��0:4�,terbuthylazine ± 0:3��0:2�, DEA ± 2:2��0:5�,

· Gda�nsk Bay: atrazine ± 3:1��0:7�, simazine ±3:9��0:9�, terbuthylazine ± 0:1��0:1�, and DEA ±3:0��0:6�.Several features of the distribution of the triazines in

the surface water (Fig. 1) are immediately apparent.Both the total concentrations, and the concentrations ofindividual triazines in September 1995 were much largerthan in April 1997 (Fig. 1). Furthermore, there is a clear-cut decrease in the concentrations in the o�shore tran-sects in 1995, whereas no such pattern is evident in 1997.Both observations can be explained if the sources of thetriazines to the marine environment are taken intoconsideration. Transport via the atmosphere is of minorimportance, since the authors of numerous studies havereached the conclusion that most of the triazines load isdischarged into the sea with the river run-o�, followingthe late spring/early summer application of these her-bicides in agriculture (Brambilla et al., 1993; Tron-czy�nski et al., 1993; Zhou et al., 1996; H�uhnerfuss et al.,1997). Therefore, both their temporal and spatial gra-dients in the marine environment can be attributed tothe dynamic of the loads entering the sea in this way.The concentrations and distribution of triazines in thestudy area in September 1997 thus re¯ect the peak loadbrought to the Baltic with the Vistula and the Odra run-o�s in Summer, 1995 prior to sampling (Pazdro et al.,1999). Much smaller concentrations of triazines and therelatively even distribution in April 1997, as comparedto September 1995 can be explained by the fact that the

TABLE 1

Concentrations of dissolved triazines in the southern Baltic (September, 1995).

Sampling stationa Depth (m) Recovery (%) Concentrations (ng/dm3)

Atrazine Simazine Terb.b DEA Total

3/95 0.5 57 7.2 7.3 6.8 )c 21.37/95 0.5 83 5.1 5.6 3.3 4.9 18.9

11/95 0.5 96 4.6 4.9 1.8 3.4 14.7Bornholm deep 5 94 4.5 5.2 2.3 4.3 16.3

20 94 3.7 4.9 2.0 4.0 14.630 59 3.9 4.6 1.5 3.5 13.560 87 3.1 4.6 1.3 3.3 12.375 73 4.3 4.9 2.6 4.1 15.990 86 3.4 4.4 3.0 3.3 14.1

110 79 3.2 3.5 1.0 2.4 10.1

16/95 0.5 86 4.0 4.9 2.0 3.4 14.3Gda�nsk deep 5 87 3.3 4.6 1.7 4.0 13.6

20 97 3.1 4.4 1.4 3.5 12.435 93 3.5 4.6 1.5 3.6 13.250 90 4.0 5.5 1.9 4.0 15.460 94 3.8 4.5 1.7 3.5 13.570 96 3.3 3.7 1.7 3.1 11.881 100 3.1 3.1 1.2 2.1 9.5

18/95 0.5 74 4.0 6.1 4.3 5.4 19.819/95 0.5 75 4.6 5.9 3.4 5.4 19.320/95 0.5 74 5.0 5.7 3.0 5.3 19.021/95 0.5 64 9.0 6.7 6.4 7.9 30.022/95 0.5 86 7.6 5.5 5.4 5.1 23.6

a See Fig. 1 for location of sampling stations.b Therbuthylazine.c Below detection limit.

1084

Marine Pollution Bulletin

load of triazines discharged to the sea decreases fromautumn to early spring (Brambilla et al., 1993; Tron-czy�nski et al. 1993). Additionally, several concomitantprocesses are occuring to decrease their concentrationsin seawater: degradation, sorption to particulate matterfollowed by sedimentation, and dilution due to largescale mixing (H�uhnerfuss et al., 1997; Rogers et al.,1996; Bester and H�uhnerfuss, 1996; Brambilla et al.,1993; Pereira and Rastad, 1990).

As a rule, concentrations in the uppermost layer ofwater (0.5 m) are larger than those in the subsurface (5m) layer. Though this di�erence can be hardly regardedas statistically signi®cant, it was nevertheless perceivedin most data sets comprising the results of analyses ofboth surface and subsurface water samples (Table 1).The di�erence can be attributed to the input of the tri-azines from the atmosphere (Wu, 1981). In a recentstudy H�uhnerfuss et al. (1997) reported an annual o�-shore deposition rate of total triazines of 20 g/km2.These authors concluded that though this is larger thanthe atmospheric input of HCH and PCBs it is still muchlower than the riverine input. Nonetheless, they are ofthe opinion that the atmospheric contribution can a�ect

concentrations of herbicides in remote and uncontami-nated areas (Bester et al., 1995). Concentrations up to0.32 ng/dm3 of individual triazines have been reported inrainwater over the North Sea Island of Helgoland re-garded as an area remote from any triazine sources(D�or¯er and Scheunert, 1997). This lends support to thepossibility that transport via the atmosphere is indeed afactor in¯uencing the distribution of triazines in thesouthern Baltic Proper.

The concentrations of triazines measured in this studyin the Pomeranian Bay are comparable to those reportedearlier for the area (Table 3) by Graeve and Wodarg(1996), but seem to exceed these measured by Bester andH�uhnerfuss (1993). One reason for the rather smallconcentrations measured in the latter study are largerecovery rates of triazines from water (0.94) assumed bythe authors. In our work, the recovery rates, assessedindividually in each sample using internal standardsranged from 0.56 to 1.00 (average 0:78� 0:13, n � 38).

The rather high concentrations of total triazines in theopen Baltic seawater found in this, and previous studiesworthy are of note (Table 3). On the other hand, con-centrations in the Vistula and the Odra estuaries are

TABLE 3

Concentration of total triazines in selected European seas.

Sea/region Concentration (ng/dm3) Literature

Baltic/Pomeranian Bay 8 Bester and H�uhnerfuss (1993)Baltic/Pomeranian Bay 12±16 Graeve and Wodarg (1996)Baltic/Pomeranian Bay 19±21 This studyBaltic/open sea; September 1995 14.5 This studyBaltic/open sea; April 1997 10.1 This studyBaltic/open sea; Summer 1991 5±8 Bester and H�uhnerfuss (1993)North/open sea 1.2 Zhou et al. (1996)North/open sea <2 Bester and H�uhnerfuss (1993)Mediterranean/Nile delta <1 Readman et al. (1993)

TABLE 2

Concentrations of dissolved triazines in the southern Baltic (April, 1997).

Sampling stationa Depth (m) Recovery (%) Concentrations (ng/dm3)

Atrazine Simazine Terb.b DEA Total

23/97 5 68 2.5 3.6 )c 1.8 7.950 80 1.8 2.4 0.33 0.4 4.9

Bornholm deep 55 66 2.5 3.0 )c 1.6 7.170 62 3.2 3.3 0.05 1.0 7.685 56 2.9 3.0 0.02 1.2 7.2

24/97 5 91 3.4 4.2 0.41 2.4 10.540 77 3.4 4.1 0.43 2.4 10.4

Gda�nk Deep 75 72 3.4 4.2 0.52 3.7 11.985 55 3.0 3.7 0.52 3.3 10.690 69 3.8 4.2 0.50 2.6 11.1100 83 3.3 3.6 0.19 2.3 9.4

25/97 5 69 3.9 5.0 0.07 3.6 12.726/97 5 66 2.7 3.6 0.18 2.6 9.027/97 2 64 2.6 3.2 )c 2.7 8.5

a See Fig. 1 for location of sampling stations.b Below detection limit.c Therbuthylazine.

1085

Volume 40/Number 12/November 2000

much smaller than those in estuaries of major riversentering the North Sea (Zhou et al., 1996) and theMediterranean (Readman et al., 1993). This suggeststhat the smaller atrazines concentrations in river watercould be an explanation for the latter phenomenon. Theformer feature may be due to the smaller dilution factorcaused by substantial river run-o� and the small volumeof the Baltic seawater, as well as the concurrent limitedexchange of water between the Baltic and the North Sea(Voipio, 1981).

The concentration ratios of individual triazines listedin Table 4 provide additional insight into the distribu-tion of triazines measured in the southern Baltic Proper.The following conclusions can be derived from the ra-tios:· Average ratio of terbuthylazine (T) to simazine (S)concentrations was 0:67� 0:23 in September 1995;but just 0:04� 0:03 in April 1997. This indicates faster

removal rates of the former, a conclusion supportedby the T/S ratios decreasing seaward in September1995 (0:96� 0:02 for near coast samples vs0:59� 0:19 for o�shore samples).

· There are no indications that the ban on the use ofatrazine and simazine introduced in Germany in theearly 1990s (Graeve and Wodarg, 1996; Bester andH�uhnerfuss, 1996) has in¯uenced the triazines concen-trations in the Pomeranian Bay. This state of a�airsmay be due to either or both of two reasons: (a) exist-ing supplies of atrazine and simazine left over in theex-GDR part of Germany are still being used (Graeveand Wodarg, 1996); (b) the fact that drainage area ofthe river Odra lies almost entirely in Poland, where norestrictions on the use of atrazine and simazine havebeen imposed.

· Increasing simazine to atrazine (S/A) ratios in the nearshore (0:89� 0:19) and o�shore (1:25� 0:17) locations

TABLE 4

Ratios of individual triazines concentrations in the investigated samples collected in the southern Baltic Sea.

Location/year Depth (m) Ratiosa

DEA/A S/A T/S T/A T/A+S+DEA

3/95 0.5 <0.01 1.01 0.94 0.94 0.477/95 0.5 0.96 1.10 0.59 0.65 0.21

11/95 0.5 0.74 1.06 0.37 0.39 0.145 0.96 1.16 0.44 0.51 0.1620 1.08 1.32 0.41 0.54 0.1630 0.90 1.18 0.33 0.38 0.1360 1.06 1.48 0.28 0.42 0.1290 0.97 1.29 0.68 0.88 0.27110 0.75 1.09 0.28 0.31 0.11

16/95 0.5 0.85 1.23 0.41 0.50 0.165 1.21 1.39 0.43 0.52 0.1420 1.13 1.42 0.32 0.45 0.1335 1.03 1.31 0.33 0.43 0.1350 1.00 1.38 0.35 0.48 0.1460 0.78 1.18 0.38 0.45 0.1470 0.84 1.12 0.46 0.52 0.1781 0.68 1.00 0.38 0.39 0.14

18/95 0.5 1.35 1.52 0.70 1.07 0.2819/95 0.5 1.17 1.28 0.58 0.74 0.2120/95 0.5 1.06 1.14 0.53 0.60 0.1921/95 0.5 0.88 0.74 0.95 0.71 0.2722/95 0.5 0.67 0.72 0.98 0.71 0.30

23/97 5 0.51 1.44 <0.01 <0.01 <0.00250 0.22 1.33 0.13 0.17 0.0655 0.64 1.20 <0.01 <0.01 <0.00270 0.31 1.03 0.02 0.02 0.0185 0.45 1.04 0.01 0.01 0.003

24/97 5 0.71 1.20 1.10 0.12 0.0440 0.71 0.21 0.10 0.13 0.0475 1.09 1.24 0.12 0.15 0.0585 1.10 1.23 0.14 0.17 0.0590 0.71 1.10 0.12 0.13 0.05100 0.72 1.09 0.05 0.06 0.02

25/97 5 0.92 1.28 0.01 0.02 0.0126/97 5 0.96 1.33 0.05 0.07 0.0227/97 2 1.04 1.23 <0.01 0.01 <0.02

aA ± atrazine, S ± simazine, T ± terbuthylazine.

1086

Marine Pollution Bulletin

may indicate that simazine is more resistant to the re-moval mechanisms, a conclusion supported by earlier®ndings (Tronczy�nski et al., 1993; Brambilla et al.,1993), i.e. the ratios of atrazine, simazine and their de-gradation products in fresh and saline water. This con-clusion is also supported by the larger ratios found in1997 (1:30� 0:09) as compared to 1995 (1:03� 0:20).Increasing DEA/A ratios suggest that DEA is being re-moved faster than to its parent compound.

· The simazine-to-atrazine ratios found in this study(1:17� 0:24) are much smaller than those (some 3.5)reported by Graeve and Wodarg (1996), a feature dif-®cult to explain. The composition of triazines in Balticseawater, west of the island of Bornholm reported byBester and H�uhnerfuss (1993) suggest ratios(1:23� 0:69) much closer to our own ®ndings.The distribution of dissolved triazines in the surface-

to-bottom pro®les is presented in Figs. 2 and 3. Thepro®les were measured in two o�shore stations locatedin the Bornholm and the Gda�nsk Deeps. The halocline

separating the less saline surface water from the moresaline stagnant, deep water lay at a depth of 60±70 min the Bornholm Deep and at 70±90 m in the Gda�nskDeep. It is characteristic of both 1995 pro®les that theconcentrations of all the triazines analysed increaseimmediately above the halocline (Fig. 2). This may beexplained by the a�nity of triazines for colloidal or-ganic matter (Tronczy�nski et al., 1993) which passesthrough the GF/F ®lters (0.8 lm e�ective pore diam-eter). Owing to the size and density of the particles,this matter gathers in the nepheloid layer above thehalocline. Of the triazines studied here, simazine showsthe largest increase in the Bornholm Deep; in theGda�nsk Deep it is atrazine that displays the greatestrise. Overall, a 15±20% increase was found, which maygive some indication of the proportion of the organi-cally bound fraction of triazines in their total concen-trations.

No increase was found in the triazines pro®les mea-sured in the Bornholm Deep in April 1997; in the

Fig. 2 Vertical pro®les of salinity, suspended particulate matter, andmeasured triazines concentrations in the Gda�nsk Deep and theBornholm Deep in September 1995.

1087

Volume 40/Number 12/November 2000

Gda�nsk Deep pro®le by contrast, the increase was of thesame magnitude as in September 1995 (Fig. 3). Thiscould have been due to increased sedimentation ofparticles, rich in triazines, but this is rather unlikelysince no such phenomenon was observed in the Gda�nskDeep. Another possible source of triazines is the in¯owof water from the North Sea. Concentrations of tria-zines in the North Sea along the western Danish coastamount to hundreds of nanograms per litre (Bester andH�uhnerfuss, 1993) which strongly supports such an ex-planation. Further support is provided by the smallconcentrations of terbuthylazine below halocline in theBornholm Deep. The short residence time explains thedepletion of the herbicide as compared to atrazine andsimazine, both of which have longer residence times.Several months elapse before water ¯owing into theBaltic from the North Sea reaches the Bornholm Deep.The elevated concentration of terbuthylazine at 50 mdepth, immediately above the halocline, could be due to

longer residence time of organically-bound terbuthyl-azine as compared to that of other species of the her-bicide, and/or to the scavenging of terbuthylazine fromthe water column by, organic-rich, suspended matterslowly falling to the bottom. It is also worth noting thatthe April 1997 terbuthylazine concentrations in theBornholm Deep were close to the detection limit.

Another feature of the pro®les is the rapid decreaseof dissolved triazines in the near-bottom samples(Figs. 2 and 3). This might be put down to adsorptionof triazines by suspended particles in the nepheloidlayer close to the muddy bottom at both locations.Although no triazines were found in coarse sandysediments of the Humber Estuary (Zhou et al. 1996),large contents of triazines were found in a variety of theWadden Sea sediments, especially those with a highorganic carbon content (Bester and H�uhnerfuss, 1996).At both stations with the vertical pro®les investigated inthis study, sediments are composed of ®ne-grained silts

Fig. 3 Vertical pro®les of salinity, chloro®l a, nitrates, phosphates, andmeasured triazines concentrations in the Gda�nsk Deep and theBornholm Deep in April 1997.

1088

Marine Pollution Bulletin

with an 8±10% organic matter content (Voipio, 1981).The relatively high a�nity of atrazine and irgarol tosuspended particulate matter, and presumably thatother triazines analysed here too, a�ects their fate in themarine environment (Rogers et al. 1996). This endorsesthe conclusion that in the near-bottom water layer,triazines are scavenged by ®ne, resuspended, organicrich particles. Again, the in¯ow of water from theNorth Sea, reaching the Bornholm Deep but not theGda�nsk Deep, prior to the sampling could explain theapparently anomalous vertical pro®les of triazines atthe former location.

Conclusions

Total concentrations of triazines in the southernBaltic lie in the range from 7 to 30 ng/dm3. Concen-trations (ng/dm3) ranges of atrazine, simazine, terbu-thylazine and de-ethylazine in September 1995/April1997 were 3:1±9:0=1:8±3:9, 3:1±7:3=2:3±5:0, 1:0±6:8=0:0±0:5, 0:0±7:9=0:4±3:6, respectively. The large con-centration of triazines in the Baltic as compared to thosein the North Sea are attributed to larger river in¯ow±seawater volume ratio in the Baltic. The higher con-centrations in the near-shore locations and the smallerones in the o�shore were thought to be due to the in-¯uence of river run-o�, while the smaller and relativelyconstant concentrations in early Spring as opposed tolarger concentrations in late Summer were put down tothe seasonal use of the herbicides. The di�erent resi-dence times are thought to explain the varying concen-tration ratios of individual triazines.

The vertical pro®les of triazines measured in twoo�shore locations show a small increase in the surfacelayer (atmospheric input), a maximum in the layer justabove the halocline (colloidal organic matter), and aminimum in the near-bottom layer (scavenging by sus-pended matter). The anomalous pro®les of individualtriazines in the Bornholm Deep in April 1997 are at-tributed to the in¯ows from the North Sea.

Bester, K. and H�uhnerfuss, H. (1996) Triazine herbicide concentra-tions in the German Wadden Sea. Chemosphere 32 (10), 1919±1928.

Bester, K. and H�uhnerfuss, H. (1993) Triazines in the Baltic and NorthSea. Marine Pollution Bulletin 26(8) 423±427.

Bester, K., H�uhnerfuss, H., Neudorf, B. and Thieman, B. (1995)Atmospheric deposition of triazine herbicides in Northern Germanyand the German Bight (North Sea). Chemosphere 30, 1639±1653.

Brambilla, A., Rindone, B., Polesello, S., Galassi, S. and Balestrini, S.(1993) The fate of triazine pesticides in River Po water. ScienceTotal Environment 132, 339±348.

D�or¯er, U. and Scheunert, I. (1997) S-triazine herbicides in rain waterwith reference to the situation in Germany. Chemosphere 35 (1/2),77±85.

Graeve, M. and Wodarg, D. (1996) Distribution of herbicides(s-triazines) in the Pomeranian Bay. Oceanological Studies 4, 31±38.

HELCOM (1998) The Third Baltic Sea Pollution Load Compilation.Baltic Sea Environmental Proceedings No. 70, Helsinki Commis-sion, Helsinki 1998, 133 pp.

H�uhnerfuss, H., Bester, K., Kandgra�, O., Pohlman, T. and Selke, K.(1997) Annual balances of hexachlorocyclohexanes, polichlorinatedbiphenyls and triazines in the German Bight. Marine PollutionBulletin 34 (6) 419±426.

Hock, B., Fedtke, C. and Schmidt, R. R. (1995) Herbicide-Entwickl-ungen, Anwendungen, Wirkungen, Nebenwirkungen. Thieme Verlag,Stuttgart, pp. 358.

Pazdro, H., Tronczynski, J. and Pempkowiak, J. (1999) Distribution oftriazine-type herbicides in the surface waters of the Southern Baltic.Oceanologia 41 (2), 255±264.

Pereira, E. and Rastad, C. (1990) Occurence, distribution andtransport of herbicides and their degradation products in the lowerMississippi river and its tributaries. Environmental Science andTechnology 24, 1400±1406.

Readman, J., Albanis, T., Barcelo, D., Galassis, S., Tronczy�nski, J. andGarbielides, G. (1993) Herbicide contamination of Mediterraneanestuarine waters: results from a MED. POL Pilot Survey. MarinePollution Bulletin 26 (11), 613±619.

Rogers, H., Watts, C. and Johnson, I. (1996) Comparative predictionsof irgarol 1051 and atrazine fate and toxicity. EnvironmentalTechnology 17, 553±556.

Strickland, J. and Parsons, T. (1972) A practical handbook of seawateranalysis. Bulletin of the Fisheries Board of Canada 167, 153±163.

Tronczy�nski, J., Muschy, C., Durand, G. and Barcelo, D. (1993)Monitoring of trace levels of herbicides and their degradationproducts in the river Rhone, France, by gas chromatography-massspectrometry. Science Total Environment 132, 327±337.

Voipio, A. (1981) The Baltic Sea. Elsevier, Amsterdam 1981, pp. 418.Wu, T. (1981). Atrazine residues in estuarine water and the aerial

deposition of atrazine into Rhode river, Maryland. Water, Air andSoil Pollution 15, 173±184.

Zhou, L., Fileman, T., Evans, S., Donkin, P., Mantoura, R. andRowland, S. (1996) Seasonal distribution of dissolved pesticides andpolynuclear aromatic hydrocarbons in the Humber estuary andHumber coastal zone. Marine Pollution Bulletin 32 (8/9), 599±608.

1089

Volume 40/Number 12/November 2000