1

Pesticide fate and transport monitoring and modeling for paddy fields

Hirozumi Watanabe, Ph.D.Tokyo University of Agriculture and Technology (TUAT)3-5-8, Saiwaicho, Fuchu, Tokyo 183-8509 JapanPhone/Fax +81-42-367-5889email pochi@cc.tuat.ac.jp

Research activities of Watanabe’s lab

2

Outline

• Pesticide runoff from rice field– Background– Current condition– Research opportunities

• Pesticide fate and transport research– Plot scale monitoring and modeling– Watershed scale monitoring and modeling– Model system approach

3

Paddy field

55%4,794 4,794

(kilo-ha)

Upland field

25%

Fruit farm7%

Pasture land

13%

Paddy field

55%4,794 4,794

(kilo-ha)

Upland field

25%

Fruit farm7%

Pasture land

13%

Paddy field in Japan( as 2001)

0

100

200

300

400

500

600

1986 1990 1994 1998

Tot

al p

astici

de u

se (10

00to

n)

Paddy field Orchard

Veg. Crop Others

Pesticide shipment in Japan農薬学事典　 2001，ｐ 31

72%

49%

Current state of rice pesticide used in JapanCurrent state of rice pesticide used in Japan

Half of the total domestic pesticide is used for paddy field in JapanMore than half of agricultural land is used for paddy fieldsRice pesticide is probably main non-point source pollution of surface water in Japan.

4

Pesticide RegistrationPesticide Registration

531528520501493473465461451登録有効性分数

12877551178失効有効成分数

15162615251315178新規登録有効性分数

226217304381287250380237271新規登録件数

530953235369543954345589578058826037有効登録件数

121110987654区分＼農薬年度

Currently Registered products

Newly Registered products

Newly Registered active ingredients

Dismissed products

Currently Registered active ingredients

20001992

531528520501493473465461451登録有効性分数

12877551178失効有効成分数

15162615251315178新規登録有効性分数

226217304381287250380237271新規登録件数

530953235369543954345589578058826037有効登録件数

121110987654区分＼農薬年度

Currently Registered products

Newly Registered products

Newly Registered active ingredients

Dismissed products

Currently Registered active ingredients

20001992

In Japan, more than 200 pesticide products with more than 15 active ingredients have been registered each year .

http://www.greenjapan.co.jp/greenjapan.htmグリーンジャパン研究会

5

New design for saving labor costs

Time of application and design of active ingredients

Pesticide fate depends on its design and type of application

Increased variety of pesticide products

Pesticide fate also depends on its design and type of application. So many kinds of products and their various design make pesticide fate study very complex and difficult. In order to help cooperate with pesticide industry as well as satisfy the public demand for environmental safety and quality, we are responsible to develop fast and efficient methods and tools for the pesticide fate and transport research.

6

Pesticide directly applied to paddy water

Inappropriate water management

Paddy field runoff may lose more than 35% of applied mass to surface water, while Upland field lose less than 10% of applied

Pesticide Runoff from Paddy FieldPesticide Runoff from Paddy Field

0

5

10

15

20

25

4/28 5/5 5/12 5/19 5/26 6/2 6/9

Con

c.(

g/l)

Mefenacet concentrations in drainage canal

WQS

Typically used herbicide, mefenacet concentrations in a secondary drainage canal increased as corresponding to the application period during or shortly after the rice transplant and its peak concentration often exceeds environmental water quality standards recommended by the Ministry of the Environment Japan.

7

Pacific Ocean

Lake Kasumigaura

Kitaura

Sotonasakaura

Saka R.

Mt. Tsukuba

Sakura R.

10km

876m

Pacific Ocean

Lake Kasumigaura

Kitaura

Sotonasakaura

Saka R.

Mt. Tsukuba

Sakura R.

10km

876m

Pesticide Conc. 　 (ug/l) in Sakura River Basin 350km2

about 20% is paddy field(By S. Ishihara et al. 2000, NIAES)

5

7 6

11

22

4

3

Co

nce

ntra

tion

( m

g/l)

5

040

1.5020

01

01

5

0

0

01

0

St. 3

Mar. Apr. May June July Aug

molinate

mefenacet

pretilachlor

cafenstrole

esprocarb

simetrynCo

nce

ntra

tion

( m

g/l)

5

040

1.5020

01

01

5

0

0

01

0

St. 3

Mar. Apr. May June July AugMar. Apr. May June July Aug

molinate

mefenacet

pretilachlor

cafenstrole

esprocarb

simetryn

3

St. 4

Mar. Apr. May June July Aug.

molinate

mefenacet

pretilachlor

cafenstrole

esprocarb

simetrynCo

nce

ntra

tion

( m

g/l)

5

040

1.5020

01

01

5

0

0

01

0

St. 4

Mar. Apr. May June July Aug.

molinate

mefenacet

pretilachlor

cafenstrole

esprocarb

simetrynCo

nce

ntra

tion

( m

g/l)

5

040

1.5020

01

01

5

0

0

01

0

St. 4

Mar. Apr. May June July Aug.Mar. Apr. May June July Aug.

molinate

mefenacet

pretilachlor

cafenstrole

esprocarb

simetrynCo

nce

ntra

tion

( m

g/l)

5

040

1.5020

01

01

5

0

0

01

0

4

Corresponding to the early season of rice production during late April to late June, commonly used herbicides are detected up to a few ppb level in Japanese rivers. The time and size of peaks are different among the active ingredients depending upon the time and location of the application.

8

New Drinking Water Quality Standards imposed by Ministry of Health, Labor and Welfare, 2003

• Pesticides （ 1.3-dichloropropane, simazine, thiram, benthiocarb ） has removed from the regulation

• Pesticides will be monitored and regulated by the integrated concentration of detected pesticides in the river basin. Possible target pesticides are selected from 101 pesticides.

9

Water Holding Requirement in California Rice Production

Water holding period for molinate is 28 days, thiobencarb is 30 days

CDPR report 2002 ( http://www.cdpr.ca.gov)

In Sacrament river basin in California, water holding requirement was imposed on rice farmer. Imposing holding water requirement successfully reduced the pesticide concentrations in the streams. California also concerns about seepage runoff from paddy field. In Japan, farmers awareness of the water quality control seems very limited since there is very limited extension or education programs for the pesticide runoff. One popular source of information is the water holding recommendation of 3-4 days after the application in pesticide product label, however more and appropriate extension of pesticide runoff control to the farmer is necessary in order to conserve the water quality

10

Monitoring and Modeling for Pesticide fate and transport

• Pesticide fate in a paddy field　– Plot scale monitoring– Plot scale simulation model (PCPF1)

• Pesticide transport in paddy field watershed– Watershed scale monitoring and modeling

• Model system for analyzing pesticide fate and transport

11

Field MonitoringMefenacet dissipation in paddy field from May 13 to July 4 in 1998 at NIAES

Water balance data

Solar and UV-B radiation

pH, Eh, Temp.

Pesticide concentrations

•For pesticide fate study in a paddy field that we conducted in 1998 and 1999 consist of 1). Plot scale monitoring and 2). Plot scale simulation model (PCPF1). This study was conducted at National Institute of Agro-Environmental Sciences in Tsukuba, Japan. We were responsible for monitoring pesticide fate in paddy field and for developing a simulation model for predicting pesticide concentration in paddy plot.

12

Conceptual pesticide fate and transport processes in paddy

water and surface soil.

Irrigation

Percolation

DissolutionDesorption

Adsorption

PhotolysisBiochemical degradation

Drainage

Paddy Water

Pesticide Source Layer（１ cm）Biochemical

degradation

Evapo-transpiration Precipitation

Desorption

Volatilization

We conceder a conceptual pesticide fate and transport processes in paddy water and surface soil. Upon pesticide application of granule pesticide, pesticide is subject to dissolution in paddy water and then, adsorption in paddy surface soil and partition between paddy soil and water proceed towards the equilibrium condition. However, as irrigation, precipitation and drainage dilute the pesticide concentration and concentration gradient between surface soil and paddy water proceed, pesticide desorbs from paddy soil in order to decrease the chemical potentials between two compartments. Pesticide also desorbs below the surface soil layer as paddy water percolates. Pesticides in paddy water as well as paddy soil are subject to photodegradation, volatilization (paddy water only) and biochemical, and these process also affect pesticide concentration in both compartment.

13

Simulation model for pesticide concentration in paddy

field（ PCPF1）

Simulated and observed mefenaset concentrations in paddy water (above) and paddy surface soil (below)

Herbicide concentrations in paddy water

0

0.2

0.4

0.6

0.8

0 10 20 30 40 50 60Days after herbicide application

Con

cent

ratio

n(m

g/L

) Simu PW Obs. PW

Herbicide concentrations in pesticide source layer

0

5

10

15

0 10 20 30 40 50 60Days after herbicide application

Con

cent

ratio

n (

mg/

kg d

ry s

oil) Simu SL Obs. SL

PCPF-1　model input data sheet

PCPF1 model is a conceptual lumped model simulating the pesticide concentration in paddy water and 1cm deep surface paddy soil. The model is programmed by visual basic application and operated as a macro in Microsoft Excel. The PCPF1 was validated with several commonly used herbicide in Japan.

14

Best Management for controlling pesticide runoff from paddy plots

0

10

20

30

40

50

60

70

0 20 40 60

Days after Herbicide Application

Her

bic

ide

Lo

ss

(% a

pp

lied

)

CDLP3.0

CDLP1.0

LDLP4

LDLP6

Continuous Irrigation and Drainage

Higher Drainage Gate

Cumulative Herbicide Losses by Overflow Drainage

Significant rain events

Intermittent irrigation

Figure shows PCPF1 simulations for evaluating the scenarios for different management practice. Continuous irrigation and drainage scheme loses significant amount of pesticide especially in earlier period as compared to intermittent irrigation scheme. Further more, model calculation implies that higher drainage gate may prevent pesticide runoff when significant rain events by storing rainwater and preventing surface discharge.

15

Best Management for controlling pesticide runoff Best Management for controlling pesticide runoff from paddy plots --- Experimentalfrom paddy plots --- Experimental

Automatic irrigation vs. Continuous drainage Automatic irrigation vs. Continuous drainage

In Tokyo University of Agriculture and Technology, we conducted the monitoring experiment for the evaluation of Best Management Practice for controlling pesticide runoff from a paddy plot from 2001. The objective of this study is to monitor and evaluate pesticide runoff from paddy field managed by automatic irrigation scheme and continuous irrigation-drainage scheme. The monitored variable consist of water balance such as irrigation, drainage, paddy water depth, rainfall, evapotranspiration as well as pesticide concentrations in paddy water and paddy soil during the monitoring period of 35 days.

16

Mefenacet mass balance in paddy field during monitoring period

DrainagePaddy water

Soil surface

Percolation

Drainage

Automatic irrigation Continuous irrigation and drainage

0%

47% 44%

4.7%

0.01% 38%0.01%

4.7%

Degradation 13%48%

Mefenacet mass balance indicate that continuous irrigation-drainage scheme lost 38% of applied pesticide whereas automatic irrigation scheme lost no pesticide since it control the paddy water depth and did not have any surface drainage during the monitoring period. In general, pesticide fate in paddy field managed by water holding scheme such as automatic irrigation scheme in this experiment indicate that more pesticide is kept and degraded within the field as compared to water releasing scheme. Such as continuous irrigation-drainage. It is recommended that water holding scheme by Intermittent irrigation using an automatic irrigation system is the best management practice for controlling the pesticide runoff from paddy field

17

Monitoring and modeling of pesticide transport in paddy field watershed( 10ha paddy block)

Block 3(2.43 ha)

ST①

ST②

ST⑧ ST⑦

ST⑤ ST④

ST③

Sakasa River

Irrigation pipe

Block 1 (3.78 ha)

Block 4 (2.88 ha)

Block 2(1.05 ha)

Rain gage ST⑨

Farm road

Plot 1

(I)

(III)

(II)

10 ha selected paddy field

Block 3(2.43 ha)

ST①

ST②

ST⑧ ST⑦

ST⑤ ST④

ST③

Sakasa River

Irrigation pipe

Block 1 (3.78 ha)

Block 4 (2.88 ha)

Block 2(1.05 ha)

Rain gage ST⑨

Farm road

Plot 1

(I)

(III)

(II)

10 ha selected paddy fieldST①

ST②

ST⑧ ST⑦

ST⑤ ST④

ST③

Sakasa River

Irrigation pipe

Block 1 (3.78 ha)

Block 4 (2.88 ha)

Block 2(1.05 ha)

Rain gage ST⑨

Farm road

Plot 1

(I)

(III)

(II)

10 ha selected paddy field

( 97ha paddy watershed)

Watershed monitoring and modeling study for the pesticide transport in paddy field watershed from 2002. The objectives of this study are 1). Monitor and investigate pesticide fate and transport characteristics in paddy field watershed; 2). Recommend the Best Management Practices (BMPs) for controlling pesticide runoff into aquatic environment in Japanese rice paddy production 3). Develop a simulation model for the pesticide transport in paddy field watershed.

18

Pesticide concentrations in different scales

Conc. in drainage water at St 6( Farm block scale) - 2003

05

101520253035

4/28 5/3 5/8 5/13 5/18 5/23 5/28 6/2 6/7 6/12 6/17

Co

nc. (

ug

/l)

Conc. in drainage water at St 8 ( watershed scale) - 2003

0.0

2.0

4.0

6.0

8.0

4/28 5/3 5/8 5/13 5/18 5/23 5/28 6/2 6/7 6/12 6/17

Co

nc.

( u

g/l

) 0.0

10.0

4/ 285/ 35/ 85/ 135/ 185/ 235/ 286/ 26/ 76/ 126/ 17

Oxaziclomef one

Molinate

Symetryn

Esprocarb

Thiobencarb

Dimethametryn

Dimepiperate

Pretilachlor

Pyriminobac-methyl (E)

Pyributicarb

Pentoxazone

Mef enacet

Caf enstrole

5ha-paddy block

97ha-watershed

Pesticide consentrations in paddy field

0

0.2

0.4

0.6

0.8

1

5/ 5 5/ 25 6/ 14 7/ 4 7/ 24

DateC

oncentr

aio

n (m

g/l)

ISMMFPTCBSM

0.01 ha Paddy plot

Plot

Drainage

Stream

In the paddy field watershed, 15 rice herbicides were detected. Peak concentration raged depending on the pesticide and significant concentrations occurred from may until early June. Pesticide concentrations ranged in different scale. Plot scale raged up to about 800 ppb, 5ha scale, up to about 30 ppb, 97ha watershed scale, up to 7ppb, and for Sakura river scale it ranges up to a few ppb.

19

Wind

Rainfall

Over Drainage

Canal

Water management practice in plot 1 ( 2002)Water management practice in plot 1 ( 2002)

However paddy water depth had been kept less than 1cm from drainage gate in most of the monitoring period.

Continuous irrigation : 10% Intermittent irrigation : 90%

High potential of pesticide runoff upon significant

rainfall and strong wind.

Low drainage

gate

0.0

2.0

4.0

6.0

8.0

4/28 5/5 5/12 5/19 5/26 6/2 6/9 6/16

Dep

th (

cm

) Rain.

Irr.

Drain.

Hpw

Height of drainage gate

Paddy field

Drainage gate

1cm

20

　Watershed discharge（ above） and Integrated detected pesticide loss（ below）

Dischagre from watershed at ST8 ( l/s)

0

100

200

300

400

4/28 5/5 5/12 5/19 5/26 6/2 6/9 6/16

Dis

ch

ag

re (

l/s)

0

1

1

2

2

3

Ra

in(c

m)Rain

Q8(L/s)

Total pesticide loss from watershed ( 2003)

0100200300400500600

4/28 5/5 5/12 5/19 5/26 6/2 6/9 6/16

Da

ily lo

ss (

g)

0

500

1000

1500

2000

Cu

m.

loss (

g)

Daily loss ( g)

Cumulative loss ( g)

Watershed discharged in creased during the significant rain events in upper figure. During the period when pesticide concentrations were high, great pesticide loss occurred with watershed discharge (lower figure). Controlling runoff from paddy field during significant rain events is important for preventing pesticide losses from the watershed.

Increased discharge in significant rain events

Increased pesticide loss in significant rain events

21

Development of simulation model for pesticide transport in paddy field watershed

RIVER

Ma

in c

an

al

Dra

ina

ge

ditc

h

Branch canal

Farm road

Pu

mp

Stn

RIVER

Ma

in c

an

al

Dra

ina

ge

ditc

h

Branch canal

Farm road

Pu

mp

Stn

Model output

Dr

Cpw1

Irr RET

p Dr

Irr RET

Cpw2p

Dr

Cpwm

Irr RET

p

Dr

Irr RET

p Cpw3

Qrain

Qout

Qin

Ground waterDownstream

Qs

Qpr

Cpr

RIVER SECTION

Qr

Qpump

PADDY BLOCK

PTG ① PTG ② PTG ③ PTG m

Upstream

Apply PCPF –1 Model

Dr

Cpw1

Irr RET

p Dr

Irr RET

Cpw2p

Dr

Cpwm

Irr RET

p

Dr

Irr RET

p Cpw3

Qrain

Qout

Qin

Ground waterDownstream

Qs

Qpr

Cpr

RIVER SECTION

Qr

Qpump

PADDY BLOCK

PTG ① PTG ② PTG ③ PTG m

Upstream

Dr

Cpw1

Cpw1

Irr RET

Irr RET

p Dr

Irr RET

Irr RET

Cpw2

Cpw2p

Dr

Cpwm

Cpwm

Irr RET

Irr RET

p

Dr

Irr RET

Irr RET

p Cpw3

Cpw3

Qrain

Qout

Qin

Ground waterDownstream

Qs

Qpr

Cpr

RIVER SECTION

Qr

Qpump

PADDY BLOCK

PTG ①PTG ① PTG ②PTG ② PTG ③PTG ③ PTG mPTG m

Upstream

Apply PCPF –1 Model

Paddy block: Pesticide Treatment Group ( PTG)

Pesticide concentration paddy plot : PCPF-1 model

22

NEW COUPLED MODEL OF PESTICIDE NEW COUPLED MODEL OF PESTICIDE FATE AND TRANSPORT IN PADDY FIELDFATE AND TRANSPORT IN PADDY FIELD

TOURNEBIZE Julien, WATANABE Hirozumi, TAKAGI Kazuhiro, NISHIMURA Taku

Tokyo University of Agriculture and TechnologyGraduate School of Agriculture (Japan)

National Institute for Agro-Environmental Sciences (Japan)

Research Institute for Agricultural and Environmental Engineering, (Antony , France)

• This project was supported by SAKURA PROJECT 03-04:• Scientific Exchange between French and Japanese researchers and financial support provided and

managed by Egide (French Association for foreign research) and JSPS (Japanese society for Promotion of Science)

• General Objectives:General Objectives:– Fate and behavior of pesticide in paddy field– Assessment of pesticide residues in soil during one full crop year

• Specific ObjectivesSpecific Objectives– Coupling PCPF-1 and HYDRUS 2D (SWMS_2D): percolation and concentration– Test and calibrate the new Model for hydraulic functioning and tracer experimen

t then validate for the pesticide fate and transport of pretilachlor

23

Coupling PCPF-1 and Coupling PCPF-1 and SWMSSWMS• Hydraulic Calculation in Water Bala

nce– Ponded Water Depth from PCPF 1 B

oundary Condition h(t) in SWMS– Water Flux from SWMS Percolation

rate in PCPF 1

• Solute Calculation – PCPF module: solute concentration in s

urface water and Pesticide Source Layer Boundary Condition C(t) in SWMS

– Solute Transfer in soil Mass Balance

Irrigation Drainage

-

Irrigation

Percolation

ConcentrationDissolution

PaddyWater

-Evapotranspiration Rainfall

Muddy Layer

Hard Pan Layer

PCPF-1 Compartment

HYDRUS_2D Compartment

First Ash Volcanic Layer

Second Ash Volcanic Layer

Concentration

1 cm Soil Sediment Layer

Transition Layer

Intermediate Layer

Irrigation Drainage

-

Irrigation

Percolation

ConcentrationDissolution

PaddyWater

-Evapotranspiration Rainfall

Muddy Layer

Hard Pan Layer

PCPF-1 Compartment

HYDRUS_2D Compartment

First Ash Volcanic Layer

Second Ash Volcanic Layer

Concentration

1 cm Soil Sediment Layer

Transition Layer

Intermediate Layer

16

6

27

20

24

PretilachlorPretilachlor

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0 10 20 30 40 50 60 70 80 90 100 110 120 130

DAHAP

TC

(n

g/m

l)

Simul (15cm)

Obs SW6 (15cm)

Obs SW9 (15cm)

Mid Term Drainage

0.00

0.01

0.02

0.03

0.04

0.05

0.06

0.07

0.08

0.09

0.10

0 10 20 30 40 50 60 70 80 90 100 110 120 130

DAHA

PT

C (

ng

/ml)

Simul (45cm)

Obs SW10 (45cm)

Obs SW7 (45cm)

Simul (85cm)

Obs SW8 (85cm)

Mid Term Drainage

Oxydative soil layerHard pan and non-puddled layerDegradation rate220 days (Fajardo et al, 2000)

Reductive soil layerPuddled layer (1-17 cm)Kd=13.0 l/kgDegradation rate (2 simple FOK halflife)-6 days (0-21 DAHA)-23 days (22-63 DAHA)

25

Research needs and Opportunities

• Public concern for water quality

• Regulations– Water quality program– PRTR program

• Increased variety of pesticides

• Limited Extension Program in Japan

• Monitoring pesticide fate and transport– Scale issue– Surface water and Ground w

ater• Development of analytical tools

– Simulation models– Lysimeter– Database

• Rapid chemical analysis– ELISA

Background Research needs

26

2. Simulation model

Determination of governing parameter

1. Micro-paddy lysimeter

Simulate pesticide fate in paddy field

Percolation

DrainageIrrigation ET

Kdiss, Kcom Cpw

Model system for analyzing pesticide fate and transport

Parameter data base for different scenario and location

Sakura river basin　 overflow drain（１ｃｍ /day） 　 Soil data

available

　 Model parameter Chemical data

Pesticide Kcom1 Kcom2 Loss Sw Kd Kow

　 /day /day％ Applie

dmg/l L/Kg /day

BSM 0.026 0.011 44 120 16 　

ISM 0.021 0.019 50 308 13.80.12

5

MF 0.023 0.016 36 4 24.1 　

PTC 0.016 0.021 53 50 130.11

4

A model system for rapid analysis of pesticide fate and transport is being developed. The system consist of a micro-paddy lysimeter (MPL), a simulation model to determine pesticide fate parameters, and parameter database for different scenarios. This system has great advantage in analyzing pesticide fate parameters within a two to three weeks with only one set of experiment over the conventional method usually take more time and experiments as well as expenses.

27

１） Micro-paddy lysimeterSimulation of pesticide fate in paddy field

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1.40

1.60

1.80

2.00

31- Oct 5- Nov 10- Nov 15- Nov 20- Nov 25- Nov 30- Nov 5- Dec 10- Dec

Wat

er

Dept

h

0.60

0.70

0.80

Poro

sity

HPR [cm] HE [cm] HSD [cm] HIrr. [cm] f

[cm]

Water Balance and PorosityWater balance tests

28

Watershed scale model is also included in the model system so that reliable pesticide fate and transport prediction make realistic evaluation and development of BMP’s and environmental risk assessments is possible.

Paddy plots

River

Drainage canal

Chemical parameter data base

Pesticide use data

Metrological data

Hydrological data

Risk Assessment

29

Happy Time!