Sunmao Chen, Clint Truman, Mark White, Dan Campbell, Jerry Wells

Syngenta Crop Protection, LLC, Greensboro, North Carolina, USA

Atrazine Ecological Monitoring Program

2

Outline

● History of Atrazine Ecological Monitoring Program (AEMP)

● Objectives

● Site Selection

● Methods

● Results

● Summary and Conclusions

Classification: Public

3

History of Atrazine Ecological Monitoring Program

• Mandatory per Atrazine Interim Registration Eligibility Decision (IRED)

and Memorandum of Agreement (MOA) in 2003.

• Monitoring started in 2004 at 20 corn/sorghum sites across six Midwest

states and 20 more sites were added to the program in 2005.

• Each site was monitored for a minimum of two consecutive years.

• Seven corn/sorghum sites were retained in the program at the end of

2009 and 25 new sites were added in 2010 as required by EPA.

• Three initial sites and six of the 25 new sites were retained for

monitoring in 2013 and will continue until the site meet EPA criteria for

decommission.

• Sampling started prior to corn/sorghum planting (e.g. early April in

Midwest) and typically continued through July or early August.

Classification: Public

4

Objectives

• Identify and select representative watersheds that are highly vulnerable

to runoff from corn and sorghum production in the U.S. for monitoring.

• Characterize atrazine exposure profiles in the streams of selected

watersheds during crop growing season.

• Enhance understanding of watershed runoff vulnerability with intensive

monitoring data.

• Validate effectives of Best Management Practices and stewardship

activities to reduce runoff from vulnerable watersheds.

• Enable calibration and validation of watershed-scale exposure models.

• Fulfill USEPA mandates under the Memorandum of Agreement (MOA).

Classification: Public

5

Watershed Selection Using USGS WARP Model (2004)

~10,000

40

1,172

5,860

Classification: Public

Reference: USGS Water-Resources

Investigation Report 03-4047 (2004)

6

Watershed Vulnerability Criteria Used in 2010 to Select New Monitoring Sites

Criteria Method 1. A numeric value obtained by multiplying the Atrazine use intensity based on (lb. ai./ watershed area) with % watershed with

depth-to-impervious layer within 60 cm for all land uses and all slopes.

Criteria Method 2. A numeric value obtained by multiplying the Pesticide Root Zone Model (PRZM) 90th percentile 30-day average FLUX with % watershed with depth-to-impervious within 30 cm for

cultivated crops on land of 2% slope or more.

Classification: Public

7

Atrazine Monitoring Program Watershed Map (2004-2015)

Classification: Public

8 Classification: Public

9

Monitoring Site Instrumentation: River Station with Autosampler

Classification: Public

10

ISCO 6712 Autosampler

Classification: Public

11

IA-05 Monitoring Site

Classification: Public

12

High Sediment Samples

Classification: Public

13

LC-MS/MS Instrument for Sample Analysis

Classification: Public

14 Classification: Public

15

MO-01 Monitoring Results

Classification: Public

16

Active Watersheds : Atrazine Concentration Distributions (2010-2014)

Classification: Public

75th percentile atrazine concentrations are ≤10 ppb

17

Active Watersheds: Nitrate Concentration Distributions (2010-2014)

Classification: Public

18

Active Watersheds: TSS Concentration Distributions (2010-2014)

Classification: Public

19

Max 60-Day Atrazine Rolling Averages (2004 – 2014)

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

45.00

2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

pp

b

MO-01 MO-02 NE-04

Classification: Public

20

MO-01 Atrazine Maximum 60-Day Rolling Averages

R² = 0.7215

0.00

5.00

10.00

15.00

20.00

25.00

30.00

2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Pp

b

Year

Classification: Public

21

MO-02 Atrazine Maximum 60-Day Rolling Averages

R² = 0.4214

0.00

2.00

4.00

6.00

8.00

10.00

12.00

14.00

16.00

18.00

2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014

Pp

b

Year

Classification: Public

22

NE-04 Atrazine Maximum 60-Day Rolling Averages

R² = 0.3617

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

40.00

45.00

2005 2006 2008 2009 2010 2011 2012 2013 2014

Pp

b

Year

Classification: Public

23

Summary and Conclusions

● More than 21,000 data points have been generated from 250 site-years

of monitoring across all major US corn, sorghum and sugarcane

producing states since 2004.

● The science-based approach successfully identified high runoff potential

watersheds for this monitoring program.

● Daily composite samples and weather data were collected during crucial

crop growing seasons (e.g., April – July in Midwest states).

● Elevated levels of atrazine were detected in some watersheds when

significant rainfall followed shortly after cumulative applications.

● However, elevated detections were short-lived and dissipated quickly

after major runoff event.

● Atrazine residue declining trend was noticed in those watersheds where

BMP had been successfully implemented.

Classification: Public

24

THANK YOU!

Classification: Public