This document summarizes the Atrazine Ecological Monitoring Program (AEMP) which has been ongoing since 2004 to monitor atrazine levels in streams and watersheds across major corn and sorghum producing states in the US. The objectives are to identify vulnerable watersheds, characterize atrazine exposure profiles, enhance understanding of runoff, validate best management practices, and fulfill EPA mandates. Watersheds are selected based on criteria like atrazine use and soil permeability. Monitoring sites are instrumented to collect daily composite samples during crop growing seasons. Results show some short-term elevated atrazine detections following heavy rainfall and application, but levels generally dissipate quickly. Declining trends are seen in waters

1. Sunmao Chen, Clint Truman, Mark White, Dan Campbell, Jerry Wells
Syngenta Crop Protection, LLC, Greensboro, North Carolina, USA
Atrazine Ecological Monitoring Program

2. 2
Outline
● History of Atrazine Ecological Monitoring Program (AEMP)
● Objectives
● Site Selection
● Methods
● Results
● Summary and Conclusions
Classification: Public

3. 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. 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. 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. 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. 7
Atrazine Monitoring Program Watershed Map
(2004-2015)
Classification: Public

8. 8 Classification: Public

9. 9
Monitoring Site Instrumentation:
River Station with Autosampler
Classification: Public

10. 10
ISCO 6712 Autosampler
Classification: Public

11. 11
IA-05 Monitoring Site
Classification: Public

12. 12
High Sediment Samples
Classification: Public

13. 13
LC-MS/MS Instrument for Sample Analysis
Classification: Public

14. 14 Classification: Public

15. 15
MO-01 Monitoring Results
Classification: Public

16. 16
Active Watersheds : Atrazine Concentration Distributions
(2010-2014)
Classification: Public
75th percentile atrazine concentrations are ≤10 ppb

17. 17
Active Watersheds: Nitrate Concentration Distributions
(2010-2014)
Classification: Public

18. 18
Active Watersheds: TSS Concentration Distributions
(2010-2014)
Classification: Public

19. 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
ppb
MO-01 MO-02 NE-04
Classification: Public

20. 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
Ppb
Year
Classification: Public

21. 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
Ppb
Year
Classification: Public

22. 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
Ppb
Year
Classification: Public

23. 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. 24
THANK YOU!
Classification: Public