Pesticide Leaching Potential in Ord River Irrigation Area

1. Pesticide Leaching Potential in Ord River Irrigation Area Lawrence AkSaing Supervisor: Dr. Faisal Anwar

2. Outline • Introduction • Objective • Pesticide cycle • Pesticides and Groundwater • Factors affecting pesticide leaching • Study area • Methodology • Results • Discussion • Conclusion & Recommendation

3. Introduction • Pesticide is a general term used to refer to the chemicals that used to kill or control pests • A very significant nonpoint source of groundwater contamination • Groundwater vulnerability assessment involves determination of how likely the area will be contaminated by the pesticides

4. Objective • To assess pesticide leaching of the study site • To identify high pesticide risk area and high leaching pesticide • To develop a better understanding of pesticide impact on groundwater resources

6. Pesticides and Groundwater • Pesticides can get into the groundwater by leaching through soil • It takes a very long time to break down • Two important processes • Sorption • Degradation

7. Factors affecting pesticide leaching • Pesticide properties (sorption and degradation) • Soil texture and structure • Environmental factors • Pesticide application

8. Study Site • Ord River Irrigation Area • Situated in the east Kimberly region of Western Australia • Main crops grown in ORIA are sugarcane, cucurbits, fruits, and hybrid seeds Cununurra Clay soil

9. Methodology • Two screening models are used to assess leaching potential of 24 pesticides in ORIA • Vulnerability Index (VI) • Index Model by Schlosser et al. • Pesticide Index Rating Index (PIRI) • Software package developed by CSIRO

10. Vulnerability Index • Vulnerability index is calculated based on the considered factor • Pesticides are grouped into three leachability groups based on their leachability ratio (Low, Moderate and High leachability groups)

11. Results - Vulnerability Index Mapping • Three vulnerability maps created for each leachability group High vulnerability map Low vulnerability map Moderate vulnerability map

12. Pesticide Impact Rating Index • Covers surface and groundwater risk assessment • Relative risk rating of different pesticides • Relative risk rating among land uses

13. Results - Pesticide Impact Rating Index • Chemical of concern for different land uses

14. Discussion • Six pesticides identified as high leaching pesticides by VI • Five pesticides identified as high leaching pesticides by PIRI

15. Discussion • Presence of pesticide residue in groundwater • Atrazine was found in some areas • None of chlorpyrifos and endosulphan were detected • Pesticide detection limits

16. Discussion • Atrazine detection borewell (November 2006) • Atrazine detection borewell (June 2006)

17. Conclusion & Recommendation • Risk assessment is for decision making • Relative risk rating of pesticides to groundwater contamination • Useful for identifying high risk pesticides and locations • Pesticides for monitoring

18. Conclusion & Recommendation • Creating the risk map with the incorporation of GIS • More field data on GW to help verify the results

19. Thank You