|Smith Jr, Sammie|
Submitted to: Water, Air, and Soil Pollution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/19/2007
Publication Date: 9/1/2007
Citation: Moore, M.T., Cooper, C.M., Smith Jr, S., Cullum, R.F., Knight, S.S., Locke, M.A., Bennett, E.R. 2007. Diazinon mitigation in constructed wetlands: influence of vegetation. Water, Air and Soil Pollution. 184:313-321. Interpretive Summary: Pesticides in runoff from farm fields can contaminate rivers, lakes, and streams. Constructed wetlands are a suggested best management practice to help reduce the detrimental effects of pesticide runoff on downstream water resources. This study simulated a storm runoff event containing the organophosphate insecticide diazinon. Over 40% of the pesticide was measured in wetland plants, indicating the effectiveness of constructed wetlands in reducing concentrations of diazinon in agricultural runoff. Mitigation of agricultural runoff through natural systems, such as wetlands, provides a new tool for farmers and landowners in the quest for improving the Nation’s aquatic resources.
Technical Abstract: In intensively cultivated areas, agriculture is a significant source of pesticides associated with storm runoff. When these pollutants enter aquatic receiving waters, they have potential to damage nearby aquatic ecosystems. Constructed wetlands are a best management practice (BMP) designed to help alleviate this potential problem. A constructed wetland (180 m x 30 m) comprised of a sediment retention basin and two treatment cells was used to determine fate and transport of a simulated storm runoff event containing the insecticide diazinon and suspended sediment. Wetland water, sediment, and plant samples were collected spatially and temporally. Results indicated that 43% of the study’s measured diazinon mass was associated with plant material, while 23% and 34% were measured in sediment and water, respectively. Mean diazinon concentrations in water, sediment, and plants for the 55-d study were 18.1 ± 4.5 ug/L, 26.0 ± 8.0 ug/kg, and 97.8 ± 10.7 ug/kg, respectively. Aqueous concentrations fluctuated in the wetlands between 51-86 ug/L for the first 4 h of the experiment; however, by 9 h, aqueous concentrations were approximately 16 ug/L. During the 55-d experiment, 0.3 m of rainfall contributed to fluctuations in diazinon concentrations. Plant pesticide concentrations indicated the importance of vegetation in sorption and mitigation. Results of this experiment can be used to model future design specifications for mitigation of diazinon and other pesticides.