ARS | Publication request: Mitigation of two pyrethroid insecticides in a Mississippi Delta constructed wetland

Submitted to: Environmental Pollution
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: July 9, 2008
Publication Date: January 1, 2009
Citation: Moore, M.T., Cooper, C.M., Smith Jr, S., Cullum, R.F., Knight, S.S., Locke, M.A., Bennett, E.R. 2009. Mitigation of two pyrethroid insecticides in a Mississippi Delta constructed wetland. Environmental Pollution. 157: 250-256.

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 two pyrethroid insecticides, cyfluthrin and lambda-cyhalothrin. Approximately 49% and 76% of the lambda-cyhalothrin and cyfluthrin, respectively, were measured in wetland plants, indicating the effectiveness of constructed wetlands in reducing concentrations of pyrethroid insecticides 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: Constructed wetlands are a suggested best management practice to help mitigate agricultural runoff before entering receiving aquatic ecosystems. A constructed wetland system (180 m x 30 m) comprised of a sediment retention basin and two treatment cells was used to determine fate and transport of simulated storm runoff containing the pyrethroid insecticides lambda-cyhalothrin and cyfluthrin, as well as suspended sediment. Wetland water, sediment, and plant samples were collected spatially and temporally over 55 d. Results indicated that 49% and 76% of the study’s measured lambda-cyhalothrin and cyfluthrin masses were associated with plant material. Based on conservative effects concentrations for invertebrates and regression analyses of maximum observed wetland aqueous concentrations, a wetland length of 215 m x 30 m width would be required to adequately mitigate 1% pesticide runoff from a 14 ha contributing acreage. Results of this experiment can be used to model future design specifications for constructed wetland mitigation of pyrethroid insecticides.