Submitted to: Chemosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: January 14, 2011
Publication Date: February 21, 2011
Citation: Locke, M.A., Weaver, M.A., Zablotowicz, R.M., Steinriede Jr, R.W., Bryson, C.T., Cullum, R.F. 2011. Constructed wetlands as a component of the agricultural landscape: Mitigation of herbicides in simulated runoff from upland drainage areas. Chemosphere. 83:1532-1538. DOI:10.1016/j.chemosphere.2011.01.034. Interpretive Summary: Buffers are sometimes placed between farms and water bodies to protect the water from erosion sediment and chemicals in runoff from fields. Artificial wetlands can be constructed in these areas to serve this purpose. A multi-cell wetland was constructed in a Mississippi Delta agricultural watershed as a buffer between farmed land and a lake. A research study was conducted to evaluate herbicide moving through the constructed wetland during a simulated runoff event. During the simulated runoff event and for several days following, concentrations of atrazine and fluometuron herbicides in water decreased as the water flowed from cell to cell. Results from this study indicate constructed wetlands can improve downstream water quality though sequestration or processing of pollutants.
Technical Abstract: Constructed wetlands are a recommended practice for buffering pollutant source areas and receiving waters. A wetland consisting of a sediment trap and two treatment cells was constructed in a Mississippi Delta lake watershed. A 3-h simulated runoff event was initiated (2003) to evaluate fate and transport of atrazine and fluometuron through the wetland. Water samples were collected during a runoff simulation and then afterward at selected intervals for 21 d, and analyzed for the herbicides. Breakthrough patterns for herbicide concentrations in water samples during the first 20 h after simulated runoff showed peak concentrations in the first 6 h, with gradual tailing as the herbicide pulse was diluted in the second, excavated (deeper) cell. Atrazine and fluometuron concentrations in the first (shallower, non-excavated) cell averaged 7- and 14-fold greater, respectively, than those in the second cell following simulated runoff, indicating entrapment in the second cell. Atrazine and fluometuron concentrations in the shallower cell decreased 32 and 22%, respectively, 9 d following simulated runoff, indicating either degradation or sorption to soil or wetland flora. In the excavated cell, concentrations were even lower, and atrazine declined more rapidly than fluometuron. Results indicate constructed wetlands can improve downstream water quality though sequestration or processing of pollutants.