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Title: Influence of varying nutrient and pesticide mixtures on abatement efficiency using a vegetated free water surface constructed wetland mesocosm

item Lizotte, Richard
item Locke, Martin
item Testa Iii, Sam

Submitted to: Chemistry and Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/24/2013
Publication Date: 3/31/2014
Citation: Lizotte Jr, R.E., Locke, M.A., Testa III, S. 2014. Influence of varying nutrient and pesticide mixtures on abatement efficiency using a vegetated free water surface constructed wetland mesocosm. Chemistry and Ecology. 30(3):280-294.

Interpretive Summary: We measured the ability of a constructed wetland to trap different combinations of nutrients and pesticides to see if the system could be used as an agriculture best management practice. The study was done to better understand how effective the constructed wetland could be in trapping nutrients and pesticides in runoff from agricultural fields. The study showed the wetland was better in trapping nutrients without pesticides, preventing them from moving downstream and entering a river, lake or stream. These results are of interest to regulatory and other agencies and farming stakeholders by providing additional information to improve and sustain lake and flood plain water quality and overall environmental quality using conservation practices.

Technical Abstract: The efficiency of a vegetated free water surface constructed wetland in abating agrichemicals was examined using varying types of pollutant mixtures. Three different mixture conditions were assessed: nutrients only (N and P); pesticides only (2 herbicides and 1 insecticide); and a mixture of nutrients and pesticides. Amended agrichemical mixtures were comprised of ammonium nitrate, triple super phosphate, atrazine, S-metolachlor, and permethrin simulating storm-generated agricultural runoff. Wetland water was sampled every 30 min during the first 4 h, every 4 h until 48 h, and again 5, 7, 14, 21, and 28 d post-amendment at 10, 20, and 40 m distant from the amendment source and analyzed for nutrients and pesticides. With nutrients only, patterns of nutrient mitigation were associated with distance and rainfall whereas with nutrient and pesticide mixtures, nutrient mitigation was associated with distance and time. With pesticides only, patterns of pesticide mitigation were associated with distance and time whereas with nutrients and pesticide mixtures, pesticide mitigation was associated primarily with distance. Dissipation half-lives were 2-10 times greater for P and 1.5-5 times greater for N when pesticides were present. Dissipation half-lives of pesticides showed no clear differences with or without nutrients present. While vegetated free water surface constructed wetlands can be effective best management practice tools to trap and abate agricultural runoff during rainfall events, efficiencies can be affected by different types of complex agrichemical mixtures and wetland design and implementation should accommodate varying efficiencies.