Citation: Bouldin, J.L., Farris, J.L., Moore, M.T., Smith Jr, S., Stephens, W.W., Cooper, C.M. 2006. Microcosm Evaluation of the Fate and Effects of Atrazine and Lambda-Cyhalothrin in Unvegetated and Vegetated Monocultures. Abstracts of the Mid-South Regional Society of Environmental Toxicology and Chemistry. p. 17. Interpretive Summary: Abstract only. Interpretive summary not required.
Technical Abstract: Contaminants such as nutrients, metals, and pesticides can interact with constructed wetlands and existing drainage ditches used as agricultural best management practices. Our research has shown that macrophyte presence and hydrologic regime aid in transfer and transformation of pesticides associated with agricultural runoff. This study consisted of applications of both atrazine (triazine herbicide) and lambda-cyhalothrin (pyrethroid insecticide) to vegetated and unvegetated microcosms to measure fate and effects of pesticides applied at suggested field application rates. Exposures focused on monocultures of Ludwigia peploides (water primrose) and Juncus effusus (soft rush). Pesticide sorption was evident through atrazine and lambda-cyhalothrin concentrations in plant tissue as high as 2461 and 87 ug/kg, respectively. Toxicity was measured in water from unvegetated microcosms through 28 d and in Chironomus tentans (midge larvae) exposed to sediments collected from 3 h to 56 d in microcosms receiving the pesticide contamination. Comparative survival of test organisms from this study suggests that effective mitigation of pesticides from runoff can be dependent upon macrophyte contact and vegetative attributes associated with ditches.