|Smith Jr, Sammie|
|Shields Jr, Fletcher|
Submitted to: Society of Environmental Toxicology and Chemistry (SETAC)
Publication Type: Abstract Only
Publication Acceptance Date: 6/1/1999
Publication Date: N/A
Technical Abstract: Drainage ditches are an integral component of the agricultural production landscape. Mitigation capacities of such ditches (transfer and transformation of nutrients, pesticides, sediments, etc.) have been scarcely examined. A 50 m portion of an agricultural drainage ditch, located in the Mississippi Delta Management Systems Evaluation Area (MDMSEA), was amended with a mixture of atrazine (herbicide) and lambda- cyhalothrin (insecticide), simulating a storm runoff event. Pesticide amendment was achieved by using a diffuser to disperse the mixture at an inflow point along the ditch (designated as "0 m"). Pesticide concentrations in water, sediment, and plants were monitored over a period of 28 days. One hour following initiation of simulated runoff, mean percentages of atrazine concentrations measured in water, sediment, and plants were 37%, 2%, and 61%, respectively; however, mean percentages of lambda-cyhalothrin concentrations were 12%, 1%, and 87%. Of the measured atrazine and lambda-cyhalothrin concentrations remaining in the ditch at day 28, over 50% and 80%, respectively, were associated with plants (Leersia and Sporobolus, dominant species). According to these data, plants serve as an important site for pesticide sorption during runoff events. This research provides fundamental answers concerning the capability of vegetated agricultural drainage ditches to mitigate pesticide-associated storm water runoff.