|Smith Jr, Sammie|
Submitted to: Chemosphere
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/1/2004
Publication Date: 12/1/2004
Citation: Bouldin, J.L., Milam, C.D., Farris, J., Moore, M.T., Smith Jr, S., Cooper, C.M. 2004. Evaluating toxicity of ASANA XL (Esfenvalerate) amendments in agricultural ditch mesocosms. Chemosphere. 56(7): 677-683. Interpretive Summary: Pesticide runoff from agricultural fields may contaminate nearby surface water bodies, but agricultural drainage ditches surrounding these fields can act as buffers for such runoff during storm events. A vegetated ditch within the Mississippi Delta Management Systems Evaluation Area (MDMSEA) was intensely monitored for 56 days following a man-made storm runoff event. To determine if the pesticides were moving down the ditch, sensitive laboratory organisms were placed in water collected from along the ditch during the 56 day experiment. The survival of laboratory organisms indicated that the pesticides moved at least 80 m down the 650 m ditch. However, the plants and sediment within the ditch were able to buffer or filter significant amounts of the pesticide out of the water before it reached the end of the ditch. This is important because it indicates that vegetated drainage ditches are capable of removing pesticides in the water before they reach aquatic receiving systems such as rivers, lakes, or streams.
Technical Abstract: Agricultural ditches primarily serve to remove and store excess water associated with irrigation and storm events. The ability of these ecosystems to mitigate potential contaminants is not well understood. Five sites along a 650-m agricultural ditch located in the Mississippi Delta Management Systems Evaluation Area (MDMSEA) were used to measure fate and effects of an esfenvalerate (insecticide) exposure. Following a 0.64 cm simulated storm event, samples were collected from water and sediments analyzed spatially from five sites and temporally from 0.5 h - 56 d. Results of aqueous toxicity bioassays indicated that lethality progressed downstream throughout all sampling intervals, while sediment toxicity bioassays only elicited biological responses at the point of pesticide application to the ditch (0 m). Significant reductions in survival of Ceriodaphnia dubia and Pimephales promelas in water were measured at the 0, 20, and 80 m sites following application. Ten day solid phase sediment testing of Chironomus tentans indicated persistent toxicity only at the point of application (0 m) and throughout 56 d (14.4% survival). No lethality or significant reduction in midge growth was measured for remaining downstream sites. These measurements were used to evaluate the potential of agricultural ditches to reduce potential deleterious effects of contaminants in agricultural drainage systems that precede receiving streams.