Submitted to: Society of Environmental Toxicology and Chemistry Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: November 20, 2002
Publication Date: N/A
Technical Abstract: Riparian buffer areas are widely touted for their ability to mitigate pollutants from agricultural fields. We are studying this abatement process for the pesticides atrazine and metolachlor, using a highly instrumented riparian wetland site located in Beltsville, Maryland. This site has clearly delineated flow pathways that intersect a well-defined riparian area with a first order stream. An important objective was to compare pesticide transport through this system with the transport of nitrate and other nutrients. Initial work involved characterizing the distribution of the parent compounds and their degradation products within the system. Another objective was to quantify the pesticide loads entering the stream. Early results showed that atrazine, deethylatrazine, and deisopropylatrazine losses followed the same distribution pattern as nitrate. Other compounds, such as hydroxy atrazine and metolachlor and its degradation products, appear to behave quite differently. In addition to hydrologic inputs to the system, another important pathway for pesticides to enter the riparian system is atmospheric deposition and subsequent sorption of the aerosol or particulate drift or gas onto surfaces (plants or surface litter). During rain events, these sorbed materials are washed off directly into the buffer area. Analyses of rain collected beneath the tree cover in the buffer area showed that 90% more of metolachlor ethane sulfonic acid was in the canopy through-fall, and 85% more of hydroxy atrazine was in the stem-flow than in the rain falling outside the forested area. Results will provide information for characterizing and modeling pesticide processes in riparian wetland systems.