Submitted to: ASA-CSSA-SSSA Annual Meeting Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: October 5, 2001
Publication Date: October 15, 2001
Citation: Shipitalo, M.J., Owens, L.B. Losses of Atrazine and Its Metabolites in Runoff from Conservation Tilled Watersheds. A05-Shipitalo125414-P. CD-ROM. 2001 ASA Annual Meeting Abstracts.
Atrazine is the most frequently detected herbicide contaminant in surface and ground water in the Corn Belt region of the US. There have been few long-term studies, however, on the losses of the atrazine metabolities deethylatrazine (DEA) and deisopropylatrazine (DIA) in surface runoff. Losses of atrazine (applied during corn years only), DEA, and DIA were monitored for 6 years on an event basis in surface runoff from 2 no-till and 2 chiseled watersheds farmed in a corn/soybean rotation and 3 disked watersheds farmed in a corn/soybean/wheat-red clover rotation. DEA was the most frequently detected metabolite with an average concentration for all watersheds during corn years of 2.5 ug/L compared to 0.7 ug/L for DIA. The ratio of DEA to atrazine (DAR) generally increased with time after atrazine application until the detection limits were reached. In the corn years the average DAR for all watersheds was 0.64 compared to 0.84 for the soybean years. The average concentration of DEA for all watersheds during the corn years was 2.5 ug/L (range 0.7 to 5.6 ug/L), which is similar to the 3 ug/L lifetimedrinking water Maximum Contaminant Level (MCL) for atrazine. There are no established MCL's for atrazine metabolites, but failure to monitor their presence may result in underestimation of the impact of atrazine usage on the environment.