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BIODEGRADATION OF ATRAZINE IN SUBSURFACE ENVIRONMENTS
Citation:
Sinclair, J. L. AND T. R. Lee. BIODEGRADATION OF ATRAZINE IN SUBSURFACE ENVIRONMENTS. U.S. Environmental Protection Agency, Washington, DC, EPA/600/S-92/001, 1992.
Impact/Purpose:
present information
Description:
The pesticide atrazine is frequently detected in ground water, including ground water used as drinking water. Little information is available on the fate of atrazine in the subsurface, including its biodegradability. The objectives of this study were to evaluate the biodegradability of atrazine under differing conditions (oxygen status, prior exposure to atrazine, subsurface sediment texture, unsaturated and saturated zone sediments) that would be commonly encountered in the subsurface. Samples of soil and sediment were taken from a borehole drilled at a location beside a highway near Stratford, Oklahoma which had received applications of atrazine annually for 12 years. A second borehole was drilled 66 feet away in a field that had not received atrazine applications. Samples were taken from different depths with respect to the water table and sediment types. Core material from the boreholes was used to make microcosms to study atrazine biodegradation. Microcosms from Stratford, OK sediment were incubated aerobically. A sample from the Norman, OK landfill was used to make microcosms that were incubated anaerobically. Identical microcosms that had been sterilized by autoclaving were used as controls to differentiate biodegradation from abiotic processes. Most or all of the atrazine spiked into active and sterile microcosms made of surface soil from both Stratford locations had disappeared by 105 days of incubation as determined by HPLC analysis. No disappearance of atrazine was observed in either the active or sterile treatment of any of the subsurface samples from either Stratford borehole. A small amount (3.8%) of MC ring labeled atrazine was mineralized to "CO2 by 161 days in the active treatment of the surface soil from the Stratford roadside. Little or no atrazine was mineralized to CO in microcosms of the surface soil from the Stratford field oMhe subsurface samples from either borehole. A slow decline of atrazine was noted in the active treatment of the Norman landfill sediments that were incubated anaerobically. Therefore, some decline of atrazine concentration was noted in anaerobic subsurface microcosms of Norman landfill sediments, but no decline was observed in the aerobic Stratford subsurface sediment microcosms. Factors responsible for the lack of atrazine degradation in the Stratford microcosms may have included the usually small bacterial populations in these samples and the resistant nature of atrazine.