Where's the Atrazine? A Regional Groundwater Synopsis

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echnical Abstract: More than 80% of the atrazine used in the United States is applied to control broadleaf weeds in cornfields in the Midwest. There is concern about the potential for contamination of groundwater by this applied atrazine. The Management Systems Evaluation Area (MSEA) Program has studies in 8 of the 11 Corn Belt states to determine the leaching of atrazine under field conditions. Atrazine occurrence in groundwater is governed by landscape topography, depth to the water table, hydrogeology of the area, and sorptive affinity and hydraulic conductivity of the soil. Time of sampling in relation to infiltration of rainfall or irrigation can also be very important. With few exceptions, the concentration of atrazine in the groundwater is well below the 3 ppb maximum contaminant level (MCL). The highest concentrations of atrazine have been in groundwater at three sites where irrigation is part of the farming management. New irrigation schemes are actually lowering the concentration of atrazine in the groundwater at one of these sites. Soil samples indicate that most of the atrazine remains near the soil surface, that the concentration in the soil is not increasing over time as more atrazine is applied, and that soil organisms are able to decompose most of the atrazine within a few months after application.

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Clean Water Clean Environment 21st Century Conference Proceedings

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