Occurrence of Herbicide Degradation Compounds in Streams and Ground Water in Agricultural Areas of Southern Georgia, 2002
Pittman, John R.
Berndt, Marian P.
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Water samples were collected during 2002 from 2 streams and 28 wells located in agricultural areas in southern Georgia and analyzed for more than 180 pesticides (including herbicides, insecticides, and their degradation compounds). The most frequently detected pesticides in stream samples were the herbicide degradation compounds metolachlor ethane sulfonic acid (ESA) (74 percent of samples), metolachlor oxanilic acid (OA) (61 percent), and alachlor ESA (61 percent). In contrast, the parent compounds, metolachlor and alachlor, were not detected in stream samples (at a reporting level of 0.05 micrograms per liter [µg/L]). Atrazine was detected in 45 percent of stream samples; and the atrazine degradation compound, deethyldeisopropylatrazine, was detected in 13 percent of stream samples. In ground water, metolachlor ESA (67 percent of samples), alachlor ESA (48 percent), and metolachlor OA (33 percent) were the most frequently detected pesticides. In contrast, metolachlor was detected in only 7 percent of ground-water samples and alachlor was not detected in any ground-water samples. Concentrations of metolachlor did not exceed 0.13 µg/L in ground water; however, metolachlor ESA concentrations were as high as 19 µg/L and metolachlor OA concentrations were as high as 4.42 µg/L in ground water. The higher detection rates and higher concentrations of the metolachlor and alachlor degradation compounds relative to their parent compounds, highlight the importance of including herbicide degradation compounds in waterquality assessments to more fully evaluate the environmental fate of herbicides in hydrologic systems.