Concentrations of most pesticides in Corn Belt streams declined or stayed the same from 1996 to 2006, according to a new report from the U.S. Geological Survey. Declines in pesticide concentrations closely followed declines in their annual applications, USGS reports.
The Corn Belt, including Illinois, Indiana, Iowa, Nebraska, Ohio and parts of adjoining states, has some of the highest pesticide use in the nation, resulting in widespread runoff into streams and rivers. "Elevated concentrations can affect aquatic organisms in streams as well as the quality of drinking water in some high-use areas where surface water is used for municipal supply," the USGA reports. One pesticide, simazine, increased during the period, leading USGS to suggest non-agricultural use had also increased during the period.
"Pesticide use is constantly changing in response to such factors as regulations, market forces, and advances in science,” Dan Sullivan, lead scientist for the study, said in a news release. He indicated that through history stream concentration decline has followed declines in use. But, concentrations of atrazine and metolachlor declined in one stream more rapidly than their estimated use. Skip Vecchia, senior author of the report on this analysis, explained “The steeper decline in these instances may be caused by agricultural management practices that have reduced pesticide transport." (Read more)
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