Tuesday, November 10, 2009

Pesticide levels lower in corn belt rivers

Environment News Service: Concentrations of 11 major pesticides declined or stayed the same in Corn Belt rivers and streams from 1996 to 2006, finds a new U.S. Geological Survey study released today. Scientists studied 11 herbicides and insecticides frequently detected in the Corn Belt region, which stretches across Illinois, Indiana, Iowa, Nebraska and Ohio, as well as parts of adjoining states.

This area has the highest pesticide use in the nation, mostly herbicides used for weed control in corn and soybeans. Borne by runoff from cropland and urban areas, these pesticides are widespread in the region’s streams and rivers. Elevated concentrations of these chemicals 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 USGS study is based on analysis of 11 pesticides for 31 stream sites in the Corn Belt for two partially overlapping time periods - 1996 to 2002 and 2000 to 2006. Pesticides included in the trend analyses were the herbicides atrazine, acetochlor, metolachlor, alachlor, cyanazine, EPTC, simazine, metribuzin and prometon, and the insecticides chlorpyrifos and diazinon.

…The declines documented in pesticide concentrations closely followed declines in their annual applications, the authors said, indicating that reducing pesticide use is an effective and reliable strategy for reducing pesticide contamination in streams….

A crop duster spraying pesticides

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