Submitted to: American Chemical Society National Meeting
Publication Type: Proceedings
Publication Acceptance Date: August 18, 2002
Publication Date: N/A
The Choptank River watershed, located on the Delmarva Peninsula of the Chesapeake Bay, is dominated by agricultural land use, making it vulnerable to both runoff and atmospheric deposition of pesticides. Nineteen currently used pesticides and their transformation products were monitored in event-based rain and weekly air samples and in surface water samples from five cruises in the Choptank River watershed. Chlorothalonil, metolachlor, atrazine, simazine, endosulfan and chlorpyrifos were frequently detected in air and in rain. The wet deposition load to the watershed was estimated at 150 +/- 16, 61 +/- 7, and 51 +/- 6 kg/yr for chlorothalonil, metolachlor, and atrazine, respectively. The high wet deposition load compared to the estimated annual uses for chlorothalonil (13%) and endosulfans (14-90%) suggests a regional transport source from an area with high rates of vegetable production. Compared with gas exchange, wet deposition, which accounted for 3-20% total metolachlor mass in the river, was a more important input source of metolachlor to the river.