Atmospheric Deposition of Pesticides to an Agricultural Watershed of the Chesapeake Bay

Abstract

The Choptank River watershed, located on the Delmarva Peninsula of the Chesapeake Bay, is dominated by agricultural land use, which makes it vulnerable to runoff and atmospheric deposition of pesticides. Agricultural and wildlife areas are in close proximity and off-site losses of pesticides may contribute to toxic effects on sensitive species of plants and animals. High-volume air samples (n = 31) and event-based rain samples (n = 71) were collected from a single location in the watershed representing regional background conditions. Surface water samples were collected from eight stations in the tidal portion of the river on five occasions during 2000. Chlorothalonil, metolachlor, atrazine, simazine, endosulfan, and chlorpyrifos were frequently detected in the air and rain, with maximal concentrations during the period when local or regional crops were planted. The wet deposition load to the watershed was estimated at 150 +/- 16, 61 +/- 7, and 51 +/- 6 kg yr(-1) for chlorothalonil, metolachlor, and atrazine, respectively. The high wet deposition load compared with the estimated annual usage for chlorothalonil (13%) and endosulfan (14-90%) suggests an atmospheric source from outside the watershed. Net air-water gas exchange fluxes for metolachlor varied from -44 +/- 19 to 9.3 +/- 4.1 ng m(-2) d(-1) with negative values indicating net deposition. Wet deposition accounted for 3 to 20% of the total metolachlor mass in the Choptank River and was a more important source to the river than gas exchange. Estimates of herbicide flux presented here are probably a low estimate and actual rates may be significantly higher in areas closer to pesticide application.

Endosulfan wet deposition in Southern Florida (USA)

“…Wet deposition measurements have been described in many studies (Carrera et al, 2002;Chan et al, 1994;Chan et al, 2003;Gioia et al, 2005;Goel et al, 2005;Kuang et al, 2003;Laabs et al, 2002;McConnell et al, 1998;Quaghebeur et al, 2004;Tuduri et al, 2006;Wong et al, 2004). Detection of both endosulfans, and in some cases endosulfan sulfate, was observed.…”

Environmental factors affecting the levels of legacy pesticides in the airshed of Delaware and Chesapeake Bays, USA

“…All samples and controls were analyzed for 15 legacy pesticides or degradation products ( [15]. Extracts for samples in 2001 to 2003 were analyzed using either a Hewlett-Packard 5890 gas chromatograph coupled to a Hewlett-Packard 5989A mass spectrometer (GC-MS) or an Agilent Technologies 6890N gas chromatograph coupled to an Agilent 5973 mass spectrometer.…”

“…Previous studies on atmospheric concentrations and deposition of organic pollutants to the Chesapeake Bay region have primarily focused on PCBs, PAHs [7][8][9]12,13], and currently used agricultural pesticides [4,14,15]. No long-term datasets of organochlorine insecticides and their degradation products in air and precipitation are available for the Chesapeake Bay area and Delmarva Peninsula.…”

Structure and binding efficiency relations of QB site inhibitors of photosynthetic reaction centres*

“…They can accumulate in agricultural products (like fresh fruits, vegetables and milk), in water sources like rivers, lakes, reservoirs and in ground water (Kuang et al 2003;Quaghebeur et al 2004), remaining their chemical structures stable for long time (Lányi and Dinya 2003). Herbicides are also referred as able to intercalate into DNA strands resulting in genetic modifications (Riahi et al 2010).…”