Wet Deposition of Current Use Pesticides at a Rural Location on the Delmarva Peninsula:  Impact of Rainfall Patterns and Agricultural Activity

Abstract

Event-based precipitation samples were collected during the main agricultural season (April-September) over 4 years (2000-2003) at one site in the Choptank River Watershed on the Delmarva Peninsula. The samples were analyzed for 19 agricultural pesticides to determine the contribution of wet deposition as a source of these compounds to the Chesapeake Bay and the factors affecting the temporal trends in deposition. Chlorothalonil was detected most frequently (92% samples) followed by metolachlor (66%) and endosulfans (49%). Although chlorothalonil is the single biggest contributor to pesticide flux (33-46%), pesticide wet deposition is dominated by herbicides (46-61%), with the greatest fluxes occurring during the time of herbicide application on corn and soybeans. The analysis suggests that the extent of wet deposition of herbicides depends on the timing of precipitation relative to herbicide application. The insecticide and fungicide flux was greater in years with above-average rainfall (2001 and 2003), suggesting that for these pesticides deposition flux is dependent on the total amount of rainfall in the agricultural season. The data indicate that the use of chlorpyrifos, an organophosphate insecticide which is on the Toxics of Concern list for the Bay, is on the increase. Total pesticide flux ranged from 90 microg/m2 (2001) to 180 microg/m2 (2000). Wet deposition can account for up to 10-20% of the annual loadings of pesticides to the Bay.

Currently used pesticides in water matrices in Central-Western Brazil

“…Pesticides have also been reported in rain water samples in other countries. 27,[46][47][48][49][50] These results highlight the possible impacts of pesticide deposition on aquatic and terrestrial ecosystems. Considering that pesticides can be dispersed in the atmosphere, the intensive use of pesticides in the study area could affect other remote and important natural ecosystems, such as the Pantanal.…”

Efficacy of Management Practices to Mitigate the Off-Site Movement and Ecological Risk of Pesticides Transported with Runoff from Agricultural and Turf Systems

“…Pesticides are biologically active compounds designed to interfere with metabolic processes (Matsumura, 1985;Manahan, 1994). The detection of pesticide in soil, water and air (Hoffman et al, 2000;Goel et al, 2005;Harman-Fetcho et al, 2005;Loague et al, 2006;Lv et al, 2010;Riederer et al, 2010;Weber et al, 2010;Hayward et al, 2010), and reported adverse effects of pesticides to non-target organisms at environmentally relevant levels (Chandler et al, 1991;Clark et al, 1993;Margni et al, 2002;Schulz, 2004) has invoked public concern. The off-site transport of pesticides and soil with runoff from agriculture is believed to be a large contributor to water quality degradation.…”

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

“…The increasing population in the Baltimore-Washington corridor exerts significant pressure on the health of this complex ecosystem. Sediments, nutrients, and other toxic chemicals enter the Chesapeake Bay via the atmosphere and the 150 major rivers and streams that feed the estuary, and studies have demonstrated that industrial and agricultural pollutants are entering the Chesapeake Bay through both riverine [1][2][3], and atmospheric sources [4][5][6][7][8][9].…”

“…These data were examined along with measured toxicity, sediment characterization, benthic community analysis, and other key parameters such as dissolved oxygen. Their report indicates that concentrations of metals and organic pollutants such as polychlorinated biphenyls (PCBs), polyaromatic hydrocarbons (PAHs), and the pesticides, 1-chloro-4-[2,2,2-trichloro-1-(4-chlorophenyl) ethyl]benzene (4,4 0 -DDT) and chlordane, were positively correlated with toxicity response. Researchers working in the nearby Delaware River and Delaware Bay found that concentrations of the organic contaminants 4,4 0 -DDE, heptachlor epoxide, chlordanes, and total PCBs) were predictive of hatching success for osprey (Pandion halieatus) [11].…”

“…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.…”