Pesticide Leaching Associated with Conventional Potato and Corn Production in Atlantic Canada

Abstract

Abstract We employed field-scale tile drainage systems, private wells in farming areas, and research piezometers installed al field edge to evaluate nonpoint source impacts of four pesticides on groundwater quality. Nitrale-N was known to be teaching at all study sites. Herbicides dinoseb and metribuzin and the fungicide chlorothalonil were common to potato production; the herbicide atrazine was common to com production. Based on chemical properties, chlorothalonil is unlikely to leach, while atrazine, dinoseb and metribuzin are identified as potential leachers. In this study, chlorothalonil leaching was indeed very limited; only 4 of 66 tile drainage samples were positive, and al concentrations close to the detection limit (0.005 µg L−1). Chlorothalonil was not detected in any of the farm wells or research piezometers located in areas of intense potato production. Conversely, atrazine, dinoseb and metribuzin were confirmed as nonpoint source leachers. They were often detected in tile drainage water and have been detected in wells, but at mean annual concentrations less than current maximum acceptable concentrations for drinking water as established by Health and Welfare Canada.