WA9 Semi-Volatile Pollutants in Polar and Alpine Ecosystems
D137-140
8:00 AM - 12:00 PM, Wednesday
() Deposition of pesticides in Rocky Mountain and Glacier National Parks.
Foreman, W1, Mast, M1, Skaates, S.1, Campbell, D1, Manthorne, D1, 1 U.S. Geological Survey, Denver, CO, USA
ABSTRACT- Results from recent studies suggest that national parks could be at risk from deposition of organic contaminants by long-range atmospheric transport. Organic contaminants may be depositing at disproportionately high rates in mountainous areas of the Western United States because of low annual air temperatures, high rates of precipitation, and proximity to agricultural areas. However, few measurements have been made in high-elevation areas, especially for current-use pesticides, and the distribution of organic contaminants in these ecosystems remains inadequately characterized. The U.S. Geological Survey (USGS) determined concentrations of selected organic contaminants deposited in high-elevation areas of Rocky Mountain and Glacier National Parks. Snowpack samples were collected in 2001–3 at various elevations on the eastern and western slopes of the Continental Divide in both parks. Lake-sediment samples were collected in 2002–3. Rainfall samples were collected in 2002 in Rocky Mountain National Park. Samples were analyzed for organochlorine insecticides (OCs), polychlorinated biphenyls (PCBs), and multiple classes of current-use pesticides by using gas chromatography with electron-capture detection or mass spectrometric detection. Banned OCs and PCBs were not detected in snow or lake-water samples and only degradates of DDT were detected in the lake-sediment samples. Current-use pesticides, such as dacthal, endosulfans, carbaryl, atrazine, and chlorothalonil, were detected in snow, rain and lake sediment. Concentrations of current-use pesticides in rain typically were an order of magnitude greater than in snowpack. Limited snowpack subsampling indicates that the majority of current-use herbicide deposition occurs during mid-to-late spring snows when the atmospheric burden of pesticides has substantially increased from spring agricultural applications. Deposition of current-use pesticides might be as important as legacy OCs and PCBs in high-elevation ecosystems.
Key words: deposition, pesticides, snowpack, rain