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1K - Tropospheric Fate (MO13/4) Passive Air Sampling of Persistent Organic Pollutants on a Continental Scale. Wania, Frank1, Shen, Li1, Lei, Ying Duan1, Teixeira, Camilla2, Muir, Derek2, 1 University of Toronto at Scarborough, Toronto, Ontario, Canada2 National Water Research Institute, Environment Canada, Burlington, Ontario, Canada ABSTRACT- The large-scale distribution patterns of persistent organic pollutants in the North American atmosphere were characterized by using a novel XAD-resin-based passive air sampling technique. The network designed for this study consisted of more than a hundred passive air samplers which were deployed for an entire year (spring/summer 2000 to spring/summer 2001) at 43 stations in five countries across North America, covering 72 degrees of latitude and longitude. These stations were chosen as remote as possible, representing a wide range with respect to climatic conditions and proximity to various potential source regions and preferential atmospheric transport pathways. The analysis of the passive air sampling data shows that the variability of atmospheric concentrations is strongly dependent on a chemical's properties and emission history. Chemicals with a low volatility and current consumption within the investigated region, such as DDT, show the largest concentration gradients (up to and exceeding two orders of magnitude between source and remote regions), whereas substances with high volatility and only minor or non-existent current sources, such HCB, show a much more uniform concentration pattern (within a factor of two across the continent). The PCBs show a subtle enhancement of the more volatile constituents at higher latitudes, consistent with the global fractionation hypothesis. Passive samplers are an efficient and simple means of obtaining a large scale picture of the continental atmospheric distribution of persistent organic compounds. Key words: persistent organic pollutants, passive air sampling, North America, long range transport |
