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(477) Sources and Trends of POPs in the Great Lakes Atmosphere: A Decade of IADN Data .
Buhler, Stephanie1, Hafner, William1, Basu, Ilora1, Hites, Ronald*,1, 1 Indiana University, Bloomington, IN, USA
ABSTRACT- The Integrated Atmospheric Deposition Network (IADN) has been measuring the concentrations of many persistent organic pollutants (POPs) in the air near the Great Lakes for more than 10 years. The network is a joint venture of the Canadian and US governments with sampling stations on each of the five Great Lakes. The goals of the network are to determine temporal trends and possible sources of these compounds, as well as estimate their annual loadings, to the Great Lakes. The most recent loadings report (data through 1998) estimated loadings for the basin as a whole and indicated that the inputs of banned pesticides and industrial chemicals were approaching equilibrium, while compounds still in-use showed little decline. A temporal trend analysis on a decade worth of polychlorinated biphenyl (PCB) gas-phase concentrations over Lakes Michigan and Superior led to the integration of IADN data with historical PCB data to properly estimate half-lives for this compound (10 and 6 years, respectively). With 10 years of data available, IADN also began to focus on source profiles for POPs in the basin. Using a probabilistic model called the Potential Source Contribution Function model, we found that the most likely source of many pesticides to the region is the heavily farmed areas between Iowa and eastern Ohio, while industrial compounds, such as PCBs, seem to come from urban areas. The extensive atmospheric data supplied by IADN indicate that some of the bans on various POPs have been effective in cleansing the air around the Great Lakes, but it is clear that the atmosphere continues to deliver pollutants to the Lakes.
Key words: POPs, Atmospheric deposition, Great Lakes
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