This study determined the importance of air-water exchange of toxaphene in the Great Lakes by comparing this flux to other inputs and outputs in a mass balance model. Our overall goal was to test the hypothesis that the current waterconcentrations of toxaphene in Lake Superior are due to physical limnological differences between it and the lower Great Lakes and secondarily to evaluate whether nonatmospheric inputs of toxaphene have had an impact on current toxaphene burdens in lakesSuperior and Michigan. A series of water samples from the Great Lakes were analyzed for toxaphene. A static mass budget is presented for lakes Superior, Michigan, and Ontario. A dynamic model of toxaphene behavior in lakes Superior and Michigan from 1950to 1995 is then presented. The results of this model support our hypothesis that the colder temperatures and lower sedimentation rates in Lake superior are responsible for its high water concentrations of toxaphene and that there is no evidence ofnonatmospheric sources of toxaphene to Lake Superior. However, the model supports the conclusion that there were nonatmospheric sources of toxaphene to Lake Michigan.
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