Polychlorinated biphenyls (PCBs) are synthetic organic chemicals which were widely used from 1929-1979 and banned in 1979 because of health risks. PCBs are still present in the environment and questions arise as to the state of environmental recovery. Previous studies have shown that atmospheric transport is the dominant pathway for PCB loadings to the environment and that urban areas can be major sources. PCB loadings have been previously reported to be higher in the southern parts of the Great Lake region and lower in the north, possibly reflecting population density. A more detailed understanding of loading patterns is limited by the coarse spatial distribution of existing sampling sites. In this study, sediment records from 34 inland lakes in Michigan were studied to better understand the spatial distribution and changes over time. Results show there is a regional pattern, as well as a localized pattern of the PCB inventories. Higher inventories in the Lower Peninsula than in the Upper Peninsula and locations of high PCB inventories near urban areas were found. During high PCB production years, the concentration and congener cluster show clear localized patterns, but more recently, concentrations and congener distributions suggest a return to a more regional signal. This indicates that during high PCB production years, the distribution of PCBs was more controlled by local sources and in current years, it's more dominant by regional atmospheric input.
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