USING SPATIAL AND TEMPORAL PATTERNS OF METAL DEPOSITION TO INLAND LAKES TO DIFFERENTIATE SOURCES
Sediment cores were collected from 7 lakes in Michigan, analyzed for a suite of metals and dated with 210-Pb. Patterns of lead deposition show a regional trend, and little relationship to population densities, indicating regional atmospheric sources are dominant in this area. Current lead deposition has a weaker regional trend, indicating a shift from regional to unique local courses. Patterns of cadmium deposition are different than those of lead. Inputs of cadmium in the 1930s-40s are strongly related to population densities, but have no regional pattern, indicating the importance of common local sources. Overall, sediment chronologies from multiple lakes can provide information about the relative importance of local and regional sources of metals to a region.