137Cs as a tracer of recent sedimentary processes in Lake Michigan |
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Authors: | Richard A. Cahill John D. Steele |
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Affiliation: | (1) Illinois State Geological Survey, 615 East Peabody Drive, 61801 Champaign, IL, USA |
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Abstract: | To determine recent sediment movement, we measured the levels of 137Cs (an artificial radionuclide produced during nuclear weapons testing) of 118 southern Lake Michigan samples and 27 in Green Bay. These samples, taken from 286 grab samples of the upper 3 cm of sediment, were collected in 1975 as part of a systematic study of Lake Michigan sediment. 137Cs levels correlated well with concentrations of organic carbon, lead, and other anthropogenic trace metals in the sediment. 137Cs had a higher correlation with silt-sized than with clay-sized sediment (0.55 and 0.46, respectively). Atmospherically derived 137Cs and trace metals are being redistributed by sedimentary processes in Lake Michigan after being incorporated in suspended sediment. We determined a distribution pattern of 137Cs that represents areas of southern Lake Michigan where sediment deposition is occurring. |
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Keywords: | Lake Michigan geochemistry 137Cs trace metals sediment movement |
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