Cesium-137 in Lake Michigan Sediments: Areal Distribution and Correlation with Other Man-made Materials

Grab samples of sediment were collected at 530 locations in Lake Michigan, primarily in the southeastern quarter of the lake. Each sample was analysed in the field and in the laboratory for fallout cesium-137. Twenty-five of the samples, collected near the mouth of the St Joseph River, were also analysed in the laboratory for 11 other man-made materials known to be discharged into the river. Two statistical methods were used to determine i f cesium-137 can be used as an environmental tracer to predict the areal distributions of other man-made materials. The results show fallout cesium-137 to be a moderate to good tracer for locating areas of accumulation of plutonium-238, plutonium-239, zinc, copper, chromium, lead, dieldrin, DDT and PCB in sediment. Little or no correlation is found between fallout cesium137 and strontium-90 or nickel.