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 analyzed 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 analyzed in the laboratory for 11 other man-made materials known to be dis- charged into the river. Two statistical methods were used to determine if 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 to locate 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 cesium-137 and strontium-90 or nickel.