Dating of mine waste in lacustrine sediments using cesium-137

• Published in: Environmental geology (Berlin) 1993-11, Vol.22 (3), p.242-245
• Main Authors: REMBER, W. C, ERDMAN, T. W, HOFFMANN, M. L, CHAMBERLAIN, V. E, SPRENKE, K. F
• Format: Article
• Language: English
• Subjects: Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Freshwater; Pollution, environment geology
• ISSN: 0943-0105; 1432-0495
• DOI: 10.1007/BF00767409

For over a century Medicine Lake in northern Idaho has received heavy-metal-laden tailings from the Coeur d'Alene mining district. Establishing the depositional chronology of the lake bottom sediments provides information on the source and rate of deposition of the tailings. Cesium-137, an isotope produced in the atmosphere by nuclear bomb tests, was virtually absent in the environment prior to 1951, but reached its apex in 1964. Our analysis of cesium-137 in the sediments of Medicine Lake revealed that 14 cm of fine-grained tailings were deposited in the lake from 1951 to 1964 and tailing deposition downstream was greatly reduced by the installation of tailings dams in the district in 1968. Cesium-137 analysis is accomplished by a fairly simple gamma-ray counting technique and should be a valuable tool for analyzing sedimentation in any lacustrine environment that was active during the 1950's and 1960's.