engleski

Cs-137 and Pb-210 in the lake sediments in the Plitivice Lakes, Croatia

Radioactive fallout 137Cs deposited across the landscape from atmospheric nuclear tests is strongly absorbed on soil particles limiting its movement by chemical and biological processes. Most 137Cs movement in the environment is by physical processes ; therefore, 137Cs is a tracer for studying erosion and sedimentation. Radioactive isotope 137Cs (half-life 30.2 yr) is used as a suitable tool in a lake sediment studies [1-3]. 137Cs is an anthropogenic isotope introduced into the atmosphere by nuclear weapon tests in fifties and sixties of the last century and additionally in 1986 as Chernobyl fallout. From the other hand, the approximately 22 yr half-life of 210Pb makes it an ideal indicator of modern sedimentation rates. The analysis of sedimentation rates by the 210Pb method is based on the radioactive decay of unsupported 210Pb with depth in a column of sediment. In lake sediments, unsupported 210Pb can originate from two sources: atmospheric deposition to the lake surface and subsequent scavenging by the depositing sediments or mobilization of sediment from the surrounding watershed. 137Cs is derived from a different source than 210Pb and thus provides a valuable cross-check of the 210Pb results. This paper presents results of the investigation of changes uppermost 40 cm thick layers of lake sediments retrieved in 2011 from 4 lakes Prošće, Kozjak, Kaluđerovac and Gradinsko in the Plitvice Lakes system using radioactive isotopes 137Cs and 210Pb.

lake sediment; Plitvice Lakes; Cs-137; Pb210

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