Preliminary characterization of the radioactivity in sediments taken from Jamske Pleso lake (Slovakia)

: Jamske Pleso lake is one of almost 200 lakes located in the Tatra Mountains. This post glacial water reservoir is set on a strictly protected area. In this work, sediment samples taken from Jamske Pleso Lake were analysed for radioactivity of natural 226 Ra, 210 Po, 210 Pb and artificial 137 Cs. The sediment core was taken by use of Limnos corer. After preparation of the physical sample, gamma measurements were executed in hermetically closed vessels. A preliminary study showed that concentration of natural radionuclides is in typical values for lakes located in this area. An elevated concentration of 226 Ra (mean 57 (cid:2) 29 Bq (cid:3) kg –1 ) is an effect of uranium rich bedrock of the lake. Radioactivity of 137 Cs is close to that reported in other Tatras lakes. Using 137 Cs as an indicator allowed a preliminary estimate of the depth of the sediments deposited in 1960s. samples. Direct analysis of 137 Cs radioactivity and the indirect measurements of 226 Ra content via daughter isotopes. Based on the 137 Cs radioactivity, preliminary dating, using this radionuclide as time marker, was performed.