Origin and behavior of radionuclides in sediment core: a case study of the sediments collected from man-made reservoirs located in the past mining region in Central Slovakia

The analyzed sediments were taken from the man-made reservoirs (Velka Richnava, Rozgrund and Vindsachta) located in an area intensively mined for polymetallic ores since the end of the eleventh century (Banska Stiavnica region, Central Europe). The aims of this study were to determine the radioactivity of natural ( 226 Ra, 228 Th, 210 Pb) and artificial ( 137 Cs and 241 Am) radionuclides, compare the radionuclides’ distribution, and indicate the correlation of radioisotopes and their origin related to sediment properties. Two analytical techniques were used. 228 Th, 226 Ra, 241 Am, and 137 Cs were measured by means of gamma spectrometry and 210 Pb was determined by its daughter radionuclide 210 Po using alpha spectrometry. The results showed that the highest mean level of 226 Ra (42.6 Bq·kg −1 ), 228 Th (49.7 Bq·kg −1 ) and 210 Pb (75.2 Bq·kg −1 ) was in the sediments collected from Rozgrund. The radioactivity of 137 Cs and 241 Am were present at a higher level in the layer related to Chernobyl (1986) accident and nuclear weapon test (1950/1960). The distribution of natural radionuclides was quite similar in all reservoirs. Chemometric analysis confirmed the radionuclides’ origin and correlation between the analyzed parameters.