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.