Sedimentary conditions based on the vertical distribution of radionuclides in small dystrophic lakes: a case study of Toporowe Stawy Lakes (Tatra Mountains, Poland)
Katarzyna Szarłowicz, Marcin Stobiński, Filip Jędrzejek, Β. Kubica
Abstract
Abstract The aim of this work was to prove the use of radionuclides deposited in sediment core taken from an overgrowing dystrophic lakes surrounded by marsh-peat vegetation to estimate sedimentary conditions. Sediment core samples were taken from the Toporowe Stawy Lakes (Niżni (TSN) and Wyżni (TSW); Tatra Mountains). The sampling was done using a Limnos corer. After the physical sample preparations, gamma measurements were performed. Radiochemical analysis was applied with the aim of determining 210 Pb radioactivity by means of 210 Po. The mean values for TSN lake are as follows: 137 Cs ~ 123 Bq∙kg −1 , 40 K ~ 389 Bq∙kg −1 , 228 Th ~ 55 Bq∙kg −1 , 226 Ra ~ 86 Bq∙kg −1 , 241 Am ~ 5 Bq∙kg −1 , and 210 Pb uns ~ 180 Bq∙kg −1 . For TSW lake, the radioactivity levels of 226 Ra and 241 Am are comparable to the TSN. The mean values of 137 Cs, 40 K, and 228 Th are almost twice as high as in TSN. The level of 210 Pb in uppermost layer of TSN is higher than in TSW. Sediments were dated by use of 210 Pb method, and the rate of sedimentation of each layer was also estimated. Basic chemometric tools were used to confirm the way of deposition of radionuclide, find the correlations between variables, and compare analyzed lakes. It was concluded that the presented type of lakes are a valuable source of information and the vertical distribution of radionuclide can be used to interpret the source of material supply and factors that influence the sedimentation process in recent 150–200 years.