Estimation of Physicochemical Parameters and Vertical Migration of Atmospheric Radionuclides in a Raised Peat Bog in the Arctic Zone of Russia

The article presents the results of a study of activity levels and features of the vertical distribution of Pb-210, Cs-137, U-234, U-238 and their relationship with the physicochemical parameters of peat deposits. Analysis of the data showed that the vertical distribution of Cs-137 and Pb-210 was related to the content of water-soluble salts, the water saturation of the deposit, and the values of Eh (oxidation-reduction potential) and rH (relative humidity), which indicates a complex geochemical barrier at a depth of 20 cm in the peat core. The Pb-210 dating of the peat core, carried out according to the CF model using the Monte Carlo method (to improve the dating accuracy), showed that the above horizon corresponded to 1963, which is consistent with the data of the Cs-137 reference horizon and in terms of several physicochemical parameters (in particular, ash content) also corresponds to the age of 1963, which confirms the correctness and adequacy of the chosen peat core dating model. The peak of anthropogenic radionuclides in peat deposits correlates with a particular major event in the history of radioactive fallout, the Partial Nuclear Test Ban Treaty of 1963, providing a benchmark for geochronological research. The obtained results of the linear accumulation rate, the mass accumulation rate of the peat deposit, and the value of the atmospheric flux of Pb-210 are congruent with the data on the peatlands of Northern Europe and the data obtained by earlier analysts of the Subarctic region of European Russia.