The Content and Speciation of Radionuclides in Water and Bottom Sediments of the Laptev Sea

Abstract—This paper examines the distribution of 137Cs and plutonium isotopes in the modern sediments collected from different parts of the Laptev Sea during cruises of the R/V Academik Mstislav Keldysh in 2017 and 2019. It was found that the 137Cs activity in water and sediments is within the global background level, which is typical for the Arctic seas. In all collected samples, the specific content of 239,240Pu isotopes is below the detection level. According to the results of isotope analysis of excess 210Pb, the sedimentation rates in two cores sampled in the Laptev Sea are 0.18 and 0.23 cm/year. The speciation of 239Pu introduced in samples of bottom sediments under laboratory conditions was analyzed by several methods. It was shown that the most part of 239Pu is associated with weakly dissolved organo-mineral components. 30–39% 239Pu were found in the organic easily soluble acids and humic substances, which include fulvic and humic acids of bottom sediments.