Accumulation and potential dissolution of Chernobyl-derived radionuclides in river bottom sediment

Areas contaminated with radionuclides from the Chernobyl nuclear accident have been identified in Pripyat River near the Chernobyl Nuclear Power Plant. The river bottom sediment cores contained 137Cs (105- 106 Bq/m2) within 0-30 cm depth, whose concentration is comparable to that in the ground soil in the vicinity of the nuclear power plant (the Exclusion Zone). The sediment cores also accumulated 90Sr (105 Bq/m2), 239,240Pu (104 Bq/m2) and 241Am (104 Bq/m2) derived from the accident. Several nuclear fuel particles have been preserved at 20-25 cm depth that is the peak area of the concentrations of the radionuclides. Th ese inventories in the bottom sediments were compared with those of the released radionuclides during the accident. An analysis using a selective sequential extraction technique was applied for the radionuclides in the sediments. Results suggest that the possibility of release of 137Cs and 239,240Pu from the bottom sediment was low compared with 90Sr. The potential dissolution and subsequent transport of 90Sr from the river bottom sediment should be taken into account with respect to the long-term radiological influence on the aquatic environment