RADIONUCLIDE ADSORPTION TO SEDIMENTS FROM NUCLEAR WASTE DUMPING SITESIN THE KARA SEA

Environmental parameters (salinity, sediment concentration, equilibrat ion time) affecting radionuclide partitioning between sediment and sea water were experimentally investigated for Kara Sea sediments collecte d from nuclear waste dumping sites in Abrosimov and Stepovogo Bays off Novaya Zemlya. Adsorption kinetics were examined and the influence of salinity and sediment concentration were evaluated over the range of concentrations expected in the bays for the following radionuclides: A g-110m; Am-241; Cd-109; Co-60; Co-57-cobalamine; Cs-134; (EU)-E-152; M n-54; Ba-133; Ru-106; and Sr-85. The major findings of this investigat ion are that 1. radionuclide distribution coefficients (K(d)s) were mo st sensitive to variations in sediment character (Am-241, Co-60,Cd-109 ) and concentration (Co-57-cobalamine, Sr-85, and Ba-133), 2. distribu tion coefficients generally decreased with increasing sediment concent ration and 3. fast adsorption kinetics (near equilibrium approximate t o 1 day) were observed only for Cs-137 and Ag-110m. The observed diffe rences in KdS for sediments from the two dumpsites exemplifies the imp ortance of undertaking site-specific determinations of K(d)s. For purp oses of confining radioactive wastes to the dumpsites in Stepovogo and Abrosimov Bags, the findings of this study indicate that based on sed iment character alone, Stepovogo Bay will be more effective at retaini ng radionuclides than Abrosimov Bay. This is unfortunate since less ra dioactive waste resides in Stepovogo Bay (0.6 PBq) than in Abrosimov B ay (1.4 PBq). (C) 1997 Elsevier Science Ltd. All rights reserved.