Estimation of the sedimentation rate for modern sediments of the Kara Sea:Evidence from radioactive tracers

Results of experimental studies of sedimentation rates in estuaries of the Yenisei and Ob' rivers and the adjoining part of the Kara Sea, which were c arried out in 1999-2000, are presented in this paper. Vertical distribution of Pb-210 and Cs-137 radionuclides was applied to interpret the data. It i s shown that the sedimentation rates determined by the two methods vary sig nificantly from 0.12-0.14 cm/y by Pb-210 to similar to0.35 cm/y by Cs-137 i n the areas of intense water mixing and bioturbation. The results obtained by the two methods are closer and range within 0.25-0.35 cm/y for the open part of the sea. In the first case, the difference in the rate estimates ma y be explained both by the various time scales defined by the methods used and the influence of frequent nuclear weapons tests in the northern regions in the 1950s-1960s that resulted in the intense mixing of water and upper layers of the bottom sediments, especially in shallow-water areas.