ESTIMATION OF THE SEDIMENTATION RATE FOR MODERN SEDIMENTS OF THE KARA SEA: EVIDENCE FROM RADIOACTIVE TRACERS

Abstract

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 carried out in 1999-2000, are presented in this paper. Vertical distribution of 210Pb and 137Cs radionuclides was applied to interpret the data. It is shown that the sedimentation rates determined by the two methods vary significantly from 0.12-0.14 cm/y by 210Pb to -0.35 cm/y by 137Cs in 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 may 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.