PALEOLIMNOLOGICAL ASSESSMENT OF RECENT ENVIRONMENTAL-CHANGE IN LAKE BAIKAL - SEDIMENT CHRONOLOGY

Sediment cores collected from six sites in Lake Baikal as part of an e xtensive investigation of sediment records of recent environmental cha nge were dated radiometrically by Pb-210. Although the results obtaine d were in some respects comparable to those obtained by previous Pb-21 0 studies, there were some significant differences. Most notably, a co re from abyssal depths in the centre of the middle basin appeared to r ecord at least two major episodes of rapid sedimentation, possibly cau sed by turbidity currents. All cores, including those from the North B asin, contained significant records of weapons test fallout Cs-137, th ough these were of little chronological value due to the long residenc e time of Cs-137 in the water column. Models and budgets for sediment and radionuclide transport through Baikal are presented and used to he lp validate the Pb-210 results.