Studies of up date radiocesium and rare-earth metals distribution in bottom sediment of the lakes of Siberia different landscape areas

Distributions of radiocesium and rare-earth metals have been studied in bottom sediments of lakes. The lakes occur in different landscape-climatic zones and are fed by both flood and ground water. The main factor of the formation of geochemical composition of sediments is the natural supply of radiocesium and rare-earth metals with solid and liquid runoffs from water-collecting areas. Throughout the study area bottom sediments of lakes and soil from water-collecting areas have background average contents of the radiocesium. Elevated contents have been established only for three regions: Altai Territory, Republics of Altai and Buryatia. The vertical section of the sediments of the lakes shows an increase in concentrations of radiocesium to top. From the 137Cs and 210Pb distribution throughout the column, we have estimated the dynamics of changes in the sediments. The known depth and time of formation of these bench marks permitted estimation of the rate of recent sedimentation in the lakes: 0,35 sm/year and 0,25 sm/year in the south and north regions of Siberia accordingly. According to the trend of distribution of the rare-earth metals in the above bottom sediments of lakes, the types of sources of materials of the silt are recognized.