Bottom Sediments of the West Siberian Arctic Lakes as Indicators of Environmental Changes

—Bottom sediment cores from the Langtibeito (Yamal Peninsula) and Gol’tsovoe (Gydan Peninsula) background arctic lakes are studied. The sedimentation rate estimated from 210 Pb and 137 Cs accounted for 0.17 and 0.20 cm/y, respectively. The element composition, grain-size composition, and loss on ignition were determined layer-by-layer in both cores. The element concentrations in the bottom sediments of both lakes throughout the entire core length are at the background level. The mercury content in the subsurface layers of sediments in both lakes, unlike other elements, was much higher than its local background contents. This is likely related to its atmospheric influx through transboundary transport. The comparison of diatom and grain-size data revealed the rebuilding of lake ecosystems in response to lake shoaling. The bioindication methods are promising for reconstructing the recent climatic changes in arctic regions.