Keywords: Siberia, aquatic ecosystems, Lake Baikal, Angara river dam cascade, Irkutsk Reservoir, sedimentation, bottom sediments, environmental pollution, chemical elements, heavy metals, pollution levels, reservoirs, water pollution
Accumulation of heavy metals in the bottom sediments of the Irkutsk Reservoir
The chemical composition of the bottom sediment, and more particularly the heavy metals content, reflects human developments and impacts on the catchment and reservoir's natural environment. The bottom sediments of the reservoir retained by the Irkutsk Dam have been analysed. The reservoir is mainly supplied by water from Lake Baikal. The following amounts of heavy metals have been found in the sediment samples analysed: cadmium - below detection threshold (<0.5 ppm), cobalt - from 16 ppm to 23 ppm, chromium - from 104 ppm to 243 ppm, copper - from 21 ppm to 35 ppm, mercury - below detection threshold (<1 ppm), molybdenum - below detection threshold (<2 ppm), nickel - from 44 ppm to 80 ppm, lead - from 13 ppm to 17 ppm and zinc - from 73 ppm to 98 ppm. Cobalt, chromium and nickel contents exceeded the natural geochemical background level. This may indicates anthropogenic impacts on the reservoir's geosystem.