The character of radionuclide contamination of natural lakes at the territory of the Semipalatinsk test site.

The paper presents data on the research of the radionuclide contamination redistribution in the ecosystems of natural lakes at the Semipalatinsk test site and adjacent territories. Natural lakes, which are the research objects, are located on the territory of the test sites, in the zone of their influence, in the zone impacted by radioactive fallout or in the "background" territories. Sampling of water, bottom sediments and plants was carried out, in which the content of radionuclides Am, Cs, Sr and Pu was determined. Based on the obtained quantitative data, distribution coefficients (K) for sediments and water, as well as concentration ratio (F) for plants and sediments were calculated.