Global pollution of the territory of South Yakutia 137Cs and radiation doses of the population

The aim of the work is to estimate the radioactivity of 137Cs in the soils of South Yakutia and to calculate the dose of internal irradiation of a critical group of people caused by the consumption of local foods containing radionuclide. An assessment of the radioactive contamination of the soil cover of South Yakutia showed that the radioactivity of 137Cs in the soils of eluvial landscapes varies between 714 and 1,665 Bq/m2 and is commensurate with the radioactivity of 137Cs in the soils of the Primorsky Krai, the Western Siberia and the Kola Peninsula. The present soil contamination levels of 137Cs, compared to the 2003 data, have been reduced on average by half due to radioactive decay of the radionuclide, the soil deepening and removal with surface water and vegetation. At present time there is no appreciable additional input of 137Cs from the atmosphere to the soil cover of automorphic taiga landscapes in the South Yakutia. The specific activity of 137Cs in watershed soils and river floodplains is low and corresponds to the background level of global pollution. The vertical distribution of 137Cs over the soil profile of eluvial landscapes is realized on regressive-cumulative and eluvial-illuvial types. In soil profiles of hydromorphic landscapes 137Cs is distributed, without any clear patterns, which is a consequence of the impact of alluvial processes. Calculations showed that at the current level of contamination of local foodstuffs, the annual effective dose of internal exposure of a critical population group from this radionuclide is 87 times less than the annual dose limit for the Russian population.