Radioactive contamination of flood land landscapes

As a result of Chernobyl accident, wide scale squares of Belarus, mainly basins of rivers Pripyat and Sozh, were heavily contaminated with radioactive fall outs , which included about 2 million human beings. The bulk of radionuclides deposited within a 30-km zone and adherent territories, water supplying system of Pripyat, Sozh and Dnieper rivers and, to lower extent, rivers Neman and Western Dvina. The aqueous medium plays the specific role at determining the consequences of nuclear accident both for man and for flora and fauna objects. The radioactive materials transfer to aqueous systems not only as a result of fall outs from atmosphere, but also by their outwash from water supplying territory. At present time, the basic radionuclide transfer is due to surface outwash with soil particles and as solutions, water migration through waterproof layers to lower terrains and further to water reservoirs, as well as due to vertical migration through cracks in soil layers, whirlpools in soil to the upper horizon of groundwaters and diffuse processes to the inner layers of sol. The object for the investigation was flood lands of Sozh river near village Novoselki of Gomel region. Landscape and geochemical characteristics of flood lands, representative for Byelorussian Polesye have been studied. 137Cs specific concentrations in soil samples were measured using spectrometric complexes Canberra and Oxford. Measurement error was not higher than 15%. The results of measurements were statistically processed using dispersion analysis built in software (Excel 7.0). Radiochemical output of 90Sr in soil samples, vegetation and samples of water was carried out using standard technique with final measurements on alpha and beta counter 'Canberra-2400'. At spring high water, dissolved in water radionuclides together with particles of the contaminated soil are washed out to lower terrain, where they are accumulated by soils during high water periods on flood lands. Part of the activity is washed out be higher layers of water to reservoirs. Thus, the processes of soil erosion and take place. When high level of water take place, lower parts of lands are flooded both on flood lands and outside their limits. The lowlands also accumulate the relative mobile forms of 90Sr, from where they are washed out to rivers. During high water season radiostrontium concentration is increased. The study of vertical distribution of radionuclides along the flood land soil profile demonstrates, that the basic concentration of 137Cs is accumulated in horizon ?1, and on different depths there are sites with higher accumulation of radionuclides, so called chemical barriers (accumulation of radionuclides in sites where ??, Fe etc. are presented). Thus, if there is an accumulation 137Cs, the concentration of 90Sr is minimum, and on the contrary. The ecological situation at present time is characterized by decrease in deposition levels of higher layers of water supply system and in out wash of radionuclides to lower terrains, reservoir flood lands and to the deeper layers of soil and resulting increase in deposition levels in lower sites and flood lands takes place. On the whole, contamination of landscapes of fluvial plains has inevitably changed due to radioactive decay, reallocation of radionuclides along a landscape and geochemical profile and out wash to rivers