Lyudmila R. The role of forest ecosystems in forming of Ukrainian Polissya population exposure doses

The thesis is dedicated to identifying the forest ecosystems impact on doses of radioactively contaminated Ukrainian Polissya territories residents in remote period (2008-2010 years) after the Chernobyl accident. The features of radioactive contamination of forest ecosystems and radionuclide migration within their components were investigated. Found that lichens, mosses and fungi still are characterized by increased specific activity for 137-Cs in forest ecosystems. The role of mosses as a barrier for radionuclides moving to deeper soil horizons is shown. Based on identified characteristics of forest ecosystem components 137-Cs contamination the mathematical model of 137-Cs migration amongst forest ecosystem components was created. The model is adapted to the Ukrainian Polissya conditions. With its help radionuclide content in the most important for human ecosystem components was predicted. Found that in the remote period after the accident reducing the 137-Cs content in the forest ecosystems with time occurs mainly due to the physical decay of the radionuclide. To calculate the internal exposure dose of Ukrainian Polissya settlements diet peculiarities were considered. On the basis of the forest ecosystems contribution to the total radiation exposure of the Ukrainian Polissya population the features of formation of the internal radiation dose of people in settlements where the products grown on household plots predominate in consumption pattern was refined. Analysis of the distribution of internal radiation dose of the Kyiv Polissya inhabitants showed significant dependence of this indicator value on the forest ecosystems availability for the peasants and on the season.