Seasonal Variation In The Content Of Cs-137 In Different Objects Of Forest Ecosystems In Chernobyl Exclusion Zone

Seasonal changes in the content of Cs-137 in the soil and vegetation of forest ecosystems in the territory of the Chernobyl exclusion zone have been studied. Samples were selected during 2013 from January till March one time per month, and from April till December - one time per two weeks. The study subjects were forest litter and the upper layers of the humus-eluvial horizon of soils, one- and two-year-old needles and branches of P. sylvestris. The Cs-137 content was measured by gamma spectrometry methods. Dependences of changes in Cs-137 concentrations from the season of the year in the soils were not revealed. The leaping increase in the content of Cs-137 in the soil layers throughout the year is likely to be related to changes in the quantity of pedobiota and the intensity of the processes of its vital activity. In the needles and branches of P. sylvestris the maximum values of Cs-137 concentration are noted in the summer. Minimum values of Cs-137 content in the studied organs of P. sylvestris are characteristic for the autumn-winter period. As a result of the studies, linear relationship was found between seasonal changes in Cs-137 concentration in needles and branches of P. sylvestris in testing areas with different levels of contamination. Changes of the Cs-137 content in the studied organs of P. sylvestris, which coincide in time at different testing areas, indicate common regularities of Cs-137 redistribution at the soil-vegetation chain in forest ecosystems throughout the year.