[The assessment of the content of 137Cs of the global and Chernobyl origin in forest soils and some types of edible fungi].

The article analyzes the density of pollution of the soil by radioisotopes of caesium and the content of 137Cs in fruit bodies of some species of forest mushrooms on the "long" trail of radioactive fallout in the Republic of Belarus in 1994 and 2012. On the basis of the calculated density of pollution of the soil with 134Cs in 1986 the contribution to the total density of pollution with 137Cs of the global radioactive fallout and emissions owing to the accident at the Chernobyl nuclear power plant was defined for the studied territory. It was established that at the density of pollution of the soil by 137Cs of 12-19 kBq/m2 in 1986 about 35% of pollution was caused by the global radioactive fallout. In 1994 and 2012, a specific activity and transfer factor of 137Cs were analyzed for fruit bodies of some species of forest mushrooms. The transfer factors of 137Cs for fruit bodies of Boletus edulis are at level of 10 x 10(-3) m2/kg, Leccinum scabrum and Leccinum aurantiacum - (15-20) x 10(-3) m2/kg, Xerocomus badius--(60-80) x 10(-3) m2/kg.

[About the contents of 40K, 226Ra and 232Th in forest soils of the Republic of Belarus].

The specific activity of 40K, 232Th and 226Ra in forest soil ecotopes (A2-B2-C2-D2) has been investigated. When the fertility of the soil increases from A2 to D2, then the specific activity of 40K increases in the rooting zone of the soil from 275 ± 6.9 up to 499 ± 11 Bq/kg, 232Th--from 11.8 ± 0.5 to 17.1 ± 1.1 Bq/kg, 226Ra- from 19.2 γ 0.8 to 27.9 ± 1.5 Bq/kg. The calculated capacity of the absorbed dose of γ-radiation conditioned by 40K, 232Th and 226Ra increases from A2 to D2 from 27.5 ± 0.5 to 44.1 ± 1.1 nGy / h at the height of 1 m.

[Estimation of the involvement of 137Cs in biological cycle of pine biogeocenoses].

The estimation of accumulated radionuclides in the biological cycle was carried out on the basis of long-term studies of distribution of 137Cs in the aboveground phytomass of pine plantations. The two main stages which differ from each other in the intensity of the involvement of 137Cs have been defined: the most intensive accumulation of 137Cs in the phytomass of pine plantations in the early 1990s (up to 2.3% of the total activity in biogeocoenose) and quasi-equilibrium distribution of 137Cs in the ecosystem since the 2000s when phytomass has received about 1% of the total activity. The accumulation of the radionuclide during the current year mainly occurs due to its transfer through the needles.

[Substantiation of radio-ecological monitoring of forest ecosystems at various stages after the accident radioactive fallout].

This study analyzes the long-term dynamics of distribution ofradionuclides in forest ecosystems. Three stages in the formation of radio-ecological situation in the forests are distinguished. Proposals for optimization of sampling for radio-ecological monitoring of forest ecosystems at various periods after a radiation accident are formulated.

[The forecasting of vertical distribution of 37Cs and 90Sr in the forest soils of the Republic of Belarus].

The study analyzes the distribution of 137Cs and 90Sr in the vertical profile of soil of forest biogeocenoses with different modes of moisture and species composition of woody vegetation on the "long" trail of radioactive fallout in the Republic of Belarus. The parameters of radionuclide migration are calculated for the two component quasi-diffusion equation, also based on this equation, pollution of root zone soil layers is predicted, as well as semi-refined periods and the contribution of migration in this process are defined. The intensity of radionuclide migration in the vertical profile of forest soils is found to increase with the change of the soil moisture regime from automorphic to hydromorphic.

[On the effect of partial flooding on 137Cs and 90Sr in forest biogeocenosis].

The analysis was made on 137Cs and 90Sr distribution oak, pine and hornbeam plantations depending on different under soil water levels. Intensity of 137Cs and of 90Sr migration along the vertical layers of soils is determined by under soil water level at a specific sampling site. The closer under soil water to the surface of the soil, the lowest radionuclide contamination is in the upper soil levels and the highest radionuclide contamination is in the deeper layers. The "fast" and "slow" quasi diffusion coefficients for 137Cs and for 90Sr and their contribution to the total migration of radionuclide through vertical soil levels were determined. A decrease in 137Cs and increase in 90Sr transfer factors to the elements of overground phytomass as a result of under soil water level lowering was established.

[The assessment of 137Cs accumulation by pine tree plantations in the closest radioactive fallouts originated from the Chernobyl Nuclear Power Plant].

The assessment of 137Cs accumulation by wood is made by using a chamber model of radionuclide behavior. Maximum of 137Cs specific activity in wany wood was in the midst of 1990s, with subsequent decrease in activity and half-time up to 22 to 25 years.

[137Cs and 90Sr accumulation in birch wood (Betula pendula Roth.) growing in regions with different soil conditions].

The studies of 137Cs and 90Sr accumulation characteristics by birch wood (Betula pendula Roth.) growing in different edaphic conditions. Were conducted was stated that the increase in soil fertility from trophotops A to D results in 5-fold 137Cs transfer factor decrease and 2-fold decrease of 90Sr. Soil humidity increase for each grade of trophic net results happens the increase of 137Cs transfer factors to wood and decrease for 90Sr. Total activity of 37Cs and 90Sr in birch wood plantation depends on plantation productivity and on radionuclide transfer factors depending on different plantation conditions. In the most prevailing edaphotops (B2, B3, C2 and C3) birch wood accumulates 0.6-1.2% of 137Cs and 13-19% of 90Sr from total activity of radionuclides in biogeocenosis.