LYSIMETRICAL STUDY OF RADIONUCLIDES IN THE FORESTS AROUND THE CHERNOBYL NUCLEAR-POWER-PLANT

Vertical intrasoil water within the 30 km zone of ChNPP was studied by lysimetrical method during 1989-1991. Explorations were carried out in different ecosystems where the sum of total accumulation deposition of the radionuclides (Ce-144; Cs-134,137; Ru-106; Sr-90) ranged from 90 M Bq/m2 to 0.5 M Bq/m2. It was shown that 0.01-0.6% of the total amount of radionuclides was lost from the 20-30 cm layer of soil every year depending on the type of radionuclide, type of ecosystem and the location of study plot. Main absorption of the radionuclides from the intrasoil flow generally took place in the 5-10 cm layer. Radionuclides were not absorbed by the soil in proportion to their ratio in lysimetrical water leached through the forest litter. The mobility of radionuclides in the intrasoil flow can be represented by the following series: Sr-90 > Ru-106 > Cs-134, 137 > Ce-144. Sr-90 and Cs-137 are absorbed by soil more intensively than their chemical macroanalogs - Ca and K.