SPECIATION OF RADIONUCLIDES IN SAMPLES COLLECTED IN THE 30-KM ZONE OFTHE CHERNOBYL NPP (RED FOREST REGION)

The speciation of radionuclides in soil samples collected in the 30-km zone of the Chernobyl NPP in the ''Red Forest' region is investigated . Most of the radionuclides (greater-than-or-equal-to 75 %) in the stu died samples in 1990 were tightly bound. Up to 13-14% of the Ru-106, 1 7-30% of the Sb-125, 5-10% of the Cs isotopes, and 16-18% of the Ce-14 4 and Eu-154 were associated with amorphous compounds, The distributio n of the radionuclides over the organic components of the samples sugg ests that the radionuclides are bound to practically all organic group s. The isotope Ru-106 is mainly bound to humic acids; Sb-125, Cs isoto pes, Ce-144, and Eu-154, to fulvic acids.