WATER ORGANISMS FROM THE 30km ZONE AFTER THE 1986 CHERNOBYL NPP ACCIDENT. RADIOACTIVE CONTAMINATION AND POSSIBLE RADIOBIOLOGICAL EFFECTS

摘要

Before the 1986 accident, hydrobionts from the NPP cooling pond usually demonstrated contamination with ~(137,134)Cs, ~(90)Sr, ~(54)Mn,~( 60)Co radionuclides (sometimes also ~(51)Cr, ~(58)Co, ~(65)Zn) at concentrations from n·10° to n·10~1 Bq/kg. In some particular cases (Autumn'82 - Spring'83) water plants taken at the sampling stations in the vicinity of NPP were contaminated with radionuclides of Cerium, Zirconium, Niobium, Ruthenium in concentrations up to 10 kBq/kg. After the 4th unit accident, followed by radioactive releases to the environment, water ecosystems of the Chernobyl NPP zone were heavily contaminated with radioactive substances. In late April and early May 1986 total radioactivity of hydrobionts in the cooling pond had increased up to millions times. It was determined mainly by short-living radionuclides. At the end of 1986 in the cooling pond of the Chernobyl NPP concentrations of certain radinuclides was 80 - 1000 kBq/kg in water plants, 0.3 - 250 kBq/kg in molluscs, up to 400 kBq/kg in fish. Afterwards, due to decay, the share of short-living radionuclides decreased and the major role in hydrobionts' radioactive contamination shifted to ~(137)Cs and ~(90)Sr[1].