Abstract
The behavior of plutonium isotopes was studied in the terrestrial and aquatic environment in the area where the Chernobyl accident took place. Radioactive concentrations and physical and chemical forms of the accident-derived Pu were investigated for soil, surface water, suspended solid, and bottom sediment samples in the vicinity of the Chernobyl nuclear power plant. The migration rate from the contaminated ground of the area by fluvial transport was estimated as about 0.1 % maximally in 1986, the year of the accident. Then it was decreased to as low as 0.01% in 2000. Chemically, most of the plutonium isotopes were found in so-called organic phase and least-soluble phase in soil and suspended solid samples. The same was for the bottom sediment collected at the Pripyat River near the power plant. This chemical form suggests limited mobility and solubility of Pu in the studied environment. This is in contrast to strontium-90 that has been found most soluble among Cs, Sr and Pu radioisotopes in the area and broadly influences on the aquatic environment. This study has also revealed that physical form of transport of Pu in river water was as follows: 60-80% of the total Pu in particulate form in suspended solid ; colloidal form 10-20%; truly dissolved form 10-20%. This phase partitioning is similar to that found for Pu derived from a reprocessing plant effluent in the Rhone River and other instances.
