Actinides and other radionuclides in sediments and submerged plants of the Yenisei River

The source of radioactive contamination of the Yenisei River floodplain, including contamination with actinides, is the Mining-and-Chemical combine (MCC), which has for many years been producing weapons-grade plutonium. Actinides have been detected not only in the soil and sediment of the river but also in the biomass of aquatic plants. The aim of our investigation was to assess the levels of actinides and other radionuclides in sediments and aquatic plants both near the MCC and at a considerable distance from it, down the Yenisei River. Investigations of the Yenisei River sediment samples revealed high activity concentrations of actinides (Pu isotopes and Am-241), which were 100 times higher than their global fallout levels. Sequential extraction of radionuclides from samples of sediments collected near the MCC showed that the amounts of extracted Am-241 were the largest (up to 98% of initial activity). It was found that aquatic plants of the Yenisei River collected both near the MCC discharge site and at a distance up to 200 km downstream contained several actinide isotopes. The aquatic moss, Fontinalis antipyretica, was found to contain higher levels of radionuclides than Potamogeton lucens. Leaves of P. lucens contained higher levels of radionuclides, including Np-239, than stems. Sequential extraction of radionuclides from samples of aquatic plants showed that Np-239 levels in exchangeable and adsorption fractions of P lucens biomass were higher than in the respective fractions of E antipyretica biomass. (c) 2007 Elsevier B.V. All rights reserved.