Radioactive contamination of the Yenisei River

Based on observational data in the period 1971–1993, radioactive contamination of the Yenisei River ecosystem was analysed within 2000 km of the site of discharges from the Krasnoyarsk Mining and Chemical Industrial Complex. Data on the content of 24Na, 32P, 46Sc, 51Cr, 54Mn, 56Mn, 58Co, 60Co, 59Fe, 65Zn, 90Sr, 95Zr, 95Nb, 103Ru, 106Ru, 134Cs, 137Cs, 140Ba, 141Ce, 144Ce and 239Np in the river ecosystem components were generalised. Radioactive contamination of water in the near zone of discharges (within 15 km) was shown to be determined mainly by the short-lived nuclides, such as 24Na, 32P, 56Mn and 239Np, as well as 51Cr. Outside the near zone the water contamination level decreased appreciably. According to observational data of 1973, the total contamination inventory of the river bottom in the near zone was as great as 5800 kBq m−2. More than half was accounted for by two radionudides: 51Cr and 65Zn. At a distance of 1930 km from the site of discharges a technogenic activity of bottom sediments amounted to 5 kBq m−2 and was accounted for by 137Cs and 65Zn. The main radionuclide accumulated in fish was 32P. Exposure doses to aquatic organisms and population were assessed in the near and far zones of the Krasnoyarsk radioactive contamination trace. Within 250km of the site of discharges the exposure dose to the population from a consumption of 1 kg of fish was shown to amount to an average of 10 μSv.