Comparative Estimation of the Plutonium (238Pu, 239+240Pu) and Radiocesium (137Cs) Content in Bottom Sediments and Hydrobionts of the Yenisei River

The contents of isotopes of plutonium ( 238 Pu and 239, 240 Pu) and 137 Cs in samples of bottom sediments and hydrobionts (water moss, amphipods, and caddisfly larvae with casings) taken in the Yenisei River in the vicinity of the radioactive discharge from the Mining and Chemical Combine in 2012 and 2018 were comparatively estimated. It is shown that the content and ratios between the specific activities of plutonium isotopes (238/239 and 240) in samples of BSs and hydrobionts increased after the recommencing of plutonium discharges into the Yenisei due to the beginning of MOX fuel production. The background content and the ratio between plutonium isotopes in BSs of the Yenisei were estimated for the first time. Hydrobionts and BSs were ranged differently according to the content of plutonium and 137 Cs: we recorded the highest content of 137 Cs in BSs and that of plutonium in water moss. The plutonium content in hydrobionts of the Yenisei River varies considerably, which permits specification of representatives of biota (water moss and caddisfly larvae with casings) that, along with BSs, can be used as effective indicators of ecosystem pollution with plutonium.