Radiocological Study of the Lake Frog Pelophylax ridibundus as a Component of the Aquatic Ecosystem of Lake Kozhakul (Southern Urals)

The accumulation of anthropogenic radionuclides Sr and Cs by the marsh frog Pelophylax ridibundus in lake Kozhakul, adjacent to the southeastern boundary of the East Ural radioactive trace, was studied. Concentrations of Sr in adult amphibians at the sampling site vary by ~100 times, and Cs — by 4 times. All compared concentrations of Sr and Cs in the components of lake Kozhakul (adult frogs, cladophora, perch, silt soil) are significantly higher than similar average values in water bodies of the Middle Urals that have not been subjected to major radioactive impacts and accidental contamination. It was found that 60% of adult frogs were contaminated with Sr above the permissible standard established for fish, and yearling frogs approached this standard. It was concluded that the studied amphibian species can be a good bioindicator of contamination of aquatic ecosystems with this radionuclide in places of radioactive contamination.