Title : Activity concentration of 90Sr and 137Cs in fish of the most contaminated lakes within the chornobyl exclusion zone
Abstract:
The levels of activity concentration of 90Sr and 137Cs in fish of two most contaminated water bodies in the Chornobyl Exclusion Zone – lakes Vershyna and Azbuchyn were studied. A change in the hydrological regime of the Chornobyl NPP cooling pond due to decommissioning of the pumping station lowering of the water level after stopping the pumps that pumped water from the Pripyat River into the Cooling Pond, the level of which was 7 m higher than the river level) in October 2014 led to a lowering of the water level and in the nearby Azbuchyn Lake, and also caused changes in the state of dynamic equilibrium in the redistribution of radionuclides in the ecosystems of these two reservoirs and an increase in their arrival in biologically available forms to water masses. This, in turn, led to increased levels of accumulation of radionuclides by aquatic organisms. In total, 5 types of fish were studied – 2 predatory and 3 "peaceful". The average number of fish in the annual sample for each species was 8 specimens or more. Determination of the specific activity of 137Cs in fish was carried out by gamma-spectrometric and radiochemical methods, and 90Sr – by radiochemistry (according to the oxalate method) with measurement on the UMF-2000 low-background device by the daughter decay product – 90Y. The specific activity of radionuclides in fish was calculated in Bq/kg mass at natural humidity. In 2021, for the studied species of fish, the radionuclide content ranges were noted at the level of 36525–213300 Bq/kg for 90Sr and 984–6234 Bq/kg for 137Cs (Vershyna Lake) and 7000–34500 Bq/kg for 90Sr and 745–5700 Bq /kg for 137Cs (Azbuchyn Lake). It was shown that the specific activity of 90Sr in representatives of the ichthyofauna of the lakes exceeds the Permissible Levels adopted in Ukraine for fish products by 200–6094 times, and 137Cs – by 5–42 times. As the results of the analysis for previous years show, the content of 90Sr in representatives of various fish species, silver Prussian carp, Rudd, Perch and Pike during the research period, has a tendency to increase, while the value of the average annual specific activity of 137?s gradually decreased or with various deviations to a greater and the smaller side, remained practically at the same level. The ratio of 90Sr/137Cs in fish is within 3–108. The distribution of radionuclides in fish organs and tissues is also given.
Audience Take Away:
- I hope that fellow scientists will be interested in what is the content of long-lived 90Sr and 137Cs in various types of fish in lakes from the Chernobyl exclusion zone? How did radionuclide contamination of ichthyofauna change in 1935-1936 after the accident at the Chornobyl nuclear power plant? Several patents have been invented and approved for calculating the specific activity of radionuclides in different species of fish in a reservoir based only on the content of radionuclides in one species. And it is also possible to determine the specific activity of 90Sr or 137Cs in fish or muscles, knowing the content of these radionuclides in scales or fins.
- Several patents have been invented and approved for calculating the specific activity of radionuclides in different species of fish in a reservoir based only on the content of radionuclides in one species. And it is also possible to determine the specific activity of 90Sr or 137Cs in fish or muscles, knowing the content of these radionuclides in scales or fin
- Since different types of fish accumulate the same radionuclides in different ways, this will help environmental radiochemists to determine the levels of radionuclide contamination of the entire ichthyofauna of the reservoir by only one of the caught species and predict their work.
- This research can be applied in radioecology, radiobiology.
