Optimization of fish sampling procedure for evaluating the specific activity of 137-Cs, 90-Sr and accumulation coefficients

Excretion of 137Сs from silver Prussian carp (Carassius gibelio) at 5 °С water temperature

“…Introduction. For many years, the activity concentration of 137 Cs in the fish organism exceeds the permissible levels of radionuclides in food products DR-2006 − 150 Bq kg -1 in the territory contaminated as a consequence of the Chernobyl accident [1−3].…”

“…Predictive analysis made by using generally accepted mathematical models showed that a decrease in the activity concentration of radiocaesium in fish should be observed with a factor of 1.5−2 in winter at a water temperature below 10 °C in comparison with the summer period [2,5,6]. This is due to a decrease of the 137 Cs uptake by fish with consumed food in winter, since the feeding is practically stopped for such fish species as silver Prussian carp, rudd and others, during November−March at a water temperature below 8-10 °С in the environment of the northern part of Ukraine [7]. However, it is believed that the rate of excretion of radiocaesium from the body of fish does not change significantly during the year.…”

“…In this case, the radioactive contamination of silver Prussian carp occurred in natural conditions in the reservoir of the ChEZ through the digestive system of fish with food, mainly in the summer [9]. It was shown that the activity concentration of 137 Cs in the body of fish will be two orders of magnitude lower in the case of radioactive contamination of water bodies in the winter at a water temperature below 8−10 °C in the absence of fish feeding and the entry of radionuclides into the body directly from the water through gills and skin, than in the case with radioactive pollution of water in the summer [9].…”

“…The aim of the study is to determine the excretion rate (biological half-life) of 137 Cs from the body of silver Prussian carp at a water temperature of 5±1 °C. To achieve this, an aquarium experiment was conducted to measure the dynamics of 137 Cs in the fish body after their radioactive contamination directly from water in the absence of feeding [9].…”

“…Before the experiment, fish were transferred in two 9-liter aquariums (7 fish per aquarium) located in a refrigerator at a water temperature of 5±1 °C for 14 days to proceed the radioactive contamination. The activity concentration of 137 Cs in aquarium water was 1 kBq 137 Cs/l. During 14 days of radioactive contamination and 77 days of the entire experiment for the 137 Cs excretion study, the silver Prussian carp were without food, since at a water temperature below 8−10 °C in the natural conditions of Ukrainian Polissia, silver Prussian carp stop feeding [7].…”