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The rate constants of 137Cs uptake in Prussian carp (Carassius gibelio) from the water with a potassium content of 2 mg∙L-1 at T = 5 °C without feeding (kw = 0.045 ± 0.001 day-1), at T = 12 °C with «clean» feeding (0.046 ± 0.002 day-1) and at T = 22 °C with «clean» feeding (0.062 ± 0.006 day-1) were obtained in a series of aquarium experiments. The results showed that rates of 137Cs uptake in fish from water without and with feeding did not significantly differ at different temperatures of water (T = 5 -22 °C) and were two orders of magnitude lower than the rate constants of 137Cs uptake in Prussian carp with feed in Chornobyl exclusion zone (11.4 ± 2.6 day-1). This makes it possible to obtain products with 137Cs content below the permissible level (150 Bq∙kg-1) while providing fish with clean feeds even in the most radioactively contaminated reservoirs of the exclusion zone. A decrease in the potassium content in water from 2 to 0.2 mg∙L-1 (no feeding, T = 5 ± 1 °C) resulted in an increase in the rate of 137Cs uptake into the fish from the water by 1.6 times. An increase in the potassium content in water by 10 times up to 20 mg L-1 resulted just in a decrease of 20 % in the rate. The levels of 137Cs activity concentration in fish in contaminated water at temperatures below 10 °C will be two orders of magnitude lower compared to radioactive contamination of water in the summer season (T = 22 °C). This is extremely important for the correct prediction of fish contamination in the autumn-winter-spring period at a water temperature of less than 10 °C when some fish stop feeding. [ABSTRACT FROM AUTHOR]

Freshwater fish such as Prussian carp (Carassius gibelio) don't need a feed at a water temperature below 10 °С. To study the rate constants of 137Cs excretion from the body of Prussian carp at different water temperatures (5 and 22 °С) and different feeding, the series of aquarium experiments were conducted. The half-life time of 137Cs activity excretion from fish in the water (T = 5 °С) without feeding (T1/2 = 433 ± 162 days) was 5.6 times higher compared to the rate constants for water temperature 22 °С (T1/2 = 78 ± 4 days) with different types of feeding. The temporal decline of 137Cs activity (Bq) in fish was the same for different feeds, but the activity concentration of 137Cs (Bq-kg-1 ) in fish differed up to 1.8 times (0.0089 ± 0.0005 day-1 and 0.016 ± 0.002 day-1 ) due to different weight gains. [ABSTRACT FROM AUTHOR]