Radioecological monitoring of water bodies in the landscapes of the Bryansk region, Russia

The study examines the dynamics of 137Cs specific activity in water, bottom sediments, and fish of small watercourses and lakes in the Bryansk region during 2022–2025. The volumetric activities of the river waters were an order of magnitude or more lower than the radionuclide levels in stagnant water bodies and generally did not exceed tenths of a becquerel. The highest 137Cs activity was found in water and bottom sediment samples collected from the Besed River in the Krasnogorsk District – 0.083 Bq/L and 0.370 Bq/g, and the Iput River in the Gordeevsky District – 0.079 Bq/L and 0.426 Bq/g. New studies of small and medium-sized lotic water bodies in the southwestern districts of the Bryansk region have shown that significant concentrations of 137Cs in water and bottom sediment samples were found in the Kamenka River in the Zlynkovsky District, the Zlynka River in the Zlynkovsky District, and the Dorogovsha River in the Krasnogorsk District: shallow depths and low flow rates contribute to the accumulation capacity of abiotic components of aquatic ecosystems. A summary and analysis of the monitoring results allow concluding that there was a slight increase in the volumetric activity of 137Cs in river water and a significant decrease in lake water. The concentration of 137Cs in bottom sediments has shown an upward trend over the study period. The highest concentrations of 137Cs are observed in crucian carp caught from Lake Kozhanovskoye – 365.4 Bq/kg, which is 2.8 times higher than the permissible standards. Consumption of aquatic biomass can significantly increase the dose of internal radiation and negatively impact public health.