Modeling the Dynamics of Radionuclide Accumulation in Freshwater Fish Species in the Post-Accident Period Following the Chornobyl NPP Disaster

This article presents the results of a study on the dynamics of radionuclide accumulation in freshwater fish species in the post-accident period following the Chornobyl Nuclear Power Plant (NPP) disaster. The research is based on the application of mathematical modeling to simulate bioaccumulation processes in aquatic ecosystems that have undergone significant radioactive contamination. Key patterns of radionuclide influx, distribution, and redistribution, particularly of artificial radionuclides such as 137Cs and 90Sr, within the trophic chains of aquatic biocenoses have been identified. The study analyzes the main factors influencing the level of radionuclide accumulation in hydrobionts, including species-specific characteristics, metabolic features, age differentiation of fish, feeding conditions, and the hydrochemical and hydrological properties of water bodies. Special attention is given to the dynamic changes in 137Cs and 90Sr concentrations in fish biomass over time, taking into account radioactive decay, dilution of radionuclides in the aquatic environment, and the migratory behavior of fish. The findings of this study are crucial for assessing long-term ecological risks associated with persistent radioactive contamination in the aquatic ecosystems of the Chornobyl Exclusion Zone and adjacent areas. The proposed mathematical modeling approaches can be applied to predict the consequences of radioactive contamination in water bodies and to develop strategies for ecological monitoring and the restoration of polluted aquatic resources. Key words: radionuclides, freshwater fish, mathematical modeling, bioaccumulation, radioecology, aquatic ecosystems, ecological monitoring, environmental safety.