Toxicity assessment of the cooling reservoir of the Zaporizhzhia nuclear power plant based on biotesting results

Purpose. To investigate the possible toxicity of the aquatic environment of the cooling reservoir of the Zaporizhzhia Nuclear Power Plant to control and prevent pollution of its ecosystem. Methodology. During the study, a biological test method was used to determine the chronic water toxicity of the cooling reservoir using Ceriodaphnia affinis Lilljeborg (Cladocera, Crustacea) as a test object. The criterion for chronic toxicity was a statistically significant decrease in survival and fertility of the Ceriodaphnia in the experiment compared to control over the three consecutive litters for 7 days. The reliability of the differences between the control and the study was determined by the methods of variation statistics. Findings. The article presents the results of the determination of the toxicity of water in the cooling reservoir of the Zaporizhzhia Nuclear Power Plant by the method of biotesting on Ceriodaphnia affinis Lilljeborg by establishing a reliable difference between survival and fertility in the control and experimental water samples. The prerequisite for studying the ecotoxicity of the aquatic environment of the investigated water body was the increased copper content in water, which was established by preliminary studies of the hydrochemical regime of the reservoir. During the experimental period, no pathological changes in the experimental daphnia were found. The conducted study allowed making a conclusion that there was no toxic effect of the aquatic environment on the biota of the cooling reservoir and the possibility of using the method of biological amelioration to ensure the stabilization of its ecosystem. Originality. The potential toxicity of the aquatic environment of the cooling reservoir of the Zaporizhzhia Nuclear Power Plant was estimated in conditions of significant anthropogenic pressure and its absence was established. Practical value. The obtained data can be used in the development and justification of methods for stabilizing the ecosystems of cooling reservoirs and managing bioproductivity for the purpose of their economic development.