Levels of accumulation of heavy metals and activity of radionuclides in narrow-clawed crayfish (Astacus leptodactylus Eschscholtz, 1823) of the Kamianske and Zaporizhzhia (Dnipro) reservoirs

Purpose. To determine the content of heavy metals as well as natural and artificial radionuclides in muscle tissue and carapaces of narrow-clawed crayfish Astacus leptodactylus of the Kamianske and Zaporizhzhia (Dnipro) reservoirs. Methodology. The material for the study were narrow-clawed crayfish collected in the spring period (March-April) 2021 in the coastal zone of the Kamianske and Zaporizhzhia (Dnipro) reservoirs. The collection of material was carried out with standard open-type crayfish traps with a mesh size No. 20, manual collection in the littoral zone as well as with the help of special baited traps. Carapaces and muscle tissue of crayfish were used to determine the content of heavy metals and radionuclides. Preparation of samples for measuring the content of heavy metals and radionuclides was carried out by separating crayfish tissues with subsequent homogenization and concentration (drying and incineration) of the collected material. The samples were dried at a temperature of +105°С to a constant weight, and then incinerated at a temperature of +450°С to obtain white ash. The content of radionuclides was determined on a gamma-beta spectrometer SE-BG-01 “AKP”. The content of heavy metals was determined on an atomic absorption spectrophotometer C115-M1 with a flame analyzer. Findings. Zn, Fe, and Cu were actively accumulated in the muscle tissue of crayfish of the Kamianske and Zaporizhzhia (Dnipro) reservoirs. This fact is explained by the intensive accumulation of elements in crayfish body that actively occurred in the course of physiological processes. Heavy metals such as Mn, Pb, Co were the most accumulated in crayfish carapace. The minimum content of heavy metals was found for Сd. It was found that Pb, Cu, Zn and Cd contents exceed the MACs in muscles of crayfish of the Zaporizhzhia (Dnipro) reservoir by 8, 6, 6.2 and 1.65 times, respectively. The norms for the content of heavy metals in the muscle tissue of river crayfish have not been established in Ukraine today, however, a comparison of the data we obtained with the norms for live fish shows a significant excess for almost all heavy metals examined. It was found that the level of radionuclide activity of in the muscle tissue of decapods of both investigated reservoirs was due to 40K, in the carapaces — 226Ra; 90Sr activity was minimal in muscles, and 226Ra activity in carapaces. Accumulation of studied radionuclides in crayfish did not exceed the MACs for crayfish as a food product. Originality. For the first time, the levels of accumulation of heavy metals and the activity of radionuclides in the muscle tissue and carapace of narrow-clawed crayfish of the Kamianske and Zaporizhzhia (Dnipro) reservoirs were determined. The content of toxic elements that are subject to control in food raw materials and food products according to the MACs in crayfish of the Kamianske and Zaporizhzhia (Dnipro) reservoirs was determined. Practical value. The results of the work can be used during monitoring of the ecotoxicological and radioecological conditions of the aquatic environment. Also, the obtained results can be applied in the study of narrow-clawed crayfish of the Dnieper River basin.