Ecological and hygienic assessment of the technogenic reservoir state of the gold extraction enterprise (Zauralye of the Republic of Bashkortostan)

Introduction. The population using waste man-made water reservoirs for recreation and providing household needs can be a potential health risk. Such pollutants as heavy metals do not undergo decomposition processes. They accumulate in the biotic and abiotic components of the reservoir. Subsequently, hazardous toxicants can enter the human body through food chains. An ecological and hygienic assessment of the state of the waste reverse reservoir of the Semyonov gold recovery plant has been carried out. Material and methods. The object of the study is located in the Zauralye of the Republic of Bashkortostan at the geographical coordinates 52° 30’20″ N, 58° 19′48″ E. The content of heavy metals (Zn, Cu, Pb, and Cd) in water, bottom sediments and biomass of aquatic macrophyte (Potamogeton perfoliatus L.) was studied. In the bottom sediments, mobile forms of metals have been detected. They are extracted by an acetate-ammonium buffer with pH = 4.8 Results. It has been revealed that in water the concentration of heavy metals is higher than the maximum permissible concentrations for fishery reservoirs: 19-27 times for copper, 10-24 times for zinc, 2.7-5.8 times for lead, 1-1.4 times for cadmium. Exceeding the standards for water bodies for drinking, domestic and cultural water use is recorded for cadmium (6 times) and lead (2.5 times). In bottom sediments, the zinc content of mobile forms is 372.00 ± 28.51 mg/kg, copper - 144.37 ± 4.08 mg/kg, lead - 14.09 ± 1.48 mg/kg, cadmium - 0.036 ± 0.002 mg/kg. The total index (ZC), reflecting the additive excess of the background, is 1686, which corresponds to an extremely high level of man-made pollution of bottom sediments. The concentrations of heavy metals in the aboveground and underground organs of Potamogeton perfoliatus L. are much higher than the background levels. Conclusion. The waste reverse reservoir of the Semenov gold extraction factory is potentially dangerous to the local population health when it is used for breeding poultry, watering cattle, and fishing. The activities aimed at improving the environmental and hygiene situation in the territory of the locality are imperative.