The concentration of chemicals in a reservoir (Saltpetryanaya Balka) located near the Orthodox village of Otrada in the Kirovsky district of Volgograd has been studied in comparative comparison with the regulatory data of the MPC of chemicals in surface water bodies of cultural, household and fisheries significance.
The material for the study was natural water samples taken in the autumn season of 2024 in a lake near the village of Otrada in the Kirovsky district of Volgograd. Natural water samples were taken in accordance with GOST R 59024-2020 "Water". The analysis of chemicals was carried out on an EDX-8000 spectrometer. The data obtained (concentrations of chemicals in natural water samples) were compared in accordance with SanPiN 1.2.3685-21 and Order No. 296 of the Federal Agency for Fisheries dated May 26, 2025 and freshwater clarifications.
The data obtained indicate that the maximum permissible concentrations of chemicals were exceeded in the natural water of the Saltpetryanaya River as an object of cultural and domestic water use and indicates the mineral water of this reservoir and its possible use for recreational purposes as a balneological resource. There is an excess of the MPC values for copper by 10,000 times as the fishery value of the reservoir and indicates risks for representatives of the aquatic ecosystem. The use of this reservoir as an amateur fish farm may carry certain risks to human health when eating fish, which requires additional research and consultations with ichthyologists. The excess of copper by 10 times in comparison with freshwater reservoirs indicates the manifestation of a hidden deposit of copper ores in the vicinity of the Orthodox settlement "Otrada" (Volgograd).

Keywords: dispersion, aerosols, surface density of particles, PM2.5, PM10, green infrastructure, natural pollution

A study of acidic impurities in the atmospheric air of the Orthodox settlement of Otrada (Volgograd) in March-October 2024 was conducted based on the preparation of aerosol suspensions by washing particles from plant leaves with distilled water. The leaves of elm (Ulmus pumila L.) with aerosol particles were used as the research material. In the settlement of Otrada, we took samples of elm leaves (Ulmus pumila L.) at 10 study points. Sampling, including the preparation of aerosol suspensions, was correlated with well-known proven international methods. The value of the acidity index was measured on electrochemical equipment (S220-Kit pH meter complete with InLab Expert Pro-ISM electrode, China). Statistical analyses of the data obtained were performed in the R program (version 3.6.1, R Core Team 2020), statistical hypotheses were tested at a=0.05. The average values of the acidity index, where the pH value is.= 5.39+0.01, which indicates the presence of acidic impurities in the atmospheric air during the specified period in the settlement of Otrada and indicates the acidity of precipitation in the study area as a crisis zone ((pH=5.0-4.5), according to Svistov P.F. et al., 2012).

Keywords: dispersion, aerosols; surface density of particles; PM2.5; PM10; green infrastructure; natural pollution