ECOLOGICAL ASSESSMENT OF GROUNDWATER IN THE KRIVOOZERSKY DISTRICT OF THE MYKOLAIV REGION FOR THE IMPACT OF TOXICANTS

Abstract

The article presents the results of a comprehensive study of groundwater from artesian well No. 104-E, located in Kryve Ozero, Kryvoozerskyi District, Mykolaiv Oblast. The research aimed to assess the water quality for domestic and drinking purposes and to determine the impact of toxicants on the aquifer within the fractured Precambrian granite. The article provides a detailed description of the well’s geographical location, technical characteristics, shaft and mouth design, as well as the geological section, which includes five main lithological layers: loams, sands, dense clay, fractured aquifer granite, and lower weakly fractured granites of negligible hydrogeological significance. The absolute elevation of the wellhead is 87.0 m, the static water level is 5.5 m, and the dynamic water level during pumping is 69.0 m, indicating a high potential of the aquifer and its suitability for domestic and drinking water supply.Detailed physicochemical, microbiological, and radiological studies of water from 2021–2023 were conducted, demonstrating consistently high water quality and compliance with all indicators of DSANPiN 2.2.4-171-10. No exceedances of the maximum permissible concentrations (MPC) of toxicants and harmful substances were detected.Nitrate, nitrite, ammonium, and radionuclide (^226Ra, ^222Rn, ^137Cs, ^90Sr) levels are within natural background or regulatory limits, indicating the absence of significant anthropogenic contamination of the aquifer. Microbiological indicators show no total coliforms, E. coli, or pathogenic enterobacteria, while the total microbial count does not exceed permissible limits, confirming the water’s safety for consumption.Special attention was given to operational aspects of the well, including optimal pump operation modes, preventive cleaning and flushing, and the establishment of a sanitary protection zone around the well. These measures ensure long- term stability of water quality and protect the aquifer from potential contamination.Promising directions for further research include regular groundwater monitoring to detect changes in composition, particularly the dynamics of toxicant accumulation, the influence of seasonal and climatic factors on water quality, and the use of biotesting to evaluate phytotoxicity and overall safety of water resources. Implementing these measures will confirm the safety of water for domestic and drinking purposes, optimize well operation regimes, and provide scientifically based recommendations for aquifer protection in Kryvoozerskyi District, Mykolaiv Oblast.