Distribution of Fluorine in Surface Waters of the Upper Don Basin During the Low-Water Period

Abstract

The purpose is to determine the level of fl uorine content in the surface waters of the Upper Don basin and its compliance with sanitary and hygienic requirements. Materials and methods. During the winter low-water period of 2019 in the Upper Don basin, 30 water samples were taken from rivers and water reservoirs, determining the fl uorine content, pH value, mineralization, and concentration of the main salt composition components. The following analytical methods were used: potentiometry (fl uorine and pH), volumetric analysis (alkalinity ≈ HCO3 ), and capillary electrophoresis (other components of the main salt composition). Results and discussion. The average fl uorine content in surface waters of the Upper Don basin during the low-water period is 0.33 mg/L with a range of values 0.18-0.53 mg/L, which closely corresponds to earlier data for river waters of the Voronezh Region: 0.26 (0.10-0.45) mg/L. A close correlation between fl uorine concentration and pH value (r = 0.84) was found in the absence of signifi cant relationships with mineralization and major ion concentrations. The main factor leading to an increase in fl uorine concentration with increasing pH is the displacement of structural and sorbed fl uorine present in mineral phases by OH– ions. Conclusion. Due to the signifi cantly lower level of fl uorine content in surface waters of the Upper Don basin com pared to the physiological optimum for humans (0.7-1.5 mg/L), it is recommended to conduct a detailed study of the f l uorine distribution in underground waters of the region and to assess the prospects of their use for drinking water supply.