FLUORINE CONCENTRATIONS IN UNDERGROUND WATER INTENDED FOR HUMAN CONSUMPTION

Minerals are the main source of fluorine in underground water, and the highest fluorine concentrations are observed in regions with phosphorite and apatite bedrock formations. The objective of this paper was to determine fluorine concentrations in underground water intended for human consumption. The following regions were investigated in the study: Starogard Lakeland (Tczew intake), Zulawy Wislane - Vistula Delta Plain (Malbork intake) and the Lower Vistula Valley (Male Walichnowy intake). The analyzed regions comprised a total of 29 wells drawing water from three water-bearing horizons: 10 - Cretaceous, 14 - Tertiary, 5 - Quaternary and Tertiary. Fluorine concentrations in the analyzed water samples ranged from 0.28 to 3.60 mg.dm(-3) with the maximum allowable concentration (MAC) of 1.5 mg.dm(-3). The results of the analysis have shown that qualitative standards were exceeded by a high 86% of samples. The highest fluorine levels were noted in water drawn from Cretaceous horizons at a depth of 150-180 m. Excessive fluorine in potable water has to be eliminated as large quantities of this microelement have adverse implications for public health. The mixing of water from different water-bearing horizons proved to be an effective solution that optimized fluorine levels only in the Tczew intake in the Starogard Lakeland.