Distribution Characteristics and Enrichment Mechanism of Fluorine Icons in Geothermal Water in Beijing

Abstract

Beijing boasts abundant geothermal resources, however, the exploitation of its subterranean hot water is often limited by significant levels of fluorine ions. To gain a better understanding of the distribution characteristics and enrichment mechanism of fluorine ions in the geothermal water surrounding Beijing, this study analyzed both normal and trace components of the geothermal water. The findings reveal that: 1) The concentration of fluorine ions in underground hot water in Beijing averages 8.59 mg/L, with Yanqing exhibiting the highest concentration and Miyun the lowest; 2) The hydrochemical types include HCO3-Ca•Mg•Na type, SO4-Na type, SO4-Na•Ca type, Cl-Na type, SO4•CO3-Na type, and SO4•Cl-Na type. Notably, the fluoride ion concentration is directly proportional to the pH value, which exerts some influence on the fluoride ion concentration. These findings have practical implications for preventing potential harm caused by excessive fluoride ions and guiding the development and exploitation of pertinent resources.