Abstract
The understanding of F− concentration in groundwater in humid areas is limited although there are lots of research on high-fluoride groundwater in arid areas. In this paper, with controlling factors of F− concentrations in humid areas as the focus, 130 groundwater samples, obtained from four subsystems in Northwest Xingguo County, Jiangxi Province, China, were investigated to demonstrate the controlling factors of F− concentrations in humid areas. According to analytical results, the following hydrogeochemical characteristics of the fluorine in humid mountainous areas were determined: (1) F− concentration is positively correlated with total dissolved solids (TDS), Ca2+, HCO 3 − , and pH; (2) the groundwater features a high flow rate and low TDS; (3) the equilibrium constant of CaF2 is less than its solubility product constant, and the fluorine-bearing minerals in rocks are in a dissolved state; and (4) the dissolved fluoride-bearing minerals constitute the main sources of F− in the groundwater. Fluorine mainly comes from groundwater fluorine-bearing minerals in metamorphic rocks. Moreover, the low F− concentration in the groundwater mainly results from the fast flow rate of groundwater. Fluoride in groundwater has great potential hazards in humid areas.
Highlights
Fluorine is an indispensable trace element in the human body
With respect to groundwater chemistry, the fluoride concentration is usually high in Na-HCO3 type groundwater and low in Ca-HCO3 type groundwater [6, 20, 31,32,33,34,35]. e deficiency of calcium ion concentration in the groundwater from calcite precipitation favors fluorite dissolution leading to excess fluoride concentration. e groundwater is oversaturated with respect to calcite and undersaturated with respect to fluorite [36,37,38,39,40,41]
In a previous study on fluorine dissolved in groundwater, most scholars focused on the source, migration, and enrichment of fluorine in arid and semiarid areas and alkaline and weak alkaline environment, and they achieved many good results. e research results of this paper have important theoretical and practical significance for people to understand the migration and enrichment characteristics of fluorine in weak acidic and acidic groundwater in humid areas. e groundwater is widely distributed and the flow rate is fast; the F− in groundwater will migrate to any areas where the groundwater flows. erefore, fluorine in groundwater has great potential harm in humid areas. e hydrogeochemistry of fluorine in humid mountainous areas is still important
Summary
Fluorine is an indispensable trace element in the human body. It is an essential component to maintain the normal development of human bones. Excessive fluoride in the human body can lead to endemic fluorosis [1]. It is stipulated in Standards for Drinking Water Quality (GB 5749-2006) and Quality Standard for Groundwater (GB/T 14848-2017) that F− concentration in drinking water should be less than 1.0 mg/L. In a previous study on fluorine dissolved in groundwater, most scholars focused on the source, migration, and enrichment of fluorine in arid and semiarid areas and alkaline and weak alkaline environment, and they achieved many good results. E research results of this paper have important theoretical and practical significance for people to understand the migration and enrichment characteristics of fluorine in weak acidic and acidic groundwater in humid areas. The hydrogeochemistry of groundwater and factors controlling the distribution of fluoride in groundwater of Northwest Xingguo County, southern China, have been evaluated. e main objectives of this paper are as follows: hydrogeochemical characteristics of fluorine in groundwater in humid areas, including the source of fluorine and its influencing factors
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