Geochemical processes controlling the groundwater chemistry and fluoride contamination in the Yuncheng Basin, China—An area with complex hydrogeochemical conditions

Abstract

Hydrogeochemical and stable isotope analyses and geochemical modeling were carried out to identify the major geochemical processes controlling the groundwater chemistry and fluoride contamination in the aquifers of the Yuncheng Basin, China, an area with complex hydrogeochemical conditions and severe fluoride contamination of the groundwater. The major findings of this case study include the following: 1) Cation exchange and salt effects are vital controls on the enrichment of fluoride in groundwater in the area by reducing the activity of Ca2+/F- in groundwater via ion complexation. Cation exchange increased the fluoride concentration by 2.7 mg/L when the Na/Ca molar ratio increased from 0.24 to 9.0, while the salt effect led to a ca. 5–10% increase in complex F- in groundwater due to the further dissolution of fluoride-bearing minerals in the aquifers, as suggested by a model calculation. 2) Anthropogenic contamination from pesticide and fertilizer use and industrial waste discharge is also a main source of fluoride in the groundwater. 3) Evaporation and ion effects favor the enrichment of fluoride in groundwater by encouraging the removal of Ca via precipitation. 4) The desorption of fluoride from mineral/organic matter surfaces is enhanced under alkaline conditions and a high HCO3 content in groundwater.

The Beach Aquifer Microbiome: Research Gaps and Data Needs

“…For instance, not all studies report groundwater flow rate and/or velocity, and properties of the sand (such as texture, grain size) were often not mentioned. In cases where sediments are not homogenous and contain ironcontaining minerals, it might not be possible to isolate the effect of groundwater chemistry on the microbiome, since sediment mineral composition co-varies with groundwater chemistry (Luo et al, 2018). Detailed sediment and site characterization can help document potential confounding effects.…”

Naturally Occurring Potentially Harmful Elements in Groundwater in Makueni County, South-Eastern Kenya: Effects on Drinking Water Quality and Agriculture

“…The major geochemical processes governing groundwater geochemistry were assessed using Gibbs [30] diagrams. To determine the source of major elements in groundwater in the area, cross-plots, which determine the strength of correlation (r 2 ) between TDS and the major ions [31] were used.…”

Enamel and Dentin Caries Risk Factors of Adolescents in the Context of the International Caries Detection and Assessment System (ICDAS): A Longitudinal Study

“…Fluoride can help the hydroxyapatite remineralization process, and it is most abundant in the outer layers of enamel, which explains why individuals using fluoride toothpaste were likely to have less enamel caries (52). Currently, there is no fluoride tap water in mainland China, and for most places like Foshan in South China, the water fluoride concentration was low (<0.30 mg/L) (53). As a result, it is critical to promote clinical and personal fluoride usage among children.…”