Hydrochemical characteristics, driving factors and health risk of fluoride in groundwater from the northwestern Ordos Basin, China

Abstract

Groundwater is essential for maintaining public health, promoting economic development, and ensuring ecosystem stability in arid and semi-arid regions. The northwestern Ordos Basin (China) primarily relies on groundwater from multilayered aquifer systems; however, our knowledge of the hydrochemical characteristics and water quality of groundwater in this region is limited. Here, we employed a newly collected dataset of 94 groundwater samples from different aquifers to constrain the source, controlling processes of fluoride in groundwater, and its potential health risk in the area. Groundwater is characterized by Na-Cl and Na-SO₄ types with a minor Na-HCO₃ type, which is primarily controlled by ion exchange, silicate weathering, and the dissolution of carbonate and evaporite minerals. Of the groundwater samples, 42% exceeded the fluoride limit of 1.5 mg/L established by the World Health Organization (WHO). This is mainly attributed to geogenic sources, including fluorine-bearing mineral dissolution, cation exchange, evaporation, and competitive adsorption. The water quality index suggests that most samples are unsuitable for drinking. Health risk assessment results based on the Monte Carlo simulation indicate that children face significantly higher non-carcinogenic health risks from fluoride exposure than adults (both males and females). These findings provide new insights into the complex hydrogeochemical evolution of fluoride in groundwater and the groundwater quality status in multi-aquifer systems, contributing to the sustainable development and management of groundwater resources in the Ordos Basin.

Keywords

Northwestern Ordos Basin / Groundwater / Fluoride / Hydrogeochemistry / Water quality / Health risk assessment

CRediT authorship contribution statement

Jiacong Tian: Writing - original draft, Visualization, Methodol-ogy, Investigation, Conceptualization. Zhanjun Wang: Writing - review & editing, Resources, Investigation. Kyriaki Daskalopou-lou: Writing - review & editing, Conceptualization. Maoliang Zhang: Writing - review & editing. Yaoqiang Huo: Writing - review & editing, Resources. Yingnan Cao: Writing - review & editing, Investigation. Jucai Yang: Writing - review & editing. Wei Liu: Writing - review & editing, Supervision, Project adminis-tration, Conceptualization. Jianguo Liu: Writing - review & editing, Supervision, Investigation. Sheng Xu: Writing - review & editing.

Declaration of competing interest

The authors declare that they have no known competing finan-cial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgments

This work was supported by the Natural Science Foundation of Inner Mongolia Autonomous Region (2024QN04014), the Open Research Fund of Yinshanbeilu Grassland Eco-hydrology National Observation and Research Station, China Institute of Water Resources and Hydropower Research (Grant No. YSS202401), Sci-entific Research Support Program for Introducing Talents at the Inner Mongolia Autonomous Region of China (DC2400002177 and DC2400003177), Major Projects of Erdos Science and Technol-ogy (Project No. 2022EEDSKJZDZX015), and Applied technology research and development project in Jungar Banner of Inner Mon-golia Autonomous Region of China (2023YY-13). We thank Huaiz-hong Chang and Yuan Fan for the water chemical analysis.

Appendix A. Supplementary data

Supplementary data to this article can be found online at https://doi.org/10.1016/j.gsf.2025.102123.

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