From hydrogeochemical genesis to public health risk: Unveiling the links between geogenic arsenic, fluoride, and iodine in groundwater.

Elucidating the formation mechanism of geogenic contaminated groundwater (GCG), mainly polluted by arsenic (As), fluorine (F) and iodine (I), is crucial for elucidating relevant processes and improving water quality. The study focused on the Huang-Huai-Hai Plain in Henan Province, China, using 484 groundwater samples collected repeatedly from 2020 to 2022 combined with hydrogeochemical analysis and Positive Matrix Factorization (PMF) to identify GCG characteristics, controlling mechanisms, and health risks. Results indicated that the groundwater ranged from weakly acidic to alkaline, with confined water being predominantly weakly alkaline to alkaline, and exhibited high salinity. Groundwater with high concentrations of As, F, and I was predominantly found in alluvial and fluvial zones. Groundwater chemical composition is affected by evaporation and water-rock interaction, and the primary types of low-quality groundwater are mainly the evaporation-concentration and burial-dissolution types. Spatial analysis indicates the distribution of As, F, and I poisoning villages corresponds with areas of high-As, high-F, and high-I groundwater. Groundwater pollution poses the highest non-carcinogenic risk for children, and high-As groundwater poses the highest carcinogenic risk to this group. Additionally, potential endemic goiter areas are mainly in the flood plain. These findings indicate that groundwater safety is intrinsically linked to endemic diseases. Mitigating health risks necessitates targeted groundwater treatment, prioritized monitoring of high-risk zones, and integrated management of GCG influences to ensure safe water access for vulnerable communities.