Occurrence, Controlling Factors and Health Hazards of Fluoride-Enriched Groundwater in the Lower Flood Plain of Yellow River, Northern China

High-fluoride groundwater is a major challenge to safe groundwater supply for global community. This study emphasized on the high-fluoride phreatic groundwater in the lower flood plain of Yellow River. A total of 86 phreatic groundwaters were sampled to elucidate the hydrochemistry, sources and driving forces of high-fluoride groundwater, and associated health hazards. Results indicate phreatic groundwaters in the study area are all slightly alkaline with TDS in a large variation of 559–4271 mg/L. High-fluoride groundwater is widespread in the study area with ~ 70% of groundwaters exceeding the Chinese drinking water permissible limit of 1 mg/L, and characterized by hydrochemical faces of HCO3− and Na+. Groundwater fluoride originates predominantly from the geogenic sources of fluorite dissolution and silicates weathering. Its release is retrained by the gypsum dissolution but stimulated by the precipitation of calcite, aragonite and dolomite. Groundwater fluoride enrichment is also facilitated by the alkaline condition, competitive adsorption of HCO3−, cation exchange process. The excessive fluoride in groundwater can pose non-carcinogenic risk to all populations at more than 50% of sampling sites via drinking water pathway, but mostly the medium risk category. Infants were more susceptible with 15.12% of groundwaters demonstrated high health risk. The high health risk to other populations is limited. Differential water supply and defluorination are recommended to effectively utilize groundwater resource and safeguard residents’ health.