Fluoride enrichment, hydrogeochemical processes, and health risks from groundwater ingestion in the Zabzugu District, Ghana

Groundwater quality in the Zabzugu District, Northern Ghana, is increasingly affected by geogenic processes and anthropogenic activities, particularly agriculture. This study examined the hydrogeochemical characteristics, controlling mechanisms, and health implications of groundwater in the district. Groundwater samples from thirteen (13) locations were analysed using physicochemical measurements, hydrogeochemical modelling, and multivariate statistical techniques, including correlation, factor, and cluster analyses. Groundwater was generally neutral to slightly alkaline (pH 7.01–8.22) and predominantly fresh, with total dissolved solids and electrical conductivity largely within WHO and Ghana Standards Authority (GSA) permissible limits. The dominant cations and anions followed the order Mg²⁺ > Ca²⁺ > Na⁺ > K⁺ and HCO₃⁻ > Cl⁻ > SO₄²⁻, respectively, with Mg–K–HCO₃ identified as the principal water type. Hydrogeochemical evolution was mainly controlled by rock–water interaction, mineral dissolution, and ion exchange, with additional anthropogenic influences from agricultural activities. Fluoride concentrations ranged from 0.231 to 6.90 mg/L, with over 76% of samples exceeding the WHO guideline value of 1.5 mg/L. Higher fluoride concentrations occurred mainly in the northwestern and north-central areas, attributed predominantly to geogenic processes, including carbonate mineral dissolution and ion exchange. Health-risk assessment using estimated daily intake and hazard quotient indicated that children were the most vulnerable, with HQ values exceeding 1 in several communities. The findings support targeted monitoring, groundwater treatment, public health interventions, low-cost defluoridation technologies, and improved agricultural practices to safeguard groundwater quality and public health in Zabzugu District.