Hydrogeochemical Characterization and Gold Mining Impacts on Groundwater Quality in the Ayanfuri Mining Enclave, Ghana: Implications for Sustainable Environmental Management

Intensive gold mining activities in Ghana’s Ayanfuri enclave pose a significant threat to groundwater quality. To evaluate this impact, a hydrogeochemical assessment was conducted on 59 groundwater samples from community boreholes (n = 22), observation boreholes (n = 13), tailings storage facility (TSF) boreholes (n = 18), and embankments (n = 6). Analytical techniques included Piper diagrams, Gibbs plots, bivariate diagrams, Ficklin diagrams, geochemical modeling, and Net Acid Production Potential (NAPP) computations to characterize hydrogeochemical facies and dominant processes. The prevailing water type is Na-Mg-HCO₃, accounting for approximately 17% of all samples. Groundwater pH is generally below seven at all sampling sites, with the highest acidity in observation boreholes, likely due to hydromorphic dispersion of metal effluents. The groundwater samples consistently exhibited negative NAPP values, indicating that they can neutralize acidity and therefore pose a low risk of acid mine drainage (AMD). Approximately 93% of the samples fall within the Near-neutral Low-metal range on the Ficklin diagram, indicating stable water chemistry and further supporting a low AMD risk. However, 7% of the samples from sites located behind the TSF embankments and observation boreholes, with pH 5.2–5.9 and elevated potentially toxic elements (up to 18.1 ppm), fall within the Colorado AMD and Acid Low Metal zones, implying that sulfide oxidation outpaces neutralization at these sites. These areas pose a higher risk of generating acidic, metal-rich drainage, potentially mobilizing harmful elements, and degrading water quality. Ion exchange and silicate weathering dominate solute acquisition, while lithology and anthropogenic inputs influence spatial variability. This study underscores aquifer vulnerability in mining regions and calls for policy interventions integrating hydrogeochemical risk assessments into mining legislation and water governance. Continuous monitoring, community-based protection, and strict regulatory enforcement are recommended to safeguard groundwater for domestic and agricultural use.