Impacts of Artisanal Gold Mining on Groundwater Quality in Korokpa, North-Central Nigeria

Artisanal gold mining can modify groundwater chemistry through excavation, ore crushing, washing, tailings disposal, sulphide oxidation, and the mobilization of potentially toxic metals. This study evaluates the spatial influence of artisanal gold mining on groundwater quality in Korokpa, North-Central Nigeria using a 24-site dataset organized into high-impact, moderate-impact, and reference zones. Physicochemical parameters, major hydrochemical indicators, and ten potentially toxic metals were assessed against drinking-water benchmarks. Water Quality Index (WQI), Heavy Metal Pollution Index (HPI), Pollution Index of Groundwater (PIG), one-way analysis of variance, Pearson correlation, and principal component analysis (PCA) were used to integrate the evidence. The high-impact zone recorded mean electrical conductivity of 875.8 ± 155.8 μS/cm, total dissolved solids of 534.6 ± 97.9 mg/L, turbidity of 10.4 ± 2.1 NTU, and WQI of 145.3 ± 16.8. Lead, cadmium, arsenic, and mercury showed the clearest exceedance pattern, with Pb exceeding the adopted guideline at 79.2% of sites, Cd and As at 66.7%, and Hg at 33.3%. Lead concentration decreased strongly with distance from mining activity (r = −0.855, p < 0.001). PCA attributed 91.9% of total variance to a dominant component characterized by conductivity, dissolved solids, turbidity, and the priority metals. The integrated pattern indicates a pronounced contamination gradient centered on the most intensively disturbed mining and ore-processing areas. The results support source control, groundwater monitoring, and treatment of affected domestic supplies.