Assessment of Groundwater Contamination and Its Impact on Public Health in Mining Communities of Zone C, Benue State, Nigeria

Abstract

Groundwater remains the primary source of domestic water supply across Zone C of Benue State, Nigeria; however, increasing artisanal mining activities raise concerns about its safety and long-term sustainability. This study assessed the physicochemical, heavy metal, microbial, and spatial characteristics of groundwater across nine Local Government Areas (Ado, Agatu, Apa, Obi, Ohimini, Okpokwu, Ogbadibo, Oju, and Otukpo), using 50 samples obtained from boreholes, hand-dug wells, and springs. Standard APHA, WHO, and USEPA protocols guided field and laboratory analyses, while geospatial techniques (Ordinary Kriging) were employed to identify contamination hotspots. Results show significant groundwater degradation across the region. Physicochemical parameters revealed acidic pH (5.6–5.9), elevated electrical conductivity (>1500 µS/cm), and high turbidity (>5 NTU) in Ado, Okpokwu, and Ogbadibo, indicating influence from acid mine drainage and dissolved solids from mine tailings. Heavy metal assessment showed widespread contamination: Pb exceeded WHO guidelines in 48% of samples (with a peak of 0.43 mg/L in Ogbadibo), As exceeded limits in 36% of samples, and Cd in 12%. Microbial analysis revealed high prevalence of total coliforms (59–82%) and E. coli (35–66%), particularly in Agatu and Okpokwu, confirming fecal contamination from poor sanitation and shallow, unprotected wells. Spatial mapping identified Ogbadibo, Ado, Okpokwu, Agatu, and Otukpo as major hotspots of contamination. The combined chemical and microbial risks pose severe public health implications, including neurological, renal, and gastrointestinal disorders. The study concludes that groundwater in many mining communities of Zone C is unsafe for consumption without treatment and recommends improved regulation of artisanal mining, enhanced sanitation infrastructure, and continuous groundwater quality monitoring.