Hydrogeochemical Evaluation of Surface and Groundwater Quality around Galadima Koko Mining Sites, Niger State, North-Central Nigeria

Abstract

Problem Statement: The impact of artisanal gold mining on surface and groundwater around Galadima koko area of Niger State, North-central Nigeria is disturbing. This is because the same surface water and hand-dug wells used for gold washing are also used for drinking and domestic purposes. This makes it imperative to ascertain the pollution status of surface water and groundwater from shallow hand-dug wells in the area. Methodology: Surface and groundwater samples were collected in the vicinity of the mining sites while control samples taken far away from the mining sites and taken to the laboratory for chemical and bacteriological analyses. Prior to the samples, physical parameters (pH, temperature, total dissolved solid, electrical conductivity and turbidity) were determined insitu using standard instruments and procedures. Summary of Findings: Geological mapping of the area revealed that gneiss, schist and granite as the major lithological unit in the area. The concentrations of all the major cations (sodium, calcium, magnesium and potassium) and anions (sulphate, chloride, bicarbonate, carbonate and nitrate) are below their respective maximum permissible limit postulated by Nigerian Standard for Drinking Water Quality. However, within the Vicinity of the mining sites, the concentrations of iron, copper and manganese were slightly higher than their respective maximum permissible limits. Their concentration in the surface and groundwater in the area may be attributed to the impact of artisanal mining. The practice of washing the rocks containing gold directly on the nearby stream as well as using the mining buckets and pan to fetch water from the shallow hand-dug wells exposes the water system in the area to pollution. High concentration of iron, cooper and manganese in the Water is due to the oxidation, dissolution and weathering of pyrite that is associated with the gold mineralization in the area. The microbial analysis indicates that both the surface and groundwater in the area is contaminated with human and animal faeces. The results of Piper, Durov, Schoeller, Stiff and Gibbs diagrams suggest the water type in the area as alkaline-bicarbonate. Conclusion: The present study has ascertained that mining and poor sanitation in the study area have deteriorated the water system in the area. Recommendation: Due to the high concentration of bacteria in the water, boiling of water before use is suggested.