The Consequence of Artisanal Gold Mining on Heavy Metals Exposure to Water in Anka, Zamfara State Nigeria

Abstract

Over the decade many villages in Zamfara State Nigeria were known for artisanal gold mining which caused pollution of vast water bodies and area of land. This makes it imperative to analyze heavy metal contamination in wells and surface water. The present study evaluated the concentrations of heavy metals (iron, lead, cadmium, zinc, nickel, and chromium) in the ore processing water and well-water in some selected villages of Anka local government area in Zamfara State where mining is taking place. Anka town served as control due to absence of mining activities. The concentrations of heavy metals in the water samples were measured using atomic absorption spectrophotometry. The concentration of Fe, Pb, and Cd ranged from 23.3 – 921.46, 0 – 132.8, and 3.3 – 4.1 ppm respectively. While Zn, Ni, and Cr were not detected in the water samples. Virtually all the detected heavy metals in the water samples exceeded the international organizations (WHO, USEPA, and EPA-EUC) maximum permissible limit of 0.3 – 1.00, 0.01 – 0.05, and 0.03 – 0.05 ppm of Fe, Pb, and Cd in water samples respectively. Interestingly, all the well-water from all the study locations was not contaminated with Pb despite its high concentrations in the processing water. Meanwhile both the processing water and well water were contaminated with Fe and Cd. These revealed that artisanal gold mining is contributing to the pollution of surface water bodies (used for irrigation and drinking) with Pb, while Fe and Cd may be in addition to their abundance in natural soil deposits.