Heavy Metal Contamination in Abuni and Adudu Lead and Zinc Mines in Southern Nasarawa State, Nigeria

Abstract

Heavy metal pollution of the environment is becoming a significant issue and a major concern due to the negative consequences it has globally. Artisanal mining, the rapidly expanding mining industries, agriculture, the metal industries, inappropriate waste management, and the use of fertilizers and pesticides are all contributing factors to the release of these inorganic pollutants into the land, water, and environment. This study investigated the concentrations of some heavy metals (Al, Cd, Cr, Cu, Fe, Mn, and Zn) in soil samples from Abuni and Adudu lead and zinc mines, Southern Nasarawa State, Nigeria. Two spots were chosen from each of the mining sites, and soil samples were taken at the topsoil, one foot, and two feet above the ground level, respectively, to achieve a fully representative sampling of the area. The soil samples were processed and analyzed for each metal using instrumental neutron activation analysis. The concentrations of the metals were in the order: Cd < Cu < Cr < Mn < Al < Zn < Fe in Abuni mine and Cd < Cu < Cr < Mn < Al < Fe < Zn in Adudu mine. The heavy metals, Al, Cr, and Cu, fall within the recommended limits. The levels of Cd, Fe, Mn, and Zn in Abuni and Adudu mines were higher than the permitted limits of 3 mg/kg, 50,000 mg/kg, 200 mg/kg, and 421 mg/kg, respectively, set by the Food and Agricultural Organization of the United Nations (FAO) and the Nigerian National Environmental Standards and Regulations Enforcement Agency (NESREA) for Nigerian soils. The study revealed that the soil samples from the mines are contaminated with heavy metals, especially Cd, Fe, and Mn, raising serious environmental and health concerns. It is worth noting that the extremely noticeable values for Zn in all the evaluated indices simply confirm its existence in commercial quantities, as both sites are mining zinc metal.