Spatial Distribution and Ecological Risk of Heavy Metals in Soils from Artisanal Mining Sites: Central Taraba State, Nigeria

Abstract

Mining activities have increasingly contributed to environmental degradation through the unregulated release of toxic metals into soils, particularly in mineral-rich regions such as Taraba State, Nigeria. This study assessed the spatial variability and ecological risks of selected heavy metals including Cadmium (Cd), Lead (Pb), Cobalt (Co), Copper (Cu), Chromium (Cr), Zinc (Zn), Nickel (Ni), Manganese (Mn), and Iron (Fe) in soils collected from seven mining sites in the central zone of the state. Soil samples were analyzed using Atomic Absorption Spectrophotometry (AAS), and the geo-accumulation index (Igeo) was applied to evaluate contamination intensity. The results revealed significant spatial heterogeneity in metal distribution, with Mayo-Sinna exhibiting the lowest contamination levels, while Lambangudu, Gidan Kara, and Maijankasa showed elevated concentrations of Pb, Co, Ni, Mn, and Fe. Cu, Cr, and Cd were below detection limits in all sites. The Igeo values classified Lambangudu and Gidan Kara as moderately to heavily polluted with respect to multiple metals, signaling ecological risk hotspots. The study stresses the pressing need for environmental regulation, continuous monitoring, and remediation programs to mitigate the health and ecological hazards posed by mining activities. These findings provide empirical evidence to inform sustainable mining practices and soil quality management in Nigeria and other developing regions facing similar challenges.