Impact Assessment of Okobo Coal Mine in Kogi State, Nigeria, Using the Rapid Impact Assessment Matrix (RIAM)

Abstract

This study presents a comprehensive assessment of the geo-environmental and socio-economic impacts of coal mining and deposits in the Okobo district of Ankpa Local Government Area, Kogi State, Nigeria. The research quantitatively evaluates heavy metal contamination and the presence of Acid Mine Drainage (AMD) resulting from both historical and persistent illegal mining activities. Using a quantitative approach, soil and water samples were analyzed, and the Rapid Impact Assessment Matrix (RIAM) was applied to evaluate the significance of various impacts on key environmental and social components. The findings revealed widespread heavy metal contamination, with elevated concentrations of Fe, Mn, Zn, Cu, Pb, Cd, and Ni in soil and water samples, often exceeding permissible environmental limits. For instance, Mn concentrations in water ranged from 0.44 to 0.81 mg/L, surpassing the 0.2 mg/L WHO standard. The pH of water samples varied from 3.2 to 6.9, with strong acidity in some locations confirming the presence of AMD. The RIAM analysis underscored high negative impacts across various environmental and socio-economic components, corroborating the observed contamination. The study concludes that coal mining in the Okobo district has severely compromised the region’s environmental integrity, presenting a critical environmental and public health concern. Based on these findings, urgent remediation strategies, stringent enforcement against illegal mining, and continuous environmental monitoring are recommended to mitigate the adverse effects and promote sustainable post-mining land-use plans. This research provides a crucial baseline for future environmental policy and intervention in coal-mining affected regions of Nigeria.