Assessment of Soil Contamination in Koukougnanou, Central Côte d'Ivoire by Trace Metal Elements (Pb, Ni, Cr, Cd, and Mn): Distribution, Sources, and Ecological Risk

 Mining activities are among the major sources of soil contamination by potentially toxic elements (PTEs). This study aimed to assess the soil quality of the Kouakougnanou mining site (Angovia, Côte d'Ivoire) in order to evaluate the level of contamination for environmental protection and sustainable soil management. Soil samples were collected from mining-affected areas and from non-mining areas.  The concentrations of PTEs (Pb, Ni, Cr, Cd, and Mn) were determined using a Portable X-ray Fluorescence (pXRF) Geochemical Analyzer. Soil contamination was assessed using five environmental indices, namely the Contamination Factor (CF), Geo-accumulation Index (Igeo), Enrichment Factor (EF), Pollution Load Index (PLI), and Potential Ecological Risk Index (RI). The results revealed varying degrees of soil contamination depending on the element and the sampling area. The highest concentrations were recorded for nickel in non-mining soils (79.73 mg/kg) and manganese in mining-affected soils (172.45 mg/kg). The Contamination Factor indicated very high cadmium contamination, with mean CF values of 210 in non-mining soils and 420.9 in mining-affected soils. The Pollution Load Index showed mean values of 1.18 in non-mining soils and 3.33 in mining-affected soils, indicating greater environmental degradation in areas impacted by mining activities. The Potential Ecological Risk Index reached 188.03 and 328.71 for non-mining and mining-affected soils, respectively, indicating a higher ecological risk in disturbed soils. Cadmium exhibited the highest Geo-accumulation Index values, with mean Igeo values of 7.13 in non-mining soils and 8.13 in mining-affected soils. Similarly, the Enrichment Factor of cadmium reached 259,259.26 in non-mining soils and 1,315.31 in mining-affected soils, highlighting a strong anthropogenic contribution.  Overall, the findings indicate that cadmium is the most critical potentially toxic element affecting the environmental quality of soils at the Kouakougnanou mining site and poses a significant ecological risk, emphasizing the need for continuous monitoring and appropriate soil management strategies.