Geochemical Fractionation of Heavy Metals Under Three Land‑Use Types in Gold Mining Areas, Côte d’Ivoire (West Africa)

Introduction: This study investigated the mobility and bioavailability potential risk of heavy metals in sediments affected by land use types in a gold mining environment. Methods: The study employed the modified Community Bureau of Reference (BCR) sequential extraction method to assess the mobility of arsenic (As), cadmium (Cd), and mercury (Hg) in sediments from gold mining areas in Côte d’Ivoire. Concentrations of these metals in surface sediment samples (n = 45) were analyzed using inductively coupled plasma atomic emission spectroscopy (ICP-AES), and the Risk Assessment Code (RAC) was applied to evaluate the potential risk associated with these metals. Results: It was found that the metals were primarily associated with the residual fraction, comprising 44–58% of the total concentration. The BCR method indicated that 41–56% of these metals were prone to leaching into the water column. Pearson correlation analysis revealed positive relationships among the extracted fractions but no correlation with pH or TOC across the three land-use types. Principal component analysis (PCA) showed high positive loadings for As and Cd on component 1, and for Hg on component 2, suggesting a geogenic influence for Hg and mixed sources for As and Cd. The RAC indicated low risk for As and medium risk for Cd and Hg across the sediments of the studied land-use types. Conclusion: The sediments exhibit a dominantly geogenic distribution with localized anthropogenic enrichment of Cd and As, and moderate ecological risk was mainly associated with Cd and Hg mobility in the three land-use types.