Geochemical speciation and distribution of trace metals in sediments around industrial and artisanal gold mining areas in northern Côte d'Ivoire

The purpose of this study was to investigate the mobility, spatial distribution, possible sources, and potential ecological risks associated with trace metals Cu, Mn, and Ni in sediments around industrial and artisanal gold mines in northern Côte d'Ivoire. The sampling was conducted in industrial and artisanal (Korhogo), and artisanal (Tengrela) gold mining sites. Analysis of variance was performed to ascertain spatial differences. The possible sources of pollution were identified using the enrichment factor, principal component, and hierarchical cluster analysis. Trace metals Cu, Ni, and Mn concentrations in sediments did not vary across the stations. The results of the geoaccumulation index indicated low-to-moderate contamination of Cu, Mn, and Ni in Korhogo and Tengrela. Potential ecological risks indicated that Cu, Mn, and Ni may pose a low risk to organisms in Korhogo and Tengrela. The enrichment factor values showed that the sediments in the areas studied are minor to moderately enriched in trace metals (Cu, Mn and Ni). The results of principal component and hierarchical cluster analysis indicated that Cu, Ni, and Mn were generated both by anthropogenic and natural inputs, which were confirmed by the enrichment factor. The sequential extraction procedure proposed by the Community Bureau of Reference (BCR) showed that a large portion (between 59.68 and 79.22%) of Cu, Ni, and Mn is highly associated with the residual fraction, showing their low mobility. The results of the risk assessment code indicated low-to-medium risk for Cu, Ni, and Mn. This study provides the first data and background level of trace metals in sediments from the Korhogo and Tengrela gold mining areas.