Fractionation, Mobility and Environmental Risk of Trace Metals in the Sediments from N’zi River, Côte d’Ivoire

Abstract

Despite increasing human activities, such as agriculture, little information is available on the status of trace metals contamination in rivers in developing countries including Côte d’Ivoire (West Africa). The aim of this study was study chemical fractions of Cu, Pb, Zn, and Ni, to identify mobility, sources and to evaluate ecological risks of traces metal in sediment of N’zi River using modified BCR sequential extraction procedure. The results showed that all metal were dominated by residual fractions. Labile fractions of Pb accounted for 0.0 – 68% of total contents indicating significant anthropogenic sources for Pb, while for Cu, Ni and Zn results suggesting natural sources. The potential mobility of the metals manifested following order:  Ni > Zn > Cu > Pb. Risk assessment code indicated low to medium risk for Pb and low risk for other metals in the sediments. Cluster analysis (CA) and Matrix correlation were used to detect the relationship between the studied sampling sites and to see if some of the parameters interrelated with each trace metal concentration in exchangeable fraction. Results indicated high anthropogenic contamination at stations near to urban and agricultural areas.