Fractionation distribution and ecological risk assessment of some trace metals in artificial estuary: Vridi channel (C?te d'Ivoire)

摘要

BACKGROUND: The modified of Community Bureau of Reference (modified BCR) sequential extraction procedure has been one of common methods used for the trace metals speciation in sediments and allowed to the assessment of the ecological risk state of aquatic ecosystem based on ecological risk indexes. OBJECTIVE: The modified BCR sequential extraction procedure was used to the fractionation distribution of Cd, Co, Cu, Ni, Pb and Zn in sediment samples of Vridi channel, and three ecological indexes based on this method were used to assessment contamination and ecological risk state of these sediments. RESULTS: show that Cd, Co and Cu are mostly under their exchangeable form and bound to carbonates (92.07%, 31.20% and 32.02% respectively for Cd, Co and Cu), Pb mostly bond to Fe-Mn oxihydroxides (32.52%) and to organic matters and sulphides (32.21%), Zn mostly under its residual fraction (18.33%) and bond to Fe-Mn oxihydroxides (20.41%) and Ni mostly under its residual fraction (42.06%). These sediments present high contamination and ecological risk states of mainly in Cd, particularly its exchangeable form and that bound to carbonates. CONCLUSION: This present state of Vridi channel is essentially due to the strong anthropogenic pressures doing on this ecosystem. This study deserves to be widened in other hazardous pollutants to establish unequivocal the sanitary state of this estuary.