Metal Pollution and Ecological Risk Assessment in Sediment of Artificial Estuary: Case of Vridi Channel, Côte d’Ivoire

Abstract

This study focused on a yearly monitoring of sediment pollution in Cd, Co, Cu, Fe, Mg, Mn, Ni, Pb, Zn and the ecological incurred risks in Vridi channel. The results, expressed per dry weight, showed that the annual mean were 0.96 (± 0.16) mg/Kg for Cd, 22.36 (± 2.41) mg/kg for Co, 33.98 (± 4.61) for Cu, 31760.5 (± 5652.7) mg/kg for Fe, 981.2 ± (377.5) mg/kg for Mg, 302.9 (± 415.4) mg/kg for Mn, 42.53 (± 9.79) mg/kg for Ni, 83.37 (± 6.66) mg/kg for Pb and 27.11 (± 11.72) mg/kg for Zn. The measured oligo-elements (Fe, Mn, Mg, Zn) originated from naturals sources and were away from accumulation, except from Fe which moderately accumulated. That hence the low sediment contamination by these metals. As for toxic trace metal (not essential) to living organisms (Co, Cu, Pb, Cd, Ni), they resulted from anthropogenic origin. These sediments were moderately contaminated in Co, Cu and Ni, significantly in Pb and strongly in Cd. All the studied trace metals were mainly from continental origin, except Cd which showed a marine origin. This estuary displayed a steady state of progressive deterioration and presented a very high ecological risk.

Keywords: Abidjan, Atlantic Ocean, Ebrié System, pollution indicators, trace metals