Dynamics of heavy metal Pollution in Tropical lagoon of Gulf of Guinea, West Africa

Abstract

In this study the accumulation of Iron (Fe), Zinc (Zn), Cobalt (Co), Chromium (Cr), Cadmium (Cd), Lead (Pb) and Nickel (Ni) in sediment, water, some fish samples (Schilbe mystus, Mormyrus rume, Gymnarchus niloticus, Cynoglossus senegalensis, and Chrysichthys nigrodigitatus) and an aquatic plant Eichhornea crassipes collected from Lekki lagoon, Lagos Nigeria were examined. Heavy metals in the water, sediment, some selected fish and an aquatic plant were determined seasonally across nine sampling Stations; in the gills, liver and muscles of the fish species and in the root stem and leaves of Eichhornea crassipes using an atomic absorption spectrometer (AAS). Heavy metals concentrations in the sediment and water varied significantly, both spatially and seasonally. Metal concentrations varied between species and body parts while Co, Cr and Pb were not detected. Ni was found in the liver and gills of S. mystus and M. rume and Cr in the gills of G. niloticus only. In Eichhornea crassipes, metals detected were in the order: root>leaves>stem for Fe, Zn, Cr, and Cd; root>stem>leaves for Pb and Ni while Co was not detected. Heavy metal presence in Lekki Lagoon calls for monitoring of activities within and around the lagoon and policy development towards the sustainable ecosystem health services.

Keywords: Pollutants, Heavy metals, Eichhornia crassipes, Bioaccumulation, Lekki lagoon