Distribution, biodisponibilite et bioaccumulation des metaux lourds dans le systeme lagunaire de Lome

Abstract

The sediments and some fishes species of the lagoon system of Lome have benn analyzed for their contents in heavy metals V, Cr, Ni, Cu, Zn, Sr, Pb, Cd, Fe, Al, Ti, Mn and As. The results show that the lagoon is very polluted by certain heavy metals such as cadmium, lead, zinc, chromium and nickel. This pollution is moderate in the case of copper, iron, aluminum and manganese. The analyzed elements show a south-north increasing distribution gradient that confirms the anthropogenic input of pollutants through the gutters entering directly into the lagoons. Domestic effluents, atmospheric pollution, the wild run off and cities dumps are the principal sources of pollution for the lagoons. The tests of extraction of metals using weak nitric acid (45 %) indicate that the high amounts of analyzed metals are bioavailable and have a man made origin. This high bioavailability is the main factor enhancing the high level of bioaccumulation of cadmium, lead and arsenic in tissues of fish species that are by ignorance fished and eaten by neighboring people