EVALUATION OF ECOTOXICAL RISKS OF SOME METALLIC TRACE ELEMENTS IN LAGOON OF PORTO- NOVO IN BENIN.

Abstract

The study focus on evaluation of concentrations of four Metallic Trace Element (MTE) Cu, Zn, Mn and Pb in the compartments of hydroaquatic system of Lagoon of Porto-Novo, located in southeastern of Benin. Levels of lead, manganese, copper and zinc in sediments, pisces and eichornia crassipes from lagoon are very important and fish from the lagoon had higher metal content and can present risk for human consumption.The highest values are 65.6 ppm of Zn in fish, 11335.7 ppm for Mn in eichornia crassipes and 41.5 ppm for Cu in sediments. In pisces, level of Pb, wich is most dangerous metal for human health among those analysed, reaches 22.8 ppm. The results show high levels which reflect anthropogenics impacts on the lagoon. The contamination sources would probably relate runoff, waste waters, solid waste discharges and the erosion of agricultural lands.