STUDY OF CONTAMINATION BY METALLIC ELEMENTS IN COASTAL SEDIMENTS: CASE OF THE COTONOU CHANNEL

Abstract

Coastal aquatic ecosystems are environments increasingly affected by human activities due to urban discharges and their use as dumps. The objective of this study is to determine the profiles of metallic elements concentration (Al, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Cd, and Pb) of Cotonou channel sediments and to evaluate their quality. For this, surface sediments (0-5cm) were sampled at 13 sites along the channel. Thus,Geoaccumulation Index (Igeo), Enrichment Factor (EF) and Sediment Pollution Index (SPI) were calculated to assess the chemical quality of these sediments. The metal contents of the sediments follow the following order of abundance: Fe >Al>Mn> Zn >Cr>Cu > Co> Ni >Pb> As> Cd. The "Igeo" geo-accumulation index and the Enrichment Factor "FE" reveal moderate polymetallic contamination by several elements. The results show Fe, Co, and Ni being the most concerning. As for the Sediment Pollution Index (SPI), it reports low, moderate and high pollution of sediments.