Mobilité relative des métaux lourds issus de la décharge d’Akouédo et risque de contamination de la nappe du Continental Terminall (Abidjan - Côte d’Ivoire)

Relative mobility of heavy metals resulting from Akouedo landfill and assessment of Continental Terminal groundwater contamination risk(Abidjan-Cote d'Ivoire) The aim of this study is to know the geochemical mechanisms which control the vertical migration of heavy metals and to evaluate the risk of the Continental Terminal groundwater contamination resulting from Akouedo landfill. The chemical analyses of 56 samples showed that the soil of Akouedo landfill is rich in Cu (20-369.7 ppm), Fe (850-12500 ppm), Zn (18.6-1163.7 ppm), Pb (10.3-1450 ppm), Cd (1-11.5 ppm) and Cr (27.7-125ppm). Adsorption, principal geochemical mechanism in the soil, allows the retention of the majority of metals (Cu, Fe, Zn, Pb, Cd) on the organic matter (NTK and Corg) very abundant in the surface layers and on the clayed layers. But chromium is not much adsorbed and migrates more towards the deep layers. Cr is thus able to reach the groundwater easily and to cause a contamination of this one.