The impact of uncontrolled municipal dumping sites on metal contamination in the surrounding waters, sediments, and soils are of great concern in many developing countries. Total concentrations of trace metals Cd, Zn, Cu, Pb, Ni, and Co were measured in 33 sediments collected in the vicinity of the Akouedo dumpsite (Abidjan, Cote d'Ivoire) and in a baseline station. The Cu, Zn, Cd, and Pb concentrations in surface sediments around the dumpsite were at least three times higher than those at the reference station, suggesting that the Akouedo dumping site is a significant contamination source of these metals to the surrounding sediments. The extent of contamination affects sediment as deep as 100 cm. Sediment pH and total organic carbon content control the distribution of Cu, Zn, and Cd in subsurface sediments. Significant Cd, Zn, and Cu enrichments were measured at the dumpsite and its surrounding environment. Zn concentrations in the sediments might cause high ecological risks at 46% of the samples based on the sediment quality guidelines (SQGs). Single and sequential extraction results showed a low mobility rate of Cd, Cu, Pb, and Ni from sediments around the dumpsite. However, the results suggest that the high total metal concentrations in the dumpsite sediments have resulted in a significant metal load in the surrounding environment.
Keywords: Heavy metals; Landfill; Pollution; Sediment; Sequential extraction.