Assessment of heavy metal contamination degree of municipal open-air dumpsite on surrounding soils: Case of dumpsite of Bonoua, Ivory Coast

In Ivory Coast, the majority of uncontrolled dumpsites are open-air. The aim of this work is to study the lateral and vertical distribution of heavy metals or metalloids in soils surrounding the open dumpsite of M'Ploussoue Park in Bonoua, which has a wet tropical climate and located at upper topographical position. The physical and chemical parameters, such as the particle size, pH, exchangeable cations, CEC and contents of heavy metals, were studied using various analytical techniques. The vertical and lateral distribution of heavy metals or metalloids in soil samples collected from the M'Ploussoue dumpsite in Bonoua were found to be in the following order: Zn > Pb > Cr > Ni > Cd > As > Cu > Se, regardless of the topographical position of the soil profile. Ours results indicate that there are high levels of heavy metals (Cr, Pb, Cd, Zn, Ni) that exceed the CCME permissible limits in agricultural and industrial soils in both the top soil layers and in soil located below the dumpsite, probably due to the migration and infiltration of dumpsite leachate. The vertical and lateral distributions of metals or metalloids at dumping sites can pose potential ecological risks if these elevated concentrations of metals migrate into soil, plants and groundwater, where they present a danger to humans. Thus, it appears to be necessary to apply proper remediation techniques.