IMPACT OF INDIGENOUS ARBUSCULAR MYCORRHIZAL FUNGI ON LEAD SPECIATION DURING PHYTOREMEDIATION OF CONTAMINATED LANDFILL SOILS IN BONOUA, COTE D IVOIRE

Abstract

This study evaluates the changes in lead (Pb) speciation induced by phytoremediation in contaminated soils from the M Ploussoue Park landfill in Bonoua, Cote d Ivoire. Acacia mangium was cultivated, with or without inoculation by indigenous mycorrhizal fungi (IMF), on landfill soils artificially contaminated with three lead concentrations: 0 mg/kg (Soil Pb0), 250 mg/kg (Soil Pb250), and 500 mg/kg (Soil Pb500).After five months of cultivation, the distribution of Pb among soil fractions before and after phytoremediation was assessed by sequential extraction according to the BCR scheme. Before the trial, lead was distributed among five fractions: Pb-Hydro, Pb-Exch, Pb-Oxy, Pb-OM, and Pb-Resi and was predominantly bound to iron and manganese oxides (45-52%).After the trial, extraction rates were consistently higher in the presence of IMF regardless of soil type: 82% versus 76% under Soil Pb0, 95% versus 92.8% under Soil Pb250, and 96% versus 94.3% under Soil Pb500, relative to the initial total Pb content. These results indicate that IMF enhance lead extraction. In addition, the easily mobilizable fractions (Pb-Hydro, Pb-Exch) showed the highest extraction rates (up to 95%) under Soil Pb0 and Soil Pb250, whereas under Soil Pb500 the highest extraction rates (up to 97%) were observed in the fractions bound to oxides and organic matter (Pb-Oxy, Pb-OM).