Phytoremediation Potentials of Indigenous Ruderal Plants Growing on Soil Contaminated with Potentially Toxic Elements within a Petrochemical Refinery Complex

The utilization of indigenous plant species for remediation of polluted soils comes at a low economic and ecological cost when compared with traditional methods. In this study, the phytoremediation potential of indigenous ruderal plants in highly polluted soil within a petrochemical refinery complex was evaluated. First, a survey of the most abundant herbaceous plant species was carried out within the complex during the wet and dry seasons. The concentration of Cd, Ni, Cr, Cu, Fe, Mn, and Zn in soil and plant samples was determined using Energy Dispersive X-ray Fluorescence. Results show ten herbaceous plant species (Calopogonium mucunoides, Terminalia macroptera, Centrosema pubescens, Piliostigma thonningii, Cochlospermum tinctorum, Isoberlinia tomentosa, Monotes kerstingii, Detarium microcarpum, Paspalum orbiculare, Borreria verticillata) with accumulation factors (of Cd and/Cu) greater of than 1, thus revealing them as metal extractors. Furthermore, they have high above ground biomass due to their rapid vegetative growth, self-sustaining and easy to propagate. There are possibilities of further evaluating and genetically improving metal tolerance traits in some of these plant species in relation to their potential use in phytoremediation programmes in metal-polluted sites.