Phytoremediation of toxic metal polluted soil: screening for new indigenous accumulator and translocator plant species, northern Anambra Basin, Nigeria

Abstract

Ten plant species were identified and sampled from seven sites in the study. Eighty-one soil samples were collected. Both plant and soil samples were digested in acid mixtures, extracted and were analysed for V, Mn, Ni, Cu, Zn, Pb and Mo. The amount of metals accumulated and translocated in plant tissues was calculated to determine native plants that are suitable as hyperaccumulators, phytoextractors and phytostabilizers of the metals under study. The bioconcentration factor (BCF), translocation factor (TF) and bioaccumulation coefficient (BAC) were calculated for all plant species to enable categorization of the species. From this study, phytoextractors of vanadium (V) are Zea mays, Sida acuta and Amaranthus hybridis and a few other species as stabilizers. Based on the BCF, TF and BAC, Amaranthus viridis, Laportea aestuans possess phytoextraction potential while Amaranthus hybridus, Corchorus aestuans, Sida acuta and Zea mays are phytostabilizers of Mn. There are no hyperaccumulators and phytoextractors of Ni in the study area but Amaranthus hybridus, Corchorus aestuans, Physalis angulata and Zea mays are potential stabilizers. Suitable phytoextractors of Cu include Amaranthus hybridus, Amaranthus viridis, Sida acuta and Zea mays. On the other hand, Abelmoschus esculentus, Cucurbita maxima, Corchorus aestuans, Laportea aestuans, Physalis angulata and Sida acuta are all potential candidates for phytostabilization of Cu. Plant species such as Sida acuta, Laportea, Cucurbita maxima and Abelmoschus esculentus have potential for phytoextraction of Zn while Amaranthus hybridus, Amaranthus viridis, Colocasia asculenta, Corchorus aestuans and Physalis angulata are suitable stabilizers of Zn. Only Physalis angulata have phytoextraction potential for Pb while Abelmoshus esculentus, Colocasia asculenta and Laportea aestuans are suitable as stabilizers. Phytoextractors of Mo include Amaranthus hybridus, Amaranthus viridis, Abelmoschus esculentus, Cucurbita maxima and Sida acuta while Colocasia asculenta, Corchorus aestuans, Sida acuta and Zea mays are stabilizers of Mo. There were no hyperaccumulator(s) of any of the metals and no suitable phytoextractor of nickel from the area.