Phytoremediation Of Soil Treated With Metalliferous Leachate From An Abandoned Industrial Site By Alternanthera Sessilis And Ipomoea Aquatica: Metal Extraction And Biochemical Responses

Metalliferous soil (MS) was collected from near an abandoned pulp and paper mill, and leachates were extracted in water to simulate natural water percolation. Metalliferous soil leachates (MSL) were added to the garden soil, and phytoremediation trials were carried out by Alternanthera sessilis and Ipomoea aquatica for 28-d in pot experiments. The aqueous leachates could extract 18-33% of the metals from the MS. The maximum accumulation of 38-43 mu g Cd/g, 211-294 mu g Pb/g, 199-218 mu g Cr/g, 92-95 mu g Ni/g, 422-511 mu g Cu/g, 2366-3531 mu g Zn/g, 6910-6105 mu g Fe/g, and 4410-5576 mu g Mn/g in the plants exceeded the respective toxic ranges, indicating their tolerance. Plants showed >50% removal efficiency for Pb, Cr, and Cu. For other metals, variable removal efficiency between 25 and 48% was also noted. The root morphology and X-ray microanalysis revealed Pb, Cr, and Fe deposits that influenced their uptake and possible interactions with other elements. The treated plants showed reduced chlorophylls, carotenoids, protein, and ascorbate, along with an increase in superoxide radical, hydrogen peroxide, and lipid peroxidation. A concomitant increase in the activities of all the vital antioxidant enzymes such as superoxide dismutase, catalase, ascorbate peroxidise, and guaiacol peroxidise helped to combat multi-metal stress in them. Overall, owing to their metal uptake efficiency, significant oxidative stress mitigation properties, rapid growth rate, and large biomass, A. sessilis, and I. aquatica can be recommended for use in the decontamination of multiple metals.