Phytoremediation with Augmentation of Oxalic Acid of Toxic Metals Contaminated Saline Soil by Suaeda salsa : Effects on Metal Translocation and Plant Physiology

Phytoremediation with augmentation of oxalic acid could improve the removal efficiencies of toxic metals in saline soil. Metal concentrations and species in saline soil, extraction of metals by Suaeda salsa, and physiology of plant were all affected by the additive concentration of oxalic acid. The addition of oxalic acid increased the availability of heavy metals in soil and promoted the metal migration from soil to plant. Low dose of oxalic acid (0.5%) application promoted plant root length and biomass, and improved the translocation of cadmium and lead from roots to shoots, which increased from 13.8 to 14.3 cm, from 102.5 to 103.1 g/pot, from 10.74 to 12.82 for cadmium, and from 0.71 to 0.95 for lead, respectively. Whereas the higher addition (1.5%) of oxalic acid induced higher plant toxicity and increased the accumulation of heavy metal in root of S. salsa significantly (p < 0.05). The highest values of translocation factor were achieved under relative low dose (0.5% or 1.0%) of oxalic acid addition, which were 0.39, 12.82, and 0.95, respectively. While the highest values of bioconcentration factors for shoot and root (BCFshoot and BCFroot) occurred at 1.0% and 1.5% oxalic acid addition, respectively. S. salsa could be more suitable for phytostabilization for combined toxic metal pollution under the addition of high dose of oxalic acid.