Phytoremediation of heavy metal-contaminated soils using high biomass plants

The main aim of this research project is to study the phytoextraction of heavy metals from soils with the application of chelates. Screening high-biomass plant species more sensitive to the application of chelates and optimizing chelate application methods were investigated for a better combination of plants and chelate applications to increase the metal phytoextraction efficiency and reduce potential metal leaching to the surrounding environment.; Understanding the mechanisms involved in enhancing metal accumulations in plants through chelate application will be helpful for optimizing chelate-induced phytoremediation. Results showed pretreatments on the roots of Indian mustard with MC, HCl, and hot water increased the concentration of Pb in shoots by 14-, 7-, and 15-fold, respectively, compared with the shoots that had not been pretreated. Using a pot experiment, the biodegradable chelating agent of EDDS was added in a hot solution at 90°C to the soil in which garland chrysanthemum and beans were growing. Results showed when 1 mmol kg -1 of EDDS as a hot solution was applied to soil, the concentrations of Cu, Pb, Zn and Cd and the total phytoextraction by the shoots of the two plant species exceeded or approximated those in the shoots of plants treated with 5 mmol kg-1 of normal EDTA solution. The concentrations of metals in the shoots of beans were significantly correlated with the relative electrolyte leakage rate of root cells, indicating that the root damage resulting from the hot solution might play an important role in the process of chelate-enhanced metal uptake.; Metal leaching study due to chelate application to soil was also carried out immediately after harvesting of the plants in pot experiments. For the treatment of 1 mmol of EDDS, the leached metals decreased to the control group 14 days after the application of EDDS. Therefore, the application of biodegradable EDDS in hot solutions to soil can be a good alternative in chelate-enhanced phytoextraction. (Abstract shortened by UMI.)...