Effect of Three Kinds of Chelating Agents on Phytoremediation in U and Cd Contaminated Soil by Zebrina pendula

To explore the effects of chelating agent on the phytoremediation in U and Cd contaminated soil, a pot experiment was performed to study the effects of 3 chelating agents (EDDS, OA and CA) and their additive concentrations (0.0, 2.5, 5.0, 7.5 mmol/kg) on U and Cd extraction, translocation, and accumulation in Zebrina pendula. The results show that the growth of Zebrina pendula is affected by the type and concentration of chelating agents. The addition of 7.5 mmol/kg EDDS inhibits the growth of Zebrina pendula. The application of 2.5 mmol/kg OA and CA increases the net weight of Zebrina pendula. The chelating agents have a positive effect on the uptake and translocation of U and Cd in Zebrina pendula. Applying 5.0 mmol/kg CA, the U content maximally increases by 5.68 times of control check, with levels of 205.9 mg/kg attained. Applying 5.0 mmol/kg EDDS, the Cd content maximally increases by 2.65 times of control check, with levels of 47.03 mg/kg attained. The maximum value of the U translocation factor is 0.342 when CA concentration is 7.5 mmol/kg, which is 2.36 times of that of control check. EDDS could better improve the translocation factor of Cd. Based on the results of U and Cd bioaccumulation, it is concluded that CA has the greatest effect on the accumulation of U and also has effect on that of Cd, EDDS has effect on the accumulation of Cd, while OA has no effect on the accumulation of U and Cd. The addition of CA and EDDS respectively enhances the available contents of U and Cd in soil. These results suggest that chelating agents could improve the effectiveness of phytoremediation with Zebrina pendula in soil contaminated with U and Cd.