The Leaching Characteristics of Chelant-Enhanced Phytoextraction of Cd and Pb Contaminated Soil with Simulated Acid Rain

A soil column-cultivation leaching experiment was conducted in greenhouse to expose the HMs leaching characteristics in the process of EDTA-enhanced Phytoremediation of Cd-Pb compound contaminated soil by Zea mays L.(in seedling stage) under the condition of acid rain. Results showed that: (1) In the chelant-enhanced phytoremediation system, both EDTA and acid rain can accelerate HMs phytoextraction and promote Cd and Pb leakage, but EDTA was more effective than simulated acid rain. (2) In the process of rain leaching, the Cd and Pb concentration in the leachate decreased linearly along with the rainfall increased. The leaching rate of Cd and Pb with EDTA was 5.40- and 87.82-fold of control (without the application of a chelator). In the acid rain-Zea mays L.-chelant (EDTA)-enhanced phytoremediation system of Cd-Pb contaminated soil, EDTA and acid rain all have the characteristics of promoting Cd and Pb activation, but the leakage of HMs (especially Pb) depends mainly on the activation rate of EDTA to HMs, and might be closely related to the dosage and usage of chelating agent.