Mechanisms and Influencing Factors of Electro-Kinetic Enhanced Phytoextraction for the Recovery of Metal-Polluted Soils

Soil contamination with various toxic metals has become a serious global concerned issue due to the potential risks to the environmental ecology and human health. So far, numerous in-situ and ex-situ methods have been developed and electro-kinetic (EK) enhanced phytoremediation is widely accepted as a sustainable alternative for the decontamination. The integrated technique contains the application of a low intensity electric field adjoined to growing plants in contaminated soil. So far, many efforts have been made while there is a clear lack of this technology in both laboratorial and field applications. Limitations such as low phytoavailaibility of target metals, unsatisfactory metal's tolerance and translocation ability of plants and undesirable soil pH environment might the main reasons that responsible for the low remediation efficiency. In order to figure out the current focusing phenomena, the possible mechanisms of phytoextraction, EKR and EKR-enhanced phytoextraction were discussed, respectively. In addition, influencing factors such as metal speciation, plant selection and electro-kinetic parameters were also discussed. The contents summarized in the present paper are believed to be an useful guideline for further investigation and optimization of EK-enhanced phytoextraction.