Electrokinetic-Assisted Phytoremediation of Pb-Contaminated Soil: Influences of Periodic Polarity Reversal Direct Current Field

Abstract

The effect of electric stimulation on the phytoremediation of Pb-contaminated soil by tall fescue and wheat seedlings was investigated by monitoring the time-dependent changes in soil properties and Pb accumulation in plants with or without a direct current (DC) exchange field. The results showed that plants could strengthen electrical conductivity (EC) and current in the soil environment. The periodic exchange electrode helped maintain a stable soil pH. Electric stimulation enhanced phytoremediation efficiency, and the enhancement effect increased with plant growth. Compared with the treatments without a DC exchange electric field, the Pb content in plots with tall fescue and wheat seedlings under DC exchange electric field increased 107–250.6% and 32.7–84.4%, respectively, after 30 d of planting. DC exchange electric field significantly increased the Pb enrichment coefficient of tall fescue and wheat seedlings. The upward transport of Pb from wheat seedling roots to shoots was greatly promoted by electric stimulation for 18 d. However, Pb transport in both plants was restrained after 18 d of electric stimulation. Additionally, DC exchange electric stimulation can improve the phytoremediation of heavy-metal-contaminated soil. More attention should be paid to the selection and testing of promising hyperaccumulators for electrokinetic-assisted phytoremediation of Pb-contaminated soil.