Effects of electrokinetic-assisted phytoremediation of a multiple-metal contaminated soil on soil metal bioavailability and uptake by Indian mustard

Electrokinetic-assisted phytoremediation is an innovative technology to decontaminate heavy metal contaminated soil. In this study, the effect of electric current on plant growth and speciation of soil heavy metals has been investigated by pot experiments, and the remediation processes of electrokinetic-assisted phytoremediation has been discussed. After Indian mustard (Brassica juncea) grew for 35 d, four voltage gradients (0, 1, 2, 4 V cm−1) of direct-current (DC) were applied timely (8 h d−1) across the soils for 16 d. The extractable soil metals by different extraction methods had a significant redistribution from the anode to the cathode after the treatments. Simple correlation analysis indicated that the correlation coefficients of the extractable soil metals with root metals were better than that with shoot metals. Plant uptake of metals increased by the electrokinetic-assisted phytoremediation, and a medium voltage gradient of 2 V cm−1 was the best due to the highest metal accumulation in the plant. Voltage gradient was the most important factor in affecting the plant growth, soil properties and metal concentrations in the soil and plant.

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► We study the change of soil properties in different soil sections after experiments.
► Impact mechanism of the combined technique on metal uptake by plant is investigated.
► The extractable soil metals has a significant redistribution form anode to cathode.
► The highest metal accumulation of plant is in the treatment of 2 V cm−1.
► Voltage is the foremost factor in affecting the metal contents in soil and plant.