Enhanced phytoremediation of heavy metal-contaminated soil and responses of plant-microbial communities in alternating current reactor system

During electrokinetic-assisted phytoremediation of heavy metal-contaminated soil, the roles of different electrode configurations (in the same dimension) and varying AC frequencies are not yet fully understood. Specifically, their effects on plants, heavy metal removal efficiency from soil, and the root microbial community structure remain unclear. In this study, the optimal electrostimulation mode was selected based on the removal efficiency of heavy metals from soil under different electrokinetic parameters. It was found that AC field with a combined vertical and horizontal electrode configuration performed best. Compared to the non-electrified control, this setup significantly increased the average removal rates of Pb, Ni, Cr, and Cd. The 10 Hz frequency was identified as optimal, achieving removal rates of 54.1% (Pb), 50.6% (Ni), 74.6% (Cr), and 66.7% (Cd). Plants under this condition also achieved the highest biomass (3.78 times initial fresh weight). Physiological data indicated enhanced heavy metal stress tolerance, evidenced by increased chlorophyll content and lower malondialdehyde (MDA) levels. Furthermore, the stimulated soil exhibited an enriched abundance of bacterial phyla like Actinobacteriota and Patescibacteria , known for heavy metal resistance. This research offers valuable insights and technical approaches for soil heavy metal remediation, and its practical application potential warrants further investigation.