Efficiency Of Direct Current(DC) Field And Sedum Alfredii Hance On Remediation To Cadmium Contaminated Soil

Cadmium(Cd) is a toxic heavy metal to living things. However, the problem of soil Cd pollution has become more and more serious and has significantly affected the people’s life. Therefore, the research on the remediation of Cd contaminated soil has become more and more popular. In this study, a combination of phytoremediation and electrokinetic remediation technologies was used in pot experiments. The purpose of this study is to explored the most efficiency of the direct-current(DC) electric field-Sedum alfredii Hance remediation(DCF-SH) on the Cd contaminated soil by the optimal voltage gradient, various voltaic time and directions of electrostatic field. The effect of additive application on DCF-SH was also examined. The main conclusions were as follows:(1) DC electric field improved plant growth of Sedum alfredii Hance. The maximum biomass of Sedum alfredii Hance was reached under the voltage gradient of 1.0 V/cm and 6 h/d conduction time. There was no significant difference of Sedum alfredii Hance biomass between two types of soils under DC electric field.(2) Shoot Cd absorption of Sedum alfredii Hance was increased by DC electric field. The maximum Cd absorption in the shoots of Sedum alfredii Hance was 90.6 mg plant-1. But under DC electric field, Cd absorption of Sedum alfredii Hance in mild Cd contaminated soil(colleted from Wenzhou) was significantly higher than that in the heavy Cd contaminated soil(colleted Fuyang).(3) Three additives were used, namely EDTA, humic acid and organic fertilizer. EDTA significantly increased soil Cd availability(58.35%) and enhanced soil Cd absorption by Sedum alfredii Hance, and this was further increased by DC electric field. Plant shoot Cd in Sedum alfredii Hance was 56.9 mg/plant when without DC electric field, and 69.0 when under DC electric field respectively. Similarly, humic acid could also significantly increase Cd uptake by the plant, and this was further increased by DC electric field(68.6 mg/plant) compared to that without electric field application(48.1 mg plant-1). However, when addition with organic fertilizer into the soil, there was no difference for plant Cd uptake under DC electric field compared to that without electric field treatment.