In this study, the spatial distribution of eight metal(loid)s in the soil of an abandoned coking plant in Shanxi, China, was mapped, and the ecological and health risks of the coking plant were assessed. The results showed that the soil Pb content of the coking plant greatly exceeded the background value, and Hg, Cd and Pb were the most polluting factors contributing to the considerable ecological risk level. There was also a non-carcinogenic risk in the coking plant, in which oral intake was the main pathway, and As, Pb and Cr were the main contributors. As the main contributor to ecological risk and non-carcinogenic risks and the most polluting metal, Pb was selected as a priority pollutant in the coking plant. Based on the detected concentration of Pb in the coking plant soil and in consideration of phytostabilization, ryegrass, alfalfa and castor were employed to study the phytoremediation and electrokinetic-enhanced phytoremediation effect in a series of Pb-contaminated soils (0, 100, 200, 300 and 400 mg/kg). It was found that the underground parts of alfalfa and castor had stronger Pb enrichment ability, and their biomass and Pb absorption capacity were improved in electrokinetic remediation methods. The Pb absorption capacities of the tested plants and the promotion efficiencies of electrokinetic-enhanced phytoremediation followed the order castor > ryegrass > alfalfa. Under the optimal electrical conditions, the remediation efficiency of castor was increased by 106 %, 83 %, 51 % and 48 % in 100, 200, 300, and 400 mg/kg Pb-contaminated soils, respectively.
Keywords: Castor; Coking plant; Ecological risk; Electrokinetic-enhanced phytoremediation; Lead; Ryegrass.
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