Effects of Cd, Cu and Zn on Ricinus communis L. Growth in single element or co-contaminated soils: Pot experiments

Using biofuel plants to remove metal pollutants is a sustainable approach for phytoremediation. Ricinus communis L. (castor bean) is a bioenergy plant that grows rapidly and has a high biomass; it has been proven to be a potential phytoaccumulator of several metals. Pot experiments with single element or co-contaminated soils were conducted to investigate Cd, Cu and Zn accumulation and their interaction in R. communis L. After growing for four months in soils with the addition of Cd (at rates of 1,5,10,20, and 40 mg/kg), Cu (at rates of 50, 100, 200, 400, and 600 mg/kg), and Zn (at rates of 100,200,400,600, and 800 mg/kg) alone or combined, the dry biomass and the concentrations of Cd, Cu, and Zn in the leaves, stems and roots of the castor bean plants were measured, and the translocation and bioaccumulation factors were calculated. It was found that all of the R. communis grew well and produced high biomass, showing a high tolerance to Cd, Cu and Zn. Our experimental results implied that R. communis showed a high phytoremediation potential for soils contaminated by Cd or Zn while displayed a low uptake of Cu. The copper concentration in R. communis was only slightly influenced by Cd and Zn additions to the soils. The interaction pattern of Cd and Zn showed an antagonistic behavior under low concentrations of the Cd and Zn combined treatment while showed a synergistic behavior under high concentrations of the Cd and Zn combined treatment.