Repeated phytoextraction of metal contaminated calcareous soil by hyperaccumulator Sedum plumbizincicola.

Most studies on the phytoextraction of cadmium (Cd) and zinc (Zn) by the hyperaccumulator Sedum plumbizincicola (S. plumbizincicola) have been conducted in metal contaminated acidic and neutral soils. However, little information is available on phytoremediation of calcareous soils. Two experiments were conducted to investigate the phytoextraction efficiency of S. plumbizincicola in a contaminated calcareous soil in He'nan province, north China. In a field experiment there was no significant decrease in shoot biomass production or metal (Cd and Zn) concentration in the shoots after three successive repeated phytoextractions. Repeated phytoextraction had no significant effect on the percentage distribution of Cd or Zn fractions in the soil even though the soil total Cd and Zn concentrations decreased by 32.8 and 19.7%, respectively. In a pot experiment the shoot biomass production and Zn and Cd uptake by S. plumbizincicola increased significantly with growth in metal contaminated calcareous soil amended with organic fertilizer, perlite and vermiculite. The results indicate that S. plumbizincicola can maintain sustainable uptake of Cd and Zn from the calcareous soil and enhancement of soil fertility and structure will significantly increase the phytoextraction efficiency. [ABSTRACT FROM AUTHOR]