Abstract:

A field experiment on vegetation restoration was carried out in the abandoned lead-zinc tailings for 3 years with 15 plant species to evaluate their potential adaptation to the tailings. Plant species expressed different tolerance to stress of the tailings. Most species appeared the heavy metal-induced etiolation, defoliation, or growing stopped. There were significant differences in the growth rate of height and base diameter, root growth, and biomass among the species. The mine tailings reduced the root distribution depth, and stimulated the max length of lateral roots, the fine root ratio, and increased to different extents the mass allocation proportion to roots in all species. Four nitrogen-fixed species, Alnus cremastogyne, Amorpha fruticosa, Lespedeza cuneata, and Medicago sativa, suffered from mild damage, and root nodules appeared in their roots. In addition, Rhus typhina and Nerium indicum had higher tolerance, which kept higher relative growth rate and biomass. The results showed that accumulation of lead (Pb), and zinc (Zn) differed dependent on plant species, their organs, and the heavy metals. Generally, most plant species had higher concentrations of Pb and Zn in roots than that in shoots, while some of tree species had higher Zn concentrations in shoots than that in roots. Among the 15 species, L. cuneata had the highest contents of Pb and Zn in shoots in per square meter of ground (65 and 199 mg·m^-2, respectively). A. fruticosa had the second high Pb and Zn contents, reaching to 43 and 127 mg·m^-2, respectively. Based on overall performance we selected eight species candidate: A. fruticosa, L. cuneata, R. typhina, N. indicum, A. cremastogyne, R. chinensis, M. sativa, and Cercis canadensis, which would be suitable for the vegetation restoration in lead and zinc mine tailings, especially the nitrogen-fixing species.

Key words: mine tailing, phytoremediation, growth, heavy metal accumulation, evaluate