Tolerance and vegetation restoration prospect of seedlings of five oak species for Pb/Zn mine tailing

Abstract

A pot experiment was conducted to evaluate the growth response and vegetation restoration prospect of seedlings of five oak species for the phytoremediation of lead/zinc (Pb/Zn) mine tailings. Seedlings of Quercus imbricaria, Q. coccinea, Q. pagoda, Q. shumardii, Q. fabri were transplanted into pots containing Pb/Zn mine tailings to comparatively examine their biomass, root morphology, absorption and transfer characteristics of nutrient elements and heavy metals 30 months later. The results showed that all the seedlings could survive in the Pb/Zn tailings after 30 months. The biomass of Q. coccinea and Q. fabri decreased in Pb/Zn tailings compared with the control, while no significant difference were found for other three species. Compared with the control, root biomass was increased to some extent in Pb/Zn tailings except Q. coccinea. The lateral root morphological parameters were reduced only for Q. coccinea . Under heavy metal stress, nutrient concentrations of root and stem of oak seedlings did not change compared with the control. Generally, the concentrations of heavy metals in plant tissues were low, and the values of bioconcentration factor (BCF) and translocation factor (TF) were less than 1. Q. pagoda could accumulate more Cd, with concentrations of 22.4 and 15.1 mg·kg-1 in leaf and stem, respectively, and could translocate more Cd from root to shoot with TF of 2.3. Our results suggested that the seedlings of tested oak species could be used as the potential species for contaminated soil. Q. shumardii had the highest tole-rance with a low BCF and TF, implying that they were better potential candidates for afforestation and ecological restoration of mine tailings.