Restoration potential of pioneer plants growing on lead-zinc mine tailings in Lanping, southwest China

This study focused on the restoration potential of ten pioneer plants (Artemisia roxburghiana, Artemisia tangutica, Carex inanis, Cyperaceae hebecarpus, Plantago depresa, Cynoglossum lanceolatum, Potentilla saundesiana, Coriaria sinica, Oxyria sinensis, and Miscanthus nepalensis) during the early phase of Pb-Zn mine tailings phytostabilization, in Lanping, China. The concentrations of heavy metals (Pb, Zn, and Cu) and soil fertility (the available N, P, K, and organic matter) in the rhizosphere of these species have been compared. The results showed a general improvement in the rhizosphere soil properties of pioneer plants. Of the ten species, the concentrations of Pb, Zn, and Cu in the rhizosphere of A. roxburghiana have the greatest reduction of 56.23%, 83.00%, and 84.36%, respectively, compared to the bulk soil. The best improvement in soil fertility was found in the rhizosphere of P. saundesiana, with an increase of 241.83%, 170.76%, 49.09%, and 81.60%, respectively, in the available N, P, K, and organic matter. Metals accumulated by the plants have been mainly distributed in the root tissues, and only small amounts transferred to the aboveground tissues. The highest contents of Pb and Zn have been recorded in C. hebecarpus with 57.84 and 87.92 mg/kg dry weight (dw), respectively. The maximum Cu content was observed in C. inanis with 1.19 mg/kg dw. Overall, pioneer plants will be ideal species for the phytostabilization of mine tailings, but the potential use varies in different pioneer plant species. Among these ten species, A. roxburghiana has been identified to be the most suitable for phytostabilization programs, due to its greatest improvement on physical-chemical properties in the rhizosphere soil.