Phytoremediation potential of indigenous plants growing in soils affected by mine activities in Gejiu City, Yunnan Province

Indigenous plants growing in mining spoils for phytoremediation have attracted great interest. To search the suitable plants, six plant species popular in the mine slag heaps of Gejiu City were collected and metal concentrations in plants and rhizosphere soils were analyzed. Results showed that the soils were greatly influenced by mine activities and heavy metal contents in plants were dependent upon those in the rhizosphere soils. However, the adaptation strategies varied among them. Bothriochloa ischcemum (Linn.) Keng and Equisetum ramosissimum Desf. had the Cr bioaccumulation factor (BAF) of 1.48 and 1.34, respectively, even though the rhizosphere soils were not contaminated by Cr. However, B. ischaemum and Agave americana Linn. showed the BAF for Pb, Zn Cu and Sn < 1.0, and Cyperus rotundus Linn. showed the similarly low BAF for Zn and Cu. Therefore, the three species had a great tolerance to phytostabilize these metals. Gymnema sylvestre (Retz.) Schult showed the translocation factor (TF) > 1.0 for Pb, Cu and Sn, so translocating these metals to the aboveground parts would be a feasible option. Similarly, Euphorbia cyathophora Murr. demonstrated the high phytotranslocate capacity for Cd and Sn, so it could be employed to remedy Cd and Sn-contaminated soils.