Evaluation of the phytoremediation potential of native plants growing on a copper mine tailing in northern Chile

Abstract

Mining operations in northern Chile are responsible for numerous mine tailings deposits, which may represent a risk to human health and the environment. This study evaluated the phytoremediation potential of three plant species (Prosopis tamarugo, Schinus molle and Atriplex nummularia) to remediate copper mine tailings in northern Chile. To improve the characteristics of the tailing, three treatments based on arbuscular mycorrhizal fungi and organic and inorganic amendments were applied. Plant roots and shoots and the associated tailings samples were collected and analyzed for total metal concentrations of Cu, Mn, Fe, Pb, Zn and Cd. Bioconcentration Factor (BCF) and Translocation Factor (TF) were estimated to evaluate the plant species potential for phytoremediation. The results show that A. nummularia presents high TF values on untreated tailings for Pb and Zn; on tailings treated with CaCO3/compost for Mn, Fe, Pb and Zn, and on tailings treated with CaCO3/compost/mycorrhizae only for Zn. P. tamarugo presents high TF values on the untreated tailings for Pb and Zn; and on tailings treated with CaCO3/compost for Mn. S. molle presents high TF values on untreated tailings for Cu, Mn, Pb and Zn; on the tailing treated with CaCO3/compost for Mn and Zn, and on the tailing treated with CaCO3/compost/mycorrhizae for Mn and Pb. High TF values show that the plants studied under the specific characteristics of the treated or untreated tailings, present the potential of being used for phytoextraction. Regarding the BCF, the experiments showed values lower than 1 for all the metals, except for Cd, which for A. nummularia developed in the amended tailing, presented potential characteristics of a hyperaccumulator. This metal even had in general BCF values higher than 1 and TF lower than 1, which shows the potential of the three evaluated species as phytostabilizers for Cd. Regarding the effect of the amendments, the untreated tailing presented lower removal efficiency than the tailings treated with CaCO3/compost (T1) and CaCO3/compost/mycorrhizae (T2). On the other hand, no significant difference was found between treatments T1 and T2.