Metal uptake by spontaneously grown Typha domingensis and introduced Chrysopogon zizanioides in a constructed wetland treating gold mine tailing storage facility seepage

This study analyzed the capability of two species to take up metals from gold mine tailing storage facility seepage in a constructed wetland with horizontal subsurface flow. Naturally populated Typha domingensis (cattail) and introduced Chrysopogon zizanioides (vetiver) were sampled on a regular basis in two experimentation cycles; a monoculture of T. domingensis in the first cycle and a mixed culture of T. domingensis and C. zizanioides in the second. Corresponding water samples were taken from the inlet and outlet sections of the system. Metals were analyzed in both sets of samples. Seepage water from the tailing storage facility had a high content of metals, characterized by large fluctuations depending on the ore type being processed at a particular time and hence no clear removal patterns could be discerned. After 75 days' growth, T. domingensis exhibited an above-ground biomass production of 12.30 to 14.18 g per plant, higher than C. zizanioides which was only 6.65 g per plant. T. domingensis revealed an average bioaccumulation factor of 7, 5, 293, 1997, 413, 225 and 583 for As, Co, Cu, Mn, Ni, Pb and Zn, respectively, whilst C. zizanioides exhibited bioaccumulation factors of 6, 2, 278, 503, 228 and 1184 for As, Co, Cu, Mn, Pb and Zn respectively. However, the translocation factor found in C. zizanioides was higher compared to T. domingensis. Due to the higher biomass production, standing stocks of As, Co, Cr, Cu, Mn, Ni, Pb and Zn were 3, 7, 4, 7, 14, 7, 5, times higher in T. domingensis than in C. zizanioides. Therefore, T. domingensis could be considered as a promising alternative for gold mine tailing seepage phytoremediation, whilst C. zizanioides revealed very low growth rates and showed adaptation difficulties. •A wetland was constructed for the remediation of gold mine tailings storage seepage.•Typha domingensis grew spontaneously while Chrysopogon zizanioides was introduced.•Metals were monitored in the inflow and outflow and in vegetation.•Typha domingensis revealed adaptability while Chrysopogon zizanioides did not.•Metal uptake was similar but Typha exhibited higher biomass production.