The Phytoremediation Potential of 14 Salix Clones Grown in Pb/Zn and Cu Mine Tailings

Abstract

Willows are suitable candidates for phytoremediation projects. A pot experiment was conducted to evaluate the potential of using Salix unrooted cuttings for the phytoremediation of lead/zinc (Pb/Zn) and copper (Cu) mine tailings. Cuttings of 14 Salix clones were directly rooted into pots containing mine tailings. The 14 clones showed different levels of tolerance to tailing treatments. A total of 71.40% and 85.70% of the S. jiangsuensis ‘172’ cuttings either grown in Pb/Zn or Cu tailings survived, respectively. However, the other clones had lower survival rates, and the values were no more than 40%. Usually, all clones produce less biomass in an extremely contaminated environment. Clonal variation in biomass yield was observed in this research. The surviving clones, such as S. integra ‘WSH’, S. matsudana ‘14’, S. chaenomeloides ‘3’, S. chaenomeloides ‘4’, and S. chaenomeloides ‘5’ (Pb/Zn tailing), S. integra ‘HY’, S. integra ‘WSH’, S. matsudana ‘14’, S. matsudana ‘19’, and S. matsudana ‘34’ (Cu tailing) produced relatively more biomass in this study. In general, all the clones presented lower bioconcentration factor values for the tailings of heavy metals. In principle, all clones could easily take up and translocate Zn and Cd from the tailings to aboveground parts, especially S. integra. All clones exhibited a huge variation in their heavy metal accumulation capacity. As stated above, the direct utilization of cuttings for phytoremediation is a viable option. S. jiangsuensis ‘172’ had a high tolerance capacity and would be a recommended candidate for future phytoremediation projects in soils containing tailings with an extremely high concentration of heavy metals. These results provide crucial information about willow growth and metal accumulation capacity in extremely adverse environments.