UBC Theses and Dissertations
An assessment of native Chilean woody plants for phytoremediation of copper-contaminated sites Milla-Moreno, Estefanía
The need to divest fossil fuels sets copper (Cu) in higher demand for use in clean energy systems. Chile’s Cu production has resulted in more than 750 tailing deposits across the northern and central regions, an area that also includes a biodiversity hotspot and the driest desert in the world. The quantity of tailings in Chile is expected to increase, and phytoremediation could help assist their management. To guide such efforts, I assessed the field performance and physiology of ten native woody plant species used for phytoremediation at a copper (Cu) mine in Chile, conducted a controlled environment experiment with a subset of these species, and undertook a ‘UBC public scholars initiative’ to discover professional stakeholders’ views on the use of phytoremediation in Chile. In the field, I assessed survival and hare damage in all species; and growth, vigor, chlorophyll content index and chlorophyll fluorescence in seven. Metal and metalloid concentrations in roots and shoots were measured in five species. Copper was most concentrated in the roots of Prosopis chilensis (Molina) Stuntz (algarrobo) and Quillaja saponaria Molina (quillay). Due to lower uptake overall and reduced mobilization to shoots, quillay is suggested for stabilizing tailings. In a controlled environment experiment with quillay and espino (Vachellia caven (Molina) Seigler and Ebinger) grown under three increasing Cu levels for 6 months in a greenhouse setting, I measured growth, photosynthetic performance and elemental concentrations of leaves and roots to further evaluate their potential for phytoremediation. Growth of quillay was unaffected by Cu increases but growth of espino was enhanced, as was its photosynthetic performance, indicating that espino may have an unusually high requirement for copper. Excess Cu was mostly restricted to the roots of both species, where X-ray fluorescence mapping indicated some tendency for Cu to accumulate in tissues outside the periderm. Finally, through an online questionnaire (n =43), I asked stakeholders linked to tailings management about the likelihood of using phytoremediation as an additional stabilization method. They were of the opinion that Chile should implement phytoremediation, but highlighted a need for more demonstrably successful phytoremediation projects, funding and access to suitable plant material.
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