PhD defence by Glenna Thomas
Phytoremediation of acid mine drainage (AMD) impacted soil
Acid mine drainage (AMD) is a type of mining wastewater generated from the oxidation of sulfide-bearing minerals. Due to its acidity and, typically, high content of various metals and metalloids, AMD has immense environmental consequences and risks to human health. Depending on the local geology, AMD may also contain high concentrations of valuable rare earth elements (REE). Phytoremediation, a technique using plants to restore degraded lands, offers a sustainable and innovative alternative to traditional remediation methods with potential to minimise the negative impacts while taking advantage of potential value or resource-generating opportunities.
The purpose of this PhD thesis was to investigate the phytoremediation potential of AMD impacted soil by establishing a continuum of research on the phytoremediation of AMD and AMD impacted environments, expanding knowledge on the geochemical impacts of AMD in soil, exploring metal and REE accumulation behaviour in AMD impacted soil-grown plants, and investigating metal and REE mobility in AMD impacted soil.
The findings support the use of acidic AMD impacted media for the possible recovery of REE. In conclusion, this PhD thesis established new evidence of the significant impact of AMD on soil systems, demonstrated a higher phytostabilising potential of select metal(loid) under co-cropping and provided supporting evidence for leachability of REE in AMD impacted soil. These studies contributed to an advanced understanding of the geochemistry of AMD pollution under different environmental conditions as well as the phytoremediation potential of mining-impacted and marginal lands.
Supervisors
Peter Engelund Holm, PhD, Professor
Craig Sheridan, Professor, PhD, Pr.Eng. School of Geography, Archaeology and Environmental Studies, University of the Witwatersrand, Johannesburg, South Africa
Assessment committee
Bjarne W. Strobel, Associate Professor (Chair)
Mansour Edraki, Associate Professor, University of Queensland
Case M. van Genuchten, Senior Researcher, Geological Survey of Denmark and Greenland