PhD Thesis · Detecting Hyperaccumulator Plants
My PhD asked a deceptively simple question: can we find plants that pull metals out of the ground, and detect them quickly enough to use at scale?
The motivation came from Bangka Island, where tin-mining tailings hold rare earth elements, but conventional extraction risks doing more damage to already degraded land. Hyperaccumulator plants offer another route: plants that concentrate metals in their tissues, which could recover value while helping restore the land. The catch is finding them. Out of hundreds of thousands of species very few hyperaccumulate, and confirming one traditionally means slow, destructive lab work.
So I developed faster ways to detect them.
- Built portable X-ray fluorescence (XRF) methods to quantify metals directly in herbarium specimens and in the field.
- Applied it systematically to Queensland flora and uncovered previously unrecorded hyperaccumulators.
- Analysed around 27,000 XRF scans across four countries to refine the thresholds that define hyperaccumulation.
- Explored reflectance spectroscopy to tell hyperaccumulators apart by their optical signature, opening the door to detecting them from a distance.
The work spans seven chapters, from discovery methods to remote-sensing potential, and it is the scientific backbone behind much of the rare-earth and phytomining research on this site.