Researchers at the University of Queensland have identified certain leafy vegetables, including kale, broccoli, and cabbage, as potential tools for extracting valuable metals from contaminated soil.
Using advanced X-ray imaging, the team found that plants in the Brassicaceae family act as 'hyperaccumulators,' drawing toxic heavy metals like thallium into their roots and shoots.
University of Queensland geochemist Dr. Amelia Corzo-Regigio said powerful X-rays confirmed these crops have strong 'phytomining' potential due to their natural ability to extract thallium from polluted environments.
While thallium is extremely toxic to humans, it is a critical component in the production of semiconductors, optical glass, and medical technologies.
A sustainable mining alternative
By studying live kale plants with micro-X-ray fluorescence and X-ray diffraction mapping, the researchers located thallium chloride crystal deposits along the veins inside the leaves.
Dr. Corzo-Remigio said this crystallized form makes the metal compatible with existing metallurgical extraction methods.
"This indicates potential for phytomining and, potentially, a sustainable thallium supply," Dr. Corzo-Remigio said.
Researchers at the Sustainable Minerals Institute (SMI) believe these non-conventional mining methods will be essential for securing metals needed for the global transition to renewable energy.
Dr. Corzo-Remigio noted that the process offers a way to address two problems at once: the need to rehabilitate contaminated mining sites and the rising demand for critical elements.
"It looks like plants in the Brassicaceae family can be part of the answer," she said.
The research was published in the journal Metallomics and involved collaborators from the University of Adelaide, Queensland University of Technology, and the Deutsches Elektronen-Synchrotron in Germany.