Leafy vegetables such as kale and cabbage could soon play an unexpected role in mining.
Researchers say these crops can extract toxic metals from contaminated soil and help supply materials for advanced technologies.
Scientists at the University of Queensland have identified a group of plants that naturally absorb heavy metals through their roots and store them in their tissues.
This process, known as phytomining, could offer a lower-impact alternative to traditional mining methods and reduce environmental damage.
Certain plants, known as hyperaccumulators, can draw toxic yet valuable metals from soil.
Members of the Brassicaceae family stand out for their ability to absorb thallium, a highly toxic but industrially important metal.
These include common vegetables such as kale, cabbage, broccoli, cauliflower, mustard, and Brussels sprouts.
Researchers have long monitored them for food safety due to this property.
Dr. Amelia Corzo-Remigio, a geochemist involved in the study, said these plants were already known to accumulate thallium.
However, scientists had not fully explored how they do it or how to use that ability.
“Thallium is extremely toxic, but it is also a valuable and industry critical metal used in medical technologies, optical glass, and semiconductors,” Dr. Corzo-Remigio said.
“So, while posing a significant health risk to humans, many of these same Brassicaceous plants could present a clear opportunity in sustainable mining.”
X-rays reveal mechanism
The research team used advanced imaging tools to understand how these plants store thallium. They combined micro-X-ray fluorescence and X-ray diffraction mapping to study live plants.
This approach gave researchers a detailed view of how the metal moves and settles within plant tissues.
“Simultaneous use of micro-X-ray fluorescence (μXRF) and X-ray diffraction mapping (XDM) on live kale plants gave us an unprecedented view of how and where thallium is located in these plants,” Dr. Corzo-Remigio said.
The team found that kale stores thallium in a crystallized form.
The metal appears as thallium chloride deposits along the veins inside leaves.
“In particular, we found thallium chloride crystal deposits along the veins inside the leaves.”
“This indicates potential for phytomining and, potentially, a sustainable thallium supply.”
This crystalline structure could make it easier to extract the metal using existing metallurgical techniques and scale up future recovery processes.
Researchers say phytomining could help address two major challenges at once. It can clean contaminated land while supplying critical materials.
Experts at the Sustainable Minerals Institute say demand for metals will grow with the expansion of renewable energy and medical technologies. Traditional mining methods often carry environmental costs.
Phytomining offers a different approach. It uses plants to recover metals from polluted or low-grade soils.
Dr. Corzo-Remigio said this dual benefit makes the method especially promising.
“There’s a dual need to remediate and rehabilitate soils while also supplying critical elements in the most sustainable way possible,” Dr. Corzo-Remigio said.
“It looks like plants in the Brassicaceae family can be part of the answer.”
The study is published in the journal Metallomics.