Researchers have made a fascinating discovery regarding the potential use of common fungi in mitigating the hazards associated with uranium contamination. According to a recent study, a type of fungi can effectively grow on and chemically lock away uranium, including depleted uranium (DU), thereby reducing its mobility and potential harm to the environment. This breakthrough finding opens up valuable avenues for the safe handling and disposal of uranium waste.
A humble fungi found in most back gardens could help clean up battlefields contaminated with depleted uranium. At present, sites can be partial decontaminated by physically collecting and disposing of fragments from shells. However, radioactive particles and dust from explosions remain in the soil, preventing full reclamation.
Now, a research team in Scotland has established that common fungi can grow on and chemically lock away the offending uranium. As their hyphal filaments sprawled across fragments of depleted uranium, the tubules gradually became coated in a yellowy mineral.
This, it turned out, locked the uranium into a chemical form inaccessible to biological organisms, and unlikely to dissolve into surface waters. At twice the density of lead, depleted uranium is added to weapons to give them extra force to penetrate targets. But the complete fallout from exploding missiles is impossible to collect physically. This means that hazardous radioactive uranium-235 in the material, which can cause kidney toxicity and has been linked with nerve damage and lung cancer, can persist in the environment for decades.
Well, decades might be a bit of an understatement. It takes, due to the physical half-life (which is 4.468 billion years for uranium-238) BILLIONS of years for DU to reach half it’s level of radiation! We humans can barely think and plan beyond seasonal news cycles. Read more about DU in the environment.
Eat your heavy elements
“The fungal-produced minerals are capable of long-term uranium retention, so this may help prevent uptake of uranium by plants, animals and microbes,” says team leader Geoffrey Gadd of the University of Dundee. “It might also prevent the spent uranium from leaching out from the soil,” he says.
Essentially, the fungi form uranyl phosphate minerals which stabilise the uranium. “They change its chemistry from being highly chemically unstable and reactive metallic uranium to one of the most chemically stable forms, thus preventing uranium migration through the food chain,” says Gadd.
Gadd says that any clean-up operation based on the fungi would be very low-tech. All that would be needed in practice would be to add moisture and nutrients to soil to help fungi flourish.
“You can go to just about any soil, and you’d find fungi that would lock away uranium,” he says. “You could literally pick them from your own back garden.”
Depleted deleted
But he cautions that the minerals probably couldn’t ever be considered harmless as they still contain uranium, and this could still be toxic if eaten. Nor have the Dundee team yet worked out a practical way to collect and dispose of the trapped uranium. The finding itself was a bonus in research mainly aimed at tracing the environmental fate of uranium. “Our work is only very preliminary,” he says. Ultimately, it might be possible to devise practical ways of using the fungi to decontaminate sites, Gadd says.
Journal reference: Current Biology (vol 18, R375). – ns
Exploiting nature’s own processes, scientists envision a future where fungi can be utilized to sequester, immobilize, and transform uranium, effectively reducing its environmental impact.