This article has been reviewed in accordance with the Science X editorial process and policies. The editors have highlighted the following attributes while ensuring the credibility of the content:
In an industrial wasteland in Los Angeles, Kreigh Hampel is uprooting California buckwheat with a pitchfork to find out how much lead it has absorbed.
The plant’s delicate white and pink flowers belie an amazing cleaning power, which scientists believe could be harnessed to remove dangerous pollutants and even recycle them.
“That’s the miracle of life,” enthuses Hampel, 68, who volunteers on the project.
“Plants really can do this job and they know how to do it, they have done it many times over millions of years,” he says.
The experiment is part of a University of California Riverside-led project that has spread carefully selected plants and fungi on this former industrial site in hopes of getting rid of the heavy metals and petrochemicals that have contaminated the area for decades.
Danielle Stevenson, who is leading the study, says that such bioremediation techniques can be much more cost-effective than traditional techniques.
“The conventional method of cleaning up sites is to just dig up all the contaminated soil and dump it somewhere else,” he told AFP.
“That approach doesn’t really solve the problem, does it? It just moves it somewhere else.” And, he says, it costs a lot of money.
Stevenson’s project, which is taking place at three sites in and around Los Angeles, is priced at around $200,000 and is showing very promising results so far.
Solar Powered Vacuums
“In three months, we had a 50 percent reduction in petrochemicals and then in six months, we were getting pretty close (to that level) with some of the metals,” he said.
Stevenson, a mycologist by training, has chosen her anti-contamination weapons carefully.
Oyster mushrooms have been incorporated into the soil due to their natural role in decomposition: their underground part, called mycelium, absorbs diesel.
“Those same fungi that in nature would eat a dead tree will also recognize diesel, for example, as a food source.
“The reason is that it’s basically the same thing. A lot of our fossil fuels are dead things that have been compressed over long periods of time.”
Several California native plants, including telegraph grass and California bush sunflower, are particularly good at absorbing heavy metals.
Stevenson thinks of plants essentially as “solar-powered vacuum cleaners: they basically suck metals, like lead, into their bodies.
“When we pull up the plants, we remove the lead from the soil.”
Lead and other metals can then be recovered from those plants and even reused.
Throughout the United States and the industrialized world, commercial sites that outlive their useful lives for the companies that pollute them are often simply abandoned, Stevenson says.
The onus to correct them falls to underfunded or ill-equipped local authorities, who are struggling to find the money or the expertise.
Historically, the problem is worse in working-class or minority-ethnic neighborhoods, where politicians feel better able to ignore complaints.
In the United States, where the Environmental Protection Agency lists nearly 1,900 problem sites, only a small number of cleanup projects take place each year, Stevenson says.
She hopes a cheaper method will allow more sites to be cleaned.
‘The last of us’
Proponents say the uses of bioremediation aren’t limited to repairing old industrial sites. The process can also be used to help clean up toxic ash left behind by some wildfires, an annual problem in fire-prone California.
So why is this technique still so underdeveloped?
“Bioremediation is still considered risky,” explains Bill Mohn, professor of microbiology at the University of British Columbia in Canada.
Unlike with soil excavation, “it is difficult to guarantee that the required level of contaminants will be consistently achieved.
“Whereas we know that if you dig up the earth and send it to someone who will take it if you pay them, then you have solved your problem.”
Meanwhile, Stevenson points to unhealthy prejudices about fungi: Think of the terrifying mushrooms that infect zombies on HBO’s hit series “The Last of Us.”
“I get asked all the time, ‘If you introduce a fungus to clean up a place, will it take over, eat our house and take over the world?'” he says.
It won’t, he hastens to add.
But that’s why it’s important to perform this kind of experiment in a real-world setting, not just in a lab.
“I think once we get more field testing of these methods, people will feel more confident choosing some of these approaches,” he says.