Editor's Note: Today we welcome Alison Kroulek to the writing team. Alison is based in Chattanooga, Tennessee, and her first post is a very interesting look at how we can harness nature to heal nature.
In Fort Bragg, California, one of the main industries in town used to be a redwood mill operated by Georgia-Pacific. The mill is closed now, but like many industrial sites, a toxic legacy lives on in the soil. In 2001-2, the mill burned wood from landfills to create power. The ash piles are now contaminated with a nasty little chemical called dioxin, which can be produced whenever organic materials are burned. At least, that’s the official version of how the site came to be contaminated.
This earlier report from the San Francisco Chronicle hints at more serious environmental misdeeds, such as dumping dioxin-containing oils. Although dioxin is a natural substance, in unnaturally high concentrations it is known to cause cancer and other diseases. According to the World Health Organization, dioxin is one of the “dirty dozen,” the worst of the long-lasting chemical pollutants.
Current plans call for cleaning up the area by digging up the contaminated soil, and then either shipping it off to landfills or creating a landfill for it onsite and burying it, with a plastic liner to keep the waste out of the environment. The New York Times reports that many residents of the city would like to try a different method: mushrooms. Yes, you read that last part right: mushrooms. If you didn’t know any better, you might be tempted to write these folks off as a bunch of old hippies on a crazy mushroom trip. Well, put this in your pipe and smoke it -- many species of mushrooms are actually powerful bioremediators, natural organisms that help break down pollutants. They colonize contaminated soil, and then secrete enzymes that break down the offending chemicals into nontoxic components. The result is clean soil and lots of mushrooms.
The advantage of using bioremediation is that instead of simply encasing the pollutants in plastic and isolating them from the rest of the environment, bioremediation can actually remove the pollutants from the environment completely. For help, the town turned to mushroom guru Paul Stamets, who pioneered the idea of mycoremediation, or bioremediation using mushrooms. This video shows Stamets describing the results of an experiment in bioremediation using oyster mushrooms to clean up soil contaminated with oil:
In 2007, mushrooms and human hair were used by volunteers to clean up a portion of the Cosco Busan spill in San Francisco Bay. Oyster mushrooms, an edible species, do such a good of breaking down these chemicals that the fungus itself remains uncontaminated and safe to eat-although you might have a hard time finding a market for it.
According to Stamets, mushrooms can also be used to filter agricultural run-off for contaminants such as the E coli bacterium. Even more amazing, one species of mushroom can break down VX nerve gas, a toxin that takes hundreds of years to break down on its own! It is truly amazing how many tools nature has to keep the environment clean, and even more amazing how much damage we humans manage to do to it anyway.
Mycoremediation is still a relatively new technology, and it takes time for the mushrooms to decontaminate large amounts of soil. Despite local residents’ hopes, it may not be feasible to use this process to clean up the entire site. In fact, Georgia-Pacific, who is in charge of the clean-up, does not seem to want to consider it as an alternative option at this time. For example, here is an excerpt from a document the company issued to respond to questions about the clean up process:
Can mushroom bioremediation be used to treat dioxins in soil?Although Georgia-Pacific does not consider bioremediation to be a workable solution to the problem in Fort Bragg, the city has resolved to approve the landfill only if pilot studies on mycoremediation can be performed during the clean-up. With any luck, these studies will uncover ways to use mushrooms to clean up pollution on a larger scale at other sites in the future.
Not at this time. As stated in the RAP, the DTSC and other treatment scientists consider bioremediation of dioxins in soil with mushrooms to be an unproven and thus far ineffective technology. The studies to date have largely been limited to laboratory scale. A few field trials have been done, but success was limited as the mushrooms only reduced concentrations of dioxin about 50% over more than a year in just a few cubic yards of material. – Response to Questions about the Remedial Action Plan (RAP) for the Coastal Trail and Parkland at the GP Mill Site