Sunday, November 25, 2001
Scientists Finding Fungi a Valuable Ally in Habitat Restoration
Mushrooms prove mettle breaking down pesticide and oil contamination
by Leslie R. Guttman, Chronicle Staff Writer
An offhand experiment in decontamination by a curious mushroom expert has led to technology that environmental scientists say could make dramatic repairs to the torn fabric of the globe's ecosystems.
When E. coli contamination threatened Paul Stamets' inlet in Olympia, Wash., the mycologist — on a lark — laid down some mushroom beds upland to filter the water. A year later, the coliform count had nearly disappeared.
Those mushroom mats have evolved into promising technology called mycoremediation, in which fungi work as eco-warriors to rapidly break down waste. Stamets partnered with a group of scientists at Pacific Northwest National Labs (PNNL) to create the technology.
Environmentalists call mycoremediation an elegant dance with the natural world that is radical in its simplicity.
Mushrooms, or fungi, feed off dead plants and animals, decomposing them in the process. Because the origin of many contaminants, including oil and gasoline, is in the natural world, their chemical structure is not so different than the normal fodder that mushrooms thrive on.
In mycoremediation, scientists train various fungal strains, alone or in combinations, to speed up the decomposition process and make it more efficient.
PNNL scientists Susan Thomas and Meg Pinza believe mycoremediation shows significant promise for cleaning up sites contaminated by pesticides and petroleum-based products, including shorelines damaged by the approximately 24,000 oil spills that, according to the Environmental Protection Agency, occur in the United States each year.
A 1998 field experiment with the Washington State Department of Transportation showed mycoremediation's promise. Scientists collected soil contaminated with oil and other petroleum compounds from the grubby floor of a maintenance yard in Bellingham, Wash. The dirt was divided into four piles, testing one with fungi, the other three with more traditional techniques.
About four weeks later, the tarps were pulled back. On the mound treated with fungi, oyster mushrooms were sprouting, the smell of oil had disappeared, the asphalt chunks were gone and there were no signs of tar and oil. The other mounds showed little change.
About eight weeks later, came another surprise on the now apparently nontoxic fungi mound: Flies came to hold a banquet on decaying mushrooms and other insects followed, attracting birds that brought seeds. A minihabitat was born.
Because chemical analysis later showed the oil was mixed unevenly through each original mound, Pinza and Thomas say they have to be more cautious than Stamets about calling the fungal-treated mound a complete success. But additional tests showed the mound treated with fungi was clean enough after the experiment to be used for landscaping.
Washington scientist Jack Word, one of the original researchers on the mycoremediation project, says the fungi appear to work so well that one day, it's conceivable you could eat a mushroom grown in an area once contaminated by nerve gas and not get sick.
The technology, experts say, also appears highly promising for cleaning up agricultural runoff, one of California's biggest environmental hurdles. Numerous state and local agencies, for example, are struggling to stem the damage caused by the Central Valley's polluted irrigation runoff. Cal-Fed, the joint state and federal agency trying to resolve California's long- running water wars, is spending $150 million over seven years in ecosystem restoration to protect the habitat for at least 20 species, including salmon.
Thomas, who heads up the Pacific Northwest mycoremediation team, says there are a handful of companies doing similar work around the world, but it's still a relatively new frontier. What makes their approach stand out, she says, is the strains are tailored to each site and are selected from a diverse biological library.
But licensing the technology, Thomas and Pinza say, is similar to getting a pharmaceutical drug approved. Its fate rests on getting funding to do evaluations that pass muster with federal, state and local regulators. Because mycoremediation's uses are so broad, the scientists say, that could take months to years, depending on the job.
Washington state EPA attorney Ann Prezyna wants to use the technology in waterways in Idaho, Oregon and Washington that have been contaminated by agricultural runoff, which threatens salmon restoration.
Mycoremediation "restores the natural community quite readily . . . quickly and cheaply. There just seems to be no downside," says Prezyna. "It's elegant."
Locally, Anna Moore, an environmental specialist in University of California at Berkeley's Department of Environment, Health and Safety, is working on a proposal to use the technology at the university's Richmond Field Station — a 120-acre piece of property used for research studies, with contamination ranging from diesel spills to heavy metals and PCBs. Moore also believes mycoremediation could clean up elevated levels of mercury, leftover from the gold-mining days, in sediment in the San Francisco Bay.
"From what I know, the costs are going to be low compared to digging (waste) up and disposing of it at formal waste contamination sites," says Moore. "And digging in the marsh and disturbing old sediment layers is not a good idea. Mycoremediation might actually take care of the problem in place."
Moore and her colleagues are now assessing the costs of cleaning up the site. Because Stamets' technology is so new, with relatively little proven commercial use, Moore is concerned her proposal will be a hard sell over traditional methods such as incineration and landfill disposal. But, Moore says, "I'm not going to give up." "If you send something away to a landfill, you haven't lost the liability," said Moore. "Liability is forever."
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