Earth provides us with over 10,000 different mushrooms, several hundred of which we can eat, with many that are absolutely delicious and highly prized in culinary realms. Foraging for or cultivating mushrooms has provided humans with nourishment, adventure and connection to nature for millennia. With so many identified varieties of mushrooms, and countless others yet to be discovered, even the most learned mushroom enthusiasts encounter fungi they can’t identify. In fact, there is an affectionate term for many such specimens: LBMs or Little Brown Mushrooms.
While the woods are filled with LBMs, over the last half century cities have become increasingly filled with LBMs of their own: Lamentable Brownfield Messes.
Brownfields are pieces of land in urban settings that were previously used for industrial purposes and whose expansion, reuse, or redevelopment is complicated by the presence of pollutants, contaminants, or other hazardous substances. In a study conducted nearly 20 years ago, Professor of Urban Studies Robert A. Simons estimated that there were more than half a million brownfield sites in the United States. This is nearly 5% of the land in these areas, places that were once factories, vehicle storage or service facilities, or simply buildings constructed with hazardous materials, such as lead and asbestos, which fell into disuse.
The Oregon Brownfields Coalition estimates there are more than 13,000 brownfields in the state, which is only the 27th most populous in the country. Several hundred of these are in Multnomah County which includes Portland – a city that has seen increased demand for housing where home prices jumped by 15% in 2016. Having so much unutilized space in an area of high demand pushes the real estate market upwards and puts pressure on suburban development. Reclaiming these abandoned spaces would make nearly a thousand of acres available for urban infill and improve the overall quality of life and the environment in one of America’s most dynamic cities.
The US Environmental Protection Agency began making grant funding available for brownfield clean-up in 1995, and since then more than $190 million has been used to remediate over 1,000 sites which has been found to have a direct impact on the livability, and real estate values, in urban areas. Cleanup efforts, while positively impacting urban areas, are not environmentally, or revenue, neutral and, in many cases, come at a steep environmental and economic cost. Contaminated land is generally excavated with heavy earth-moving equipment and shipped to landfills or cleaned through arduous washing or vapor-extraction techniques. Polluted soil that is moved from one place to another is still polluted, and it has high embedded carbon costs for transport and extraction. Cleaning processes can be expensive and can involve harsh chemicals that present different environmental dilemmas.
Over the last few decades, mycologists in the Pacific Northwest have been pioneering efforts to use mushrooms to clean-up toxic soil and remove harmful contaminants, leading to impressive results and the potential for a future where Lamentable Brownfield Messes are cleansed with the help of Little Brown Mushrooms –and quite a few white ones, too.
Known as mycoremediation, this technique uses fungi to degrade and remove toxins from the soil. The process involves mixing mycelium, which is a membrane of interweaving and constantly branching chains of cells that constitute the vegetative part of a fungus, into contaminated soil under careful conditions.
Mycelium is efficient and pervasive throughout the world’s soil. While mycelial strands are a mere one-cell wall thick, if you took a cubic inch of topsoil and could lay the strands inside end to end they would stretch for over eight miles.
Mycologist and author Paul Stamets and his company Fungi Perfecti have been involved in research projects that have led to breakthroughs in the field. Stamets collaborated with the Washington Department of Transportation on an experimental remediation of soil from a site that had been used for diesel truck maintenance for over 30 years. The level of diesel and oil contamination at the site was nearly 20,000 parts per million, meaning that 2% of the soil composition was actually fuel contaminants – about the same concentration detected on beaches after the Exxon Valdez spilled 11 million gallons (41.6 million liters) of crude oil into the Prince William Sound in 1989.
Soil was inoculated with oyster mushrooms, a white rot fungus that grows on wood and other organic plant matter and produces enzymes that break down carbon bonds and dissolve the fiber in its host. As the fossilized remains of ancient plants, petroleum has very a similar carbon bond structure.
After four weeks, the contaminated soil had changed in color from dark black to light brown and had produced a massive flush of oyster mushrooms, some of which were 12 inches (30.5 centimeters) in diameter. By eight weeks, the level of contamination had gone from 20,000 parts per million to 200 parts per million. Perhaps even more amazingly, the mushrooms contained no detectable petroleum residues, having dissolved them with the remaining by-products being carbon dioxide, water, and, of course, mushrooms.
Since these initial experiments, companies like Fungi For The People, based in Eugene, Oregon, have begun offering workshops that teach mycoremediation techniques that are used to cleanup residue in bicycle repair shops and polluted garden soil.
Community organizations like Commonwealth Urban Farms in Oklahoma City are currently conducting pilot studies with elm oyster mushrooms to remediate contaminated lots that will be turned into urban gardens, and advocacy groups like the Green Building Alliance are beginning to recommended mycoremediation as a tool for restoring brownfields.
Mycoremediation is also proving to be effective at cleaning contamination from pesticides, chemical warfare agents, and some heavy metals. Stamets has done extensive research to find different species of mushrooms that are best suited for each type of contaminant – including indications that several varieties of boletes remove radioactive cesium from soils. He details his findings in his book Mycelium Running: How Mushrooms Can Help Save the World.
And while Stamets and other researchers caution that there is still much to learn about mycoremediation and how it can be most effectively used, there are emerging opportunities for mycoremediation contractors, community organizations and property owners to use the technique to heal urban spaces in a manner that makes ecological sense while adding to the body of knowledge on this amazing restoration approach. Besides, it doesn’t look like we will be running out of brownfields anytime soon.