Nav: Home

Mining for answers on abandoned mines

May 31, 2017

Soil scientist Jim Ippolito believes in local solutions to local problems. The problem he's working on is contaminated soils near abandoned mines.

In the western United States 160,000 abandoned mines contaminate soils in the region. Ippolito, associate professor of soil science at Colorado State University, hopes to solve this problem with biochar, a charcoal-like substance that can reduce the toxic consequences of mining for metals.

Biochar is made by burning plant material in a low-oxygen kiln. Ippolito proposes using western states plant materials such as dead lodge pole pine trees or pesky, nuisance trees--like the invasive tamarisk--as fodder for the kiln.

"I thought, why don't we just use this stuff to make biochar?" said Ippolito. "It's using local materials to solve a local problem."

Abandoned mine sites are common in western states. Over the years, extracting precious metals like gold or silver left a legacy of high acidity in mining-affected soils.

"When you dig holes in the ground via mining and pull out rock that hasn't seen the atmosphere in millions of years, the materials undergo a change," said Ippolito. "These materials can start to acidify."

When certain rock minerals are exposed to the atmosphere, they can form sulfuric acid. The sulfuric acid spreads like an infection, breaking down rocks around it. Some of these rocks contain heavy metals, like lead or copper, and most of the time the metals are harmless. The heavy metals turn into a problem when they become bioavailable--or when plants are able absorb them. Sulfuric acid makes metals more bioavailable to plants by releasing metals from rocks.

"A good analogy would be that the process sort of works just like the way our stomach acid works to break down food into components that are bioavailable to us," said Ippolito.

The bioavailable heavy metals can pass into plant cell membranes and poison the plant. "You'll find places near abandoned mines that are completely void of vegetation because of elevated bioavailable metals," said Ippolito.

Most people cleaning up old mine sites mix lime into the soil to reduce acidity. Less acidity in the soil means less opportunity for plants to absorb heavy metals, because the metals change form from more to less bioavailable in the presence of lime.

Instead of lime, Ippolito wants to use biochar to reduce soil acidity. Biochar is typically produced by heating plant material in a sealed environment. "Basically you take wood, put it into a drum, seal it, and start a fire underneath it," said Ippolito. "The material that's left in the drum looks like charcoal."

The research on the uses of biochar is extensive: it's been tested as a water purifier, a fertilizer, a carbon sink and more. Ippolito's biochar is special because it's made from local trees that pose problems in western states. One of the trees is the lodge pole pine. Mountain pine beetles have decimated millions of acres of the lodge pole pine in western states and Canada. Rows and rows of trees lay like matchsticks. In dry regions, felled pines are a tinderbox for forest fires. Ippolito said making something useful from flammable, wasted trees can only be a good thing. He's also proposing using tamarisk as a biochar feedstock. Tamarisk is an invasive species in western states. It clogs watersheds, robbing nutrients and water from native species.

The researchers made biochar from both trees and mixed it into four different soils from abandoned mine sites in Colorado and Idaho. They analyzed the bioavailability of the metals present in the soil. Both biochar types decreased soil acidity in all four soils. The biochar successfully interrupted the toxic combination of acidified soils and heavy metals, converting those metals to less bioavailable forms.

Ippolito's next step is to take his locally-sourced biochar into the field. He said he's ready to put it to use. "I've spent at least a decade testing biochars in the lab and greenhouse," he said. "It's finally time to apply the biochar to some mine sites." Ippolito is working with the USDA Agricultural Research Service to test the biochar on a western U.S. mine site as well as in Missouri.
-end-
Ippolito collaborated with a team of scientists from the USDA Agricultural Research Service, the University of Idaho, and two private entities in Colorado (Confluence Energy in Kremmling, CO and Ascension Soil Co. in Evergreen, CO). Their work is published in the Journal of Environmental Quality.

American Society of Agronomy

Related Heavy Metals Articles:

Sunscreens release metals and nutrients into seawater
Beachgoers are becoming increasingly aware of the potentially harmful effects UV filters from sunscreens can have on coral and other marine organisms when the protective lotions wash off their bodies into the ocean.
Bending the rules: A revolutionary new way for metals to be malleable
For nearly 100 years, scientists thought they understood everything there was to know about how metals bend.
How light steers electrons in metals
Researchers in the Department of Physics of ETH Zurich have measured how electrons in so-called transition metals get redistributed within a fraction of an optical oscillation cycle.
BioSA -- Bridging the gap with biodegradable metals
The University of Malta has teamed up with Mater Dei Hospital to address the shortcomings of current bone scaffolds on the market in a project entitled Biodegradable Iron for Orthopaedic Scaffold Applications -- BioSA.
Earth's heavy metals result of supernova explosion, University of Guelph Research Reveals
New research by a University of Guelph physicist suggests most of Earth's heavy metals were spewed from a largely overlooked kind of star explosion called a collapsar.
More Heavy Metals News and Heavy Metals Current Events

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Erasing The Stigma
Many of us either cope with mental illness or know someone who does. But we still have a hard time talking about it. This hour, TED speakers explore ways to push past — and even erase — the stigma. Guests include musician and comedian Jordan Raskopoulos, neuroscientist and psychiatrist Thomas Insel, psychiatrist Dixon Chibanda, anxiety and depression researcher Olivia Remes, and entrepreneur Sangu Delle.
Now Playing: Science for the People

#537 Science Journalism, Hold the Hype
Everyone's seen a piece of science getting over-exaggerated in the media. Most people would be quick to blame journalists and big media for getting in wrong. In many cases, you'd be right. But there's other sources of hype in science journalism. and one of them can be found in the humble, and little-known press release. We're talking with Chris Chambers about doing science about science journalism, and where the hype creeps in. Related links: The association between exaggeration in health related science news and academic press releases: retrospective observational study Claims of causality in health news: a randomised trial This...