From Sanford Underground Research Facility-SURF: “Researchers evaluate SURF extremophiles in effort to trap carbon dioxide deep underground”

SURF-Sanford Underground Research Facility, Lead, South Dakota, USA.

From Sanford Underground Research Facility-SURF

Homestake Mining, Lead, South Dakota, USA.


Homestake Mining Company

September 7, 2021
Erin Lorraine Broberg

South Dakota Mines researchers study microbial acceleration of carbon mineralization with extremophiles found at SURF.

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Core samples, drilled from the drifts of SURF, contain colonies of microscopic life. Photo by Adam Gomez.

When first learning about the Sanford Underground Research Facility (SURF), it can help to imagine it as a vast, inverted apartment complex. Experiments move into the large, underground caverns. And SURF provides the usual amenities: electricity, running water, elevator maintenance, radon mitigation, liquid nitrogen deliveries and, of course, shielding from cosmic rays.

But amidst the facility’s 370 miles of tunnels, shafts and drifts, there is one group of tenants who pay no rent at all. At SURF, billions of microorganisms—known to biologists as “extremophiles” for their ability to carve out a living far from sunlight and with limited oxygen—live deep underground.

This summer, a research group from South Dakota Mines (Mines) retrieved a core sample—a smooth cylinder of grey rock—from 4,100 feet below of the surface of SURF. Under a microscope, it wriggled with SURF’s hardiest inhabitants.

From this sample, the research group hopes to find a microbe with a distinct set of characteristics that could help store excess greenhouse gases deep underground.

Locking away carbon dioxide

While extremophiles have slowly evolved to withstand their adverse habitat, scientists are on a mission to keep the Earth’s atmosphere as hospitable as possible. And so, a global effort is underway to store carbon dioxide (CO2) emissions in deep underground reservoirs. One promising method to keep it locked in place is called “carbon mineralization.”

“Carbon dioxide gas is captured from the atmosphere, then pumped in liquid form deep into underground rock formations,” said Bret Lingwall, a geotechnical, bio-geotechnical and earthquake engineering researcher, who leads the Mines research group. Deep underground, a chemical reaction transforms the CO2 into a stable, solid carbonate mineral—effectively trapping it for millennia.

But this process has a severe limitation: speed.

The crippling pace of the method’s chemical reaction is measured—not in weeks or months—but in years. Currently, the largest carbon mineralization project on Earth can sequester 10,000 tons of CO2 each year—barely a drop in the bucket when climatologists measure carbon emissions by the gigaton (one billion tons).

Meanwhile, Earth is in a bit of a rush.

For carbon mineralization to have an effect, the process desperately needs some added speed.

“What we are trying to do is to accelerate that timescale from a couple of years to a couple of weeks,” Lingwall said. “How we propose to do that is through microbial acceleration.”

Scientists have identified certain microbes that at the surface produce enzymes that can greatly accelerate carbon mineralization. “However, these microbes can’t stand the temperatures, pressures and acidic pH of the deep subsurface,” Lingwall said.

At depths of 4 to 8 kilometers deep, pressures are intense and temperatures climb to 60-90 degrees Celsius (140-194 degrees Fahrenheit). While these conditions are ideal for carbon storage, they aren’t hospitable to most microbes.

But most microbes weren’t born on the 4100 Level of SURF.

Enter: Extremophiles

Rajesh Sani, a microbiologist with the Mines research group, has studied various SURF extremophiles for 15 years. In that time, he’s worked with “thermophiles” a type of extremophile that can survive temperatures from 54 to 70 degrees Celsius (130 – 158 degrees Fahrenheit).

Sani will examine the gene expressions of microbes found in the core sample. “This process will give us an idea of how these microorganisms function, what are they eating, how they are breathing, how they are producing biomass, and how they are interacting with rock samples underground,” Sani said.

It will also help researchers determine if SURF’s extremophiles can produce the sought-after enzyme that hastens carbon mineralization.

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Magan Vaughn, a chemical and biological engineering masters student at South Dakota Mines, crushes a core sample from 4100 Level of Sanford Underground Research Facility, preparing the sample for DNA extraction. Photo by Tanvi Govil.

“Our project will sample and survey extremophiles from SURF, looking at their enzymatic genes to determine if any of them have the right profile to both survive deep underground and accelerate carbon mineralization,” Lingwall said.

Determining the rate

While the team’s microbiologists are sifting through microbial samples, other researchers are trying to establish just how quickly carbon mineralization takes place without extremophiles.

“Currently these types of experiments were replicated in the field, but not in laboratory environment. When you are conducting large scale investigations in the field, you are limited to the conditions (composition, pressure temperature, biological activity) that field site can offer,” said Gokce Ustunisik, a petrologist and high-temperature geochemist at Mines. “The beauty of experimental work is that you are the one—not Mother Nature—putting the controls on the system. You systematically change parameters, so that you can right away see the contribution of each parameter in a multi-component system.”

When her biology and engineering colleagues first described the temperatures and pressures needed for this research, Ustunisik thought, “High temperatures and pressures? Those are low temperatures and pressures!”

For Ustunisik, who studies the formation and evolution of the Moon, Mars and Earth, those parameters are quite low. In her experimental petrology lab, Ustunisik can easily replicate conditions comparable to the Earth’s lower crust and upper mantle, where temperatures begin at 1,400 degrees Celsius (2,552 degrees Fahrenheit).

But for this research, both the microbes and the deep subsurface create strict limitations for each other. The extremophiles must be hardy enough to survive the upper limits of life, while the rock formations must be deep and vast enough to store gigatons of carbon, without killing the extremophiles.

The key is finding an overlap.

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Earlier this summer, RESPEC researcher Brian Bormes and Gokce Ustunisik took initial observations of the core sample on the 4100 Level of Sanford Underground Research Facility. Photo courtesy Gokce Ustunisik.

Layers of expertise

Currently the two major inquiries—understanding the extremophiles and pinpointing carbon mineralization rates—are being done in parallel. In 2022, the group will introduce the microbes to the carbon mineralization process to see if the rate ticks up.

Many questions will guide the next phase of the research: Can SURF extremophiles accelerate the carbon mineralization process? If so, by how much? Can they adapt to different rock environments? Or are they limited to their native rock formations?

The effort, funded by an Eager Award from the National Science Foundation, brings together experts in geology, engineering, chemistry, petrology and microbiology.

“The novelty of this project is not necessarily the microbial acceleration of carbon mineralization. The real innovation is the bringing together of a team of different backgrounds to study this new, interesting, complex problem in a different way,” Lingwall said.

The current NSF grant supports two years of initial research. If, by the end of that period, the experiment’s results are promising, a larger experiment will be undertaken.

And, perhaps, these extremophiles might be worth their back rent after all.

See the full article here .


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About us: The Sanford Underground Research Facility-SURF in Lead, South Dakota, advances our understanding of the universe by providing laboratory space deep underground, where sensitive physics experiments can be shielded from cosmic radiation. Researchers at the Sanford Lab explore some of the most challenging questions facing 21st century physics, such as the origin of matter, the nature of dark matter and the properties of neutrinos. The facility also hosts experiments in other disciplines—including geology, biology and engineering.

The Sanford Lab is located at the former Homestake gold mine, which was a physics landmark long before being converted into a dedicated science facility. Nuclear chemist Ray Davis earned a share of the Nobel Prize for Physics in 2002 for a solar neutrino experiment he installed 4,850 feet underground in the mine.

Homestake closed in 2003, but the company donated the property to South Dakota in 2006 for use as an underground laboratory. That same year, philanthropist T. Denny Sanford donated $70 million to the project. The South Dakota Legislature also created the South Dakota Science and Technology Authority to operate the lab. The state Legislature has committed more than $40 million in state funds to the project, and South Dakota also obtained a $10 million Community Development Block Grant to help rehabilitate the facility.

In 2007, after the National Science Foundation named Homestake as the preferred site for a proposed national Deep Underground Science and Engineering Laboratory (DUSEL), the South Dakota Science and Technology Authority (SDSTA) began reopening the former gold mine.

In December 2010, the National Science Board decided not to fund further design of DUSEL. However, in 2011 the Department of Energy, through the Lawrence Berkeley National Laboratory, agreed to support ongoing science operations at Sanford Lab, while investigating how to use the underground research facility for other longer-term experiments. The SDSTA, which owns Sanford Lab, continues to operate the facility under that agreement with Berkeley Lab.

The first two major physics experiments at the Sanford Lab are 4,850 feet underground in an area called the Davis Campus, named for the late Ray Davis. The Large Underground Xenon (LUX) experiment is housed in the same cavern excavated for Ray Davis’s experiment in the 1960s.

In October 2013, after an initial run of 80 days, LUX was determined to be the most sensitive detector yet to search for dark matter—a mysterious, yet-to-be-detected substance thought to be the most prevalent matter in the universe. The The U Washington MAJORANA Neutrinoless Double-beta Decay Experiment Demonstrator experiment (US), also on the 4850 Level, is searching for a rare phenomenon called “neutrinoless double-beta decay” that could reveal whether subatomic particles called neutrinos can be their own antiparticle. Detection of neutrinoless double-beta decay could help determine why matter prevailed over antimatter. The Majorana Demonstrator experiment is adjacent to the original Davis cavern.

The LUX Xenon dark matter detector | Sanford Underground Research Facility mission was to scour the universe for WIMPs, vetoing all other signatures. It would continue to do just that for another three years before it was decommissioned in 2016.

In the midst of the excitement over first results, the LUX collaboration was already casting its gaze forward. Planning for a next-generation dark matter experiment at Sanford Lab was already under way. Named LUX-ZEPLIN (LZ), the next-generation experiment would increase the sensitivity of LUX 100 times.

SLAC National Accelerator Laboratory(US) physicist Tom Shutt, a previous co-spokesperson for LUX, said one goal of the experiment was to figure out how to build an even larger detector.

“LZ will be a thousand times more sensitive than the LUX detector,” Shutt said. “It will just begin to see an irreducible background of neutrinos that may ultimately set the limit to our ability to measure dark matter.”

We celebrate five years of LUX, and look into the steps being taken toward the much larger and far more sensitive experiment.

Another major experiment, the Long Baseline Neutrino Experiment (LBNE)—a collaboration with Fermi National Accelerator Laboratory (Fermilab) and Sanford Lab, is in the preliminary design stages. The project got a major boost last year when Congress approved and the president signed an Omnibus Appropriations bill that will fund LBNE operations through FY 2014. Called the “next frontier of particle physics,” LBNE will follow neutrinos as they travel 800 miles through the earth, from FermiLab in Batavia, Ill., to Sanford Lab.

FNAL DUNE LBNF (US) from FNAL to SURF, Lead, South Dakota, USA

FNAL DUNE LBNF (US) Caverns at Sanford Lab.

The MAJORANA DEMONSTRATOR will contain 40 kg of germanium; up to 30 kg will be enriched to 86% in 76Ge. The DEMONSTRATOR will be deployed deep underground in an ultra-low-background shielded environment in the Sanford Underground Research Facility (SURF) in Lead, SD. The goal of the DEMONSTRATOR is to determine whether a future 1-tonne experiment can achieve a background goal of one count per tonne-year in a 4-keV region of interest around the 76Ge 0νββ Q-value at 2039 keV. MAJORANA plans to collaborate with Germanium Detector Array (or GERDA) experiment is searching for neutrinoless double beta decay (0νββ) in Ge-76 at the underground Laboratori Nazionali del Gran Sasso (LNGS) for a future tonne-scale 76Ge 0νββ search.

CASPAR is a low-energy particle accelerator that allows researchers to study processes that take place inside collapsing stars.

The scientists are using space in the Sanford Underground Research Facility (SURF) in Lead, South Dakota, to work on a project called the Compact Accelerator System for Performing Astrophysical Research (CASPAR). CASPAR uses a low-energy particle accelerator that will allow researchers to mimic nuclear fusion reactions in stars. If successful, their findings could help complete our picture of how the elements in our universe are built. “Nuclear astrophysics is about what goes on inside the star, not outside of it,” said Dan Robertson, a Notre Dame assistant research professor of astrophysics working on CASPAR. “It is not observational, but experimental. The idea is to reproduce the stellar environment, to reproduce the reactions within a star.”