Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Study in 'Science' finds missing piece of biogeochemical puzzle in aquifers

02.05.2014

A study published today in Science by researchers from the U.S. Department of Energy’s Argonne National Laboratory may dramatically shift our understanding of the complex dance of microbes and minerals that takes place in aquifers deep underground. This dance affects groundwater quality, the fate of contaminants in the ground and the emerging science of carbon sequestration.

Deep underground, microbes don’t have much access to oxygen. So they have evolved ways to breathe other elements, including solid minerals like iron and sulfur.

The part that interests scientists is that when the microbes breathe solid iron and sulfur, they transform them into highly reactive dissolved ions that are then much more likely to interact with other minerals and dissolved materials in the aquifer. This process can slowly but steadily make dramatic changes to the makeup of the rock, soil and water.

“That means that how these microbes breathe affects what happens to pollutants — whether they travel or stay put — as well as groundwater quality,” said Ted Flynn, a scientist from Argonne and the Computation Institute at the University of Chicago and the lead author of the study.

... more about:
»APS »Computation »Iron »Laboratory »Photon »Science »energy »microbes

About a fifth of the world’s population relies on groundwater from aquifers for their drinking water supply, and many more depend on the crops watered by aquifers.

For decades, scientists thought that when iron was present in these types of deep aquifers, microbes who can breathe it would out-compete those who cannot. There’s an accepted hierarchy of what microbes prefer to breathe, according to how much energy each reaction can theoretically yield. (Oxygen is considered the best overall, but it is rarely found deep below the surface.)

According to these calculations, of the elements that do show up in these aquifers, breathing iron theoretically provides the most energy to microbes. And iron is frequently among the most abundant minerals in many aquifers, while solid sulfur is almost always absent.

But something didn’t add up right. A lot of the microorganisms had equipment to breathe both iron and sulfur. This requires two completely different enzymatic mechanisms, and it’s evolutionarily expensive for microbes to keep the genes necessary to carry out both processes. Why would they bother, if sulfur was so rarely involved?

The team decided to redo the energy calculations assuming an alkaline environment—“Older and deeper aquifers tend to be more alkaline than pH-neutral surface waters,” said Argonne coauthor Ken Kemner—and found that in alkaline environments, it gets harder and harder to get energy out of iron.

“Breathing sulfur, on the other hand, becomes even more favorable in alkaline conditions,” Flynn said.

The team reinforced this hypothesis in the lab with bacteria under simulated aquifer conditions. The bacteria, Shewanella oneidensis, can normally breathe both iron and sulfur. When the pH got as high as 9, however, it could breathe sulfur, but not iron.

There was still the question of where microorganisms like Shewanella could find sulfur in their native habitat, where it appeared to be scarce.

The answer came from another group of microorganisms that breathe a different, soluble form of sulfur called sulfate, which is commonly found in groundwater alongside iron minerals. These microbes exhale sulfide, which reacts with iron minerals to form solid sulfur and reactive iron. The team believes this sulfur is used up almost immediately by Shewanella and its relatives.

“This explains why we don’t see much sulfur at any fixed point in time, but the amount of energy cycling through it could be huge,” Kemner said.

Indeed, when the team put iron-breathing bacteria in a highly alkaline lab environment without any sulfur, the bacteria did not produce any reduced iron.

“This hypothesis runs counter to the prevailing theory, in which microorganisms compete, survival-of-the-fittest style, and one type of organism comes out dominant,” Flynn said. Rather, the iron-breathing and the sulfate-breathing microbes depend on each other to survive.

Understanding this complex interplay is particularly important for sequestering carbon. The idea is that in order to keep harmful carbon dioxide out of the atmosphere, we would compress and inject it into deep underground aquifers. In theory, the carbon would react with iron and other compounds, locking it into solid minerals that wouldn’t seep to the surface.

Iron is one of the major players in this scenario, and it must be in its reactive state for carbon to interact with it to form a solid mineral. Microorganisms are essential in making all that reactive iron. Therefore, understanding that sulfur—and the microbe junkies who depend on it—plays a role in this process is a significant chunk of the puzzle that has been missing until now.

The study, “Sulfur-Mediated Electron Shuttling During Bacterial Iron Reduction,” appears online today in the May 1 edition of Science Express and will be published in Science at the end of the month. Other authors on the study were Argonne scientists Bhoopesh Mishra (also of the Illinois Institute of Technology) and Edward O’Loughlin and Georgia Tech scientist Thomas DiChristina.

Funding for the research was provided by the U.S. Department of Energy’s Office of Science. The Advanced Photon Source (APS) is also supported by the DOE’s Office of Science. The team conducted X-ray analysis at the APS GeoSoilEnviroCARS beamline 13-ID-E, which is operated by the University of Chicago and jointly supported by the National Science Foundation and the DOE’s Office of Science. Additional support came from the National Institutes of Health and the National Science Foundation.

T‪he Computation Institute (CI), a joint institute of the University of Chicago and Argonne National Laboratory, is an intellectual nexus for scientists and scholars pursuing multi-disciplinary research, and a resource center for developing and applying innovative computational approaches. Founded in 1999, it is home to over 200 faculty, fellows, and staff researching complex, system-level problems in such areas as biomedicine, energy and climate, astronomy and astrophysics, computational economics, social sciences and molecular engineering. CI is home to diverse projects including the Center for Robust Decision Making on Climate and Energy Policy, the Center for Multiscale Theory and Simulation, the Urban Center for Computation and Data and Globus.

The Advanced Photon Source at Argonne National Laboratory is one of five national synchrotron radiation light sources supported by the U.S. Department of Energy’s Office of Science to carry out applied and basic research to understand, predict, and ultimately control matter and energy at the electronic, atomic, and molecular levels, provide the foundations for new energy technologies, and support DOE missions in energy, environment, and national security. To learn more about the Office of Science X-ray user facilities, visit the user facilities directory.

Argonne National Laboratory seeks solutions to pressing national problems in science and technology. The nation's first national laboratory, Argonne conducts leading-edge basic and applied scientific research in virtually every scientific discipline. Argonne researchers work closely with researchers from hundreds of companies, universities, and federal, state and municipal agencies to help them solve their specific problems, advance America's scientific leadership and prepare the nation for a better future. With employees from more than 60 nations, Argonne is managed by UChicago Argonne, LLC for the U.S. Department of Energy's Office of Science. For more, visit www.anl.gov.

DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, visit science.energy.gov

Brian Grabowski | Eurek Alert!
Further information:
http://www.anl.gov/articles/study-science-finds-missing-piece-biogeochemical-puzzle-aquifers

Further reports about: APS Computation Iron Laboratory Photon Science energy microbes

More articles from Studies and Analyses:

nachricht New study: How does Europe become a leading player for software and IT services?
03.04.2017 | Fraunhofer-Institut für System- und Innovationsforschung (ISI)

nachricht Reusable carbon nanotubes could be the water filter of the future, says RIT study
30.03.2017 | Rochester Institute of Technology

All articles from Studies and Analyses >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Making lightweight construction suitable for series production

More and more automobile companies are focusing on body parts made of carbon fiber reinforced plastics (CFRP). However, manufacturing and repair costs must be further reduced in order to make CFRP more economical in use. Together with the Volkswagen AG and five other partners in the project HolQueSt 3D, the Laser Zentrum Hannover e.V. (LZH) has developed laser processes for the automatic trimming, drilling and repair of three-dimensional components.

Automated manufacturing processes are the basis for ultimately establishing the series production of CFRP components. In the project HolQueSt 3D, the LZH has...

Im Focus: Wonder material? Novel nanotube structure strengthens thin films for flexible electronics

Reflecting the structure of composites found in nature and the ancient world, researchers at the University of Illinois at Urbana-Champaign have synthesized thin carbon nanotube (CNT) textiles that exhibit both high electrical conductivity and a level of toughness that is about fifty times higher than copper films, currently used in electronics.

"The structural robustness of thin metal films has significant importance for the reliable operation of smart skin and flexible electronics including...

Im Focus: Deep inside Galaxy M87

The nearby, giant radio galaxy M87 hosts a supermassive black hole (BH) and is well-known for its bright jet dominating the spectrum over ten orders of magnitude in frequency. Due to its proximity, jet prominence, and the large black hole mass, M87 is the best laboratory for investigating the formation, acceleration, and collimation of relativistic jets. A research team led by Silke Britzen from the Max Planck Institute for Radio Astronomy in Bonn, Germany, has found strong indication for turbulent processes connecting the accretion disk and the jet of that galaxy providing insights into the longstanding problem of the origin of astrophysical jets.

Supermassive black holes form some of the most enigmatic phenomena in astrophysics. Their enormous energy output is supposed to be generated by the...

Im Focus: A Quantum Low Pass for Photons

Physicists in Garching observe novel quantum effect that limits the number of emitted photons.

The probability to find a certain number of photons inside a laser pulse usually corresponds to a classical distribution of independent events, the so-called...

Im Focus: Microprocessors based on a layer of just three atoms

Microprocessors based on atomically thin materials hold the promise of the evolution of traditional processors as well as new applications in the field of flexible electronics. Now, a TU Wien research team led by Thomas Müller has made a breakthrough in this field as part of an ongoing research project.

Two-dimensional materials, or 2D materials for short, are extremely versatile, although – or often more precisely because – they are made up of just one or a...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Expert meeting “Health Business Connect” will connect international medical technology companies

20.04.2017 | Event News

Wenn der Computer das Gehirn austrickst

18.04.2017 | Event News

7th International Conference on Crystalline Silicon Photovoltaics in Freiburg on April 3-5, 2017

03.04.2017 | Event News

 
Latest News

DGIST develops 20 times faster biosensor

24.04.2017 | Physics and Astronomy

Nanoimprinted hyperlens array: Paving the way for practical super-resolution imaging

24.04.2017 | Materials Sciences

Atomic-level motion may drive bacteria's ability to evade immune system defenses

24.04.2017 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>