Research gives clues to CO2 trapping underground

CO2 is an environmentally important gas that plays a crucial role in climate change.

It is a compound that is also present in the depth of the Earth but very little information about it is available. What happens to CO2 in the Earth’s mantle? Could it be eventually hosted underground? A new publication in Nature Communications unveils some key findings.

Carbon dioxide is a widespread simple molecule in the Universe. In spite of its simplicity, it has a very complex phase diagram, forming both amorphous and crystalline phases above the pressure of 40 GPa. In the depths of the Earth, CO2 does not appear as we know it in everyday life. Instead of being a gas consisting of molecules, it has a polymeric solid form that structurally resembles quartz (a main mineral of sand) due to the pressure it sustains, which is a million times bigger than that at the surface of the Earth.

Researchers have been long studying what happens to carbonates at high temperature and high pressure, the same conditions as deep inside the Earth. Until now, the majority of experiments had shown that CO2 decomposes, with the formation of diamond and oxygen. These studies were all focused on CO2 at the upper mantle, with a 70 GPa of pressure and 1800-2800 Kelvin of temperature.

>Read more on the European Synchrotron (ESRF) website

Picture: Mohamed Mezouar, scientist in charge of ID27, on the beamline.
Credit: S. Candé. 

Direct and Efficient Utilization of Solid-phase Iron by Diatoms

A research team indicates that diatoms, can directly uptake iron from insoluble iron sediments, and thereby potentially affect atmospheric carbon dioxide level.

A research team from Columbia University indicates that diatoms, photosynthetic marine organisms responsible for as much as 20% of photosynthesis in the world’s oceans, can directly uptake iron from insoluble iron sediments, and thereby potentially affect atmospheric carbon dioxide level. Although iron is often present in the ocean, usually there is insufficient iron for diatoms and other organisms to grow quickly unless this iron is dissolved and in a form that can be used readily. This research establishes that iron from mineral phases can be quite bioavailable, and that the diatoms can use most forms of iron, but appear to have a preference for a specific form of iron, ferrous iron, in the mineral phases. This research is applicable to a wide variety of questions in earth and ocean sciences, including basic biology of nutrient acquisition, the coupling of physical and geological processes such as glaciers to climate and geoengineering.

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Picture: Glacial striations seen near Upsala Glacier, Argentina, where scientists collected glacial samples. This physical scraping produces sediments and dust that can fertilize plankton when it is delivered to the ocean.
Photo by Michael Kaplan/Lamont-Doherty Earth Observatory

Speedy X-Ray Detector Arrives at NSLS-II

Advanced detector fuels discovery by allowing users to collect massive datasets in less time.

The National Synchrotron Light Source II (NSLS-II), a DOE Office of Science User Facility at the U.S. Department of Energy’s Brookhaven National Laboratory, is a truly international resource. Geoscientists from Australia and France recently trekked across the globe to aim NSLS-II’s tiny, intense beams of x-ray light at thin samples of nickel-rich mineral gathered from a mine in far-off Siberia. They scanned these slices of geological material to see what other chemical elements were associated with the nickel. The group also examined slices of minerals grown in a lab, and compared results from the two sample suites to learn how massive metal deposits form.

Their experiment was the first to use a newly installed x-ray detector, called Maia, mounted at NSLS-II’s Submicron Resolution X-Ray Spectroscopy (SRX) beamline. Scientists from around the world come to SRX to create high-definition images of mineral deposits, aerosols, algae—just about anything they need to examine with millionth-of-a-meter resolution. Maia, developed by a collaboration between NSLS-II, Brookhaven’s Instrumentation Division and Australia’s Commonwealth Scientific and Industrial Research Organization (CSIRO), can scan centimeter-scale sample areas at micron scale resolution in just a few hours—a process that used to take weeks.