Scientists estimate that the Earth's mantle holds as much water as all the oceans on the planet, but understanding how this water behaves is difficult. Water in the mantle exists under high pressure and at elevated temperatures, extreme conditions that are challenging to recreate in the laboratory.
That means many of its physical and chemical properties--relevant to understanding magma production and the Earth's carbon cycle -- aren't fully understood. If scientists could better understand these conditions, it would help them better understand the carbon cycle's consequences for climate change.
A team led by Prof. Giulia Galli and Prof. Juan de Pablo from the Pritzker School of Molecular Engineering (PME) at the University of Chicago and Prof. Francois Gygi from the University of California, Davis has created complex computer simulations to better understand the properties of salt in water under mantle conditions.
By coupling simulation techniques developed by the three research groups and using sophisticated codes, the team has created a model of saltwater based on quantum mechanical calculations. Using the model, the researchers discovered key molecular changes relative to ambient conditions that could have implications in understanding the interesting chemistry that lies deep beneath the Earth's surface.
"Our simulations represent the first study of the free energy of salts in water under pressure," Galli said. "That lays the foundation to understand the influence of salt present in water at high pressure and temperature, such as the conditions of the Earth's mantle." The results were published June 16 in the journal Nature Communications.
Important in fluid-rock interactions
Understanding the behavior of water in the mantle is challenging -- not only because it is difficult to measure its properties experimentally, but because the chemistry of water and saltwater differs at such extreme temperatures and pressures (which include temperatures of up to 1000K and pressures of up to 11 GPa, 100,000 times greater than on the Earth's surface.)
While Galli previously published research on the behavior of water in such conditions, she and her collaborators at the Midwest Integrated Center for Computational Materials (MICCoM) have now extended their simulations to salt in water, managing to predict much more complex properties than previously studied.
The simulations, performed at UChicago's Research Computing Center using optimized codes supported by MICCoM, showed key changes of ion-water and ion-ion interactions at extreme conditions. These ion interactions affect the free energy surface of salt in water.
Specifically, researchers found that dissociation of water that happens due to high pressure and temperature influences how the salt interacts with water and in turn how it is expected to interact with surfaces of rocks at the Earth's surface.
"This is foundational to understanding chemical reactions at the conditions of the Earth's mantle," de Pablo said.
"Next we hope to use the same simulation techniques for a variety of solutions, conditions, and other salts," Gygi said.
Other authors on the paper include Cunzhi Zhang of Peking University; UChicago postdoctoral research fellow Federico Giberti; and UChicago graduate student Emre Sevgen.
Citation: "Dissociation of salts in water under pressure." Zhang et al, Nature Communications. DOI: 10.1038/s41467-020-16704-9
Funding: Department of Energy
Ryan Goodwin | EurekAlert!
Typhoon changed earthquake patterns
03.07.2020 | GFZ GeoForschungsZentrum Potsdam, Helmholtz Centre
Groundwater protection on Spiekeroog Island - first installation of a salt water monitoring system
01.07.2020 | Leibniz-Institut für Angewandte Geophysik (LIAG)
Solar cells based on perovskite compounds could soon make electricity generation from sunlight even more efficient and cheaper. The laboratory efficiency of these perovskite solar cells already exceeds that of the well-known silicon solar cells. An international team led by Stefan Weber from the Max Planck Institute for Polymer Research (MPI-P) in Mainz has found microscopic structures in perovskite crystals that can guide the charge transport in the solar cell. Clever alignment of these "electron highways" could make perovskite solar cells even more powerful.
Solar cells convert sunlight into electricity. During this process, the electrons of the material inside the cell absorb the energy of the light....
Empa researchers have succeeded in applying aerogels to microelectronics: Aerogels based on cellulose nanofibers can effectively shield electromagnetic radiation over a wide frequency range – and they are unrivalled in terms of weight.
Electric motors and electronic devices generate electromagnetic fields that sometimes have to be shielded in order not to affect neighboring electronic...
A promising operating mode for the plasma of a future power plant has been developed at the ASDEX Upgrade fusion device at Max Planck Institute for Plasma...
Live event – July 1, 2020 - 11:00 to 11:45 (CET)
"Automation in Aerospace Industry @ Fraunhofer IFAM"
The Fraunhofer Institute for Manufacturing Technology and Advanced Materials IFAM l Stade is presenting its forward-looking R&D portfolio for the first time at...
With an X-ray experiment at the European Synchrotron ESRF in Grenoble (France), Empa researchers were able to demonstrate how well their real-time acoustic monitoring of laser weld seams works. With almost 90 percent reliability, they detected the formation of unwanted pores that impair the quality of weld seams. Thanks to a special evaluation method based on artificial intelligence (AI), the detection process is completed in just 70 milliseconds.
Laser welding is a process suitable for joining metals and thermoplastics. It has become particularly well established in highly automated production, for...
02.07.2020 | Event News
19.05.2020 | Event News
07.04.2020 | Event News
03.07.2020 | Life Sciences
03.07.2020 | Studies and Analyses
03.07.2020 | Power and Electrical Engineering