Domestic researchers experimentally identified the phenomenon of mineral formation during the freezing of water. At low temperatures, chemical reactions do not occur easily, leading to differing opinions about the principles behind the formation of some minerals in ice.
The National Research Foundation of Korea (NRF) announced on the 8th that Professor Lee Gi-hyun from Yonsei University’s Department of Earth System Science has identified the phenomenon of unique minerals forming as water freezes in the cryospheric environments of the North and South Poles. The findings of this study were published in the Proceedings of the National Academy of Sciences (PNAS) on May 29.
Until now, ice has been regarded as chemically inert in geochemical research. Generally, as the temperature decreases, chemical reactions slow down. This is why reactions between solutes dissolved in water are difficult to occur in the solid state of ice.
However, recent reports have indicated phenomena where various chemical reactions are activated as aqueous solutions freeze. This is due to the 'freeze concentration effect,' where some unsolidified solution is found between ice crystals, leading to the concentration of solutes.
The researchers froze an aqueous solution containing manganese ions and carbonate ions at minus 5 degrees Celsius and 20 degrees Celsius. No precipitation occurred at room temperature, but precipitation was observed only when the saturation of manganese carbonate mineral, manganite, was increased more than 300 times.
Conversely, it was confirmed that manganite forms under theoretically impossible conditions when ice freezes. Precipitation occurred even under conditions where the saturation of manganite was about 30,000 times lower than at room temperature. The manganite formed under freezing conditions appeared as spherical shapes with crystals sized in nanometers (10^-9 m) aggregated.
The research team used the U.S. Argonne National Laboratory and Pohang's synchrotron radiation accelerator to conduct the first real-time observation of manganite formation as ice freezes. Until now, no systematic research had been conducted on the phenomenon of mineral formation during the freezing process of water.
Professor Lee Gi-hyun noted, "The phenomenon of minerals forming as unsaturated aqueous solutions freeze is reported for the first time in this study," and added, "This can enhance understanding of Earth's circulation and cryospheric ecosystems and can be applied to research in material development using freezing and in the preservation of frozen foods."
References
PNAS (2025), DOI: https://doi.org/10.1073/pnas.2421822122