Iron oxides are the main components of mineral dust in the atmosphere, and are main sources of ferrous iron for the oceanic microalgae. Iron oxides, however, must be converted to ferrous iron in photochemical and biological processes. Prof. Choi’s research team uncovered that iron oxides trapped in icebergs in polar regions are rapidly converted into ferrous iron Fe(II)(aq), due to the freeze-concentration effect.
When a solution freezes, iron oxides condense in the boundary area around the ice crystals. If the sunlight is shone, the electron transfer becomes easier and the reduction of Fe(III) to Fe(II) ferrous iron takes place. These are enriched in this boundary until ice melts. This is called the freeze-concentration effect.
This research holds its significance in the fact that a new role of ice was discovered. Previously, the icebergs in polar regions were only thought to affect the sea level, but this research revealed ice’s new function in the process of transformation of iron oxides.
It can also be applied as a new ferrous iron supplement mechanism to increase the productivity of oceanic microalgae. This is another reason why this research is so highly praised because oceanic microalgae are responsible for absorbing carbon dioxide molecules from the atmosphere. Increase in number and productivity of microalgae will consequently lead to increase in absorption of carbon dioxide and decrease in the global warming effect. Prof. Choi expressed the further relevance of this research by suggesting that “it will be very helpful in the recent study of change in productivity of microalgae photosynthesis following the climate change.”
