A research group led by Minako Kurisu, a graduate student at the University of Tokyo (2nd year doctoral course) and Professor Yoshio Takahashi, conducted an analysis of atmospheric fine particles (aerosol) collected near the ironworks, and found that iron originating from combustion is specifically low in iron. It has a stable isotope ratio and has been shown to be a clue to the contribution of combustion-derived iron transported to the surface of the ocean.
In the open ocean, the concentration of dissolved iron in seawater is low, which limits the bioproductivity of phytoplankton in some areas.The supply of iron absorbs carbon dioxide in the atmosphere and affects the carbon cycle due to the increase in photosynthesis associated with biological production, and is also associated with climate change.The importance of naturally occurring iron contained in yellow sand and iron in aerosols (fine particles such as PM2.5) generated by human activities such as coal combustion has been suggested as a source of iron, but its contribution. There were many unclear points regarding.
"Iron stable isotope ratio" is the abundance ratio of iron isotopes with different mass numbers, and the value differs depending on the iron source.Expected as a tracer of iron origin, there was little data on combustion-origin iron.This time, when aerosols were collected and analyzed by dividing the particle size into small pieces near the steelworks, it was found that the iron stable isotope ratio of the combustion-origin iron was very low with that of the naturally-origin iron.It is said that iron with a small mass number (light) was preferentially vaporized during the combustion process to cause isotope fractionation.Combustion-derived iron with a low isotope ratio has been found to be usable as a tracer because it is universally present near other emission sources and in the general environment of Japan.Low isotopic ratios were also observed in coastal areas, revealing that combustion-derived iron has reached the ocean.
The results are also important for assessing the quantitative contribution of combustion-derived iron to the marine iron cycle and elucidating its relevance to the carbon cycle and climate change.
Paper information:[ACS Earth and Space Chemistry] Stable isotope ratios of combustion iron produced by evaporation in a steel plant
