Elucidation of iodine activation mechanism in polar regions

2023 Fiscal Year Final Research Report

• Project/Area Number: 18K03746
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 17020:Atmospheric and hydrospheric sciences-related
• Research Institution: Aichi University of Technology (2023); Kyushu University (2018)
• Principal Investigator: YABUSHITA AKIHIRO 愛知工科大学, 工学部, 教授 (70371151)
• Project Period (FY): 2018-04-01 – 2024-03-31
• Keywords: ヨウ素 / ヨウ化物イオン / オゾン / 二酸化窒素 / キャビティリングダウン分光 / 不均一反応 / 氷 / 極域環境

Outline of Final Research Achievements

High concentrations of iodine (I2) and iodine monoxide radical (IO) have been observed in the Weddell Sea, which cannot be explained solely by biological releases. This observation suggests that there are other sources of production, such as inorganic chemical reactions. In this study, iodine compounds released from the photooxidation of iodide ions (I－) in ice and from the ice surface by the reaction of ozone (O3) or nitrogen dioxide (NO2) with the surface of frozen aqueous solutions containing iodide ions (I－) was studied in order to identify the source of these iodine compounds. The results suggested that reactions in/on ice, such as sea ice and snow ice, can be a source of iodine release in polar regions. The mechanism of iodine activation was elucidated.

Free Research Field

大気化学

Academic Significance and Societal Importance of the Research Achievements

ヨウ素原子は微量ながら触媒サイクルにより対流圏オゾン濃度を減少させたり、エアロゾルを生成したりして気候に影響を与えている。極域で生物放出のみでは説明できない高濃度のヨウ素が観測されていたが、本研究により新たな放出源を明らかにすることができた。
氷表面上での不均一反応によって気相中に放出されたガス種の高感度計測装置を開発した。雪氷や海氷での反応は、本研究の反応以外にも極域大気に影響を及ぼしているため今後の不均一反応機構の研究に役立つ。