In-situ observation of ice evaporation processes promoted by carbon dioxide

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K05315
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 29020:Thin film/surface and interfacial physical properties-related
• Research Institution: Hokkaido University
• Principal Investigator: Nagashima Ken 北海道大学, 低温科学研究所, 助教 (60436079)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 氷 / 二酸化炭素 / 地球温暖化 / 高分解能光学顕微鏡 / マクロステップ / VLS成長

Outline of Final Research Achievements

Surfaces of ice act as sites of various chemical reactions of atmospheric acidic gases, which cause serious environmental issues, such as catalytic ozone depletion. On the other hand, CO2 gas causes global warming in the earth. Here, we show direct observations of ice basal faces by advanced optical microscopy under atmospheric-concentration CO2, HCl, or HNO3 gases.
We found acidic droplets on the ice basal faces at under -10°C. Such acidic droplets pinned the lateral advancement of spiral steps, resulting in the formation of bunched steps. The acidic droplets were finally embedded in the ice crystals by further growth of the bunched steps. In conclusion, acidic gases suppress ice growth and promote ice evaporation by making acidic droplets on the ice surfaces.

Free Research Field

結晶成長

Academic Significance and Societal Importance of the Research Achievements

これまで氷表面での酸性ガスの化学反応が、オゾン層破壊など環境問題に大きな影響を与えている事が知られている。それに加えて地球温暖化の主要因であるCO2ガスも含めた酸性ガスは、氷表面に吸着することで酸性液滴の出現を促し、氷の水蒸気からの成長を著しく阻害し、氷の蒸発を促進させることがわかった。これまで氷の成長・蒸発について大気微量成分の影響は考慮されておらず、地球環境における氷の存在量の予測が過大評価されている可能性を示唆する結果である。