Photochemical formation and destruction of surfactants present in the atmospheric aerosols

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K12136
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 63010:Environmental dynamic analysis-related
• Research Institution: University of the Ryukyus
• Principal Investigator: ARAKAKI TAKEMITSU 琉球大学, 理学部, 教授 (80343375)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 大気エアロゾル / 界面活性剤 / 海塩 / MBAS

Outline of Final Research Achievements

Surfactants in atmospheric aerosols, due to their partially hydrophilic nature that can influence the hygroscopicity of aerosol particles, reduce the surface tension of aqueous solutions, allowing them to absorb moisture from the air and facilitate cloud formation. Although their impact during typhoons is speculated, the harsh meteorological conditions make sampling challenging, resulting in limited data on aerosol quantity and characteristics. Additionally, the relationship between surfactants and typhoon intensity remains unclear. Therefore, this study tried to chemically elucidate the characteristics of aerosols by focusing on water-soluble organic carbon and anionic surfactants through sampling during both normal and typhoon conditions at the University of the Ryukyus on Okinawa Island.

Free Research Field

環境化学

Academic Significance and Societal Importance of the Research Achievements

本研究の結果、東アジアにおいて雲形成に大きく影響するエアロゾル中の界面活性剤の特徴が明らかとなった。中国大陸で発生した黄砂が北西から到来する春季において、全エアロゾル濃度や溶存有機炭素濃度（WSOC）は大きくなっていた。また、WSOC当たりの界面活性剤（MBAS）濃度は、中国大陸から気団が到来したときに高く、他の方向から気団が到来したときに小さくなる傾向であった。台風時には、海塩の寄与が大きく(最大92%)、WSOC濃度に対する寄与は小さい(最大3.2%)ことが明らかになった。