Wide-range transport of volcanic gases and the formation of sulfate aerosols and the behavior of mercury at the central mountain sites

2023 Fiscal Year Final Research Report

• Project/Area Number: 21K04319
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 22060:Environmental systems for civil engineering-related
• Research Institution: Toyama Prefectural University
• Principal Investigator: WATANABE Koichi 富山県立大学, 工学部, 教授 (70352789)
• Project Period (FY): 2021-04-01 – 2024-03-31
• Keywords: 火山ガス / 硫酸 / 水銀 / 二酸化硫黄 / 過酸化水素 / ヘリコプター / 立山 / 乗鞍岳

Outline of Final Research Achievements

To evaluate the impact of increasing volcanic activity in Japan on the atmospheric environment over central Japan, atmospheric observations were conducted at Mt. Tateyama, Mt. Norikura, and the mountain site of Oyabe City. In addition to mountain observations, atmospheric observations at high-altitude atmosphere were also performed using a helicopter. Chemical components in fog water tended to be in lower concentrations than before. During the warm seasons, high concentrations of sulfur dioxide and aerosol particles derived from Sakurajima were observed. Hydrogen peroxide was higher than sulfur dioxide at high altitude during the warm months.
Analysis of the chemical compositions in the surface snow at Mt. Tateyama in the summer season revealed that a large amount of sulfuric acid was produced during unfiltered storage in a refrigerator, which is due to the oxidation of volcanic sulfur to sulfuric acid. It was revealed that particulate mercury derived from volcano was concentrated.

Free Research Field

大気物理化学

Academic Significance and Societal Importance of the Research Achievements

本研究から、中国の大気汚染が大幅に改善されている現在では、国内の硫酸エアロゾルの重要な起源として火山ガスによる影響が無視できない可能性が示唆された。また、ヘリコプターが上空大気観測に非常に有効利用できることが明らかとなった。ヘリコプター観測から暖候期の中部日本上空では過酸化水素が十分に存在し、二酸化硫黄を酸化させる能力が高いことが示された。ただし、火山ガスが直接輸送される際には酸化剤が不足する可能性がある。また、融雪期の立山では表層雪中に火山由来の非水溶性の硫黄や粒子状水銀が濃縮していることが明らかとなった。