Source of chemical contents of sea-fog in foggy area at the North-West Pacific margin

2019 Fiscal Year Final Research Report

• Project/Area Number: 19K21561
• Project/Area Number (Other): 18H06499 (2018)
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund (2019); Single-year Grants (2018)
• Review Section: 1101:Environmental analyses and evaluation, environmental conservation measure and related fields
• Research Institution: Nagoya University
• Principal Investigator: Kamauchi Hiromitsu 名古屋大学, 環境学研究科, 研究員 (00398942)
• Project Period (FY): 2018-08-24 – 2020-03-31
• Keywords: 海霧 / 沈着 / イオウ

Outline of Final Research Achievements

The object of this research was to determine the source of chemical contents in sea-fog at the Pacific coast of eastern Hokkaido, Japan, through the analysis of stable isotope of sulfur.
Results on lichens that were collected at three sites commonly indicated decline with exponential function along transect from coastline to inland. Values were converged into around 5 permil at all inland sites, and it indicates the major source of the deposited sulfur would be rainwater. On the other hand, values at coastline were commonly higher than its in inland. Fog is mainly occupied by advection sea-fog in this region, and additionally there are no large city nor large factory around each transect. Then the major source of deposited sulfur would be ocean along the Pacific coast of eastern Hokkaido, although its degree were different among area. Order among its value in coastline was partly disagree with the inclination of frequency of fog day from east to west along the Pacific coast in Hokkaido.

Free Research Field

生態系間相互作用

Academic Significance and Societal Importance of the Research Achievements

これまでの研究では、時折観測される北西太平洋の酸性海霧は、東アジアの人為負荷源から輸送されたSOxやNOxに由来するとされてきた。しかし北海道の内陸部では天水がイオウの起源であり、長距離輸送された人為由来のイオウが北西太平洋に広範囲に沈着しているという従来の説を覆すものである。
東アジアがSOxやNOxの大規模な排出源であることは疑いないが、その輸送過程や沈着範囲を明らかにする上で、本研究は海洋、つまり自然由来のイオウの循環の過程の一端を明らかにした。