Assessing impact of air pollutants on precipitation systems using water stable isotope ratios

2022 Fiscal Year Final Research Report

• Project/Area Number: 18K11616
• 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: Kanazawa University
• Principal Investigator: Inomata Yayoi 金沢大学, 環日本海域環境研究センター, 准教授 (90469792)
• Co-Investigator(Kenkyū-buntansha): 佐瀬 裕之 一般財団法人日本環境衛生センターアジア大気汚染研究センター, 生態影響研究部, 部長 (20450801)
• Project Period (FY): 2018-04-01 – 2023-03-31
• Keywords: 東アジア / 降水 / 水安定同位体比 / 越境大気汚染

Outline of Final Research Achievements

The stable isotope ratios of oxygen and hydrogen in water and the d-excess value, a measure of isotope fractionation inferred from them, have been used to estimate the origin of water vapor, etc. The d-excess values of precipitation samples collected daily in urban and remote areas from 2015 to 2019 show high values in winter and low values in summer Seasonal variations were observed. The d-excess values in winter precipitation suggest a continental origin, while the d-excess values in summer precipitation suggest a marine origin. The relationship between stable isotope ratios of oxygen and hydrogen and water-soluble ions in precipitation indicates that air pollutants decrease with decreasing isotope ratios in the remote Ogasawara Islands. while there is no significant difference in the decrease of air pollutants in urban areas. These differences were thought to suggest a constant supply of air pollutants in urban areas.

Free Research Field

環境科学

Academic Significance and Societal Importance of the Research Achievements

従来報告されている研究よりも短い時間分解能で、大気環境の異なる都市域・遠隔等で降水試料を採取した。降水中安定同位体比と水溶性イオン濃度の関係から、都市域では降水時に発生源近傍からの汚染物質が供給されていることが示唆された。近年、これまでとは異なる降水パターンが起きており、降水量や降水強度の変化により大気汚染物質の沈着量や沈着パターンも変化する可能性があることが示唆された。