Developing a new approach for reconstruction of the past atmospheric oxidative capacity: oxygen isotopic composition of H2O2

2022 Fiscal Year Final Research Report

• Project/Area Number: 20K19961
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 63010:Environmental dynamic analysis-related
• Research Institution: Kanazawa University (2021-2022); National Institute of Polar Research (2020)
• Principal Investigator: Ishino Sakiko 金沢大学, 環日本海域環境研究センター, 助教 (70867431)
• Project Period (FY): 2020-04-01 – 2023-03-31
• Keywords: 三酸素同位体組成（Δ17O） / 大気酸化力 / 過酸化水素 / アイスコア

Outline of Final Research Achievements

We aimed at establishing an analytical method for the triple oxygen isotopic composition of hydrogen peroxide (Δ17O(H2O2)), as a new paleoenvironmental proxy that could reconstruct the past atmospheric oxidizing capacity. We completed to construct the beta version of the Δ17O(H2O2) measurement system, composed of a continuous-flow sample injection line through a reactor chamber to an O2 gas pre-concentration trap and a stable isotope ratio mass spectrometer (IRMS). We have also developed an in-house H2O2 concentration measurement system for precipitation, snow, and ice samples, then applied it to the H2O2 concentration measurement of the ice core drilled at southeast dome, Greenland. Based on the seasonal variation of H2O2 concentration, which is high in summer and low in winter, the ice core was dated to be the 221 years record from 1799 to 2020.

Free Research Field

大気化学

Academic Significance and Societal Importance of the Research Achievements

オゾン（O3）やOHラジカル、過酸化水素（H2O2）等の大気酸化剤の存在量によって規定される「大気酸化力」は、過去から未来にかけて大気環境変動の原因と対策を講じる上で非常に重要な情報である。しかしながら、産業革命以降から現在までの大気酸化力の変化は、数値モデルを用いて推定されているのみであり、アイスコア等の古環境記録から復元できるプロキシが求められている。本研究で開発したΔ17O(H2O2)値分析装置を用い、今後、指標情報を精査した上で、過去の大気酸化力の復元という社会的意義の高い課題解決を目指す。