表題番号：2025C-189
日付：2026/02/03
研究課題所沢における大気中ペルオキシアシルナイトレート全量の観測事例の蓄積（５）
| 研究者所属（当時） | 資格 | 氏名 | |
|---|---|---|---|
| （代表者） | 人間科学学術院 人間科学部 | 教授 | 松本 淳 |
- 研究成果概要
- Photochemical oxidant, Ox, is one of the most important issues on air pollution. In Japan, in spite of reduction of precursors like NOx and VOCs, the concentration level of Ox has been still flat. It is urgent to grasp current situations on Ox in detail and to explore more effective control plans. Ox is composed mainly of ozone, O3. In Japan, constant monitoring of Ox is based on measurements of ozone concentrations. Peroxyacyl nitrates, PANs, are considered second to O3 as major compounds as Ox. However, ozone monitoring cannot reflect the contributions of PANs to Ox. To capture situations on Ox more precisely, it is necessary to consider PANs' contributions. In this study, examples of simultaneous observations on PANs and O3 were accumulated as possible and more analyses were conducted in order to deepen our knowledge on PANs and O3. The observations has been conducted continuously from June 9th in 2021 to November 5th in 2024 at Tokorozawa Campus, Waseda University. The site was placed ca. 30 km to the northwest of downtown Tokyo and surrounded by forests. Thus, the campus was suitable for studying Ox in suburban areas around Tokyo. In fiscal year 2025, the observation was conducted in relatively high temperature period, from March 12th to October 16th. Consequently, especially in daytime of summer, PANs were correlated to potential ozone, PO (=O3+NO2). When temperature was high and the ratio NOx/VOCs was low, high Ox cases with high PO and PANs could be captured. It was indicated that high Ox events could be seen under the following conditions: (1) sunny days, (2) high temperature, (3) low NOx/NMHC ratio (NOx-limited regime for O3), (4) sufficiently high Ox intercepts and/or slopes for day-by-day regression lines between PANs and Ox, and (5) long lifetime of PAN in spite of high temperature. It was also confirmed that the correlation between total PANs and Ox could be promising for evaluating and capturing the situations on photochemical ozone, including outstanding ozone event. The thermal decomposition of PANs (equilibrium between PANs and NO2) could increase O3 level additionally.