Total hydroxyl radical reactivity measurements in a suburban area during AQUAS–Tsukuba campaign in summer 2017

• Published in: The Science of the total environment 2020-10, Vol.740, p.139897-139897, Article 139897
• Main Authors: Li, Jiaru, Sakamoto, Yosuke, Kohno, Nanase, Fujii, Tomihide, Matsuoka, Kohei, Takemura, Marina, Zhou, Jun, Nakagawa, Maho, Murano, Kentaro, Sadanaga, Yasuhiro, Nakashima, Yoshihiro, Sato, Kei, Takami, Akinori, Yoshino, Ayako, Nakayama, Tomoki, Kato, Shungo, Kajii, Yoshizumi
• Format: Article
• Language: English
• Subjects: Missing OH reactivity; Ozone mitigation; Ozone-production potential; Ozone-production sensitivity; Secondary products
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2020.139897

Missing hydroxyl radical (OH) reactivity from unknown/unmeasured trace species empirically accounts for 10%–30% of total OH reactivity and may cause significant uncertainty regarding estimation of photochemical ozone production. Thus, it is essential to unveil the missing OH reactivity for developing an effective ozone mitigation strategy. In this study, we conducted simultaneous observations of total OH reactivity and 54 reactive trace species in a suburban area as part of the Air QUAlity Study (AQUAS)–Tsukuba campaign for the summer of 2017 to gain in-depth insight into total OH reactivity in an area that experienced relatively high contributions of secondary pollutants. The campaign identified on average 35.3% of missing OH reactivity among total OH reactivity (12.9 s−1). In general, ozone-production potential estimation categorized ozone formation in this area as volatile organic compound (VOC)-limited conditions, and missing OH reactivity may increase ozone production potential 40% on average if considered. Our results suggest the importance of photochemical processes of both AVOCs and BVOCs for the production of missing OH reactivity and that we may underestimate the importance of reducing precursors in approach to suppressing ozone production if we ignore the contribution of their photochemical products. [Display omitted] •Total OH reactivity measurements were conducted in a suburban area.•In general, missing OH reactivity accounted for 35% of the 12.9 s−1 total OH reactivity.•Ozone production was VOC limited and missing OH reactivity may double its potential.•Moderate correlations exist between secondary products and missing OH reactivity.•Secondary products from both AVOCs and BVOCs may explain missing OH reactivity.