A quantitative understanding of total OH reactivity and ozone production in a coastal industrial area during the Yokohama air quality study (AQUAS) campaign of summer 2019. (15th December 2021)

• Record Type: Journal Article
• Authors: Li, Jiaru; Kohno, Nanase; Sakamoto, Yosuke; Fukusaki, Yukiko; Kousa, Yuka; Sadanaga, Yasuhiro; Nakashima, Yoshihiro; Sato, Kei; Ramasamy, Sathiyamurthi; Takami, Akinori; Yoshino, Ayako; Nakayama, Tomoki; Kato, Shungo; Ono, Natsuki; Zhou, Jun; Bai, Yu; Kajii, Yoshizumi
• Is Part Of: Atmospheric environment. Volume 267(2021)
• Publication Date: 2021-12-15
• Subjects: VOC budget -- NOx–HOx–VOCs chemistry -- LP-LIF -- Missing OH reactivity -- Ozone production; Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2021.118754
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: Field measurements performed in the Keihin coastal industrial area during summer 2019 were used to characterize the air quality and ozone production potential. The total hydroxyl radical (OH) reactivity was found to be moderate, peaking with a 2-h average of 29.0 s −1, corresponding to an OH lifetime of ∼34 ms. The average hourly total OH reactivity was 11.4 ± 5.2 s −1 (average ± standard deviation), and the measured OH sinks (from over 90 trace species) accounted for 92.3% of the total OH reactivity. Compared with a previous series of campaigns in urban/suburban Japan, this field work investigated an area often overlooked for atmospheric observations and found the smallest missing OH reactivity (on average, 0.88 s −1 ). The near-zero missing OH reactivity indicated that photochemical procedures were less important to the Yokohama air quality study (AQUAS–Yokohama) than the ubiquitous substantial secondary products in other areas. This study also demonstrated that oceanic air masses may quickly flush coastal industrial areas and that a limited activity of photochemistry due to elevated NOx effectively terminates OH radical recycling. A comparison with other campaigns in Japan exhibited a positive correlation with oxidants (ozone and formaldehyde), indicating secondary products have a critical role in explaining missing OH reactivity. The ozone production potential was corresponding to a volatile organic compound (VOC)-limited regime, while the missing OH reactivity led to an ∼8% increase in ozone formation. Finally, a positive correlation was found between the ozone production rate and the reactivity ratio between VOCs and NOx, in both the current study and various other field campaigns in urban areas. Highlights: Moderate total OH reactivity (11.4 s −1 ) was obtained in a coastal industrial area with 8% of missing OH reactivity. Ozone formation was constrained because of the termination of HOx by copious NOx . A comparison over campaigns in Japan identified a positive correlation between missing OH reactivity and oxidants. Ozone production rate in the VOC-limited regime areas will be likely stimulated by the increase of kVOC /kNOx ratio.