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Strong marine-derived nitrous acid (HONO) production observed in the coastal atmosphere of northern China
Abstract Despite its important roles in the formation of hydroxyl radical (OH) and ozone (O3), the characteristics and sources of nitrous acid (HONO) in the marine atmosphere are still poorly understood. In this study, the HONO production in maritime air masses was explored based on a field observation conducted at a coastal site in Qingdao, China in the summer of 2019. The “sea case” and the “land case” were carefully distinguished according to wind direction and backward air mass trajectory. About four times larger nocturnal NO2-to-HONO conversion rate and ~60% larger daytime Pother (production rate of HONO other than gas-phase OH + NO reaction) at noon were observed in the “sea case” compared to the “land case” (0.045 ± 0.014 h−1 versus 0.012 ± 0.007 h−1, and 1.83 ± 0.02 ppbv h−1 versus 1.14 ± 0.07 ppbv h−1, respectively). Correlation analysis implied that heterogeneous conversion of NO2 and photolysis of nitrogen-containing compounds were potentially important sources of marine atmospheric HONO in the nocturnal and daytime, respectively, though alkaline oceans are previously considered as sinks of HONO. The impacts of these marine-derived HONO on OH and O3 were comparable to or larger than that of the “land case”. These results suggest that strong marine-derived HONO production may have been overlooked previously, and more studies are required to explore its detailed formation mechanisms in the marine atmosphere.
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Highlights The marine-derived HONO in the coastal atmosphere was confirmed. High HONO production was observed in both the day and night of maritime air masses. The marine-derived HONO contributed significantly to the formation of OH and O3.
Strong marine-derived nitrous acid (HONO) production observed in the coastal atmosphere of northern China
Abstract Despite its important roles in the formation of hydroxyl radical (OH) and ozone (O3), the characteristics and sources of nitrous acid (HONO) in the marine atmosphere are still poorly understood. In this study, the HONO production in maritime air masses was explored based on a field observation conducted at a coastal site in Qingdao, China in the summer of 2019. The “sea case” and the “land case” were carefully distinguished according to wind direction and backward air mass trajectory. About four times larger nocturnal NO2-to-HONO conversion rate and ~60% larger daytime Pother (production rate of HONO other than gas-phase OH + NO reaction) at noon were observed in the “sea case” compared to the “land case” (0.045 ± 0.014 h−1 versus 0.012 ± 0.007 h−1, and 1.83 ± 0.02 ppbv h−1 versus 1.14 ± 0.07 ppbv h−1, respectively). Correlation analysis implied that heterogeneous conversion of NO2 and photolysis of nitrogen-containing compounds were potentially important sources of marine atmospheric HONO in the nocturnal and daytime, respectively, though alkaline oceans are previously considered as sinks of HONO. The impacts of these marine-derived HONO on OH and O3 were comparable to or larger than that of the “land case”. These results suggest that strong marine-derived HONO production may have been overlooked previously, and more studies are required to explore its detailed formation mechanisms in the marine atmosphere.
Graphical abstract Display Omitted
Highlights The marine-derived HONO in the coastal atmosphere was confirmed. High HONO production was observed in both the day and night of maritime air masses. The marine-derived HONO contributed significantly to the formation of OH and O3.
Strong marine-derived nitrous acid (HONO) production observed in the coastal atmosphere of northern China
Yang, Juan (author) / Shen, Hengqing (author) / Guo, Ming-Zhi (author) / Zhao, Min (author) / Jiang, Ying (author) / Chen, Tianshu (author) / Liu, Yuhong (author) / Li, Hongyong (author) / Zhu, Yujiao (author) / Meng, He (author)
Atmospheric Environment ; 244
2020-09-17
Article (Journal)
Electronic Resource
English