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- Title
Night-time NO emissions strongly suppress chlorine and nitrate radical formation during the winter in Delhi.
- Authors
Haslett, Sophie L.; Bell, David M.; Kumar, Varun; Slowik, Jay G.; Wang, Dongyu S.; Mishra, Suneeti; Rastogi, Neeraj; Singh, Atinderpal; Ganguly, Dilip; Thornton, Joel; Feixue Zheng; Yuanyuan Li; Wei Nie; Yongchun Liu; Wei Ma; Chao Yan; Kulmala, Markku; Daellenbach, Kaspar R.; Hadden, David; Baltensperger, Urs
- Abstract
Atmospheric pollution in urban regions is highly influenced by oxidants due to their important role in the formation of secondary organic aerosol (SOA) and smog. These include the nitrate radical (NO3), which is typically considered a nighttime oxidant, and the chlorine radical (Cl), an extremely potent oxidant that can be released in the morning in chloride-rich environments as a result of nocturnal build-up of nitryl chloride (ClNO2). Chloride makes up a higher percentage of particulate matter in Delhi than has been observed anywhere else in the world, which results in Cl having an unusually strong influence in this city. Here, we present observations and model results revealing that atmospheric chemistry in Delhi exhibits an unusual diel cycle, controlled by high concentrations of NO during the night. As a result of this, the formation of both NO3 and dinitrogen pentoxide (N2O5), a precursor of ClNO2 and thus Cl, are suppressed at night and increase to unusually high levels during the day. Our results indicate that a substantial reduction in night-time NO has the potential to increase both nocturnal oxidation via NO3 and the production of Cl during the day.
- Subjects
DELHI (India); AIR pollution; URBAN pollution; ATMOSPHERIC chemistry; CHLORINE; CIRCADIAN rhythms; CARBONACEOUS aerosols
- Publication
Atmospheric Chemistry & Physics Discussions, 2023, p1
- ISSN
1680-7367
- Publication type
Article
- DOI
10.5194/egusphere-2023-497