Production of N2O5 and ClNO2 in summer in urban Beijing, China

Wei Zhou*, Jian Zhao, Bin Ouyang, Archit Mehra, Weiqi Xu, Yuying Wang, Thomas J. Bannan, Stephen D. Worrall, Michael Priestley, Asan Bacak, Qi Chen, Conghui Xie, Qingqing Wang, Junfeng Wang, Wei Du, Yingjie Zhang, Xinlei Ge, Penglin Ye, James D. Lee, Pingqing FuZifa Wang, Douglas Worsnop, Roderic Jones, Carl J. Percival, Hugh Coe, Yele Sun

*Corresponding author for this work

Research output: Contribution to journalArticle

Abstract

The heterogeneous hydrolysis of dinitrogen pentoxide (N2O5) has a significant impact on both nocturnal particulate nitrate formation and photochemistry on the following day through the photolysis of nitryl chloride (ClNO2), yet these processes in highly polluted urban areas remain poorly understood. Here we present measurements of gas-phase N2O5 and ClNO2 by high-resolution time-of-flight chemical ionization mass spectrometer (ToF-CIMS) during summer in urban Beijing, China as part of the Air Pollution and Human Health (APHH) campaign. N2O5 and ClNO2 show large day-to-day variations with average (±1σ ) mixing ratios of 79.2±157.1 and 174.3±262.0 pptv, respectively. High reactivity of N2O5, with ., (N2O5)'1 ranging from 0.20 × 10'2 to 1.46 × 10'2 s'1, suggests active nocturnal chemistry and a large nocturnal nitrate formation potential via N2O5 heterogeneous uptake. The lifetime of N2O5, ., (N2O5), decreases rapidly with the increase in aerosol surface area, yet it varies differently as a function of relative humidity with the highest value peaking at 1/4 40 %. The N2O5 uptake coefficients estimated from the product formation rates of ClNO2 and particulate nitrate are in the range of 0.017-0.19, corresponding to direct N2O5 loss rates of 0.00044-0.0034 s'1. Further analysis indicates that the fast N2O5 loss in the nocturnal boundary layer in urban Beijing is mainly attributed to its indirect loss via NO3, for example through the reactions with volatile organic compounds and NO, while the contribution of the heterogeneous uptake of N2O5 is comparably small (7-33 %). High ClNO2 yields ranging from 0.10 to 0.35 were also observed, which might have important implications for air quality by affecting nitrate and ozone formation.

Original languageEnglish
Pages (from-to)11581-11597
Number of pages17
JournalAtmospheric Chemistry and Physics
Volume18
Issue number16
DOIs
Publication statusPublished - 16 Aug 2018

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© Author(s) 2018. This work is distributed under
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    Zhou, W., Zhao, J., Ouyang, B., Mehra, A., Xu, W., Wang, Y., Bannan, T. J., Worrall, S. D., Priestley, M., Bacak, A., Chen, Q., Xie, C., Wang, Q., Wang, J., Du, W., Zhang, Y., Ge, X., Ye, P., Lee, J. D., ... Sun, Y. (2018). Production of N2O5 and ClNO2 in summer in urban Beijing, China. Atmospheric Chemistry and Physics, 18(16), 11581-11597. https://doi.org/10.5194/acp-18-11581-2018