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Chlorine oxidation of VOCs at a semi-rural site in Beijing: Significant chlorine liberation from ClNO2 and subsequent gas- A nd particle-phase Cl-VOC production

Research output: Contribution to journalArticle

  • Michael Le Breton
  • Åsa M. Hallquist
  • Ravi Kant Pathak
  • David Simpson
  • Yujue Wang
  • John Johansson
  • Jing Zheng
  • Yudong Yang
  • Dongjie Shang
  • Haichao Wang
  • Qianyun Liu
  • Chak Chan
  • Tao Wang
  • Thomas J. Bannan
  • Michael G Priestley
  • Carl J. Percival
  • Dudley E. Shallcross
  • Keding Lu
  • Song Guo
  • Min Hu
  • Mattias Hallquist
Original languageEnglish
Pages (from-to)13013-13030
Number of pages18
JournalAtmospheric Chemistry and Physics
Volume18
Issue number17
Early online date11 Sep 2018
DOIs
DateAccepted/In press - 21 Aug 2018
DateE-pub ahead of print - 11 Sep 2018
DatePublished (current) - 30 Sep 2018

Abstract

Nitryl chloride (ClNO2) accumulation at night acts as a significant reservoir for active chlorine and impacts the following day's photochemistry when the chlorine atom is liberated at sunrise. Here, we report simultaneous measurements of N2O5 and a suite of inorganic halogens including ClNO2 and reactions of chloride with volatile organic compounds (Cl-VOCs) in the gas and particle phases utilising the Filter Inlet for Gas and AEROsols time-of-flight chemical ionisation mass spectrometer (FIGAERO-ToF-CIMS) during an intensive measurement campaign 40km northwest of Beijing in May and June 2016. A maximum mixing ratio of 2900ppt of ClNO2 was observed with a mean campaign nighttime mixing ratio of 487ppt, appearing to have an anthropogenic source supported by correlation with SO2, CO and benzene, which often persisted at high levels after sunrise until midday. This was attributed to such high mixing ratios persisting after numerous e-folding times of the photolytic lifetime enabling the chlorine atom production to reach 2.3 × 105moleculescm-3 from ClNO2 alone, peaking at 09:30LT and up to 8.4 × 105moleculescm-3 when including the supporting inorganic halogen measurements. Cl-VOCs were observed in the particle and gas phases for the first time at high time resolution and illustrate how the iodide ToF-CIMS can detect unique markers of chlorine atom chemistry in ambient air from both biogenic and anthropogenic sources. Their presence and abundance can be explained via time series of their measured and steady-state calculated precursors, enabling the assessment of competing OH and chlorine atom oxidation via measurements of products from both of these mechanisms and their relative contribution to secondary organic aerosol (SOA) formation.

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    Rights statement: This is the final published version of the article (version of record). It first appeared online via Copernicus at https://www.atmos-chem-phys.net/18/13013/2018/ . Please refer to any applicable terms of use of the publisher.

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    Rights statement: This is the final published version of the article (version of record). It first appeared online via Copernicus at https://www.atmos-chem-phys.net/18/13013/2018/ . Please refer to any applicable terms of use of the publisher.

    Final published version, 835 KB, PDF-document

    Licence: CC BY

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