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
Journal article, 2018
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 N2O5and a suite of inorganic halogens including ClNO2and 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 ClNO2was 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-3from ClNO2alone, peaking at 09:30LT and up to 8.4 × 105moleculescm-3when 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.
Author
Michael Le Breton
University of Gothenburg
Åsa M. Hallquist
IVL Swedish Environmental Research Institute
Ravi Kant Pathak
University of Gothenburg
David Simpson
Chalmers, Space, Earth and Environment, Microwave and Optical Remote Sensing
Norwegian Meteorological Institute
Yujue Wang
Beijing University of Technology
John Johansson
Chalmers, Space, Earth and Environment, Microwave and Optical Remote Sensing
Jing Zheng
Beijing University of Technology
Yudong Yang
Beijing University of Technology
Dongjie Shang
Beijing University of Technology
Haichao Wang
Beijing University of Technology
Qianyun Liu
Hong Kong University of Science and Technology
Chak Chan
City University of Hong Kong
Tao Wang
Hong Kong Polytechnic University
Thomas J. Bannan
University of Manchester
Michael Priestley
University of Manchester
C. J. Percival
Jet Propulsion Laboratory, California Institute of Technology
University of Manchester
Dudley E. Shallcross
University of the Western Cape
University of Bristol
Keding Lu
Beijing University of Technology
Song Guo
Beijing University of Technology
Min Hu
Beijing University of Technology
Mattias Hallquist
University of Gothenburg
Atmospheric Chemistry and Physics
1680-7316 (ISSN) 1680-7324 (eISSN)
Vol. 18 17 13013-13030ModElling the Regional and Global Earth system (MERGE)
Lund University (9945095), 2010-01-01 -- .
Subject Categories
Meteorology and Atmospheric Sciences
Atom and Molecular Physics and Optics
Other Chemistry Topics
DOI
10.5194/acp-18-13013-2018