Oxidizing capacity of the rural atmosphere in Hong Kong, Southern China

Zeyuan Li, Likun Xue, Xue Yang, Qiaozhi Zha, Yee Jun Tham, Chao Yan, Peter K.K. Louie, Connie W.Y. Luk, Tao Wang, Wenxing Wang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

29 Citations (Scopus)

Abstract

Atmospheric oxidizing capacity (AOC), dominated by the hydroxyl radical (OH), is an important index of the self-cleaning capacity of atmosphere and plays a vital role in the tropospheric chemistry. To better understand the key processes governing the chemistry of rural atmosphere of southern China, we analyzed the oxidation capacity and radical chemistry at a regional background site in Hong Kong from 23 August to 22 December 2012, which covered the summer, autumn and winter seasons. A chemical box model built on the latest Master Chemical Mechanism (v3.3) was used to elucidate the OH reactivity and sources of ROXradicals (ROX= OH + HO2+ RO2). The AOC showed a clear seasonal pattern with stronger intensity in late summer compared to autumn and winter. Reactions with NO2(30%) and oxygenated volatile organic compounds (OVOCs) (31%) together dominated the OH loss in summer, while reactions with CO (38% in autumn and 39% in winter) and OVOCs (34% in autumn and 25% in winter) made larger contributions in autumn and winter. Photolysis of O3(36%–47%) presented the major ROXsource during all three seasons. The second largest ROx source was HONO photolysis (25%) in summer compared to HCHO photolysis in autumn (20%) and winter (21%). Besides, photolysis of other OVOCs was another important primary source of ROx radicals with average contributions of 14%, 13% and 20% for the summer, autumn and winter cases, respectively. Overall, the present study evaluates the oxidizing capacity of the rural atmosphere of South China and elucidates the varying characteristics of photochemical processes in different air masses.
Original languageEnglish
Pages (from-to)1114-1122
Number of pages9
JournalScience of the Total Environment
Volume612
DOIs
Publication statusPublished - 15 Jan 2018

Keywords

  • Atmospheric oxidizing capacity
  • Observation-based model
  • OH reactivity
  • Radical source
  • Southern China

ASJC Scopus subject areas

  • Environmental Engineering
  • Environmental Chemistry
  • Waste Management and Disposal
  • Pollution

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