Oxidative capacity and radical chemistry in the polluted atmosphere of Hong Kong and Pearl River Delta region: analysis of a severe photochemical smog episode - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Atmospheric Chemistry and Physics Année : 2016

Oxidative capacity and radical chemistry in the polluted atmosphere of Hong Kong and Pearl River Delta region: analysis of a severe photochemical smog episode

Rongrong Gu
  • Fonction : Auteur
Xinfeng Wang
Sandra Saunders
  • Fonction : Auteur
Donald Blake
  • Fonction : Auteur
Peter Louie
  • Fonction : Auteur
Connie Luk
  • Fonction : Auteur
Isobel Simpson
  • Fonction : Auteur
Zheng Xu
  • Fonction : Auteur
Zhe Wang
  • Fonction : Auteur
Yuan Gao
  • Fonction : Auteur
Shuncheng Lee
Wenxing Wang
  • Fonction : Auteur

Résumé

Abstract. We analyze a photochemical smog episode to understand the oxidative capacity and radical chemistry of the polluted atmosphere in Hong Kong and the Pearl River Delta (PRD) region. A photochemical box model based on the Master Chemical Mechanism (MCM v3.2) is constrained by an intensive set of field observations to elucidate the budgets of ROx (ROx = OH+HO2+RO2) and NO3 radicals. Highly abundant radical precursors (i.e. O3, HONO and carbonyls), nitrogen oxides (NOx) and volatile organic compounds (VOCs) facilitate strong production and efficient recycling of ROx radicals. The OH reactivity is dominated by oxygenated VOCs (OVOCs), followed by aromatics, alkenes and alkanes. Photolysis of OVOCs (except for formaldehyde) is the dominant primary source of ROx with average daytime contributions of 34–47 %. HONO photolysis is the largest contributor to OH and the second-most significant source (19–22 %) of ROx. Other considerable ROx sources include O3 photolysis (11–20 %), formaldehyde photolysis (10–16 %), and ozonolysis reactions of unsaturated VOCs (3.9–6.2 %). In one case when solar irradiation was attenuated, possibly by the high aerosol loadings, NO3 became an important oxidant and the NO3-initiated VOC oxidation presented another significant ROx source (6.2 %) even during daytime. This study suggests the possible impacts of daytime NO3 chemistry in the polluted atmospheres under conditions with the co-existence of abundant O3, NO2, VOCs and aerosols, and also provides new insights into the radical chemistry that essentially drives the formation of photochemical smog in the high-NOx environment of Hong Kong and the PRD region.

Dates et versions

hal-03578997 , version 1 (17-02-2022)

Identifiants

Citer

Likun Xue, Rongrong Gu, Tao Wang, Xinfeng Wang, Sandra Saunders, et al.. Oxidative capacity and radical chemistry in the polluted atmosphere of Hong Kong and Pearl River Delta region: analysis of a severe photochemical smog episode. Atmospheric Chemistry and Physics, 2016, 16 (15), pp.9891-9903. ⟨10.5194/acp-16-9891-2016⟩. ⟨hal-03578997⟩
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