Summertime C1-C5alkyl nitrates over Beijing, northern China: Spatial distribution, regional transport, and formation mechanisms

Jingjing Sun, Zeyuan Li, Likun Xue, Tao Wang, Xinfeng Wang, Jian Gao, Wei Nie, Isobel J. Simpson, Rui Gao, Donald R. Blake, Fahe Chai, Wenxing Wang

Research output: Journal article publicationJournal articleAcademic researchpeer-review

7 Citations (Scopus)

Abstract

Alkyl nitrates (RONO2) are an important class of nitrogen oxides reservoirs in the atmosphere and play a key role in tropospheric photochemistry. Despite the increasing concern for photochemical air pollution over China, the knowledge of characteristics and formation mechanisms of alkyl nitrates in this region is limited. We analyzed C1-C5alkyl nitrates measured in Beijing at a polluted urban site in summer 2008 and at a downwind rural site in summers of both 2005 and 2008. Although the abundances of NOxand hydrocarbons were much lower at the rural site, the mixing ratios of RONO2were comparable between both sites, emphasizing the regional nature of alkyl nitrate pollution. Regional transport of urban plumes governed the elevated RONO2levels at the rural site. The concentrations of C1-C2RONO2were significantly higher at the rural site in 2008 compared to 2005 despite a decline in NOxand anthropogenic VOCs, mainly owing to enhanced contributions from biogenic VOCs. The photochemical formation regimes of RONO2were evaluated by both a simplified sequential reaction model and a detailed master chemical mechanism box model. The observed C4-C5RONO2levels can be well explained by the photochemical degradation of n-butane and n-pentane, while the sources of C1-C3RONO2were rather complex. In addition to the C1-C3alkanes, biogenic VOCs and reactive aromatics were also important precursors of methyl nitrate, and alkenes and long-chain alkanes contributed to the formation of C2-C3RONO2. This study provides insights into the spatial distribution, inter-annual variation and photochemical formation mechanisms of alkyl nitrate pollution over the Beijing area.
Original languageEnglish
Pages (from-to)102-109
Number of pages8
JournalAtmospheric Research
Volume204
DOIs
Publication statusPublished - 15 May 2018

Keywords

  • Alkyl nitrate
  • Beijing
  • Master chemical mechanism
  • Observation-based model
  • Regional transport

ASJC Scopus subject areas

  • Atmospheric Science

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