Diurnal profiles of isoprene, methacrolein and methyl vinyl ketone at an urban site in Hong Kong

K. Cheung, Hai Guo, J. M. Ou, I. J. Simpson, B. Barletta, S. Meinardi, D. R. Blake

Research output: Journal article publicationJournal articleAcademic researchpeer-review

17 Citations (Scopus)

Abstract

Methacrolein (MACR) and methyl vinyl ketone (MVK) are major oxidation products of isoprene, but they also have primary emissions in urban environments, for example from fuel use. To examine whether MACR and MVK could be used as a direct measurement of the oxidation rate of isoprene in an urban setting, the diurnal variations of isoprene, MACR and MVK were characterized at an urban site in Hong Kong from September to November, 2010. Ozone (O3), carbon monoxide (CO), sulfur dioxide (SO2), and nitrogen oxides (NOx) were simultaneously monitored. The average isoprene mixing ratio was 252±204pptv, with a bell-shaped distribution observed on most sampling days. Higher levels of isoprene were recorded in the beginning of the sampling period, when the temperature was higher. The average mixing ratios of MACR and MVK were 101±85pptv and 175±131pptv, respectively. While isoprene, MACR and MVK experienced peak concentrations from 11 a.m. to 3 p.m., increased levels of MACR and MVK during the morning rush hour did not coincide with isoprene. The low associations between isoprene and MACR/MVK suggest that either MACR/MVK were not formed from local isoprene oxidation and/or they could partly originate from primary emissions such as fuel evaporation or combustion. Statistical analyses of linear regression and positive matrix factorization revealed that approximately 20-29% of the measured MACR and MVK was associated with biogenic emissions, and 55-71% was impacted by vehicular emissions, particularly during morning rush hours. Since MACR and MVK originated from both primary emissions and biogenic emissions at this urban site, they can therefore overestimate the actual rate of isoprene oxidation and its contribution to O3production in urban areas with strong primary emissions.
Original languageEnglish
Pages (from-to)323-331
Number of pages9
JournalAtmospheric Environment
Volume84
DOIs
Publication statusPublished - 1 Feb 2014

Keywords

  • Hong Kong
  • Isoprene oxidation products
  • Methacrolein
  • Methyl vinyl ketone

ASJC Scopus subject areas

  • Environmental Science(all)
  • Atmospheric Science

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