Secondary organic aerosol from VOC mixtures in an oxidation flow reactor

Research output: Contribution to journalArticle

Abstract

The atmospheric organic aerosol is a tremendously complex system in terms of chemical content. Models generally treat the mixtures as ideal, something which has been questioned owing to model-measurement discrepancies. We used an oxidation flow reactor to produce secondary organic aerosol (SOA) mixtures containing oxidation products of biogenic (α-pinene, myrcene and isoprene) and anthropogenic (m-xylene) volatile organic compounds (VOCs). The resulting volume concentration and chemical composition was measured using a scanning mobility particle sizer (SMPS) and a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS), respectively. The SOA mass yield of the mixtures was compared to a partitioning model constructed from single VOC experiments. The single VOC SOA mass yields with no wall-loss correction applied are comparable to previous experiments. In the mixtures containing myrcene a higher yield than expected was produced. We attribute this to an increased condensation sink, arising from myrcene producing a significantly higher number of nucleation particles compared to the other precursors. Isoprene did not produce much mass in single VOC experiments but contributed to the mass of the mixtures. The effect of high concentrations of isoprene on the OH exposure was found to be small, even at OH reactivities that previously have been reported to significantly suppress OH exposures in oxidation flow reactors. Furthermore, isoprene shifted the particle size distribution of mixtures towards larger sizes, which could be due to a change in oxidant dynamics inside the reactor.

Details

Authors
Organisations
External organisations
  • University of Helsinki
  • Pennsylvania State University
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Meteorology and Atmospheric Sciences

Keywords

  • Oxidation flow reactor, Secondary organic aerosol, SOA yield, VOC mixtures
Original languageEnglish
Pages (from-to)210-220
Number of pages11
JournalAtmospheric Environment
Volume161
Publication statusPublished - 2017 Jul 1
Publication categoryResearch
Peer-reviewedYes