Articles | Volume 16, issue 2
Atmos. Chem. Phys., 16, 1187–1205, 2016

Special issue: BEACHON Rocky Mountain Organic Carbon Study (ROCS) and Rocky...

Atmos. Chem. Phys., 16, 1187–1205, 2016

Research article 02 Feb 2016

Research article | 02 Feb 2016

Speciated measurements of semivolatile and intermediate volatility organic compounds (S/IVOCs) in a pine forest during BEACHON-RoMBAS 2011

A. W. H. Chan1,a, N. M. Kreisberg2, T. Hohaus3,b, P. Campuzano-Jost4, Y. Zhao1,c, D. A. Day4, L. Kaser5,d, T. Karl6, A. Hansel5, A. P. Teng2,e, C. R. Ruehl1,f, D. T. Sueper3,4, J. T. Jayne3, D. R. Worsnop3, J. L. Jimenez4, S. V. Hering2, and A. H. Goldstein1 A. W. H. Chan et al.
  • 1Department of Environmental Science, Policy, and Management, University of California, Berkeley, California, USA
  • 2Aerosol Dynamics Inc., Berkeley, California, USA
  • 3Aerodyne Research Inc., Billerica, Massachusetts, USA
  • 4Department of Chemistry and Biochemistry, University of Colorado, Boulder, Colorado, USA
  • 5Institut für Ionenphysik & Angewandte Physik, University of Innsbruck, Innsbruck, Austria
  • 6National Center for Atmospheric Research, Boulder, Colorado, USA
  • anow at: Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario, Canada
  • bnow at: Forschungszentrum Jülich, Jülich, Germany
  • cnow at: Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA
  • dnow at: National Center for Atmospheric Research, Boulder, Colorado, USA
  • enow at: Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California, USA
  • fnow at: California Air Resources Board, Sacramento, California, USA

Abstract. Understanding organic composition of gases and particles is essential to identifying sources and atmospheric processing leading to organic aerosols (OA), but atmospheric chemical complexity and the analytical techniques available often limit such analysis. Here we present speciated measurements of semivolatile and intermediate volatility organic compounds (S/IVOCs) using a novel dual-use instrument (SV-TAG-AMS) deployed at Manitou Forest, CO, during the Bio-hydro-atmosphere interactions of Energy, Aerosols, Carbon, H2O, Organics & Nitrogen – Rocky Mountain Biogenic Aerosol Study (BEACHON-RoMBAS) 2011 campaign. This instrument provides on-line speciation of ambient organic compounds with 2 h time resolution. The species in this volatility range are complex in composition, but their chemical identities reveal potential sources. Observed compounds of biogenic origin include sesquiterpenes with molecular formula C15H24 (e.g., β-caryophyllene and longifolene), which were most abundant at night. A variety of other biogenic compounds were observed, including sesquiterpenoids with molecular formula C15H22, abietatriene and other terpenoid compounds. Many of these compounds have been identified in essential oils and branch enclosure studies but were observed in ambient air for the first time in our study. Semivolatile polycyclic aromatic hydrocarbons (PAHs) and alkanes were observed with highest concentrations during the day and the dependence on temperature suggests the role of an evaporative source. Using statistical analysis by positive matrix factorization (PMF), we classify observed S/IVOCs by their likely sources and processes, and characterize them based on chemical composition. The total mass concentration of elutable S/IVOCs was estimated to be on the order of 0.7 µg m−3 and their volatility distributions are estimated for modeling aerosol formation chemistry.

Short summary
Using a novel instrument, we have made measurements of organic compounds that can exist as a gas or particle in the rural atmosphere. Through hourly measurements, we have identified the sources and atmospheric processes of these compounds, which are important for modeling the climate and health impact of these emissions.
Final-revised paper