08 Aug 2022
08 Aug 2022

Source Apportionment of VOCs, IVOCs, and SVOCs by Positive Matrix Factorization in Suburban Livermore, California

Rebecca A. Wernis1,2, Nathan M. Kreisberg3, Robert J. Weber2, Greg T. Drozd4, and Allen H. Goldstein1,2 Rebecca A. Wernis et al.
  • 1Department of Civil and Environmental Engineering, University of California Berkeley, Berkeley, CA 94720, USA
  • 2Department of Environmental Science, Policy and Management, Berkeley, CA 94720, USA
  • 3Aerosol Dynamics, Inc., Berkeley, CA 94710, USA
  • 4Department of Chemistry, Colby College, Waterville, ME 04901, USA

Abstract. Gas- and particle–phase molecular markers provide highly specific information about the sources and atmospheric processes that contribute to air pollution. In urban areas, major sources of pollution are changing as regulation selectively mitigates some pollution sources and climate change impacts the surrounding environment. In this study, a Comprehensive Thermal Desorption Aerosol Gas Chromatograph (cTAG) was used to measure volatile, intermediate volatility, and semi-volatile molecular markers every other hour over a 10-day period from 11 April to 21 April 2018 in suburban Livermore, California. Source apportionment via Positive Matrix Factorization (PMF) was performed to identify major sources of pollution. The PMF analysis identified 13 components, including emissions from gasoline, consumer products, biomass burning, secondary oxidation, aged regional transport, and several factors associated with single compounds or specific events with unique compositions. The gasoline factor had a distinct morning peak in concentration but lacked a corresponding evening peak, suggesting commute-related traffic emissions are dominated by cold starts in residential areas. More monoterpene and monoterpenoid mass was assigned to consumer product emissions than biogenic sources, underscoring the increasing importance of volatile chemical products to urban emissions. Daytime isoprene concentrations were controlled by biogenic sunlight- and temperature-dependent processes, mediated by strong midday mixing, but gasoline was found to be the dominant and likely only source of isoprene at night. Biomass burning markers indicated residential wood burning activity remained an important pollution source even in the springtime. This study demonstrates the utility of specific high-time-resolution molecular marker measurements across a wide range of volatility in more comprehensively describing pollution source profiles than a narrower volatility range would allow.

Rebecca A. Wernis et al.

Status: final response (author comments only)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2022-667', Anonymous Referee #2, 25 Aug 2022
  • RC2: 'Comment on egusphere-2022-667', Anonymous Referee #1, 29 Aug 2022

Rebecca A. Wernis et al.

Rebecca A. Wernis et al.


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Short summary
We measured volatile and intermediate-volatility gases and semi-volatile gas- and particle-phase compounds in the atmosphere during an 11-day period in a Bay Area suburb. We separated compounds based on variability in time to arrive at 13 distinct sources. Some compounds emitted from plants are found in greater quantities as fragrance compounds in consumer products. The wide volatility range of these measurements enables the construction of more complete source profiles.