Organic aerosol in the summertime southeastern United States: components and their link to volatility distribution, oxidation state and hygroscopicity
Abstract
The volatility distribution of the organic aerosol (OA) and its sources during the Southern Oxidant and Aerosol Study (SOAS; Centreville, Alabama) was constrained using measurements from an Aerodyne high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and a thermodenuder (TD). Positive matrix factorization (PMF) analysis was applied on both the ambient and thermodenuded high-resolution mass spectra, leading to four factors: more oxidized oxygenated OA (MO-OOA), less oxidized oxygenated OA (LO-OOA), an isoprene epoxydiol (IEPOX)-related factor (isoprene-OA) and biomass burning OA (BBOA). BBOA had the highest mass fraction remaining (MFR) at 100 °C, followed by the isoprene-OA, and the LO-OOA. Surprisingly the MO-OOA evaporated the most in the TD. The estimated effective vaporization enthalpies assuming an evaporation coefficient equal to unity were 58 ± 13 kJ mol^(−1) for the LO-OOA, 89 ± 10 kJ mol^(−1) for the MO-OOA, 55 ± 11 kJ mol^(−1) for the BBOA, and 63 ± 15 kJ mol^(−1) for the isoprene-OA. The estimated volatility distribution of all factors covered a wide range including both semi-volatile and low-volatility components. BBOA had the lowest average volatility of all factors, even though it had the lowest O : C ratio among all factors. LO-OOA was the more volatile factor and its high MFR was due to its low enthalpy of vaporization according to the model. The isoprene-OA factor had intermediate volatility, quite higher than suggested by a few other studies. The analysis suggests that deducing the volatility of a factor only from its MFR could lead to erroneous conclusions. The oxygen content of the factors can be combined with their estimated volatility and hygroscopicity to provide a better view of their physical properties.
Additional Information
© Author(s) 2018. This work is distributed under the Creative Commons Attribution 4.0 License. Published by Copernicus Publications on behalf of the European Geosciences Union. Received: 28 Oct 2017 – Discussion started: 23 Nov 2017. Revised: 26 Mar 2018 – Accepted: 03 Apr 2018 – Published: 26 Apr 2018. Data availability. The data from this work are available upon request from Spyros Pandis (spyros@chemeng.upatras.gr). This work was funded by the National Oceanic and Atmospheric Administration CPO Award NA10OAR4310102 and the US Environmental Protection Agency (EPA-STAR) through grants RD-835410 and RD-835405. This research was also supported by the European Research Council Project PyroTRACH (Pyrogenic TRansformations Affecting Climate and Health) grant agreement 726165. Athanasios Nenes, Lu Xu, and Nga L. Ng acknowledge support from an NSF grant (1242258). Lu Xu and Nga L. Ng acknowledge support from EPA STAR grant RD-83540301. The authors acknowledge the Atmospheric Research and Analysis Institute (ARA) for providing meteorological and gas-phase species data. The contents of this publication are solely the responsibility of the authors and do not necessarily represent the official views of the US EPA. Further, the US EPA does not endorse the purchase of any commercial products or services mentioned in the publication. The authors declare that they have no conflict of interest.Attached Files
Published - acp-18-5799-2018.pdf
Supplemental Material - acp-18-5799-2018-supplement.pdf
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Additional details
- Eprint ID
- 86423
- Resolver ID
- CaltechAUTHORS:20180516-132632080
- NA10OAR4310102
- National Oceanic and Atmospheric Administration (NOAA)
- RD-835410
- Environmental Protection Agency (EPA)
- RD-835405
- Environmental Protection Agency (EPA)
- 726165
- European Research Council (ERC)
- AGS-1242258
- NSF
- RD-83540301
- Environmental Protection Agency (EPA)
- Created
-
2018-05-18Created from EPrint's datestamp field
- Updated
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2023-02-22Created from EPrint's last_modified field