 |
| Titel |
Primary to secondary organic aerosol: evolution of organic emissions from mobile combustion sources |
| VerfasserIn |
A. A. Presto, T. D. Gordon, A. L. Robinson |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 14, no. 10 ; Nr. 14, no. 10 (2014-05-22), S.5015-5036 |
| Datensatznummer |
250118729
|
| Publikation (Nr.) |
 copernicus.org/acp-14-5015-2014.pdf |
|
|
|
|
|
| Zusammenfassung |
| A series of smog chamber experiments were conducted to investigate the
transformation of primary organic aerosol (POA) and formation of secondary
organic aerosol (SOA) during the photooxidation of dilute exhaust from a
fleet of gasoline and diesel motor vehicles and two gas-turbine engines. In
experiments where POA was present in the chamber at the onset of
photooxidation, positive matrix factorization (PMF) was used to determine
separate POA and SOA factors from aerosol mass spectrometer data. A
2-factor solution, with one POA factor and one SOA factor, was sufficient
to describe the organic aerosol for gasoline vehicles, diesel vehicles, and
one of the gas-turbine engines. Experiments with the second gas-turbine
engine required a 3-factor PMF solution with a POA factor and two SOA
factors. Results from the PMF analysis were compared to the residual method
for determining SOA and POA mass concentrations. The residual method
apportioned a larger fraction of the organic aerosol mass as POA because it
assumes that all mass at m / z 57 is associated with POA. The POA
mass spectrum for the gasoline and diesel vehicles exhibited high abundances
of the CnH2n+1 series of ions (m / z 43, 57, etc.) and
was similar to the mass spectra of the hydrocarbon-like organic aerosol
factor determined from ambient data sets with one exception, a diesel vehicle
equipped with a diesel oxidation catalyst. POA mass spectra for the
gas-turbine engines are enriched in the CnH2n−1 series of ions
(m / z 41, 55, etc.), consistent with the composition of the
lubricating oil used in these engines. The SOA formed from the three sources
exhibits high abundances of m / z 44 and 43, indicative of mild
oxidation. The SOA mass spectra are consistent with less-oxidized ambient
SV-OOA (semivolatile oxygenated organic aerosols) and fall within the triangular
region of f44 versus f43 defined by ambient measurements. However there is poor
absolute agreement between the experimentally derived SOA mass spectra and
ambient OOA factors, though this poor agreement should be expected based on
the variability of ambient OOA factors. Van Krevelen analysis of the POA and
SOA factors for gasoline and diesel experiments reveal slopes of −0.50 and
−0.40, respectively. This suggests that the oxidation chemistry in these
experiments is a combination of carboxylic acid and alcohol/peroxide
formation, consistent with ambient oxidation chemistry. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|