 |
| Titel |
Major components of atmospheric organic aerosol in southern California as determined by hourly measurements of source marker compounds |
| VerfasserIn |
B. J. Williams, A. H. Goldstein, N. M. Kreisberg, S. V. Hering, D. R. Worsnop, I. M. Ulbrich, K. S. Docherty, J. L. Jimenez |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 10, no. 23 ; Nr. 10, no. 23 (2010-12-07), S.11577-11603 |
| Datensatznummer |
250008942
|
| Publikation (Nr.) |
 copernicus.org/acp-10-11577-2010.pdf |
|
|
|
|
|
| Zusammenfassung |
| We report the first hourly in-situ measurements of speciated organic aerosol
(OA) composition in an urban environment. Field measurements were made in
southern California at the University of California–Riverside during the
2005 Study of Organic Aerosol at Riverside (SOAR), which included two
separate measurement periods: a summer study (15 July–15 August) and a
fall study (31 October–28 November). Hourly measurements of over 300
semivolatile and nonvolatile organic compounds were made using the thermal
desorption aerosol gas chromatograph (TAG). Positive matrix factorization
(PMF) was performed on a subset of these compounds to identify major
components contributing to submicron (i.e., PM1) OA at the site, as
measured by an aerosol mass spectrometer (AMS). PMF analysis was performed
on an 11-day focus period in each season, representing average seasonal
conditions during the summer and a period of urban influence during the
fall. As a result of this analysis, we identify multiple types of primary
and secondary OA (POA and SOA). Secondary sources contribute substantially
to fine OA mass at Riverside, which commonly receives regional air masses
that pass through metropolitan Los Angeles during the summer. Four
individual summertime SOA components are defined, and when combined, they
are estimated to contribute an average 88% of the total fine OA mass
during summer afternoons according to PMF results. These sources appear to
be mostly from the oxidation of anthropogenic precursor gases, with one SOA
component having contributions from oxygenated biogenics. During the fall,
three out of four aerosol components that contain SOA are inseparable from
covarying primary emissions, and therefore we cannot estimate the fraction
of total OA that is secondary in nature during the fall study. Identified
primary OA components are attributed to vehicle emissions, food cooking,
primary biogenics, and biomass burning aerosol. While a distinction between
local and regional vehicle emissions is made, a combination of these two
factors accounted for approximately 11% of observed submicron OA during
both sampling periods. Food cooking operations contributed ~10% of
submicron OA mass during the summer, but was not separable from SOA during
the fall due to high covariance of sources. Biomass burning aerosol
contributed a larger fraction of fine OA mass during the fall (~11%) than compared to summer (~7%). Primary biogenic aerosol
was also identified during the summer, contributing ~1% of the OA,
but not during the fall. While the contribution of both local and regional
primary vehicle OA accounts for only ~11% of total OA during both
seasons, gas-phase vehicle emissions likely create a substantial fraction of
the observed SOA as a result of atmospheric processing. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|