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| Titel |
Organic composition of single and submicron particles in different regions of western North America and the eastern Pacific during INTEX-B 2006 |
| VerfasserIn |
D. A. Day, S. Takahama, S. Gilardoni, L. M. Russell |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1680-7316
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| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 9, no. 15 ; Nr. 9, no. 15 (2009-08-03), S.5433-5446 |
| Datensatznummer |
250007551
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| Publikation (Nr.) |
 copernicus.org/acp-9-5433-2009.pdf |
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| Zusammenfassung |
| Single particles were collected from an aircraft platform as part of the
Intercontinental Chemical Transport Experiment – Phase B (INTEX-B) conducted
over the eastern Pacific and western North America. Single particle spectra
were obtained using scanning transmission X-ray microscopy-near edge X-ray
absorption fine structure spectroscopy (STXM-NEXAFS). Bulk submicron
particles were also collected and organic functional group and elemental
concentrations were quantified with Fourier transform infrared (FTIR)
spectroscopy and X-ray fluorescence (XRF). Single particle spectra were
classified into metaclasses associated with different sources and atmospheric
processing. Particles with spectra indicative of secondary organic aerosol
production and combustion sources were found at several locations and a range
of altitudes. At lower altitudes, particles with spectra resembling soil dust
and biomass burning fingerprints were commonly observed. The types of
particle spectra most commonly observed aloft were similar to those observed
during a previous study over the northwestern Pacific, indicating that
long-range transport may have been an important particle source. Single
particle spectra provided evidence that condensation and surface-limited
oxidation contributed to particle growth. Organic mass (OM) concentrations
ranged from 1 to 7 μg m−3 and averaged 2.4–4.1 μg m−3.
Alkane functional groups were the largest fraction of OM, averaging
1.9–2.1 μg m−3 or 50–76% of OM, followed by alcohol
functional groups (0.35–0.39 μg m−3, 9–14%). Organic and
elemental concentrations are compared within and among geographical air mass
regions: "Pacific" free troposphere, "Continental" free troposphere,
"Seattle" metropolitan region, and the California "Central Valley". OM
concentrations were highest and most variable in the Central Valley
(3.5±2 μg m−3). Oxygen-to-carbon ratios were relatively
constant in the Central Valley but variable for the Continental air masses.
Overall, the OM concentrations showed greater variability within air mass
categories as compared to averages among them, suggesting sampled air mass
regions included a variety of sources and processing of organic aerosol. |
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