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| Titel |
SOA formation from the atmospheric oxidation of 2-methyl-3-buten-2-ol and its implications for PM2.5 |
| VerfasserIn |
M. Jaoui, T. E. Kleindienst, J. H. Offenberg, M. Lewandowski, W. A. Lonneman |
| 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 ; 12, no. 4 ; Nr. 12, no. 4 (2012-02-27), S.2173-2188 |
| Datensatznummer |
250010745
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| Publikation (Nr.) |
 copernicus.org/acp-12-2173-2012.pdf |
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| Zusammenfassung |
The formation of secondary organic aerosol (SOA) generated by irradiating
2-methyl-3-buten-2-ol (MBO) in the presence and/or absence of NOx,
H2O2, and/or SO2 was examined. Experiments were conducted in
smog chambers operated in either dynamic or static mode. A filter/denuder
sampling system was used for simultaneously collecting gas- and
particle-phase products. The structural characterization of gas and
particulate products was investigated using BSTFA, BSTFA + PFBHA, and DNPH
derivatization techniques followed by GC-MS and liquid chromatography
analysis. This analysis showed the occurrence of more than 68 oxygenated
organic compounds in the gas and particle phases, 28 of which were
tentatively identified. The major components observed include
2,3-dihydroxyisopentanol (DHIP), 2-hydroxy-2-oxoisopentanol,
2,3-dihydroxy-3-methylbutanal, 2,3-dihydroxy-2-methylsuccinic acid,
2-hydroxy-2-methylpropanedioic acid, acetone, glyoxal, methylglyoxal,
glycolaldehyde, and formaldehyde. Most of these oxygenated compounds were
detected for the first time in this study.
While measurements of the gas-phase photooxidation products have been made,
the focus of this work has been an examination of the particle phase. SOA
from some experiments was analyzed for the organic mass to organic carbon
ratio (OM/OC), the effective enthalpy of vaporization (ΔHvapeff), and the aerosol yield. Additionally, aerosol size,
volume, and number concentrations were measured by a Scanning Mobility
Particle Sizer coupled to a Condensation Particle Counter system. The OM/OC
ratio was 2.1 in the MBO/H2O2 system. The ΔHvapeff
was 41 kJ mol−1, a value similar to that of isoprene
SOA. The laboratory SOA yield measured in this study was 0.7% in
MBO/H2O2 for an aerosol mass of 33 μg m−3. Secondary
organic aerosol was found to be negligible under conditions with oxides of
nitrogen (NOx) present. Time profiles and proposed reaction schemes are
provided for selected compounds.
The contribution of SOA products from MBO oxidation to ambient PM2.5
was investigated by analyzing a series of ambient PM2.5 samples
collected in several places around the United States. In addition to the
occurrence of several organic compounds in both field and laboratory
samples, DHIP was found to originate only from the oxidation of MBO, and
therefore this compound could potentially serve as a tracer for MBO SOA.
Initial attempts have been made to quantify the concentrations of DHIP and
other compounds based on surrogate compound calibrations. The average
concentrations of DHIP in ambient PM2.5 samples from Duke Forest in
North Carolina ranged from zero during cold seasons to approximately 1 ng m−3 during warm seasons. This appears to be the first time that DHIP
has been detected in ambient PM2.5 samples. The occurrence of several
other compounds in both laboratory and field samples suggests that SOA
originating from MBO can contribute under selected ambient conditions to the
ambient aerosol mainly in areas where MBO emissions are high. |
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