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| Titel |
Condensational uptake of semivolatile organic compounds in gasoline engine exhaust onto pre-existing inorganic particles |
| VerfasserIn |
S.-M. Li, J. Liggio, L. Graham, G. Lu, J. Brook, C. Stroud, J. Zhang, P. Makar, M. D. Moran |
| 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 ; 11, no. 19 ; Nr. 11, no. 19 (2011-10-10), S.10157-10171 |
| Datensatznummer |
250010118
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| Publikation (Nr.) |
 copernicus.org/acp-11-10157-2011.pdf |
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| Zusammenfassung |
| This paper presents the results of laboratory studies on the condensational
uptake of gaseous organic compounds in the exhaust of a light-duty gasoline
engine onto preexisting sulfate and nitrate seed particles. Significant
condensation of the gaseous organic compounds in the exhaust occurs onto
these inorganic particles on a time scale of 2–5 min. The amount of
condensed organic mass (COM) is proportional to the seed particle
mass, suggesting that the uptake is due to dissolution determined by the
equilibrium partitioning between gas phase and particles, not adsorption. The
amount of dissolution in unit seed mass, S, decreases as a power function with increased dilution
of the exhaust, ranging from 0.23 g g−1 at a dilution ratio of 81, to
0.025 g g−1 at a dilution ratio of 2230. It
increases nonlinearly with increasing concentration of the total hydrocarbons
in the gas phase (THC), rising from 0.12 g g−1 to 0.26 g g−1
for a CTHC increase of 1 to 18 μg m−3, suggesting
that more organics are partitioned into the particles at higher gas phase
concentrations. In terms of gas-particle partitioning, the condensational
uptake of THC gases in gasoline engine exhaust can account for up to 30%
of the total gas + particle THC. The organic mass spectrum of COM
has the largest fragment at m/z 44, with mass ratios of mass fragments 43/44
and 57/44 at 0.59 and 2.91, much lower than those reported for gasoline
engine primary organic aerosols. The mass fragment 44/total organic mass ratio of
0.097 indicates that COM contains large oxygenated components. By
incorporating the present findings, regional air quality modelling results
suggest that the condensational uptake of THC onto sulfate particles alone
can be comparable to the primary particle mass under moderately polluted
ambient conditions. These findings are important for modelling and regulating
the air quality impacts of gasoline vehicular emissions. |
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