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| Titel |
Secondary organic aerosol formation from road vehicle emissions |
| VerfasserIn |
Simone M. Pieber, Stephen M. Platt, Imad El Haddad, Alessandro A. Zardini, Ricardo Suarez-Bertoa, Jay G. Slowik, Ru-Jin Huang, Stig Hellebust, Brice Temime-Roussel, Nicolas Marchand, Luca Drinovec, Griša Močnik, Urs Baltensperger, Covadogna Astorga, André S. H. Prévôt |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250099550
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| Publikation (Nr.) |
 EGU/EGU2014-15344.pdf |
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| Zusammenfassung |
| Organic aerosol particles (OA) are a major fraction of the submicron particulate matter. OA
consists of directly emitted primary (POA) and secondary OA (SOA). SOA is formed in-situ
in the atmosphere via the reaction of volatile organic precursors. The partitioning of SOA
species depends not only on the exposure to oxidants, but for instance also on temperature,
relative humidity (RH), and the absorptive mass chemical composition (presence of
inorganics) and concentration.
Vehicle exhaust is a known source of POA and likely contributes to SOA formation in
urban areas [1;2]. This has recently been estimated by (i) analyzing ambient data from urban
areas combined with fuel consumption data [3], (ii) by examining the chemical composition
of raw fuels [4], or (iii) smog chamber studies [5, 6]. Contradictory and thus somewhat
controversial results in the relative quantity of SOA from diesel vs. gasoline vehicle exhaust
were observed.
In order to elucidate the impact of variable ambient conditions on the potential SOA
formation of vehicle exhaust, and its relation to the emitted gas phase species, we studied
SOA formed from the exhaust of passenger cars and trucks as a function of fuel and
engine type (gasoline, diesel) at different temperatures (T 22 vs. -7oC) and RH
(40 vs. 90%), as well as with different levels of inorganic salt concentrations. The
exhaust was sampled at the tailpipe during regulatory driving cycles on chassis
dynamometers, diluted (200 – 400x) and introduced into the PSI mobile smog chamber [6],
where the emissions were subjected to simulated atmospheric ageing. Particle phase
instruments (HR-ToF-AMS, aethalometers, CPC, SMPS) and gas phase instruments
(PTR-TOF-MS, CO, CO2, CH4, THC, NH3 and other gases) were used online during the
experiments.
We found that gasoline emissions, because of cold starts, were generally larger than
diesel, especially during cold temperatures driving cycles. Gasoline vehicles also showed the
highest SOA formation. Furthermore, we observed that vehicle emissions and SOA are
significantly affected by temperature and RH: doubling the RH in the chamber
resulted in significantly increased SOA formation. Primary emissions and secondary
aerosol formation from diesel and gasoline vehicles will be compared at different
temperature and RH. Also the interaction and influence of inorganics on organics will be
discussed.
References: [1] Robinson, A.L., et al. (2007) Science 315, 1259. [2] Weitkamp, E.A., et
al. (2007) Environ. Sci. Technol. 41, 6969. [3] Bahreini, R., et al. (2012) Geophys. Res. Lett.
39, L06805. [4] Gentner, D.R. et al. (2012) PNAS 109, 18318. [5] Gordon, T.D. et al. (2013)
Atmos. Chem. Phys. Discuss 13, 23173. [6] Platt, S.M., et al. (2013) Atmos. Chem. Phys.
Discuss. 12, 28343. |
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