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- Nordin, Erik, et al.
(författare)
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Smog Chamber Experiments of SOA Formation from Gasoline Exhaust and Light Aromatics
- 2010
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Experiments where gasoline exhaust was exposed to UV-radiation to examine Secondary Organic Aerosol (SOA) formation were performed in a smog chamber. The Aerosol Mass Yield (formed SOA/reacted precursor mass) was determined and compared with the yield from a pure precursor experiment in the chamber and from results reported in literature. Preliminary results show that the majority of the organic aerosol mass emitted from idling gasoline cars is secondary. Further, the SOA yields when taking only C6-C10 light aromatics into account are within a similar range to pure precursor experiments, suggesting that light aromatics are dominating precursors in gasoline exhaust SOA.
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- Roldin, Pontus
(författare)
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Process based Modelling of Chemical and Physical Aerosol Properties Relevant for Climate and Health
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Atmospheric aerosol particles have substantial influence on climate and air quality. However, the anthropogenic influence on the atmospheric aerosol is still poorly known. This limits the understanding of past and future climate changes. Additionally, both epidemiological and toxicological studies indicate adverse health effects of inhaled aerosol particles. In order to study the effect of atmospheric processes on the particle properties relevant for climate and health, two models were developed and implemented. The first is a 2D-Lagrangian model for Aerosol Dynamics, gas phase CHEMistry and radiative transfer (ADCHEM), which treats the dispersion in the vertical and horizontal direction perpendicular to air mass trajectories. The second model is a kinetic multilayer model for Aerosol Dynamics, gas and particle phase chemistry in laboratory CHAMber environments (ADCHAM). With ADCHAM it is possible to study process based formation and evaporation of secondary organic aerosol particles, and mass transfer limitations and reactions within the particle phase. ADCHEM was used to quantify the anthropogenic influence from the city of Malmö (280 000 inhabitants) in southern Sweden. In Malmö and a few tens of kilometres downwind, the primary particle emissions have a large influence on the particle number concentration. However, more than 2 hours downwind Malmö, the anthropogenic particle mass contribution is dominated by secondary ammonium nitrate. To quantify the direct and indirect climate impact of urban aerosol emissions, the secondary aerosol formation which changes the optical and hygroscopic properties of the primary soot particles, needs to be addressed in future measurements and process modelling. ADCHAM was used to simulate different laboratory chamber experiment, with focus on potential influential but poorly known processes for secondary organic aerosol properties, formation and evaporation rates in the atmosphere (i.e. oligomerization, organic salt formation, salting-out effects, oxidation of organic compounds in the particle phase and mass transfer limitations in the particle phase). The model results reveal that formation of small amounts of low-volatile and long lived oligomers, which accumulate in the particle surface layers, can effectively prevent the evaporation of more volatile compounds. This can significantly prolong the lifetime of SOA in the atmosphere.
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