ACPD Atmospheric Chemistry and Physics Discussions ACPD Atmos. Chem. Phys. Discuss. 1680-7375 Göttingen, Germany 10.5194/acp-2016-50 Chamber simulation on the formation of secondary organic aerosols (SOA) from diesel vehicle exhaust in China Deng Wei https://orcid.org/0000-0002-3832-3150 1 2 Hu Qihou https://orcid.org/0000-0002-3007-3724 1 Liu Tengyu 1 2 Wang Xinming https://orcid.org/0000-0002-1982-0928 1 Zhang Yanli https://orcid.org/0000-0003-0614-2096 1 Ding Xiang https://orcid.org/0000-0002-1218-1879 1 Sun Yele https://orcid.org/0000-0003-2354-0221 3 Bi Xinhui https://orcid.org/0000-0002-3929-5470 1 Yu Jianzhen https://orcid.org/0000-0002-6165-6500 4 Yang Weiqiang 1 2 Huang Xinyu 1 2 Zhang Zhou 1 2 Huang Zhonghui 1 2 He Quanfu https://orcid.org/0000-0002-3229-8206 1 2 Mellouki A. https://orcid.org/0000-0002-6594-5262 5 George Christian https://orcid.org/0000-0003-1578-7056 6 State Key Laboratory of Organic Geochemistry and Guangdong Key Laboratory of Environmental Protection and Resources Utilization, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China University of Chinese Academy of Sciences, Beijing 100049, China Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China Division of Environment, Hong Kong University of Science & Technology, Clear Water Bay, Kowloon, Hong Kong, China Institut de Combustion, Aérothermique, Réactivité et Environnement (ICARE), CNRS, 45071 Orléans cedex 02, France Institut de Recherches sur la Catalyse et l’Environnement de Lyon (IRCELYON), CNRS, UMR5256, Villeurbanne F-69626, France 01 03 2016 2016 1 46 Copyright: © 2016 Wei Deng et al. 2016 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://acp.copernicus.org/preprints/acp-2016-50/ The full text article is available as a PDF file from https://acp.copernicus.org/preprints/acp-2016-50/acp-2016-50.pdf

In China primary particulate matter emission from on-road vehicles is predominantly coming from diesels, yet secondary organic aerosols (SOA) formed from diesel emission may be also of greater significance due to more intermediate volatile organic compounds (IVOC) in the exhaust. Here we introduced exhaust from in-use diesel vehicles under warm idling condition directly into an indoor smog chamber with a 30 m<sup>3</sup> Teflon reactor, and investigated the SOA formation as well as chemical aging of organic aerosols during photo-oxidation. The emission factors of primary organic aerosol (POA) and black carbon (BC) for the three typical Chinese diesel vehicles ranged 0.18&ndash;0.91 and 0.15&ndash;0.51 g kg-fuel<sup>&minus;1</sup>, respectively; and the SOA production factors ranged 0.50&ndash;1.8 g kg-fuel<sup>&minus;1</sup> with an average SOA/POA ratio of 1.6. Aromatic hydrocarbons could only explain less than 3 % of SOA formed during aging, and IVOC and oxygenated VOC might contribute substantially to SOA formation. High resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) resolved that POA dominated by CH classes (alkanes, cycloalkanes and alkenes) with high abundances of the C<sub><i>n</i></sub>H<sub>2<i>n</i>+1</sub> and C<sub><i>n</i></sub>H<sub>2<i>n</i>-1</sub> fragments, and after photo-oxidation the fraction of CH classes and the H/C ratios decreased, while the fraction of CHO, as well as the ratios of O/C and of organic matter to organic carbon (OM/OC), all increased. The plot of <i>f</i><sub>44</sub> (ratio of <i>m/z</i> 44 to the total signal in a mass spectrum) versus <i>f</i><sub>43</sub> indicated that diesel SOA were semi-volatile oxygenated organic aerosols (SV-OOA). The slopes of O:C versus H:C element ratios in the Van Krevelen diagram ranged from &minus;0.47 to &minus;0.68, suggesting a combination of carboxylic acid and alcohols/peroxides formed during the aging of diesel exhaust.

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