1. Effects of inorganic seed aerosols on the growth and chemical composition of secondary organic aerosol formed from OH-initiated oxidation of toluene.
- Author
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Huang, Mingqiang, Hao, Liqing, Gu, Xuejun, Hu, Changjin, Zhao, Weixiong, Wang, Zhenya, Fang, Li, and Zhang, Weijun
- Subjects
ATMOSPHERIC aerosols ,TIME-of-flight mass spectrometry ,TOLUENE ,PHOTOOXIDATION ,CITIES & towns ,CALCIUM chloride ,SODIUM compounds ,HYDROXYL group - Abstract
(NH)SO, CaCl, NaSiO and NaNO were selected as surrogates of inorganic seed aerosols of ambient atmosphere of Chinese urban areas, respectively, to study their effects on the formation of secondary organic aerosol (SOA) in the toluene/CHONO/NO photooxidation system. The SMPS and aerosol laser time-of-flight mass spectrometer (ALTOFMS) was used to measure the aerodynamic size and chemical composition of individual SOA particles in real-time. Experimental results indicate that either the growth or products of SOA is affected by the presence of inorganic seed aerosol. Inorganic seed aerosols would promote growth rates of SOA formation at the start of the reaction and inhibits its formation rate with prolonging the reaction time. In the case of about 100 μg m seed aerosol load, the addition of NaSiO induced a same growth rate of SOA formation as NaNO. The influence of four individual seed aerosols on the generation of SOA decreased in the order of CaCl > (NH)SO > NaNO, NaSiO. The presence of NaSiO or NaNO has no obvious effect on the growth rates of SOA formation, but it does increase the yield of organic acid and nitrogen-containing organic compounds, respectively. Besides the significantly effect on the growth rate of SOA formation, the presence of CaCl or (NH)SO can lead to the formation of high-molecular weight species which is found to be positively correlated with the hygroscopic behavior of seed aerosols. The CaCl shows the strongest hygroscopic behavior among the four individual seed aerosols, and the most significant promotion effect on the formation of the high-molecular weight species. It is proposed that the SOA generation enhancement and high-molecular weight products are achieved by particle-phase heterogeneous reactions induced and catalyzed by the acidity of CaCl and (NH)SO seed aerosols. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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