Status: this preprint was under review for the journal ACP but the revision was not accepted.
Secondary organic aerosol formation from photooxidation of furan:
effects of NOx level and humidity
Xiaotong Jiang,Narcisse T. Tsona,Long Jia,Shijie Liu,Yongfu Xu,and Lin Du
Abstract. Atmospheric furan is both primary and secondary pollutants in the atmosphere, and their emission contributes to the formation of ultrafine particles and ground-level ozone. We investigate the effects of NOx level and humidity on the formation of secondary organic aerosol (SOA) generated from the photooxidation of furan in the presence of NaCl seed particles. The particle mass concentration and size distribution were determined with a scanning mobility particle sizer (SMPS). SOA mass concentration and yield were determined under different NOx and humidity levels. Owing to condensation and coagulation, the particle number concentration decreases with increasing particle size. A significant difference is observed both in the SOA mass concentration and SOA yield variation with the initial experiment conditions. A relatively high NOx level, ranging from 16.8 to 97.5 ppb, contributes to effective formation of SOA in the presence of NaCl seed particles, with the mass concentration of SOA and SOA yield ranging from 0.96 μg m−3 to 23.46 μg m−3 and from 0.04 % to 1.01 %, respectively. Likewise, the SOA mass concentration and yield increase with increasing humidity, because the increasing RH increases the aerosol liquid water content, which contributes to the liquid phase reactions. Nine organic nitrate species were detected by electrospray ionization exactive orbitrap mass spectrometry (ESI-Exactive-Orbitrap MS). The -COOH，-OH，-C = O and NO2 functional groups were assigned in the FTIR spectra and used as the indicator for the mechanism inference. The present study directly addresses NOx effects and reinforces the implication of humidity on SOA formation during the furan-NOx-NaCl photooxidation. Furthermore, the results illustrate the importance of studying SOA formation over a comprehensive range of environmental conditions. Only such evaluations can induce meaningful SOA mechanisms to be implemented in air quality models.
Received: 12 May 2018 – Discussion started: 25 Jun 2018
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State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China
Shijie Liu
Environment Research Institute, Shandong University, Qingdao, 266237, China
Yongfu Xu
State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing, 100029, China
The roles of NOx level and RH on the formation of SOA from the photooxidation of furan in the presence of NaCl seed particles were elucidated. The aerosol liquid water (ALW) effects on SOA mass concentration and yield were also evaluated. The chemical composition of furan SOA was investigated by ESI-Exactive-Orbitrap MS, with focus on the formation of organic nitrates. Strong evidences indicate that both the RH and different NOx levels have a significant effect on SOA formation.
The roles of NOx level and RH on the formation of SOA from the photooxidation of furan in the...
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