Significant source of secondary aerosol: formation from gasoline evaporative emissions in the presence of SO<sub>2</sub> and NH<sub>3</sub>

Abstract

Abstract. Gasoline evaporative emissions have become an important anthropogenic source of urban atmospheric volatile organic compounds (VOCs) and secondary organic aerosol (SOA). These emissions have a significant impact on regional air quality, especially in China where car ownership is growing rapidly. However, the contribution of evaporative emissions to secondary aerosol (SA) is not clear in an air pollution complex in which a high concentration of SO2 and NH3 was present. In this study, the effects of SO2 and NH3 on SA formation from unburned gasoline vapor were investigated in a 30 m3 indoor smog chamber. It was found that an increase in SO2 and NH3 concentrations (0–151 and 0–200 ppb, respectively) could linearly promote the formation of SA, which could be enhanced by a factor of 1.6–2.6 and 2.0–2.5, respectively. Sulfate was most sensitive to the SO2 concentration, followed by organic aerosol, which was due not only to the acid catalytic effect, but was also related to the formation of organic sulfur-containing compounds. In the case of an increasing NH3 concentration, ammonium nitrate increased more significantly than organic aerosol, and nitrogen-containing organics were also enhanced, as revealed by the results of positive matrix factorization (PMF) analysis. New particle formation (NPF) and particle size growth were also significantly enhanced in the presence of SO2 and NH3. This work indicates that gasoline evaporative emissions will be a significant source of SA, especially in the presence of high concentrations of SO2 and NH3. Meanwhile, these emissions might also be a potential source of sulfur- and nitrogen-containing organics. Our work provides a scientific basis for the synergistic emission reduction of secondary aerosol precursors, including NOx, SO2, NH3, and particularly VOCs, to mitigate particulate matter (PM) pollution in China.

Direct contribution of ammonia to <i>α</i>-pinene secondary organic aerosol formation

“…Similar results have also been observed in the photooxidation and ozonolysis of α-pinene SOA experiments: that SOA mass yield increased by 13 % as a response to NH 3 addition (Babar et al, 2017). Besides, the addition of NH 3 could also promote the SOA formation from photooxidation of vehicle exhaust (Chen et al, 2019;, anthropogenic VOCs (Wang et al, 2018;Huang et al, 2018) and acrolein (Li et al, 2019). The promotion mechanism of NH 3 to SOA formation can be both through base-acid reaction (Schlag et al, 2017;Babar et al, 2017;Rubach et al, 2013;Mensah et al, 2012;Na et al, 2007) and by the NH 3 uptake to the carbonyl group (Zhu et al, 2018;.…”

“…The size-resolved chemical composition and mass concentration of aerosol particles were measured directly with an online high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS, hereafter referred to as AMS) (DeCarlo et al, 2006). A detailed description of AMS operational procedure is provided in previous publications Jayne et al, 2000).…”

Direct contribution of ammonia to CCN-size alpha-pinene secondary organic aerosol formation

“…Similar results have also been observed in the photooxidation and ozonolysis of a-pinene SOA experiments that SOA mass yield increased 50 by 13% as a response to NH3 addition (Babar et al, 2017). Besides, the addition of NH3 could also promote the SOA formation from photooxidation of vehicle exhaust (Chen et al, 2019;, anthropogenic VOCs (Wang et al, 2018;Huang et al, 2018) and acrolein (Li et al, 2019). The promotion mechanism of NH3 to SOA formation can be both through base-acid reaction (Schlag et al, 2017;Babar et al, 2017;Na et al, 2007) and by the NH3 uptake to the carbonyl group (Zhu et al, 2018;.…”

Increased Primary and Secondary H<sub>2</sub>SO<sub>4</sub> Showing the Opposing Roles in SOA Formation from Ethyl Methacrylate Ozonolysis

“…CC BY 4.0 License. analytical techniques, and experimental procedures are described in detail elsewhere (Chen et al, 2019). Only a brief description on the specific procedures relevant to this work is presented here.…”

“…The length of sampling pipes of various monitoring instruments ranged from 0.5-1.0 m. A scanning mobility particle sizer (SMPS, TSI, Inc.), consisting of a nano-differential mobility analyzer (DMA; model 3082), condensation particle counter (CPC; model 1720), and Po210 bipolar neutralizer, was applied to measure number size distribution. Total particle number and mass concentrations were calculated assuming a uniform density for aerosol particles of 1.4 g cm -3 (Liu et al, 2019b;Chen et al, 2019). The sheath flow and aerosol flow in the SMPS were set to 3.0 and 0.3 L min -1 , respectively.…”