The effects of humidity and ammonia on the chemical composition of secondary aerosols from toluene/NOx photo-oxidation

Gao, Xiang; Bao, Zhier; Li, Kangwei; Han, Lixia; Zhao, Xing-ya; Zhang, Xin; Wang, Zhihua; Azzi, Merched; Cen, Kefa

doi:10.1016/j.scitotenv.2020.138671

Cited by 19 publications

(12 citation statements)

References 73 publications

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“…Interestingly, compared with the particles from TMB / NO x experiments, there was a new peak at 615 cm −1 for the particles generated from TMB / NO x / SO 2 experiments, regardless of lowor high-NO x conditions. The 615 cm −1 peak is characteristic of inorganic sulfates and further highlights that the presence of SO 2 promotes the formation of inorganic sulfates as pointed out in previous studies (Chen et al, 2019;Liu et al, 2016). The strong absorption at 1081 cm −1 arises from the S = O bands in the particle components.…”

Section: Particle Chemical Composition In So 2 -Added Photooxidationsupporting

confidence: 76%

“…Another study by Babar et al (2017) utilized a newly developed flow reactor and confirmed that the presence of NH 3 can enhance SOA formation from both ozonolysis and photooxidation of α-pinene. Besides α-pinene, the promoting effects of NH 3 on particle formation were also discovered in the photooxidation of aromatics (Chu et al, 2016) and vehicle exhaust (Chen et al, 2019). In contrast, addition of NH 3 decreased aerosol particle formation from the reaction of styrene with ozone, owing to the decomposition of products by NH 3 nucleophilic attack (Na et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

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SO2 and NH3 emissions enhance organosulfur compounds and fine particle formation from the photooxidation of a typical aromatic hydrocarbon

Yang

Tsona

et al. 2021

Atmos. Chem. Phys.

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Abstract. Aromatic hydrocarbons can dominate the volatile organic compound budget in the urban atmosphere. Among them, 1,2,4-trimethylbenzene (TMB), mainly emitted from solvent use, is one of the most important secondary organic aerosol (SOA) precursors. Although atmospheric SO2 and NH3 levels can affect secondary aerosol formation, the influenced extent of their impact and their detailed driving mechanisms are not well understood. The focus of the present study is to examine the chemical compositions and formation mechanisms of SOA from TMB photooxidation influenced by SO2 and/or NH3. Here, we show that SO2 emission could considerably enhance aerosol particle formation due to SO2-induced sulfate generation and acid-catalyzed heterogeneous reactions. Orbitrap mass spectrometry measurements revealed the generation of not only typical TMB products but also hitherto unidentified organosulfates (OSs) in SO2-added experiments. The OSs designated as being of unknown origin in earlier field measurements were also detected in TMB SOA, indicating that atmospheric OSs might also be originated from TMB photooxidation. For NH3-involved experiments, results demonstrated a positive correlation between NH3 levels and particle volume as well as number concentrations. The effects of NH3 on SOA composition were slight under SO2-free conditions but stronger in the presence of SO2. A series of multifunctional products with carbonyl, alcohols, and nitrate functional groups were tentatively characterized in NH3-involved experiments based on infrared spectra and mass spectrometry analysis. Plausible formation pathways were proposed for detected products in the particle phase. The volatility distributions of products, estimated using parameterization methods, suggested that the detected products gradually condense onto the nucleation particles to contribute to aerosol formation and growth. Our results suggest that strict control of SO2 and NH3 emissions might remarkably reduce organosulfates and secondary aerosol burden in the atmosphere. Updating the aromatic oxidation mechanism in models could result in more accurate treatment of particle formation for urban regions with considerable SO2, NH3, and aromatics emissions.

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Section: Particle Chemical Composition In So 2 -Added Photooxidationsupporting

confidence: 76%

Section: Introductionmentioning

confidence: 99%

SO2 and NH3 emissions enhance organosulfur compounds and fine particle formation from the photooxidation of a typical aromatic hydrocarbon

Yang

Tsona

et al. 2021

Atmos. Chem. Phys.

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“…The composition of SOA was determined by a high-resolution time of flight aerosol mass spectrometry (HR-ToF-AMS, hereafter AMS; Aerodyne Research Inc., USA), with method described in detail in our previous studies 57,58 . In brief, the AMS was operated in the high sensitivity V-mode and the high resolution W-mode every 2 min, alternately.…”

Section: Instrumentation and Analysismentioning

confidence: 99%

Suppression of anthropogenic secondary organic aerosol formation by isoprene

Zhang

Zhao

et al. 2022

npj Clim Atmos Sci

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Secondary organic aerosol (SOA) represents a major fraction of atmospheric fine particles. Both biogenic and anthropogenic volatile organic compounds (VOCs) can contribute to SOA through (photo-) oxidation. However, the current understanding of their combined, interactive effect on SOA formation and composition is still limited, challenging the accuracy in assessing global SOA budget, sources, and climate effect. Here we combine laboratory experiments and modelling to show that isoprene can suppress SOA formation from photo-oxidation of anthropogenic aromatics (toluene and p-xylene) with the presence of NOx, and similar SOA suppression phenomena are observed when replacing isoprene with propene. We find that the decreased SOA in such mixed-VOC conditions can be largely attributed to OH scavenging effect, resulting in reduced consumption of parent aromatics. However, various changes in SOA oxidation state (i.e., O/C) and oxidation pathways (i.e., more carbonyls formation) are observed following addition of isoprene, and the SOA chemical composition may not be similar to any single parent hydrocarbon, which implies the existence of complex interactions between the degradation chemistry for alkenes and aromatics. Under the conditions of this work, the OH scavenging effect is largely determined by gas-phase chemistry, which is expected to be widespread in binary or more complex systems in ambient air. More broadly, we infer that the global budget of anthropogenic SOA and its corresponding radiative forcing could be affected by biogenic emission of isoprene, particularly in urban environments with appreciable vegetation coverage.

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“…In addition, toluene-derived SOA formation involves aqueous chemistry relevant to cloud processing and aqueous aerosols . A recent experimental study found that NH 3 enhances the SOA mass loading from toluene photooxidation in the presence of nitrogen oxides (NO x = NO + NO 2 ) especially under wet conditions, attributable to the formation of carboxylates and organic nitrates . Another recent smog chamber study on toluene photooxidation observed an increasing SOA yield with increasing NO x under low-NO x conditions but a suppressed SOA yield under high-NO x conditions .…”

Section: Introductionmentioning

confidence: 99%

Multigeneration Production of Secondary Organic Aerosol from Toluene Photooxidation

Jin

Wang

et al. 2021

Environ. Sci. Technol.

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Photooxidation of volatile organic compounds (VOCs) produces secondary organic aerosol (SOA) and lightabsorbing brown carbon (BrC) via multiple reaction steps/ pathways, reflecting significant chemical complexity relevant to gaseous oxidation and subsequent gas-to-particle conversion. Toluene is an important VOC under urban conditions, but the fundamental chemical mechanism leading to SOA formation remains uncertain. Here, we elucidate multigeneration SOA production from toluene by simultaneously tracking the evolutions of gas-phase oxidation and aerosol formation in a reaction chamber. Large size increase and browning of monodisperse submicrometer seed particles occur shortly after initiating oxidation by hydroxyl radical (OH) at 10−90% relative humidity (RH). The evolution in gaseous products and aerosol properties (size/density/optical properties) and chemical speciation of aerosol-phase products indicate that the aerosol growth and browning result from earlier generation products consisting dominantly of dicarbonyl and carboxylic functional groups. While volatile dicarbonyls engage in aqueous reactions to yield nonvolatile oligomers and lightabsorbing nitrogen heterocycles/heterochains (in the presence of NH 3 ) at high RH, organic acids contribute to aerosol carboxylates via ionic dissociation or acid−base reaction in a wide RH range. We conclude that toluene contributes importantly to SOA/BrC formation from dicarbonyls and organic acids because of their prompt and high yields from photooxidation and unique functionalities for participation in aerosol-phase reactions.

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The effects of humidity and ammonia on the chemical composition of secondary aerosols from toluene/NOx photo-oxidation

Cited by 19 publications

References 73 publications

SO<sub>2</sub> and NH<sub>3</sub> emissions enhance organosulfur compounds and fine particle formation from the photooxidation of a typical aromatic hydrocarbon

SO<sub>2</sub> and NH<sub>3</sub> emissions enhance organosulfur compounds and fine particle formation from the photooxidation of a typical aromatic hydrocarbon

Suppression of anthropogenic secondary organic aerosol formation by isoprene

Multigeneration Production of Secondary Organic Aerosol from Toluene Photooxidation

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The effects of humidity and ammonia on the chemical composition of secondary aerosols from toluene/NOx photo-oxidation

Cited by 19 publications

References 73 publications

SO&lt;sub&gt;2&lt;/sub&gt; and NH&lt;sub&gt;3&lt;/sub&gt; emissions enhance organosulfur compounds and fine particle formation from the photooxidation of a typical aromatic hydrocarbon

SO&lt;sub&gt;2&lt;/sub&gt; and NH&lt;sub&gt;3&lt;/sub&gt; emissions enhance organosulfur compounds and fine particle formation from the photooxidation of a typical aromatic hydrocarbon

Suppression of anthropogenic secondary organic aerosol formation by isoprene

Multigeneration Production of Secondary Organic Aerosol from Toluene Photooxidation

Contact Info

Product

Resources

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SO<sub>2</sub> and NH<sub>3</sub> emissions enhance organosulfur compounds and fine particle formation from the photooxidation of a typical aromatic hydrocarbon

SO<sub>2</sub> and NH<sub>3</sub> emissions enhance organosulfur compounds and fine particle formation from the photooxidation of a typical aromatic hydrocarbon