scholarly journals Role of glyoxal in SOA formation from aromatic hydrocarbons: gas-phase reaction trumps reactive uptake

2011 ◽  
Vol 11 (11) ◽  
pp. 30599-30625 ◽  
Author(s):  
S. Nakao ◽  
Y. Liu ◽  
P. Tang ◽  
C.-L. Chen ◽  
J. Zhang ◽  
...  
Keyword(s):  
Aromatic Hydrocarbon ◽  
Gas Phase ◽  
Phase Reaction ◽  
Oh Radical ◽  
Near Surface ◽  
Aerosol Mass Spectrometer ◽  
Seed Particles ◽  
Aerosol Mass ◽  
Experimental Approaches

Abstract. This study evaluates the significance of glyoxal acting as an intermediate species leading to SOA formation from aromatic hydrocarbon photooxidation under humid conditions. Rapid SOA formation from glyoxal uptake onto aqueous (NH4)2SO4 seed particles is observed; however, glyoxal did not partition to SOA or SOA coated aqueous seed during all aromatic hydrocarbon experiments (RH up to 80%). Glyoxal is found to only influence SOA formation by raising hydroxyl (OH) radical concentrations. Four experimental approaches supporting this conclusion are presented in this paper: (1) increased SOA formation and decreased SOA volatility in the toluene + NOx photooxidation system with additional glyoxal was reproduced by matching OH radical concentrations through H2O2 addition; (2) glyoxal addition to SOA seed formed from toluene + NOx photooxidation did not increase observed SOA volume; (3) SOA formation from toluene + NOx photooxidation with and without deliquesced (NH4)2SO4 seed resulted in similar SOA growth, consistent with a coating of SOA preventing glyoxal uptake onto deliquesced (NH4)2SO4 seed; and (4) the fraction of a C4H9+ fragment (observed by Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer, HR-ToF-AMS) from SOA formed by 2-tert-butylphenol (BP) oxidation was unchanged in the presence of additional glyoxal despite enhanced SOA formation. This study suggests that glyoxal uptake onto aerosol is minor when the surface (and near-surface) of aerosols are primarily composed of secondary organic compounds.

scholarly journals Chamber studies of SOA formation from aromatic hydrocarbons: observation of limited glyoxal uptake

2012 ◽  
Vol 12 (9) ◽  
pp. 3927-3937 ◽  
Author(s):  
S. Nakao ◽  
Y. Liu ◽  
P. Tang ◽  
C.-L. Chen ◽  
J. Zhang ◽  
...  
Keyword(s):  
Aromatic Hydrocarbon ◽  
Aromatic Hydrocarbons ◽  
Organic Aerosol ◽  
Oh Radical ◽  
Aerosol Mass Spectrometer ◽  
Seed Particles ◽  
Aerosol Mass ◽  
Experimental Approaches ◽  
Chamber Studies ◽  
A Minor

Abstract. This study evaluates the significance of glyoxal acting as an intermediate species leading to secondary organic aerosol (SOA) formation from aromatic hydrocarbon photooxidation under humid conditions. Rapid SOA formation from glyoxal uptake onto aqueous (NH4)2SO4 seed particles is observed in agreement with previous studies; however, glyoxal did not partition significantly to SOA (with or without aqueous seed) during aromatic hydrocarbon photooxidation within an environmental chamber (RH less than 80%). Rather, glyoxal influences SOA formation by raising hydroxyl (OH) radical concentrations. Four experimental approaches supporting this conclusion are presented in this paper: (1) increased SOA formation and decreased SOA volatility in the toluene + NOx photooxidation system with additional glyoxal was reproduced by matching OH radical concentrations through H2O2 addition; (2) glyoxal addition to SOA seed formed from toluene + NOx photooxidation did not increase SOA volume under dark; (3) SOA formation from toluene + NOx photooxidation with and without deliquesced (NH4)2SO4 seed resulted in similar SOA growth, consistent with a minor contribution from glyoxal uptake onto deliquesced seed and organic coatings; and (4) the fraction of a C4H9+ fragment (observed by Aerodyne High Resolution Time-of-Flight Aerosol Mass Spectrometer, HR-ToF-AMS) in SOA from 2-tert-butylphenol (BP) oxidation was unchanged in the presence of additional glyoxal despite enhanced SOA formation. This study suggests that glyoxal uptake onto aerosol during the oxidation of aromatic hydrocarbons is more limited than previously thought.

scholarly journals Airborne observations of IEPOX-derived isoprene SOA in the Amazon during SAMBBA

2014 ◽  
Vol 14 (20) ◽  
pp. 11393-11407 ◽  
Author(s):  
J. D. Allan ◽  
W. T. Morgan ◽  
E. Darbyshire ◽  
M. J. Flynn ◽  
P. I. Williams ◽  
...  
Keyword(s):  
Amazon Rainforest ◽  
South American ◽  
Aerosol Mass Spectrometer ◽  
Mass Spectral ◽  
Seed Particles ◽  
Aerosol Mass ◽  
Research Aircraft ◽  
The Uk ◽  
The Tropics

Abstract. Isoprene is a potentially highly significant but currently poorly quantified source of secondary organic aerosols (SOA). This is especially important in the tropics, where large rainforests act as significant sources of isoprene. Methylfuran, produced through thermal decomposition during analysis, has recently been suggested as a marker for isoprene SOA formation through the isoprene epoxydiol (IEPOX) route, which mostly occurs under low NOx conditions. This is manifested as a peak at m/z=82 in Aerodyne Aerosol Mass Spectrometer (AMS) data. Here we present a study of this marker measured during five flights over the Amazon rainforest on board the UK Facility for Airborne Atmospheric Measurement (FAAM) BAe-146 research aircraft during the South American Biomass Burning Analysis (SAMBBA) campaign. Cases where this marker is and is not present are contrasted and linked to the presence of acidic seed particles, lower NOx concentrations and higher humidities. There are also data to suggest a role of organic nitrogen in the particulate composition. Furthermore, an inspection of the vertical trends of the marker indicates that concentrations are highest at the top of the boundary layer (possibly due to semivolatile repartitioning) and that upwards through the free troposphere, the mass spectral profile evolves towards that of low volatility oxygenated aerosol. These observations offer insights into the behaviour of IEPOX-derived SOA formation above the Amazon rainforest and the suitability of methylfuran as a marker for this process.

scholarly journals Airborne observations of IEPOX-derived isoprene SOA in the Amazon during SAMBBA

2014 ◽  
Vol 14 (9) ◽  
pp. 12635-12671 ◽  
Author(s):  
J. D. Allan ◽  
W. T. Morgan ◽  
E. Darbyshire ◽  
M. J. Flynn ◽  
P. I. Williams ◽  
...  
Keyword(s):  
Amazon Rainforest ◽  
South American ◽  
Aerosol Mass Spectrometer ◽  
Mass Spectral ◽  
Seed Particles ◽  
Aerosol Mass ◽  
Research Aircraft ◽  
The Uk ◽  
The Tropics

Abstract. Isoprene is a potentially highly significant but currently poorly quantified source of secondary organic aerosols (SOA). This is especially important in the tropics, where large rainforests act as significant sources of isoprene. Methylfuran, produced through thermal decomposition during analysis, has recently been suggested as a marker for isoprene SOA formation through the isoprene epoxydiol (IEPOX) route, which occurs under low NOx conditions. This is manifested as a peak at m / z = 82 in Aerodyne Aerosol Mass Spectrometer (AMS) data. Here we present a study of this marker measured during 5 flights over the Amazon rainforest on board the UK Facility for Airborne Atmospheric Measurement (FAAM) BAe-146 research aircraft during the South American Biomass Burning Analysis (SAMBBA) campaign. Cases where this marker is and is not present are contrasted and linked to the presence of acidic seed particles, lower NOx concentrations and higher humidities. There is also data to suggest a role of organic nitrogen in the particulate composition. Furthermore, an inspection of the vertical trends of the marker indicates that concentrations are highest at the top of the boundary layer (possibly due to semivolatile repartitioning) and upwards through the free troposphere, the mass spectral profile evolves towards that of low volatility oxygenated aerosol. These observations offer insights into the behaviour of IEPOX-derived SOA formation above the Amazon rainforest and the suitability of methylfuran as a marker for this process.

scholarly journals Cause Analysis of PM2.5 pollution during the COVID-19 lockdown in Nanning, China

2021 ◽  
Author(s):  
Jiongli Huang ◽  
Zhiming Chen ◽  
Bin Zhou ◽  
Kaixian Zhu ◽  
Huilin Liu ◽  
...  
Keyword(s):  
Motor Vehicle ◽  
Control Strategies ◽  
Feedback Mechanism ◽  
Vehicle Exhaust ◽  
Near Surface ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Pollution Accumulation ◽  
Positive Feedback Mechanism

Abstract To analyze the cause of atmospheric PM2.5 pollution occurred during the COVID-19 lockdown in Nanning of Guangxi, China, Single Particulate Aerosol Mass Spectrometer, Aethalometer, Particulate Lidar, coupled with the monitoring of near-surface gaseous pollutants, meteorological conditions, remote fire spots sensing by satellite and Backward Trajectory Models were conducted during 18–24, Feb 2020. Three haze stages of pre-pollution period (PPP), pollution accumulation period (PAP) and pollution dissipation period (PDP) were identified. The dominant source of PM2.5 in PPP was biomass burning (BB) (40.4%), followed by secondary inorganics (28.1%) and motor vehicle exhaust (11.7%). The PAP was characterized by a large abundance of secondary inorganics, which contributed for 56.1% of the total PM2.5 concentration, followed by BB (17.4%). The absorption Ångström exponent (2.2) in PPP was higher than those of the other two periods. The analysis of fire spots monitored by remote satellite sensing indicated that open BB in regions around Nanning city could be one of the main facotrs matters. The planetary boundary layer-relative humidity-secondary particles matter-particulate matter positive feedback mechanism was employed to elucidate the atompheric process in this study. This study highlights the importance of understanding the role of BB and meteorology in air pollution formation to call for policy for emission control strategies.

scholarly journals Role of (H2O)n (n = 1–2) in the Gas-Phase Reaction of Ethanol with Hydroxyl Radical: Mechanism, Kinetics, and Products

ACS Omega ◽  
2019 ◽  
Vol 4 (3) ◽  
pp. 5805-5817 ◽  
Author(s):  
Li Xu ◽  
Narcisse T. Tsona ◽  
Shanshan Tang ◽  
Junyao Li ◽  
Lin Du
Keyword(s):  
Hydroxyl Radical ◽  
Gas Phase ◽  
Radical Mechanism ◽  
Phase Reaction ◽  
Gas Phase Reaction

ChemInform Abstract: Products of the Gas-Phase Reaction of Methyl tert-Butyl Ether with the OH Radical in the Presence of NOx

ChemInform ◽  
2010 ◽  
Vol 23 (5) ◽  
pp. no-no
Author(s):  
E. C. TUAZON ◽  
W. P. L. CARTER ◽  
S. M. ASCHMANN ◽  
R. ATKINSON
Keyword(s):  
Gas Phase ◽  
Methyl Tert Butyl Ether ◽  
Phase Reaction ◽  
Oh Radical ◽  
Butyl Ether ◽  
Gas Phase Reaction ◽  
Tert Butyl

Impact of water on the BrO + HO2 gas-phase reaction: mechanism, kinetics and products

2019 ◽  
Vol 21 (36) ◽  
pp. 20296-20307 ◽  
Author(s):  
Narcisse T. Tsona ◽  
Shanshan Tang ◽  
Lin Du
Keyword(s):  
Reaction Mechanism ◽  
Gas Phase ◽  
Hydrogen Abstraction ◽  
Phase Reaction ◽  
Gas Phase Reaction

The role of water in preventing the barrierless hydrogen abstraction in the BrO + HO2 reaction is highlighted.

scholarly journals Effect of oxidant concentration, exposure time, and seed particles on secondary organic aerosol chemical composition and yield

2015 ◽  
Vol 15 (6) ◽  
pp. 3063-3075 ◽  
Author(s):  
A. T. Lambe ◽  
P. S. Chhabra ◽  
T. B. Onasch ◽  
W. H. Brune ◽  
J. F. Hunter ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Gas Phase ◽  
Flow Reactor ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Short Exposure ◽  
Heterogeneous Oxidation ◽  
Seed Particles ◽  
Aerosol Mass ◽  
Environmental Chambers

Abstract. We performed a systematic intercomparison study of the chemistry and yields of secondary organic aerosol (SOA) generated from OH oxidation of a common set of gas-phase precursors in a Potential Aerosol Mass (PAM) continuous flow reactor and several environmental chambers. In the flow reactor, SOA precursors were oxidized using OH concentrations ranging from 2.0 × 108 to 2.2 × 1010 molec cm−3 over exposure times of 100 s. In the environmental chambers, precursors were oxidized using OH concentrations ranging from 2 × 106 to 2 × 107 molec cm−3 over exposure times of several hours. The OH concentration in the chamber experiments is close to that found in the atmosphere, but the integrated OH exposure in the flow reactor can simulate atmospheric exposure times of multiple days compared to chamber exposure times of only a day or so. In most cases, for a specific SOA type the most-oxidized chamber SOA and the least-oxidized flow reactor SOA have similar mass spectra, oxygen-to-carbon and hydrogen-to-carbon ratios, and carbon oxidation states at integrated OH exposures between approximately 1 × 1011 and 2 × 1011 molec cm−3 s, or about 1–2 days of equivalent atmospheric oxidation. This observation suggests that in the range of available OH exposure overlap for the flow reactor and chambers, SOA elemental composition as measured by an aerosol mass spectrometer is similar whether the precursor is exposed to low OH concentrations over long exposure times or high OH concentrations over short exposure times. This similarity in turn suggests that both in the flow reactor and in chambers, SOA chemical composition at low OH exposure is governed primarily by gas-phase OH oxidation of the precursors rather than heterogeneous oxidation of the condensed particles. In general, SOA yields measured in the flow reactor are lower than measured in chambers for the range of equivalent OH exposures that can be measured in both the flow reactor and chambers. The influence of sulfate seed particles on isoprene SOA yield measurements was examined in the flow reactor. The studies show that seed particles increase the yield of SOA produced in flow reactors by a factor of 3 to 5 and may also account in part for higher SOA yields obtained in the chambers, where seed particles are routinely used.

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