scholarly journals Nocturnal isoprene oxidation over the Northeast United States in summer and its impact on reactive nitrogen partitioning and secondary organic aerosol

2009 ◽  
Vol 9 (1) ◽  
pp. 225-269
Author(s):  
S. S. Brown ◽  
J. A. deGouw ◽  
C. Warneke ◽  
T. B. Ryerson ◽  
W. P. Dubé ◽  
...  
Keyword(s):  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Nitrogen Partitioning ◽  
Photochemical Oxidation ◽  
Reactive Nitrogen ◽  
Organic Nitrates ◽  
Isoprene Oxidation ◽  
Northeast Us ◽  
Aircraft Study

Abstract. Isoprene is the largest single VOC emission to the atmosphere. Although it is primarily oxidized photochemically during daylight hours, late-day emissions that remain in the atmosphere at sunset undergo oxidation by NO3 in regionally polluted areas with large NOx levels. A recent aircraft study examined isoprene and its nocturnal oxidants in a series of night flights across the Northeast US, a region with large emissions of both isoprene and NOx. Substantial amounts of isoprene that were observed after dark were strongly anticorrelated with measured NO3 and were the most important factor determining the lifetime of this radical. The products of photochemical oxidation of isoprene, methyl vinyl ketone and methacrolein, were more uniformly distributed, and served as tracers for the presence of isoprene at sunset, prior to its oxidation by NO3. Comparison of a determination of the mass of isoprene oxidized in darkness by NO3 to a calculation of integrated isoprene emissions showed that large amounts (>20%) of emitted isoprene may undergo nocturnal oxidation in this region. Organic nitrates produced from the NO3+isoprene reaction, though not directly measured, were estimated to account for 2–9% of total reactive nitrogen and 7–31% of other long-lived organic nitrates such as PAN. The mass of isoprene oxidized by NO3 was comparable to and correlated with the organic aerosol loading for flights with relatively low organic aerosol background. The contribution of nocturnal isoprene oxidation to secondary organic aerosol was determined in the range 1–17%, and isoprene SOA mass derived from NO3 was calculated to exceed that due to OH by approximately 50%.

scholarly journals Nocturnal isoprene oxidation over the Northeast United States in summer and its impact on reactive nitrogen partitioning and secondary organic aerosol

2009 ◽  
Vol 9 (9) ◽  
pp. 3027-3042 ◽  
Author(s):  
S. S. Brown ◽  
J. A. deGouw ◽  
C. Warneke ◽  
T. B. Ryerson ◽  
W. P. Dubé ◽  
...  
Keyword(s):  
Secondary Organic Aerosol ◽  
Large Fraction ◽  
Organic Aerosol ◽  
Nitrogen Partitioning ◽  
Photochemical Oxidation ◽  
Reactive Nitrogen ◽  
Organic Nitrates ◽  
Isoprene Oxidation ◽  
Northeast Us

Abstract. Isoprene is the largest single VOC emission to the atmosphere. Although it is primarily oxidized photochemically during daylight hours, late-day emissions that remain in the atmosphere at sunset undergo oxidation by NO3 in regionally polluted areas with large NOx levels. A recent aircraft study examined isoprene and its nocturnal oxidants in a series of night flights across the Northeast US, a region with large emissions of both isoprene and NOx. Substantial amounts of isoprene that were observed after dark were strongly anticorrelated with measured NO3 and were the most important factor determining the lifetime of this radical. The products of photochemical oxidation of isoprene, methyl vinyl ketone and methacrolein, were more uniformly distributed, and served as tracers for the presence of isoprene at sunset, prior to its oxidation by NO3. A determination of the mass of isoprene oxidized in darkness showed it to be a large fraction (>20%) of emitted isoprene. Organic nitrates produced from the NO3+isoprene reaction, though not directly measured, were estimated to account for 2–9% of total reactive nitrogen. The mass of isoprene oxidized by NO3 was comparable to and correlated with the organic aerosol loading for flights with relatively low organic aerosol background. The contribution of nocturnal isoprene oxidation to secondary organic aerosol was determined in the range 1–17%, and isoprene SOA mass derived from NO3 was calculated to exceed that due to OH by approximately 50%.

scholarly journals Molecular composition and volatility of isoprene photochemical oxidation secondary organic aerosol under low and high NO<sub>x</sub> conditions

2016 ◽  
Author(s):  
Emma L. D'Ambro ◽  
Ben H. Lee ◽  
Jiumeng Liu ◽  
John E. Shilling ◽  
Cassandra J. Gaston ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Group Contribution ◽  
Molecular Composition ◽  
Photochemical Oxidation ◽  
Organic Nitrates ◽  
Ionization Mass ◽  
Equilibrium Partitioning ◽  
Group Contribution Methods

Abstract. We present measurements of secondary organic aerosol (SOA) formation from isoprene photochemical oxidation formed in an environmental simulation chamber using dry neutral seed particles, thereby suppressing the role of acid catalyzed multiphase chemistry, at a variety of oxidant conditions. A high-resolution time-of-flight chemical ionization mass spectrometer (HRToF-CIMS) utilizing iodide-adduct ionization coupled to the Filter Inlet for Gases and AEROsols (FIGAERO) allowed for the simultaneous online sampling of the gas and particle composition. Under high HO2 and low NO conditions, highly oxygenated (O : C ≥ 1) C5 compounds were major components (~ 50 %) of the SOA. The overall composition of the SOA evolved both as a function of time and as a function of input NO concentrations. As the level of input NO increased, organic nitrates increased in both the gas- and particle-phases, but the dominant non-nitrate particle-phase components monotonically decreased. We use comparisons of measured and predicted gas-particle partitioning of individual components to assess the validity of literature-based group-contribution methods for estimating saturation vapor concentrations. While there is evidence for equilibrium partitioning being achieved on the chamber residence time scale (5.2 hours) for some individual components, significant errors in group-contribution methods are revealed. In addition, > 30 % of the SOA mass, detected as low-molecular weight compounds, cannot be reconciled with equilibrium partitioning. These compounds desorb from the FIGAERO at unexpectedly high temperatures given their molecular composition, indicative of thermal decomposition of effectively lower volatility components, likely larger molecular weight oligomers. We use these insights from the laboratory and observations of the same SOA components made during the Southern Oxidant and Aerosol Study (SOAS) to assess the importance of isoprene photooxidation as a local SOA source.

scholarly journals Molecular composition and volatility of isoprene photochemical oxidation secondary organic aerosol under low- and high-NO<sub><i>x</i></sub> conditions

2017 ◽  
Vol 17 (1) ◽  
pp. 159-174 ◽  
Author(s):  
Emma L. D'Ambro ◽  
Ben H. Lee ◽  
Jiumeng Liu ◽  
John E. Shilling ◽  
Cassandra J. Gaston ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Group Contribution ◽  
Molecular Composition ◽  
Photochemical Oxidation ◽  
Organic Nitrates ◽  
Ionization Mass ◽  
Equilibrium Partitioning ◽  
Group Contribution Methods

Abstract. We present measurements of secondary organic aerosol (SOA) formation from isoprene photochemical oxidation in an environmental simulation chamber at a variety of oxidant conditions and using dry neutral seed particles to suppress acid-catalyzed multiphase chemistry. A high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS) utilizing iodide-adduct ionization coupled to the Filter Inlet for Gases and Aerosols (FIGAERO) allowed for simultaneous online sampling of the gas and particle composition. Under high-HO2 and low-NO conditions, highly oxygenated (O : C  ≥  1) C5 compounds were major components (∼ 50 %) of SOA. The SOA composition and effective volatility evolved both as a function of time and as a function of input NO concentrations. Organic nitrates increased in both the gas and particle phases as input NO increased, but the dominant non-nitrate particle-phase components monotonically decreased. We use comparisons of measured and predicted gas-particle partitioning of individual components to assess the validity of literature-based group-contribution methods for estimating saturation vapor concentrations. While there is evidence for equilibrium partitioning being achieved on the chamber residence timescale (5.2 h) for some individual components, significant errors in group-contribution methods are revealed. In addition, > 30 % of the SOA mass, detected as low-molecular-weight semivolatile compounds, cannot be reconciled with equilibrium partitioning. These compounds desorb from the FIGAERO at unexpectedly high temperatures given their molecular composition, which is indicative of thermal decomposition of effectively lower-volatility components such as larger molecular weight oligomers.

scholarly journals Modeling secondary organic aerosol formation from isoprene oxidation under dry and humid conditions

2011 ◽  
Vol 11 (2) ◽  
pp. 893-909 ◽  
Author(s):  
F. Couvidat ◽  
C. Seigneur
Keyword(s):  
Experimental Data ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Organic Nitrates ◽  
Atmospheric Conditions ◽  
Aerosol Formation ◽  
Yield Increase ◽  
Isoprene Oxidation ◽  
Smog Chambers

Abstract. A new model for the formation of secondary organic aerosol (SOA) from isoprene was developed. This model uses surrogate molecular species (hydroxy-hydroperoxides, tetrols, methylglyceric acid, organic nitrates) to represent SOA formation. The development of this model used available experimental data on yields and molecular composition of SOA from isoprene and methacrolein oxidation. This model reproduces the amount of particles measured in smog chambers under both low-NOx and high-NOx conditions. Under low-NOx conditions, the model reproduces the transitional formation of hydroxy-hydroperoxides particles, which are photolyzed and lead to SOA mass decrease after reaching a maximum. Under high-NOx conditions, particles are assumed to be formed mostly from the photo-oxidation of a PAN-type molecule derived from methacrolein (MPAN). This model successfully reproduces the complex NOx-dependence of isoprene oxidation and suggests a possible yield increase under some high-NOx conditions. Experimental data correspond to dry conditions (RH < 10%). However, particles formed from isoprene are expected to be highly hydrophilic, and isoprene oxidation products would likely partition between an aqueous phase and the gas phase at high humidity in the atmosphere. The model was extended to take into account the hydrophilic properties of SOA, which are relevant under atmospheric conditions, and investigate the effect of particulate liquid water on SOA formation. An important increase in SOA mass was estimated for humid conditions due to the hydrophilic properties. Experiments under high relative humidity conditions should be conducted to confirm the results of this study, which have implications for SOA modeling.

scholarly journals Modeling secondary organic aerosol formation from isoprene oxidation under dry and humid conditions

2010 ◽  
Vol 10 (8) ◽  
pp. 20559-20605
Author(s):  
F. Couvidat ◽  
C. Seigneur
Keyword(s):  
Experimental Data ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Organic Nitrates ◽  
Atmospheric Conditions ◽  
Aerosol Formation ◽  
Yield Increase ◽  
Isoprene Oxidation ◽  
Smog Chambers

Abstract. A new model for the formation of secondary organic aerosol (SOA) from isoprene was developed. This model uses surrogate molecular species (hydroxy-hydroperoxides, tetrols, methylglyceric acid, organic nitrates) to represent SOA formation. The development of this model used available experimental data on yields and molecular composition of SOA from isoprene and methacrolein oxidation. This model reproduces the amount of particles measured in smog chambers under both low-NOx and high-NOx conditions. Under low-NOx conditions, the model reproduces the transitional formation of hydroxy-hydroperoxides particles, which are photolyzed and lead to SOA mass decrease after reaching a maximum. Under high-NOx conditions, particles are assumed to be formed mostly from the photo-oxidation of a PAN-type molecule derived from methacrolein (MPAN). This model successfully reproduces the complex NOx-dependence of isoprene oxidation and suggests a possible yield increase under some high-NOx conditions. Experimental data correspond to dry conditions (RH<10%). However, particles formed from isoprene are expected to be highly hydrophilic, and isoprene oxidation products would likely partition between an aqueous phase and the gas phase at high humidity in the atmosphere. The model was extended to take into account the hydrophilic properties of SOA, which are relevant under atmospheric conditions, and investigate the effect of particulate liquid water on SOA formation. An important increase in SOA mass was estimated for atmospheric conditions due to the hydrophilic properties. Experiments should be conducted to confirm the results of this study, which have implications for SOA modeling.

Experimental determination of chemical diffusion within secondary organic aerosol particles

2013 ◽  
Vol 15 (8) ◽  
pp. 2983 ◽  
Author(s):  
Evan Abramson ◽  
Dan Imre ◽  
Josef Beránek ◽  
Jacqueline Wilson ◽  
Alla Zelenyuk
Keyword(s):  
Experimental Determination ◽  
Secondary Organic Aerosol ◽  
Aerosol Particles ◽  
Chemical Diffusion ◽  
Organic Aerosol

scholarly journals Isoprene oxidation by nitrate radical: alkyl nitrate and secondary organic aerosol yields

2009 ◽  
Vol 9 (2) ◽  
pp. 8857-8902 ◽  
Author(s):  
A. W. Rollins ◽  
A. Kiendler-Scharr ◽  
J. Fry ◽  
T. Brauers ◽  
S. S. Brown ◽  
...  
Keyword(s):  
First Generation ◽  
Secondary Organic Aerosol ◽  
Model Simulation ◽  
Effective Rate Constant ◽  
Organic Aerosol ◽  
Effective Rate ◽  
Oxidation Products ◽  
Alkyl Nitrates ◽  
Alkyl Nitrate ◽  
Isoprene Oxidation

Abstract. Alkyl nitrates and secondary organic aerosol (SOA) produced during the oxidation of isoprene by nitrate radicals has been observed in the SAPHIR chamber. We find the yield of nitrates is 70±8% from the isoprene+NO3 reaction, and the yield for secondary dinitrates produced in the reaction of primary isoprene nitrates with NO3 is 40±20%. We find an effective rate constant for reaction of NO3 with the group of first generation oxidation products to be 7×10−14 cm3 s−1. At the low total organic aerosol concentration in the chamber (max ≈0.6 μg m−3) we observed a mass yield (ΔSOA mass/Δisoprene mass) of 2% for the entire 16 h experiment. However a comparison of the timing of the observed SOA production to a box model simulation of first and second generation oxidation products shows that the yield from the first generation products was <0.2% while the further oxidation of the initial products leads to a yield of 10% (defined as ΔSOA/Δisoprene2x where Δisoprene2x is the mass of isoprene which reacted twice with NO3). The SOA yield of 10% is consistent with equilibrium partitioning of highly functionalized C5 products of isoprene oxidation.

Secondary organic aerosol yields from cloud-processing of isoprene oxidation products

2008 ◽  
Vol 35 (2) ◽  
Author(s):  
Barbara Ervens ◽  
Annmarie G. Carlton ◽  
Barbara J. Turpin ◽  
Katye E. Altieri ◽  
Sonia M. Kreidenweis ◽  
...  
Keyword(s):  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Oxidation Products ◽  
Cloud Processing ◽  
Isoprene Oxidation ◽  
Isoprene Oxidation Products

scholarly journals Low-volatility compounds contribute significantly to isoprene secondary organic aerosol (SOA) under high-NO<sub><i>x</i></sub> conditions

2019 ◽  
Vol 19 (11) ◽  
pp. 7255-7278 ◽  
Author(s):  
Rebecca H. Schwantes ◽  
Sophia M. Charan ◽  
Kelvin H. Bates ◽  
Yuanlong Huang ◽  
Tran B. Nguyen ◽  
...  
Keyword(s):  
Ring Opening ◽  
Secondary Organic Aerosol ◽  
Inorganic Ions ◽  
Organic Aerosol ◽  
Organic Nitrates ◽  
Glyceric Acid ◽  
Mass Yield ◽  
Atmospheric Conditions ◽  
Ring Opening Reactions ◽  
The Impact

Abstract. Recent advances in our knowledge of the gas-phase oxidation of isoprene, the impact of chamber walls on secondary organic aerosol (SOA) mass yields, and aerosol measurement analysis techniques warrant reevaluating SOA yields from isoprene. In particular, SOA from isoprene oxidation under high-NOx conditions forms via two major pathways: (1) low-volatility nitrates and dinitrates (LV pathway) and (2) hydroxymethyl-methyl-α-lactone (HMML) reaction on a surface or the condensed phase of particles to form 2-methyl glyceric acid and its oligomers (2MGA pathway). These SOA production pathways respond differently to reaction conditions. Past chamber experiments generated SOA with varying contributions from these two unique pathways, leading to results that are difficult to interpret. This study examines the SOA yields from these two pathways independently, which improves the interpretation of previous results and provides further understanding of the relevance of chamber SOA yields to the atmosphere and regional or global modeling. Results suggest that low-volatility nitrates and dinitrates produce significantly more aerosol than previously thought; the experimentally measured SOA mass yield from the LV pathway is ∼0.15. Sufficient seed surface area at the start of the reaction is needed to limit the effects of vapor wall losses of low-volatility compounds and accurately measure the complete SOA mass yield. Under dry conditions, substantial amounts of SOA are formed from HMML ring-opening reactions with inorganic ions and HMML organic oligomerization processes. However, the lactone organic oligomerization reactions are suppressed under more atmospherically relevant humidity levels, where hydration of the lactone is more competitive. This limits the SOA formation potential from the 2MGA pathway to HMML ring-opening reactions with water or inorganic ions under typical atmospheric conditions. The isoprene SOA mass yield from the LV pathway measured in this work is significantly higher than previous studies have reported, suggesting that low-volatility compounds such as organic nitrates and dinitrates may contribute to isoprene SOA under high-NOx conditions significantly more than previously thought and thus deserve continued study.

scholarly journals Enhancement of Secondary Organic Aerosol Formation and its Oxidation State by SO<sub>2</sub> during Photooxidation of 2-Methoxyphenol

2018 ◽  
Author(s):  
Changgeng Liu ◽  
Tianzeng Chen ◽  
Yongchun Liu ◽  
Jun Liu ◽  
Hong He ◽  
...  
Keyword(s):  
Oxidation State ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Wood Smoke ◽  
Organic Nitrates ◽  
Carbon Oxidation ◽  
Formation Processes ◽  
Aerosol Formation ◽  
Product Model ◽  
Seed Particles

Abstract. 2-Methoxyphenol (guaiacol) is derived from the lignin pyrolysis and taken as a potential tracer for wood smoke emissions. In this work, the effect of SO2 at atmospheric levels (0–56 ppb) on secondary organic aerosol (SOA) formation and its oxidation state during guaiacol photooxidation was investigated in the presence of various inorganic seed particles (NaCl and (NH4)2SO4). Without SO2 and seed particles, SOA yields (9.46–26.37 %) obtained at different guaiacol concentration (138.83–2197.36 μg m−3) could be well expressed by a one-product model. The presence of SO2 resulted in enhancing SOA yield by 14.05–23.66 %. With (NH4)2SO4 and NaCl seed particles, SOA yield was enhanced by 23.06 % and 29.57 %, respectively, which further increased significantly to 29.78–53.47 % in the presence of SO2, suggesting that SO2 and seed particles have a synergetic contribution to SOA formation. It should be noted that SO2 was found to be in favor of increasing the carbon oxidation state (OSC) of SOA, indicating that the functionalization reaction should be more dominant than oligomerization reaction. In addition, the average N/C ratio of SOA was 0.037, which revealed that NOx participated in the photooxidation process, consequently leading to the formation of organic nitrates. The experimental results demonstrate the importance of SO2 on the formation processes of SOA and organosulfates, and also are helpful to further understand SOA formation from the atmospheric photooxidation of guaiacol and its subsequent impacts on air quality and climate.

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