Light Absorption of Secondary Organic Aerosol: Composition and Contribution of Nitroaromatic Compounds

Cloud condensation nuclei (CCN) activity and the hygroscopicity of secondary organic aerosol (SOA) depends on the particle size and composition, explicitly, the thermodynamic properties of the aerosol solute and subsequent interactions with water. The gas-to-aerosol phase partitioning is critical for aerosol composition and thus gas-phase vapors and kinetics can play an important role in the CCN activity of SOA.

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Influence of organic aerosol composition determined by offline FIGAERO-CIMS on particle absorptive properties in autumn Beijing

10.5194/acp-2021-528 ◽

2021 ◽

Author(s):

Jing Cai ◽

Cheng Wu ◽

Jiandong Wang ◽

Wei Du ◽

Feixue Zheng ◽

...

Keyword(s):

Optical Properties ◽

Urban Environment ◽

Light Absorption ◽

Radiative Forcing ◽

Dicarboxylic Acids ◽

Organic Aerosol ◽

Molecular Composition ◽

Absorption Enhancement ◽

Ionization Mass ◽

Aerosol Composition

Abstract. Organic aerosol (OA) is a major component of fine particulate matter (PM) affecting air quality, human health, and the climate. The absorptive and reflective behavior of OA components contributes to determining particle optical properties and thus their effects on the radiative budget of the troposphere. There is limited knowledge on the influence of the molecular composition of OA on particle optical properties in the polluted urban environment. In this study, we characterized the molecular composition of oxygenated OA collected on filter samples in autumn of 2018 in Beijing, China, with a filter inlet for gases and aerosols coupled to a high-resolution time-of-flight chemical ionization mass spectrometer (FIGAERO-CIMS). Three haze episodes occurred during our sampling period with daily maximum concentrations of OA of 50, 30, and 55 µg m−3, respectively. We found that the signal intensities of dicarboxylic acids and sulfur-containing compounds increased during the two more intense haze episodes, while the relative contributions of wood-burning markers and other aromatic compounds were enhanced during the cleaner periods. We further assessed the optical properties of oxygenated OA components by combining the detailed chemical composition measurements with collocated particle light absorption measurements. We show that light-absorption enhancement (Eabs) of black carbon (BC) was mostly related to more oxygenated OA (e.g. dicarboxylic acids), likely formed in aqueous-phase reactions during the intense haze periods with higher relative humidity, and speculate that they might contribute to lensing effects. Aromatics and nitro-aromatics (e.g. nitrocatechol and its derivatives) were mostly related to a high light absorption coefficient (babs) consistent with light-absorbing (brown) carbon (BrC). Our results provide information on oxygenated OA components at the molecular level associated with BrC and BC particle light-absorption and can serve as a basis for further studies on the effects of anthropogenic OA on radiative forcing in the urban environment.

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Secondary Organic Aerosol Composition from C12 Alkanes

The Journal of Physical Chemistry A ◽

10.1021/jp501779w ◽

2014 ◽

Vol 119 (19) ◽

pp. 4281-4297 ◽

Cited By ~ 36

Author(s):

Katherine A. Schilling Fahnestock ◽

Lindsay D. Yee ◽

Christine L. Loza ◽

Matthew M. Coggon ◽

Rebecca Schwantes ◽

...

Keyword(s):

Secondary Organic Aerosol ◽

Organic Aerosol ◽

Aerosol Composition

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Formation of anthropogenic secondary organic aerosol (SOA) and its influence on biogenic SOA properties

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-2837-2013 ◽

2013 ◽

Vol 13 (5) ◽

pp. 2837-2855 ◽

Cited By ~ 48

Author(s):

E. U. Emanuelsson ◽

M. Hallquist ◽

K. Kristensen ◽

M. Glasius ◽

B. Bohn ◽

...

Keyword(s):

Volume Fraction ◽

Secondary Organic Aerosol ◽

Morphological Changes ◽

Ambient Air ◽

Organic Aerosol ◽

Oxidation Products ◽

Enhancement Effect ◽

Oh Radicals ◽

Strong Positive Correlation ◽

Aerosol Composition

Abstract. Secondary organic aerosol (SOA) formation from mixed anthropogenic and biogenic precursors has been studied exposing reaction mixtures to natural sunlight in the SAPHIR chamber in Jülich, Germany. In this study aromatic compounds served as examples of anthropogenic volatile organic compound (VOC) and a mixture of α-pinene and limonene as an example for biogenic VOC. Several experiments with exclusively aromatic precursors were performed to establish a relationship between yield and organic aerosol mass loading for the atmospheric relevant range of aerosol loads of 0.01 to 10 μg m−3. The yields (0.5 to 9%) were comparable to previous data and further used for the detailed evaluation of the mixed biogenic and anthropogenic experiments. For the mixed experiments a number of different oxidation schemes were addressed. The reactivity, the sequence of addition, and the amount of the precursors influenced the SOA properties. Monoterpene oxidation products, including carboxylic acids and dimer esters were identified in the aged aerosol at levels comparable to ambient air. OH radicals were measured by Laser Induced Fluorescence, which allowed for establishing relations of aerosol properties and composition to the experimental OH dose. Furthermore, the OH measurements in combination with the derived yields for aromatic SOA enabled application of a simplified model to calculate the chemical turnover of the aromatic precursor and corresponding anthropogenic contribution to the mixed aerosol. The estimated anthropogenic contributions were ranging from small (&approx;8%) up to significant fraction (>50%) providing a suitable range to study the effect of aerosol composition on the aerosol volatility (volume fraction remaining (VFR) at 343 K: 0.86–0.94). The aromatic aerosol had higher oxygen to carbon ratio O/C and was less volatile than the biogenic fraction. However, in order to produce significant amount of aromatic SOA the reaction mixtures needed a higher OH dose that also increased O/C and provided a less volatile aerosol. The SOA yields, O/C, and f44 (the mass fraction of CO2+ ions in the mass spectra which can be considered as a measure of carboxylic groups) in the mixed photo-chemical experiments could be described as linear combinations of the corresponding properties of the pure systems. For VFR there was in addition an enhancement effect, making the mixed aerosol significantly less volatile than what could be predicted from the pure systems. A strong positive correlation was found between changes in volatility and O/C with the exception during dark hours where the SOA volatility decreased while O/C did not change significantly. Thus, this change in volatility under dark conditions as well as the anthropogenic enhancement is due to chemical or morphological changes not affecting O/C.

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Characterization of a large biogenic secondary organic aerosol event from eastern Canadian forests

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-2825-2010 ◽

2010 ◽

Vol 10 (6) ◽

pp. 2825-2845 ◽

Cited By ~ 140

Author(s):

J. G. Slowik ◽

C. Stroud ◽

J. W. Bottenheim ◽

P. C. Brickell ◽

R. Y.-W. Chang ◽

...

Keyword(s):

Secondary Organic Aerosol ◽

Transport Model ◽

Cloud Condensation Nuclei ◽

Coniferous Forest ◽

Organic Aerosol ◽

Chemical Mechanism ◽

Rural Site ◽

Chemical Transport Model ◽

Aerosol Composition ◽

Aerosol Mass

Abstract. Measurements of aerosol composition, volatile organic compounds, and CO are used to determine biogenic secondary organic aerosol (SOA) concentrations at a rural site 70 km north of Toronto. These biogenic SOA levels are many times higher than past observations and occur during a period of increasing temperatures and outflow from Northern Ontario and Quebec forests in early summer. A regional chemical transport model approximately predicts the event timing and accurately predicts the aerosol loading, identifying the precursors as monoterpene emissions from the coniferous forest. The agreement between the measured and modeled biogenic aerosol concentrations contrasts with model underpredictions for polluted regions. Correlations of the oxygenated organic aerosol mass with tracers such as CO support a secondary aerosol source and distinguish biogenic, pollution, and biomass burning periods during the field campaign. Using the Master Chemical Mechanism, it is shown that the levels of CO observed during the biogenic event are consistent with a photochemical source arising from monoterpene oxidation. The biogenic aerosol mass correlates with satellite measurements of regional aerosol optical depth, indicating that the event extends across the eastern Canadian forest. This regional event correlates with increased temperatures, indicating that temperature-dependent forest emissions can significantly affect climate through enhanced direct optical scattering and higher cloud condensation nuclei numbers.

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Impact of model grid spacing on regional- and urban-scale air quality predictions of organic aerosol

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-30347-2010 ◽

2010 ◽

Vol 10 (12) ◽

pp. 30347-30379 ◽

Cited By ~ 4

Author(s):

C. A. Stroud ◽

P. A. Makar ◽

M. D. Moran ◽

W. Gong ◽

S. Gong ◽

...

Keyword(s):

Air Quality ◽

Great Lakes ◽

Secondary Organic Aerosol ◽

Chemical Transport ◽

Organic Aerosol ◽

Great Lakes Region ◽

Grid Spacing ◽

Aerosol Composition ◽

Resolution Model ◽

Bear Creek

Abstract. Regional-scale chemical transport model predictions of urban organic aerosol to date tend to be biased low relative to observations, a limitation with important implications for applying such models to human exposure health studies. We used a nested version of Environment Canada's AURAMS model (42-to-15-to-2.5 km nested grid spacing) to predict organic aerosol concentrations for a temporal and spatial domain corresponding to the Border Air Quality and Meteorology Study (BAQS-Met), an air-quality field study that took place in the southern Great Lakes region in the summer of 2007. The use of three different horizontal grid spacings allowed the influence of this parameter to be examined. A domain-wide average for the 2.5 km domain and a matching 15 km subdomain yielded very similar organic aerosol averages (4.8 vs. 4.3 μg m−3, respectively). On regional scales, secondary organic aerosol dominated the organic aerosol composition and was adequately resolved by the 15 km model simulation. However, the shape of the organic aerosol concentration histogram for the Windsor urban station improved for the 2.5 km simulation relative to those from the 42 and 15 km simulations. The model histograms for the Bear Creek and Harrow rural stations were also improved in the high concentration "tail" region. As well the highest-resolution model results captured the midday 4 July organic-aerosol plume at Bear Creek with very good temporal correlation. These results suggest that accurate simulation of urban and large industrial plumes in the Great Lakes region requires the use of a high-resolution model in order to represent urban primary organic aerosol emissions, urban VOC emissions, and the secondary organic aerosol production rates properly. The positive feedback between the secondary organic aerosol production rate and existing organic mass concentration is also represented more accurately with the highest-resolution model. Not being able to capture these finer-scale features may partly explain the consistent negative bias reported in the literature when urban-scale organic aerosol evaluations are made using coarser-scale chemical transport models.

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Real refractive indices and volatility of secondary organic aerosol generated from photooxidation and ozonolysis of limonene, α-pinene and toluene

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-7711-2013 ◽

2013 ◽

Vol 13 (15) ◽

pp. 7711-7723 ◽

Cited By ~ 52

Author(s):

H. Kim ◽

S. E. Paulson

Keyword(s):

Refractive Index ◽

Secondary Organic Aerosol ◽

Organic Aerosol ◽

Refractive Indices ◽

Radical Scavenger ◽

Hydrocarbon Oxidation ◽

Aerosol Composition ◽

Genetic Algorithm Method ◽

Oxidation Chemistry ◽

532 Nm

Abstract. Thermodenuding particles can provide insights into aerosol composition and may be a way to create particles in laboratory chambers that better mimic the atmosphere. The relative volatility of secondary organic aerosol (SOA) was investigated by evaporating organics from the particles using a thermodenuder (TD) at temperatures between ∼60 and 100 °C. Volatility was influenced by the parent hydrocarbon, oxidation chemistry and relative humidity (RH). For SOA generated from ozonolysis, limonene had lower volatility than α-pinene, and OH scavengers had no influence on volatility. For photooxidation, α-pinene SOA was slightly more volatile than limonene SOA. Increasing RH also modestly increased volatility, while toluene SOA was unaffected by heating to 98 °C. For both α-pinene and limonene, the concentration of NOx and the HC / NOx ratio had no discernible effect on SOA volatility. Refractive indices for the original and denuded particles were retrieved from polar nephelometer measurements using parallel and perpendicular polarized 532 nm light. Retrievals were performed with a genetic algorithm method using Mie–Lorenz scattering theory and measured particle size distributions. Retrieved refractive indices for the SOA before thermodenuding varied between 1.35 and 1.61 depending on several factors, including parent hydrocarbon, oxidation chemistry, and SOA generation temperature. For high NOx SOA, as particles shrink, their refractive index returns to the value of the corresponding size particles before heating (limonene) or slightly higher (α-pinene). For low NOx however, the resulting refractive index is 0.05 ± 0.02 lower than the corresponding size undenuded particles. Additionally, for α-pinene SOA from ozonolysis with OH radical scavenger, resulting refractive indices were higher by about 0.03 after heating. Consistent with no change in size, refractive indices of toluene SOA were unaffected by heating. Finally, refractive index data available to date are reviewed, leading to the suggestion that the most representative values for mr at λ =532 nm for biogenic and anthropogenic SOA are 1.44 and 1.55, respectively.

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Determination of the biogenic secondary organic aerosol fraction in the boreal forest by NMR spectroscopy

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-941-2012 ◽

2012 ◽

Vol 12 (2) ◽

pp. 941-959 ◽

Cited By ~ 38

Author(s):

E. Finessi ◽

S. Decesari ◽

M. Paglione ◽

L. Giulianelli ◽

C. Carbone ◽

...

Keyword(s):

Nmr Spectroscopy ◽

Boreal Forest ◽

Functional Group ◽

Secondary Organic Aerosol ◽

Organic Aerosol ◽

Spectroscopic Techniques ◽

Aerosol Composition ◽

Air Masses ◽

The North ◽

Aerosol Mass

Abstract. The study investigates the sources of fine organic aerosol (OA) in the boreal forest, based on measurements including both filter sampling (PM1) and online methods and carried out during a one-month campaign held in Hyytiälä, Finland, in spring 2007. Two aerosol mass spectrometers (Q-AMS, ToF-AMS) were employed to measure on-line concentrations of major non-refractory aerosol species, while the water extracts of the filter samples were analyzed by nuclear magnetic resonance (NMR) spectroscopy for organic functional group characterization of the polar organic fraction of the aerosol. AMS and NMR spectra were processed separately by non-negative factorization algorithms, in order to apportion the main components underlying the submicrometer organic aerosol composition and depict them in terms of both mass fragmentation patterns and functional group compositions. The NMR results supported the AMS speciation of oxidized organic aerosol (OOA) into two main fractions, which could be generally labelled as more and less oxidized organics. The more oxidized component was characterized by a mass spectrum dominated by the m/z 44 peak, and in parallel by a NMR spectrum showing aromatic and aliphatic backbones highly substituted with oxygenated functional groups (carbonyls/carboxyls and hydroxyls). Such component, contributing on average 50% of the OA mass throughout the observing period, was associated with pollution outbreaks from the Central Europe. The less oxidized component was enhanced in concomitance with air masses originating from the North-to-West sector, in agreement with previous investigations conducted at this site. NMR factor analysis was able to separate two distinct components under the less oxidized fraction of OA. One of these NMR-factors was associated with the formation of terrestrial biogenic secondary organic aerosol (BSOA), based on the comparison with spectral profiles obtained from laboratory experiments of terpenes photo-oxidation. The second NMR factor associated with western air masses was linked to biogenic marine sources, and was enriched in low-molecular weight aliphatic amines. Such findings provide evidence of at least two independent sources originating biogenic organic aerosols in Hyytiälä by oxidation and condensation mechanisms: reactive terpenes emitted by the boreal forest and compounds of marine origin, with the latter relatively more important when predominantly polar air masses reach the site. This study is an example of how spectroscopic techniques, such as proton NMR, can add functional group specificity for certain chemical features (like aromatics) of OA with respect to AMS. They can therefore be profitably exploited to complement aerosol mass spectrometric measurements in organic source apportionment studies.

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Chlorine-initiated oxidation of n-alkanes under high NOx conditions: Insights into secondary organic aerosol composition and volatility using a FIGAERO-CIMS

10.5194/acp-2018-443 ◽

2018 ◽

Cited By ~ 1

Author(s):

Dongyu S. Wang ◽

Lea Hildebrandt Ruiz

Keyword(s):

Secondary Organic Aerosol ◽

Organic Aerosol ◽

Ionization Mass ◽

Aerosol Composition ◽

Atmospheric Lifetime ◽

Thermal Fragmentation ◽

Oligomer Formation ◽

Filter Loading ◽

Dry Conditions ◽

Unit Mass Resolution

Abstract. Chlorine-initiated oxidation of n-alkanes (C8-12) under high nitrogen oxides conditions was investigated. Observed secondary organic aerosol yields (0.16 to 1.65) are higher than those for OH-initiated oxidation of C8-12 alkanes (0.04 to 0.35). A High-Resolution Time-of-Flight Chemical Ionization Mass Spectrometer coupled to a Filter Inlet for Gases and AEROsols (FIGAERO-CIMS) was used to characterize the gas- and particle-phase molecular composition. Chlorinated organics were observed, which likely originated from chlorine addition to the double bond present on the heterogeneously produced dihydrofurans. A two-dimensional thermogram representation was developed to visualize composition and relative volatility of organic aerosol components using unit-mass resolution data. Evidence of oligomer formation, thermal fragmentation and thermal decomposition was observed. Aerosol yield and oligomer formation were suppressed under humid conditions (35 to 67 % RH) relative to dry conditions (under 5 % RH). The temperature at peak desorption signal, Tmax, a proxy for aerosol volatility, was shown to change with aerosol filter loading, which should be constrained when evaluating aerosol volatilities using the FIGAERO-CIMS. Results suggest that long-chain anthropogenic alkanes could contribute significantly to ambient aerosol loading over their atmospheric lifetime.

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