Optical Absorptivity versus Molecular Composition of Model Organic Aerosol Matter

2009 ◽  
Vol 113 (39) ◽  
pp. 10512-10520 ◽  
Author(s):  
Angela G. Rincón ◽  
Marcelo I. Guzmán ◽  
M. R. Hoffmann ◽  
A. J. Colussi
Keyword(s):  
Organic Aerosol ◽  
Molecular Composition

scholarly journals Molecular characterization of gaseous and particulate oxygenated compounds at a remote site in Cape Corsica in the western Mediterranean Basin

2021 ◽  
Vol 21 (10) ◽  
pp. 8067-8088
Author(s):  
Vincent Michoud ◽  
Elise Hallemans ◽  
Laura Chiappini ◽  
Eva Leoz-Garziandia ◽  
Aurélie Colomb ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Carboxylic Acids ◽  
Organic Aerosol ◽  
Western Mediterranean ◽  
Water Soluble ◽  
Molecular Composition ◽  
Particle Phase ◽  
Western Mediterranean Basin ◽  
Partitioning Coefficients

Abstract. The characterization of the molecular composition of organic carbon in both gaseous and aerosol is key to understanding the processes involved in the formation and aging of secondary organic aerosol. Therefore a technique using active sampling on cartridges and filters and derivatization followed by analysis using a thermal desorption–gas chromatography–mass spectrometer (TD–GC–MS) has been used. It is aimed at studying the molecular composition of organic carbon in both gaseous and aerosol phases (PM2.5) during an intensive field campaign which took place in Corsica (France) during the summer of 2013: the ChArMEx (Chemistry and Aerosol Mediterranean Experiment) SOP1b (Special Observation Period 1B) campaign. These measurements led to the identification of 51 oxygenated (carbonyl and or hydroxyl) compounds in the gaseous phase with concentrations between 21 and 3900 ng m−3 and of 85 compounds in the particulate phase with concentrations between 0.3 and 277 ng m−3. Comparisons of these measurements with collocated data using other techniques have been conducted, showing fair agreement in general for most species except for glyoxal in the gas phase and malonic, tartaric, malic and succinic acids in the particle phase, with disagreements that can reach up to a factor of 8 and 20 on average, respectively, for the latter two acids. Comparison between the sum of all compounds identified by TD–GC–MS in the particle phase and the total organic matter (OM) mass reveals that on average 18 % of the total OM mass can be explained by the compounds measured by TD–GC–MS. This number increases to 24 % of the total water-soluble OM (WSOM) measured by coupling the Particle Into Liquid Sampler (PILS)-TOC (total organic carbon) if we consider only the sum of the soluble compounds measured by TD–GC–MS. This highlights the important fraction of the OM mass identified by these measurements but also the relative important fraction of OM mass remaining unidentified during the campaign and therefore the complexity of characterizing exhaustively the organic aerosol (OA) molecular chemical composition. The fraction of OM measured by TD–GC–MS is largely dominated by di-carboxylic acids, which represent 49 % of the PM2.5 content detected and quantified by this technique. Other contributions to PM2.5 composition measured by TD–GC–MS are then represented by tri-carboxylic acids (15 %), alcohols (13 %), aldehydes (10 %), di-hydroxy-carboxylic acids (5 %), monocarboxylic acids and ketones (3 % each), and hydroxyl-carboxylic acids (2 %). These results highlight the importance of polyfunctionalized carboxylic acids for OM, while the chemical processes responsible for their formation in both phases remain uncertain. While not measured by the TD–GC–MS technique, humic-like substances (HULISs) represent the most abundant identified species in the aerosol, contributing for 59 % of the total OM mass on average during the campaign. A total of 14 compounds were detected and quantified in both phases, allowing the calculation of experimental partitioning coefficients for these species. The comparison of these experimental partitioning coefficients with theoretical ones, estimated by three different models, reveals large discrepancies varying from 2 to 7 orders of magnitude. These results suggest that the supposed instantaneous equilibrium being established between gaseous and particulate phases assuming a homogeneous non-viscous particle phase is questionable.

Molecular Composition and Volatility of Organic Aerosol in the Southeastern U.S.: Implications for IEPOX Derived SOA

2016 ◽  
Vol 50 (5) ◽  
pp. 2200-2209 ◽  
Author(s):  
F. D. Lopez-Hilfiker ◽  
C. Mohr ◽  
E. L. D’Ambro ◽  
A. Lutz ◽  
T. P. Riedel ◽  
...  
Keyword(s):  
Organic Aerosol ◽  
Molecular Composition

Organic aerosol source apportionment from highly time-resolved molecular composition measurements

2009 ◽  
Vol 43 (18) ◽  
pp. 2901-2910 ◽  
Author(s):  
Matthew A. Dreyfus ◽  
Kouame Adou ◽  
Steven M. Zucker ◽  
Murray V. Johnston
Keyword(s):  
Source Apportionment ◽  
Organic Aerosol ◽  
Molecular Composition ◽  
Time Resolved ◽  
Aerosol Source ◽  
Composition Measurements

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

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.

scholarly journals Resolving Ambient Organic Aerosol Formation and Aging Pathways with Simultaneous Molecular Composition and Volatility Observations

2020 ◽  
Vol 4 (3) ◽  
pp. 391-402 ◽  
Author(s):  
Ben H. Lee ◽  
Emma L. D’Ambro ◽  
Felipe D. Lopez-Hilfiker ◽  
Siegfried Schobesberger ◽  
Claudia Mohr ◽  
...  
Keyword(s):  
Organic Aerosol ◽  
Molecular Composition ◽  
Aerosol Formation

scholarly journals Seasonal characteristics of organic aerosol chemical composition and volatility in Stuttgart, Germany

2019 ◽  
Vol 19 (18) ◽  
pp. 11687-11700 ◽  
Author(s):  
Wei Huang ◽  
Harald Saathoff ◽  
Xiaoli Shen ◽  
Ramakrishna Ramisetty ◽  
Thomas Leisner ◽  
...  
Keyword(s):  
Chemical Composition ◽  
High Resolution ◽  
Organic Compounds ◽  
Mass Spectrometer ◽  
Time Of Flight ◽  
Organic Aerosol ◽  
Molecular Composition ◽  
Winter Period ◽  
Ionization Mass ◽  
Resolution Time

Abstract. The chemical composition and volatility of organic aerosol (OA) particles were investigated during July–August 2017 and February–March 2018 in the city of Stuttgart, one of the most polluted cities in Germany. Total non-refractory particle mass was measured with a high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS; hereafter AMS). Aerosol particles were collected on filters and analyzed in the laboratory with a filter inlet for gases and aerosols coupled to a high-resolution time-of-flight chemical ionization mass spectrometer (FIGAERO-HR-ToF-CIMS; hereafter CIMS), yielding the molecular composition of oxygenated OA (OOA) compounds. While the average organic mass loadings are lower in the summer period (5.1±3.2 µg m−3) than in the winter period (8.4±5.6 µg m−3), we find relatively larger mass contributions of organics measured by AMS in summer (68.8±13.4 %) compared to winter (34.8±9.5 %). CIMS mass spectra show OOA compounds in summer have O : C of 0.82±0.02 and are more influenced by biogenic emissions, while OOA compounds in winter have O : C of 0.89±0.06 and are more influenced by biomass burning emissions. Volatility parametrization analysis shows that OOA in winter is less volatile with higher contributions of low-volatility organic compounds (LVOCs) and extremely low-volatility organic compounds (ELVOCs). We partially explain this by the higher contributions of compounds with shorter carbon chain lengths and a higher number of oxygen atoms, i.e., higher O : C in winter. Organic compounds desorbing from the particles deposited on the filter samples also exhibit a shift of signal to higher desorption temperatures (i.e., lower apparent volatility) in winter. This is consistent with the relatively higher O : C in winter but may also be related to higher particle viscosity due to the higher contributions of larger-molecular-weight LVOCs and ELVOCs, interactions between different species and/or particles (particle matrix), and/or thermal decomposition of larger molecules. The results suggest that whereas lower temperature in winter may lead to increased partitioning of semi-volatile organic compounds (SVOCs) into the particle phase, this does not result in a higher overall volatility of OOA in winter and that the difference in sources and/or chemistry between the seasons plays a more important role. Our study provides insights into the seasonal variation of the molecular composition and volatility of ambient OA particles and into their potential sources.

Molecular Composition of Oxygenated Organic Molecules and Their Contributions to Organic Aerosol in Beijing

2021 ◽  
Author(s):  
Yonghong Wang ◽  
Petri Clusius ◽  
Chao Yan ◽  
Kaspar Dällenbach ◽  
Rujing Yin ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Organic Aerosol ◽  
Molecular Composition

scholarly journals Impact of anthropogenic and biogenic sources on the seasonal variation of the molecular composition of urban organic aerosols: a field and laboratory study using ultra-high resolution mass spectrometry

2018 ◽  
Author(s):  
Kaspar R. Daellenbach ◽  
Ivan Kourtchev ◽  
Alexander L. Vogel ◽  
Emily A. Bruns ◽  
Jianhui Jiang ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
High Resolution ◽  
Secondary Organic Aerosol ◽  
High Resolution Mass Spectrometry ◽  
Organic Aerosol ◽  
Molecular Composition ◽  
Wood Burning ◽  
High Resolution Mass ◽  
Alpine Valleys ◽  
Resolution Mass

Abstract. This study presents the molecular composition of OA using ultra-high resolution mass spectrometry (Orbitrap) at an urban site in Central Europe (Zurich, Switzerland). Specific source spectra were also analysed, including samples representative of wood burning emissions from Alpine valleys during wood burning pollution episodes and chamber investigations of wood smoke as well as samples from Hyytiälä strongly influenced by biogenic secondary organic aerosol. While samples collected during winter in Alpine valleys have a molecular composition remarkably similar to fresh laboratory wood burning emissions, winter samples from Zurich are influenced by more aged wood burning emissions. In addition, other organic aerosol emission or formation pathways seem to be important at the latter location in winter. Samples from Zurich during summer are similar to those collected in Hyytiälä, predominantly impacted by oxygenated compounds with an H / C ratio of 1.5, indicating the importance of biogenic precursors for SOA formation at this location. We could explain the strong seasonality of the molecular composition at a typical European site by primary and aged wood burning emissions and biogenic secondary organic aerosol formation during winter and summer, respectively. Results presented here likely explain the seasonally rather constant predominance of non-fossil organic carbon at European locations.

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