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 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.

scholarly journals Formation of highly oxygenated organic molecules from chlorine-atom-initiated oxidation of alpha-pinene

2020 ◽  
Vol 20 (8) ◽  
pp. 5145-5155 ◽  
Author(s):  
Yonghong Wang ◽  
Matthieu Riva ◽  
Hongbin Xie ◽  
Liine Heikkinen ◽  
Simon Schallhart ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Organic Aerosol ◽  
Heterogeneous Reactions ◽  
Peroxy Radicals ◽  
Chlorine Atoms ◽  
Uncertainty Range ◽  
Nitryl Chloride ◽  
Alpha Pinene ◽  
Calibration Methods ◽  
Substantial Uncertainty

Abstract. Highly oxygenated organic molecules (HOMs) from atmospheric oxidation of alpha-pinene can irreversibly condense to particles and contribute to secondary organic aerosol (SOA) formation. Recently, the formation of nitryl chloride (ClNO2) from heterogeneous reactions, followed by its subsequent photolysis, is suggested to be an important source of chlorine atoms in many parts of the atmosphere. However, the oxidation of monoterpenes such as alpha-pinene by chlorine atoms has received very little attention, and the ability of this reaction to form HOMs is completely unstudied. Here, chamber experiments were conducted with alpha-pinene and chlorine under low- and high-nitrogen-oxide (NOx, NOx=NO+NO2) conditions. A nitrate-based CI-APi-ToF (chemical ionization–atmospheric pressure interface–time of flight) mass spectrometer was used to measure HOM products. Clear distributions of monomers with 9–10 carbon atoms and dimers with 18–20 carbon atoms were observed under low-NOx conditions. With increased concentration of NOx within the chamber, the formation of dimers was suppressed due to the reactions of peroxy radicals with NO. We estimated the HOM yields from chlorine-initiated oxidation of alpha-pinene under low-NOx conditions to be around 1.8 %, though with a substantial uncertainty range (0.8 %–4 %) due to lack of suitable calibration methods. Corresponding yields at high NOx could not be determined because of concurrent ozonolysis reactions. Our study demonstrates that also the oxidation of alpha-pinene by chlorine atoms and yield low-volatility organic compounds.

scholarly journals Mixing times of organic molecules within secondary organic aerosol particles: a global planetary boundary layer perspective

2017 ◽  
Author(s):  
Adrian M. Maclean ◽  
Christopher L. Butenhoff ◽  
James W. Grayson ◽  
Kelley Barsanti ◽  
Jose L. Jimenez ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Secondary Organic Aerosol ◽  
Transport Model ◽  
Laboratory Data ◽  
Chemical Transport ◽  
Organic Aerosol ◽  
Mixing Times ◽  
Chemical Transport Model ◽  
Transport Models ◽  
Lack Of Information

Abstract. When simulating the formation and life cycle of secondary organic aerosol (SOA) with chemical transport models, it is often assumed that organic molecules are well mixed within SOA particles on the time scale of 1 h. While this assumption has been debated vigorously in the literature, the issue remains unresolved in part due to a lack of information on the mixing times within SOA particles as a function of both temperature and relative humidity. Using laboratory data, meteorological fields and a chemical transport model, we determine how often mixing times are

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

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 Effect of NO<sub><i>x</i></sub> on 1,3,5-trimethylbenzene (TMB) oxidation product distribution and particle formation

2019 ◽  
Vol 19 (23) ◽  
pp. 15073-15086 ◽  
Author(s):  
Epameinondas Tsiligiannis ◽  
Julia Hammes ◽  
Christian Mark Salvador ◽  
Thomas F. Mentel ◽  
Mattias Hallquist
Keyword(s):  
Urban Areas ◽  
Organic Molecules ◽  
Flow Reactor ◽  
Organic Aerosol ◽  
Product Distribution ◽  
Particle Formation ◽  
Product Distributions ◽  
Tropospheric Aerosol ◽  
Volatile Organic ◽  
Free Environment

Abstract. Secondary organic aerosol (SOA) represents a significant fraction of the tropospheric aerosol and its precursors are volatile organic compounds (VOCs). Anthropogenic VOCs (AVOC) dominate the VOC budget in many urban areas with 1,3,5-trimethylbenzene (TMB) being among the most reactive aromatic AVOCs. TMB formed highly oxygenated organic molecules (HOMs) in an NOx-free environment, which could contribute to new particle formation (NPF) depending on oxidation conditions where elevated OH oxidation enhanced particle formation. The experiments were performed in an oxidation flow reactor, the Go:PAM unit, under controlled OH oxidation conditions. By addition of NOx to the system we investigated the effect of NOx on particle formation and on the product distribution. We show that the formation of HOMs, and especially HOM accretion products, strongly varies with NOx conditions. We observe a suppression of HOM and particle formation with increasing NOx/ΔTMB ratio and an increase in the formation of organonitrates (ONs) mostly at the expense of HOM accretion products. We propose reaction mechanisms and pathways that explain the formation and observed product distributions with respect to oxidation conditions. We hypothesise that, based on our findings from TMB oxidation studies, aromatic AVOCs may not contribute significantly to NPF under typical NOx/AVOC conditions found in urban atmospheres.

scholarly journals On the fate of oxygenated organic molecules in atmospheric aerosol particles

2020 ◽  
Vol 6 (11) ◽  
pp. eaax8922 ◽  
Author(s):  
V. Pospisilova ◽  
F. D. Lopez-Hilfiker ◽  
D. M. Bell ◽  
I. El Haddad ◽  
C. Mohr ◽  
...  
Keyword(s):  
Organic Molecules ◽  
Measurement Techniques ◽  
Organic Aerosol ◽  
Particle Phase ◽  
Ionization Time ◽  
Global Carbon Budget ◽  
Atmospheric Fate ◽  
Condensed Phase Reactions ◽  
Earth’S Climate ◽  
Global Carbon

Highly oxygenated organic molecules (HOMs) are formed from the oxidation of biogenic and anthropogenic gases and affect Earth’s climate and air quality by their key role in particle formation and growth. While the formation of these molecules in the gas phase has been extensively studied, the complexity of organic aerosol (OA) and lack of suitable measurement techniques have hindered the investigation of their fate post-condensation, although further reactions have been proposed. We report here novel real-time measurements of these species in the particle phase, achieved using our recently developed extractive electrospray ionization time-of-flight mass spectrometer (EESI-TOF). Our results reveal that condensed-phase reactions rapidly alter OA composition and the contribution of HOMs to the particle mass. In consequence, the atmospheric fate of HOMs cannot be described solely in terms of volatility, but particle-phase reactions must be considered to describe HOM effects on the overall particle life cycle and global carbon budget.

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
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