MOLECULAR CHARACTERIZATION OF ATMOSPHERIC ORGANIC MATTER IN BIOGENIC SECONDARY ORGANIC AEROSOL, AMBIENT AEROSOL AND CLOUDS

Abstract. The chemical complexity of atmospheric organic aerosol (OA) requires novel methods for characterization of its components and description of its atmospheric processing-induced transformations. We present the first field deployment of the Toronto Photooxidation Tube (TPOT), a field-deployable flow reactor for the controlled exposure of ambient aerosol to OH radicals. The system alternates between sampling of (1) unreacted ambient aerosol, (2) aerosol subjected to a ~4 °C temperature increase, and (3) aerosol that is both heated and oxidized by OH. This allows both characterization of the aging process and classification of aerosol in terms of its volatility and reaction-based properties. Summertime measurements by an aerosol mass spectrometer coupled to the TPOT were performed in the remote forest of Western Canada, resulting in aerosol dominated by biogenic secondary organic aerosol. Volatilization resulted in an approximately 10 to 25% decrease in organic mass and resulted in a slight increase in oxygenation. OH oxidation resulted in a further organic mass decrease (additional ~25%) and yielded an aerosol with O:C values comparable to those characteristic of low volatility, highly oxygenated OA. Most OH-induced changes occurred within the equivalent of ~3 days of atmospheric processing, with further reactions generally proceeding at a greatly reduced rate. Positive matrix factorization (PMF) analysis of the TPOT data yielded five factors. One factor is related to primary biomass burning organic aerosol, while the others describe oxygenated organic aerosol (OOA) components in terms of reactivity and volatility: (1) volatile and reactive; (2) non-volatile and reactive; (3) non-volatile and reactive early-generation product; (4) non-volatile and non-reactive product. This PMF classification of aerosol components directly in terms of reactivity and volatility is enabled by the TPOT-modulated perturbation of aerosol composition, and is not otherwise accessible. The particle-phase reaction end products have mass spectra similar to the low-volatility oxygenated organic aerosol (LV-OOA) factors widely reported in the literature, providing supporting evidence for aged organic aerosol formation from OH-driven oxidation processes.

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Real-time, controlled OH-initiated oxidation of biogenic secondary organic aerosol

Atmospheric Chemistry and Physics ◽

10.5194/acp-12-9775-2012 ◽

2012 ◽

Vol 12 (20) ◽

pp. 9775-9790 ◽

Cited By ~ 24

Author(s):

J. G. Slowik ◽

J. P. S. Wong ◽

J. P. D. Abbatt

Keyword(s):

Temperature Increase ◽

Secondary Organic Aerosol ◽

Organic Aerosol ◽

Uv Exposure ◽

Oh Radicals ◽

Organic Mass ◽

Ambient Aerosol ◽

Atmospheric Processing

Abstract. The chemical complexity of atmospheric organic aerosol (OA) requires novel methods for characterization of its components and description of its atmospheric processing-induced transformations. We present the first field deployment of the Toronto Photooxidation Tube (TPOT), a field-deployable flow reactor for the controlled exposure of ambient aerosol to OH radicals. The system alternates between sampling of (1) (unreacted) ambient aerosol, (2) aerosol exposed to UV light and subjected to a ~4 to 10 °C temperature increase, and (3) aerosol that is oxidized by OH (in addition to the aforementioned UV exposure/temperature increase). This allows both characterization of the aging process and classification of aerosol in terms of its volatility and reaction-based properties. Summertime measurements by an aerosol mass spectrometer coupled to the TPOT were performed in the remote forest of western Canada, resulting in aerosol dominated by biogenic secondary organic aerosol. Volatilization/UV exposure resulted in an approximately 10 to 25% decrease in organic mass and resulted in a slight increase in oxygenation. OH oxidation resulted in a further organic mass decrease (additional ~25%) and yielded an aerosol with O:C values comparable to those characteristic of low volatility, highly oxygenated OA. Most OH-induced changes occurred within ~3 day-equivalents of atmospheric processing, with further reactions generally proceeding at a greatly reduced rate. Positive matrix factorization (PMF) analysis of the TPOT data yielded five factors. One factor is related to primary biomass burning organic aerosol, while the others describe oxygenated organic aerosol (OOA) components in terms of reactivity and volatility: (1) volatile and reactive; (2) non-volatile and reactive; (3) non-volatile and reactive early-generation product; (4) non-volatile and non-reactive product. This PMF classification of aerosol components directly in terms of reactivity and volatility is enabled by the TPOT-modulated perturbation of aerosol composition, and is not otherwise accessible. The particle-phase reaction end products have mass spectra similar to the low-volatility oxygenated organic aerosol (LV-OOA) factors widely reported in the literature, providing supporting evidence for aged organic aerosol formation from OH-driven oxidation processes.

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Secondary Organic Aerosol Formation from Isoprene: Selected Research, Historic Account and State of the Art

Atmosphere ◽

10.3390/atmos12060728 ◽

2021 ◽

Vol 12 (6) ◽

pp. 728

Author(s):

Magda Claeys ◽

Willy Maenhaut

Keyword(s):

Molecular Characterization ◽

Secondary Organic Aerosol ◽

Organic Aerosol ◽

Quality Data ◽

Formation Mechanisms ◽

Aerosol Formation ◽

Fine Aerosol ◽

Aerosol Sources ◽

Different Sources

In this review, we cover selected research on secondary organic aerosol (SOA) formation from isoprene, from the beginning of research, about two decades ago, to today. The review begins with the first observations of isoprene SOA markers, i.e., 2-methyltetrols, in ambient fine aerosol and focuses on studies dealing with molecular characterization, speciation, formation mechanisms, and source apportionment. A historic account is given on how research on isoprene SOA has developed. The isoprene SOA system is rather complex, with different pathways being followed in pristine and polluted conditions. For SOA formation from isoprene, acid-catalyzed hydrolysis is necessary, and sulfuric acid enhances SOA by forming additional nonvolatile products such as organosulfates. Certain results reported in early papers have been re-interpreted in the light of recent results; for example, the formation of C5-alkene triols. Attention is given to mass spectrometric and separation techniques, which played a crucial role in molecular characterization. The unambiguous structural characterization of isoprene SOA markers has been achieved, owing to the preparation of reference compounds. Efforts have also been made to use air quality data to estimate the influence of biogenic and pollution aerosol sources. This review examines the use of an organic marker-based method and positive matrix factorization to apportion SOA from different sources, including isoprene SOA.

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Molecular characterization of brown carbon (BrC) chromophores in secondary organic aerosol generated from photo-oxidation of toluene

Physical Chemistry Chemical Physics ◽

10.1039/c5cp02563j ◽

2015 ◽

Vol 17 (36) ◽

pp. 23312-23325 ◽

Cited By ~ 104

Author(s):

Peng Lin ◽

Jiumeng Liu ◽

John E. Shilling ◽

Shawn M. Kathmann ◽

Julia Laskin ◽

...

Keyword(s):

Molecular Characterization ◽

Secondary Organic Aerosol ◽

Organic Aerosol ◽

Brown Carbon ◽

Photo Oxidation

BrC chromophores of toluene SOA have been identified using the HPLC–UV/Vis–ESI/HRMS platform.

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Characterization of Polar Organosulfates in Secondary Organic Aerosol from the Green Leaf Volatile 3-Z-Hexenal

Environmental Science & Technology ◽

10.1021/es503226b ◽

2014 ◽

Vol 48 (21) ◽

pp. 12671-12678 ◽

Cited By ~ 26

Author(s):

Mohammad Safi Shalamzari ◽

Ariane Kahnt ◽

Reinhilde Vermeylen ◽

Tadeusz E. Kleindienst ◽

Michael Lewandowski ◽

...

Keyword(s):

Secondary Organic Aerosol ◽

Organic Aerosol ◽

Green Leaf ◽

Green Leaf Volatile

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Molecular characterization of dissolved organic matter (DOM): a critical review

Analytical and Bioanalytical Chemistry ◽

10.1007/s00216-012-6363-2 ◽

2012 ◽

Vol 405 (1) ◽

pp. 109-124 ◽

Cited By ~ 279

Author(s):

Antonio Nebbioso ◽

Alessandro Piccolo

Keyword(s):

Organic Matter ◽

Dissolved Organic Matter ◽

Molecular Characterization ◽

Critical Review

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Molecular characterization of suspended and sedimentary organic matter in an Arctic delta

Limnology and Oceanography ◽

10.4319/lo.1996.41.3.0488 ◽

1996 ◽

Vol 41 (3) ◽

pp. 488-497 ◽

Cited By ~ 45

Author(s):

S. Peulvé ◽

M.-A. Sicre ◽

A. Saliot ◽

J. W. De Leeuw ◽

M. Baas

Keyword(s):

Organic Matter ◽

Molecular Characterization ◽

Sedimentary Organic Matter

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Molecular characterization of an end-residue of humeomics applied to a soil humic acid

RSC Advances ◽

10.1039/c4ra01619j ◽

2014 ◽

Vol 4 (45) ◽

pp. 23658-23665 ◽

Cited By ~ 18

Author(s):

A. Nebbioso ◽

A. Piccolo ◽

M. Lamshöft ◽

M. Spiteller

Keyword(s):

Organic Matter ◽

Humic Acid ◽

Molecular Characterization ◽

Natural Organic Matter ◽

Molecular Composition ◽

Chemical Fractionation ◽

Soil Humic Acid

Humeomics encompasses step-wise chemical fractionation and instrumental determination to fully characterize the heterogeneous molecular composition of natural organic matter.

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Characterization of a real-time tracer for isoprene epoxydiols-derived secondary organic aerosol (IEPOX-SOA) from aerosol mass spectrometer measurements

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-11807-2015 ◽

2015 ◽

Vol 15 (20) ◽

pp. 11807-11833 ◽

Cited By ~ 121

Author(s):

W. W. Hu ◽

P. Campuzano-Jost ◽

B. B. Palm ◽

D. A. Day ◽

A. M. Ortega ◽

...

Keyword(s):

Mass Spectrometer ◽

Secondary Organic Aerosol ◽

Transport Model ◽

Organic Aerosol ◽

Oxidation Products ◽

Chemical Transport Model ◽

Aerosol Mass Spectrometer ◽

Aerosol Mass ◽

Multiple Field

Abstract. Substantial amounts of secondary organic aerosol (SOA) can be formed from isoprene epoxydiols (IEPOX), which are oxidation products of isoprene mainly under low-NO conditions. Total IEPOX-SOA, which may include SOA formed from other parallel isoprene oxidation pathways, was quantified by applying positive matrix factorization (PMF) to aerosol mass spectrometer (AMS) measurements. The IEPOX-SOA fractions of organic aerosol (OA) in multiple field studies across several continents are summarized here and show consistent patterns with the concentration of gas-phase IEPOX simulated by the GEOS-Chem chemical transport model. During the Southern Oxidant and Aerosol Study (SOAS), 78 % of PMF-resolved IEPOX-SOA is accounted by the measured IEPOX-SOA molecular tracers (2-methyltetrols, C5-Triols, and IEPOX-derived organosulfate and its dimers), making it the highest level of molecular identification of an ambient SOA component to our knowledge. An enhanced signal at C5H6O+ (m/z 82) is found in PMF-resolved IEPOX-SOA spectra. To investigate the suitability of this ion as a tracer for IEPOX-SOA, we examine fC5H6O (fC5H6O= C5H6O+/OA) across multiple field, chamber, and source data sets. A background of ~ 1.7 ± 0.1 ‰ (‰ = parts per thousand) is observed in studies strongly influenced by urban, biomass-burning, and other anthropogenic primary organic aerosol (POA). Higher background values of 3.1 ± 0.6 ‰ are found in studies strongly influenced by monoterpene emissions. The average laboratory monoterpene SOA value (5.5 ± 2.0 ‰) is 4 times lower than the average for IEPOX-SOA (22 ± 7 ‰), which leaves some room to separate both contributions to OA. Locations strongly influenced by isoprene emissions under low-NO levels had higher fC5H6O (~ 6.5 ± 2.2 ‰ on average) than other sites, consistent with the expected IEPOX-SOA formation in those studies. fC5H6O in IEPOX-SOA is always elevated (12–40 ‰) but varies substantially between locations, which is shown to reflect large variations in its detailed molecular composition. The low fC5H6O (< 3 ‰) reported in non-IEPOX-derived isoprene-SOA from chamber studies indicates that this tracer ion is specifically enhanced from IEPOX-SOA, and is not a tracer for all SOA from isoprene. We introduce a graphical diagnostic to study the presence and aging of IEPOX-SOA as a triangle plot of fCO2 vs. fC5H6O. Finally, we develop a simplified method to estimate ambient IEPOX-SOA mass concentrations, which is shown to perform well compared to the full PMF method. The uncertainty of the tracer method is up to a factor of ~ 2, if the fC5H6O of the local IEPOX-SOA is not available. When only unit mass-resolution data are available, as with the aerosol chemical speciation monitor (ACSM), all methods may perform less well because of increased interferences from other ions at m/z 82. This study clarifies the strengths and limitations of the different AMS methods for detection of IEPOX-SOA and will enable improved characterization of this OA component.

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