Aerosol composition and the contribution of SOA formation over Mediterranean forests

Abstract. As part of the Chemistry-Aerosol Mediterranean Experiment (ChArMEx), a series of aerosol and gas phase measurements were deployed aboard the SAFIRE ATR-42 research aircraft in summer 2014. The present study focuses on the 4 flights performed in late June early July over two forested regions in the south of France. We combine in situ observations and model simulations to aid in the understanding of secondary organic aerosol (SOA) formation over these forested areas in the Mediterranean and to highlight the role of different gas-phase precursors. The non-refractory particulate species measured by C-ToF-AMS instrument were dominated by organic species (60 to 72 %) followed by a combined contribution of 25 % by ammonia and sulphate aerosols. The contribution from the anthropogenic nitrate and black carbon (BC) concentrations, measured by an SP2, never contributed to more than 5 % each to the total PM1 mass concentration. Measurements of non-refractory species from off-line transmission electron microscopy (TEM) were coherent with the C-ToF-AMS instrument, showing a large contribution of externally mixed organic aerosol and externally mixed sulphate particles. Externally mixed organic aerosols, were equally identified with S signals, which may suggest the presence of organo-sulphates. Measurements of refractory species from TEM analysis showed a significant contribution of both sea salt and dust particles depending on the air mass trajectory. The organic aerosol measured by the C-ToF-AMS contained only evidence of oxidised organic aerosol (OOA), without a contribution of fresh primary organic aerosol. Positive matrix factorization (PMF) on the combined organic/inorganic matrices separated the oxidised organic aerosol into a more oxidised organic aerosol (MOOA), and a less oxidised organic aerosol (LOOA). The MOOA component is associated with inorganics species and had higher O : C ratios than the LOOA factor. The LOOA factor is not associated with inorganic species and correlates well with biogenic volatile organic species measured with a PTR-MS, such as isoprene and its oxidation products (methylvinylketone (MVK), methacroleine (MACR), and isoprene hydroxyhydroperoxides (ISOPOOH)). Despite a significantly high mixing ratio of isoprene (2– ppbV) and oxidation products (0.6 and 1.2 ppbV), the contribution of specific signatures for isoprene epoxydiols SOA (IEPOX) within the aerosol organic mass spectrum (m / z 53 and m / z 82) were very weak, suggesting that isoprene SOA may be formed through a non-IEPOX route here, or with different precursors without clear mass spectral signatures in the C-ToF-AMS. This was corroborated through simulations performed with the Polyphemus model showing that 60 to 80 % of SOA originated from biogenic precursors: about 15 to 32 % isoprene (non-IEPOX) SOA, 10 % sesquiterpenes SOA and 35 to 40 % monoterpenes SOA). A total of 20 to 34 % was attributed to purely anthropogenic precursors (aromatics and intermediate/semi volatile compounds).

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Aerosol composition and the contribution of SOA formation over Mediterranean forests

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-7041-2018 ◽

2018 ◽

Vol 18 (10) ◽

pp. 7041-7056 ◽

Cited By ~ 8

Author(s):

Evelyn Freney ◽

Karine Sellegri ◽

Mounir Chrit ◽

Kouji Adachi ◽

Joel Brito ◽

...

Keyword(s):

Gas Phase ◽

Mass Spectrometer ◽

Organic Aerosol ◽

Proton Transfer Reaction ◽

Oxidation Products ◽

Mediterranean Forests ◽

Aerosol Composition ◽

Total Contribution ◽

Inorganic Species ◽

Forested Areas

Abstract. As part of the Chemistry-Aerosol Mediterranean Experiment (ChArMEx), a series of aerosol and gas-phase measurements were deployed aboard the SAFIRE ATR42 research aircraft in summer 2014. The present study focuses on the four flights performed in late June early July over two forested regions in the south of France. We combine in situ observations and model simulations to aid in the understanding of secondary organic aerosol (SOA) formation over these forested areas in the Mediterranean and to highlight the role of different gas-phase precursors. The non-refractory particulate species measured by a compact aerosol time-of-flight mass spectrometer (cToF-AMS) were dominated by organics (60 to 72 %) followed by a combined contribution of 25 % by ammonia and sulfate aerosols. The contribution from nitrate and black carbon (BC) particles was less than 5 % of the total PM1 mass concentration. Measurements of non-refractory species from off-line transmission electron microscopy (TEM) showed that particles have different mixing states and that large fractions (35 %) of the measured particles were organic aerosol containing C, O, and S but without inclusions of crystalline sulfate particles. The organic aerosol measured using the cToF-AMS contained only evidence of oxidized organic aerosol (OOA), without a contribution of fresh primary organic aerosol. Positive matrix factorization (PMF) on the combined organic–inorganic matrices separated the oxidized organic aerosol into a more-oxidized organic aerosol (MOOA), and a less-oxidized organic aerosol (LOOA). The MOOA component is associated with inorganic species and had higher contributions of m∕z 44 than the LOOA factor. The LOOA factor is not associated with inorganic species and correlates well with biogenic volatile organic species measured with a proton-transfer-reaction mass spectrometer, such as isoprene and its oxidation products (methyl vinyl ketone, MVK; methacroleine, MACR; and isoprene hydroxyhydroperoxides, ISOPOOH). Despite a significantly high mixing ratio of isoprene (0.4 to 1.2 ppbV) and its oxidation products (0.2 and 0.8 ppbV), the contribution of specific signatures for isoprene epoxydiols SOA (IEPOX-SOA) within the aerosol organic mass spectrum (m∕z 53 and m∕z 82) were very weak, suggesting that the presence of isoprene-derived SOA was either too low to be detected by the cToF-AMS, or that SOA was not formed through IEPOX. This was corroborated through simulations performed with the Polyphemus model showing that although 60 to 80 % of SOA originated from biogenic precursors, only about 15 to 32 % was related to isoprene (non-IEPOX) SOA; the remainder was 10 % sesquiterpene SOA and 35 to 40 % monoterpene SOA. The model results show that despite the zone of sampling being far from industrial or urban sources, a total contribution of 20 to 34 % of the SOA was attributed to purely anthropogenic precursors (aromatics and intermediate or semi-volatile compounds). The measurements obtained during this study allow us to evaluate how biogenic emissions contribute to increasing SOA concentrations over Mediterranean forested areas. Directly comparing these measurements with the Polyphemus model provides insight into the SOA formation pathways that are prevailing in these forested areas as well as processes that need to be implemented in future simulations.

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Large contribution to secondary organic aerosol from isoprene cloud chemistry

Science Advances ◽

10.1126/sciadv.abe2952 ◽

2021 ◽

Vol 7 (13) ◽

pp. eabe2952

Author(s):

Houssni Lamkaddam ◽

Josef Dommen ◽

Ananth Ranjithkumar ◽

Hamish Gordon ◽

Günther Wehrle ◽

...

Keyword(s):

Radiative Forcing ◽

Flow Reactor ◽

Secondary Organic Aerosol ◽

Cloud Droplet ◽

Organic Aerosol ◽

Global Scale ◽

Oxidation Products ◽

Oh Radicals ◽

Large Contribution ◽

Cloud Processing

Aerosols still present the largest uncertainty in estimating anthropogenic radiative forcing. Cloud processing is potentially important for secondary organic aerosol (SOA) formation, a major aerosol component: however, laboratory experiments fail to mimic this process under atmospherically relevant conditions. We developed a wetted-wall flow reactor to simulate aqueous-phase processing of isoprene oxidation products (iOP) in cloud droplets. We find that 50 to 70% (in moles) of iOP partition into the aqueous cloud phase, where they rapidly react with OH radicals, producing SOA with a molar yield of 0.45 after cloud droplet evaporation. Integrating our experimental results into a global model, we show that clouds effectively boost the amount of SOA. We conclude that, on a global scale, cloud processing of iOP produces 6.9 Tg of SOA per year or approximately 20% of the total biogenic SOA burden and is the main source of SOA in the mid-troposphere (4 to 6 km).

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Atmospheric β-Caryophyllene-Derived Ozonolysis Products at Interfaces

10.26434/chemrxiv.7228694 ◽

2018 ◽

Author(s):

Ariana Gray Bé ◽

Hilary M. Chase ◽

Liu, Yangdongliu ◽

Mary Alice Upshur ◽

Zhang, Yue ◽

...

Keyword(s):

Gas Phase ◽

Structural Information ◽

High Surface ◽

Organic Aerosol ◽

Oxidation Products ◽

Laboratory Studies ◽

Sum Frequency ◽

Sum Frequency Generation Spectroscopy ◽

Surface Active ◽

Cloud Activation

<p>By integrating organic synthesis, secondary organic aerosol synthesis and collection, DFT calculations, and vibrational sum frequency generation spectroscopy, we identify close spectral matches between the surface vibrational spectra of β-caryophyllene-derived secondary organic material and those of β-caryophyllene aldehyde and β-caryophyllonic acid at various interfaces. Combined with the record high surface tension depression described previously for these same oxidation products, we discuss possibilities for an intrinsically chemical origin for cloud activation by terpene-derived surfactants. Although the present study does not unequivocally identify the synthesized and analyzed oxidation products on the β-caryophyllenederived SOM surfaces, these two compounds appear to be the most surface active out of the series, and have also been foci of previous β-caryophyllene field and laboratory studies.</p><p>An orientation analysis by phase-resolved SFG spectroscopy reveals a “pincer-like” configuration of the β-caryophyllene oxidation products, albeit on a model quartz surface, that somewhat resembles the orientation of inverse double-tailed surfactants at the surfaces biological systems. The structural information suggests that the less polar moiety of a surface-localized oxidation product, such as those studied here, may be the first site-of-contact for a gas-phase molecule approaching an SOA particle containing surface-active β-caryophyllene oxidation products.</p>

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Characterization of secondary organic aerosol from heated-cooking-oil emissions: evolution in composition and volatility

Atmospheric Chemistry and Physics ◽

10.5194/acp-21-5137-2021 ◽

2021 ◽

Vol 21 (6) ◽

pp. 5137-5149 ◽

Cited By ~ 1

Author(s):

Manpreet Takhar ◽

Yunchun Li ◽

Arthur W. H. Chan

Keyword(s):

Gas Phase ◽

Organic Compounds ◽

Secondary Organic Aerosol ◽

Carbon Number ◽

Complex Mixture ◽

Organic Aerosol ◽

Oxidation Products ◽

Atmospheric Evolution ◽

Oxidative Aging ◽

Cooking Oil

Abstract. Cooking emissions account for a major fraction of urban organic aerosol. It is therefore important to understand the atmospheric evolution in the physical and chemical properties of organic compounds emitted from cooking activities. In this work, we investigate the formation of secondary organic aerosol (SOA) from oxidation of gas-phase organic compounds from heated cooking oil. The chemical composition of cooking SOA is analyzed using thermal desorption–gas chromatography–mass spectrometry (TD–GC–MS). While the particle-phase composition of SOA is a highly complex mixture, we adopt a new method to achieve molecular speciation of the SOA. All the GC-elutable material is classified by the constituent functional groups, allowing us to provide a molecular description of its chemical evolution upon oxidative aging. Our results demonstrate an increase in average oxidation state (from −0.6 to −0.24) and decrease in average carbon number (from 5.2 to 4.9) with increasing photochemical aging of cooking oil, suggesting that fragmentation reactions are key processes in the oxidative aging of cooking emissions within 2 d equivalent of ambient oxidant exposure. Moreover, we estimate that aldehyde precursors from cooking emissions account for a majority of the SOA formation and oxidation products. Overall, our results provide insights into the atmospheric evolution of cooking SOA, a majority of which is derived from gas-phase oxidation of aldehydes.

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The influences of ammonia on aerosol formation in the ozonolysis of styrene: roles of Criegee intermediate reactions

Royal Society Open Science ◽

10.1098/rsos.172171 ◽

2018 ◽

Vol 5 (5) ◽

pp. 172171 ◽

Cited By ~ 3

Author(s):

Qiao Ma ◽

Xiaoxiao Lin ◽

Chengqiang Yang ◽

Bo Long ◽

Yanbo Gai ◽

...

Keyword(s):

Gas Phase ◽

Quantum Chemical Calculations ◽

Quantum Chemical ◽

Organic Aerosol ◽

Aerosol Formation ◽

Gas Phase Reactions ◽

Aerosol Composition ◽

Theoretical Methods ◽

Criegee Intermediates ◽

Secondary Ozonide

The influences of ammonia (NH 3 ) on secondary organic aerosol (SOA) formation from ozonolysis of styrene have been investigated using chamber experiments and quantum chemical calculations. With the value of [O 3 ] 0 /[styrene] 0 ratios between 2 and 4, chamber experiments were carried out without NH 3 or under different [NH 3 ]/[styrene] 0 ratios. The chamber experiments reveal that the addition of NH 3 led to significant decrease of SOA yield. The overall SOA yield decreased with the [NH 3 ] 0 /[styrene] 0 increasing. In addition, the addition of NH 3 at the beginning of the reaction or several hours after the reaction occurs had obviously different influence on the yield of SOA. Gas phase reactions of Criegee intermediates (CIs) with aldehydes and NH 3 were studied in detail by theoretical methods to probe into the mechanisms behind these phenomena. The calculated results showed that 3,5-diphenyl-1,2,4-trioxolane, a secondary ozonide formed through the reactions of C 6 H 5 ĊHOO· with C 6 H 5 CHO, could make important contribution to the aerosol composition. The addition of excess NH 3 may compete with aldehydes, decreasing the secondary ozonide yield to some extent and thus affect the SOA formation.

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Gas-phase kinetics modifies the CCN activity of a biogenic SOA

Physical Chemistry Chemical Physics ◽

10.1039/c8cp00075a ◽

2018 ◽

Vol 20 (9) ◽

pp. 6591-6597

Author(s):

A. E. Vizenor ◽

A. A. Asa-Awuku

Keyword(s):

Particle Size ◽

Thermodynamic Properties ◽

Gas Phase ◽

Secondary Organic Aerosol ◽

Cloud Condensation Nuclei ◽

Organic Aerosol ◽

Aerosol Composition ◽

Phase Partitioning ◽

Gas Phase Kinetics ◽

Ccn Activity

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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Formation of Highly Oxygenated Low-Volatility Products from Cresol Oxidation

10.5194/acp-2016-887 ◽

2016 ◽

Author(s):

Rebecca H. Schwantes ◽

Katherine A. Schilling ◽

Renee C. McVay ◽

Hanna Lignell ◽

Matthew M. Coggon ◽

...

Keyword(s):

Mass Spectrometry ◽

Gas Phase ◽

Ring Opening ◽

Chemical Ionization ◽

First Generation ◽

Direct Analysis ◽

Organic Aerosol ◽

Oxidation Products ◽

Ionization Mass ◽

Particle Phase

Abstract. Hydroxyl radical (OH) oxidation of toluene produces the ring-retaining products cresol and benzaldehyde, and the ring-opening products bicyclic intermediate compounds and epoxides. Here, first- and later-generation OH oxidation products from cresol and benzaldehyde are identified in laboratory chamber experiments. For benzaldehyde, first-generation ring-retaining products are identified, but later-generation products are not detected. For cresol, low-volatility (saturation mass concentration, C* ~ 3.5 × 104–7.7 × 10−3 μg m−3) first- and later-generation ring-retaining products are identified. Subsequent OH addition to the aromatic ring of o-cresol leads to compounds such as hydroxy, dihydroxy, and trihydroxy methyl benzoquinones and dihydroxy, trihydroxy, tetrahydroxy, and pentahydroxy toluenes. These products are detected in the gas phase by chemical ionization mass spectrometry (CIMS) and in the particle phase using offline direct analysis in real time mass spectrometry (DART-MS). Our data suggest that the yield of trihydroxy toluene from dihydroxy toluene is substantial. While an exact yield cannot be reported as authentic standards are unavailable, we find that a yield for trihydroxy toluene from dihydroxy toluene of ~ 0.7 (equal to the yield of dihydroxy toluene from o-cresol) is consistent with experimental results for o-cresol oxidation under low-NO conditions. These results suggest that even though the cresol pathway accounts for only ~ 20 % of the oxidation products of toluene, it is the source of a significant fraction (~ 20–40 %) of toluene secondary organic aerosol (SOA) due to the formation of low-volatility products.

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Campholenic aldehyde ozonolysis: a mechanism leading to specific biogenic secondary organic aerosol constituents

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-719-2014 ◽

2014 ◽

Vol 14 (2) ◽

pp. 719-736 ◽

Cited By ~ 21

Author(s):

A. Kahnt ◽

Y. Iinuma ◽

A. Mutzel ◽

O. Böge ◽

M. Claeys ◽

...

Keyword(s):

Mass Spectrometry ◽

Gas Phase ◽

Secondary Organic Aerosol ◽

Organic Aerosol ◽

Oxidation Products ◽

Negative Ion ◽

Mass Spectrometry Analysis ◽

Radical Scavenger ◽

Ambient Aerosol ◽

Campholenic Aldehyde

Abstract. In the present study, campholenic aldehyde ozonolysis was performed to investigate pathways leading to specific biogenic secondary organic aerosol (SOA) marker compounds. Campholenic aldehyde, a known α-pinene oxidation product, is suggested to be a key intermediate in the formation of terpenylic acid upon α-pinene ozonolysis. It was reacted with ozone in the presence and absence of an OH radical scavenger, leading to SOA formation with a yield of 0.75 and 0.8, respectively. The resulting oxidation products in the gas and particle phases were investigated employing a denuder/filter sampling combination. Gas-phase oxidation products bearing a carbonyl group, which were collected by the denuder, were derivatised by 2,4-dinitrophenylhydrazine (DNPH) followed by liquid chromatography/negative ion electrospray ionisation time-of-flight mass spectrometry analysis and were compared to the gas-phase compounds detected by online proton-transfer-reaction mass spectrometry. Particle-phase products were also analysed, directly or after DNPH derivatisation, to derive information about specific compounds leading to SOA formation. Among the detected compounds, the aldehydic precursor of terpenylic acid was identified and its presence was confirmed in ambient aerosol samples from the DNPH derivatisation, accurate mass data, and additional mass spectrometry (MS2 and MS3 fragmentation studies). Furthermore, the present investigation sheds light on a reaction pathway leading to the formation of terpenylic acid, involving α-pinene, α-pinene oxide, campholenic aldehyde, and terpenylic aldehyde. Additionally, the formation of diaterpenylic acid acetate could be connected to campholenic aldehyde oxidation. The present study also provides insights into the source of other highly functionalised oxidation products (e.g. m / z 201, C9H14O5 and m / z 215, C10H16O5), which have been observed in ambient aerosol samples and smog chamber-generated monoterpene SOA. The m / z 201 and 215 compounds were tentatively identified as a C9- and C10-carbonyl-dicarboxylic acid, respectively, based on reaction mechanisms of campholenic aldehyde and ozone, as well as detailed interpretation of mass spectral data, in conjunction with the formation of corresponding DNPH derivatives.

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Explicit modelling of SOA formation from α-pinene photooxidation: sensitivity to vapour pressure estimation

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-10121-2011 ◽

2011 ◽

Vol 11 (3) ◽

pp. 10121-10158 ◽

Cited By ~ 2

Author(s):

R. Valorso ◽

B. Aumont ◽

M. Camredon ◽

T. Raventos-Duran ◽

C. Mouchel-Vallon ◽

...

Keyword(s):

Organic Compounds ◽

Vapour Pressure ◽

Estimation Method ◽

Organic Aerosol ◽

Reaction Scheme ◽

Oxidation Products ◽

Organic Species ◽

Structure Activity ◽

Volatile Organic ◽

Kinetics Of

Abstract. The sensitivity of the formation of secondary organic aerosol (SOA) to the estimated vapour pressures of the condensable oxidation products is explored. A highly detailed reaction scheme was generated for α-pinene photooxidation using the Generator for Explicit Chemistry and Kinetics of Organics in the Atmosphere (GECKO-A). Vapour pressures (Pvap) were estimated with three commonly used structure activity relationships. The values of Pvap were compared for the set of secondary species generated by GECKO-A to describe α-pinene oxidation. Discrepancies in the predicted vapour pressures were found to increase with the number of functional groups borne by the species. For semi-volatile organic compounds (i.e. organic species of interest for SOA formation), differences in the predicted Pvap range between a factor of 5 to 200 in average. The simulated SOA concentrations were compared to SOA observations in the Caltech chamber during three experiments performed under a range of NOx conditions. While the model captures the qualitative features of SOA formation for the chamber experiments, SOA concentrations are systematically overestimated. For the conditions simulated, the modelled SOA speciation appears to be rather insensitive to the Pvap estimation method.

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The composition and variability of atmospheric aerosol over Southeast Asia during 2008

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-11-22033-2011 ◽

2011 ◽

Vol 11 (8) ◽

pp. 22033-22073 ◽

Cited By ~ 3

Author(s):

W. Trivitayanurak ◽

P. I. Palmer ◽

M. P. Barkley ◽

N. H. Robinson ◽

H. Coe ◽

...

Keyword(s):

Southeast Asia ◽

Gas Phase ◽

Organic Aerosol ◽

Sea Salt ◽

Dust Aerosol ◽

Oxidation Products ◽

Small Scale ◽

Sulphate Aerosol ◽

Modis Aod ◽

Phase Oxidation

Abstract. We use a nested version of the GEOS-Chem global 3-D chemistry transport model to better understand the composition and variation of aerosol over Borneo and the broader Southeast Asian region in conjunction with aircraft and satellite observations. We particularly focus on July 2008 during when the UK BAe-146 research aircraft was deployed over northern Malaysian Borneo as part of the ACES/OP3 measurement campaign. During July 2008 we find using the model that Borneo (defined as Borneo Island and the surrounding Indonesian islands) was a net exporter of primary organic aerosol (42 kT) and black carbon aerosol (11 kT). We find only 13 % of volatile organic compound oxidation products partition to secondary organic aerosol (SOA), with Borneo being a net exporter of SOA (15 kT). SOA represents approximately 19 % of the total organic aerosol over the region. Sulphate is mainly from aqueous-phase oxidation (68 %), with smaller contributions from gas-phase oxidation (15 %) and advection into the regions (14 %). We find that there is a large source of sea salt, as expected, but this largely deposits within the region; we find that dust aerosol plays only a relatively small role in the aerosol burden. In contrast to coincident surface measurements over Northern Borneo that find a pristine environment with evidence for substantial biogenic SOA formation we find that the free troposphere is influenced by biomass burning aerosol transported from the northwest of the Island and further afield. We find several transport events during July 2008 over Borneo associated with elevated aerosol concentrations, none of which coincide with the aircraft flights. We use MODIS aerosol optical depth (AOD) data and the model to put the July campaign into a longer temporal perspective. We find that Borneo is where the model has the least skill at reproducing the data, reflecting the small-scale island-marine environment, with the model showing more skill at reproducing observed AOD over larger regions such as China and other parts of Southeast Asia. The model shows that AOD over Borneo is approximately evenly split between organic and sulphate aerosol with sea salt representing 10–20 % during May to September; there is a similar breakdown over continental Southeast Asia but with less sea salt aerosol and more dust aerosol. In contrast, East China AOD is determined mainly by sulphate aerosol and a seasonal source of dust aerosol, as expected. Realistic sensitivity runs designed to test our underlying assumptions about emissions and chemistry over Borneo constrained by MODIS AOD show that the model is most sensitive to isoprene emissions and organic gas-phase partitioning.

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