Molecular characterization of organic aerosol in Himalayas: insight from ultra-high resolution mass spectrometry

An, Yanqing; Xu, Jianzhong; Li, Feng; Zhang, Xinhua; Liu, Yanmei; Kang, Shichang

doi:10.5194/acp-2018-693

Cited by 10 publications

(12 citation statements)

References 5 publications

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“…We have reported in Fig. 8 our measurements and have associated to these results the different biogenic VOCs families defined in the literature (low-volatility oxygenated organic aerosol, LV-OOA; semi-volatile oxygenated organic aerosol, SV-OOA; hydrocarbon-like organic aerosol, HOA; and biomass burning organic aerosol, BBOA) corresponding to particulates (Kroll et al, 2011;An et al, 2019). The development of advanced oxidation, specific to autoxidation, is confirmed with an OS c close to 1.…”

Section: Complementary Methods Of Screeningsupporting

confidence: 65%

On the similarities and differences between the products of oxidation of hydrocarbons under simulated atmospheric conditions and cool flames

et al. 2021

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Abstract. Atmospheric oxidation chemistry and, more specifically, photooxidation show that the long-term oxidation of organic aerosol (OA) progressively erases the initial signature of the chemical compounds and can lead to a relatively uniform character of oxygenated organic aerosol (OOA). This uniformity character observed after a long reaction time seems to contrast with the great diversity of reaction mechanisms observed in the early stages of oxidation. The numerous studies carried out on the oxidation of terpenes, and more particularly on limonene for its diversity of reaction sites (endo- and oxocyclic), allow this evolution to be studied. We have selected, for their diversity of experimental conditions, nine studies of limonene oxidation at room temperature over long reaction times to be compared to the present data set obtained at elevated temperature and short reaction time in order to investigate the similarities in terms of reaction mechanisms and chemical species formed. Here, the oxidation of limonene–oxygen–nitrogen mixtures was studied using a jet-stirred reactor at elevated temperature and atmospheric pressure. Samples of the reacting mixtures were collected and analyzed by high-resolution mass spectrometry (Orbitrap) after direct injection or after separation by reverse-phase ultra-high-pressure liquid chromatography and soft ionization, i.e., (+/-) HESI and (+/-) APCI. Unexpectedly, because of the diversity of experimental conditions in terms of continuous-flow tank reactor, concentration of reactants, temperature, reaction time, mass spectrometry techniques, and analysis conditions, the results indicate that among the 1138 presently detected molecular formulae, many oxygenates found in earlier studies of limonene oxidation by OH and/or ozone are also produced under the present conditions. Among these molecular formulae, highly oxygenated molecules and oligomers were detected in the present work. The results are discussed in terms of reaction pathways involving the initial formation of peroxy radicals (RO2), isomerization reactions yielding keto-hydroperoxides, and other oxygenated intermediates and products up to C25H32O17, products which could derive from RO2 autoxidation via sequential H shift and O2 addition (C10H14O3,5,7,9,11) and products deriving from the oxidation of alkoxy radicals (produced by RO2 self-reaction or reaction with HO2) through multiple H shifts and O2 additions (C10H14O2,4,6,8,10). The oxidation of RO2, with possible occurrence of the Waddington mechanism and of the Korcek mechanism, involving H shifts is also discussed. The present work demonstrates similitude between the oxidation products and oxidation pathways of limonene under simulated atmospheric conditions and in those encountered during the self-ignition of hydrocarbons at elevated temperatures. These results complement those recently reported by Vereecken and Nozière and confirm for limonene the existence of an oxidative chemistry of the alkylperoxy radical beyond 450 K based on the H shift (Nozière and Vereecken, 2019; Vereecken and Nozière, 2020).

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Section: Complementary Methods Of Screeningsupporting

confidence: 65%

On the similarities and differences between the products of oxidation of hydrocarbons under simulated atmospheric conditions and cool flames

et al. 2021

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“…20. I'm surprised that the long-range transported aerosol reported in Dzepina et al is similar to the samples reported here.…”

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confidence: 72%

Review of An et al.

Anonymous

2018

Preprint

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The manuscript presented by Y. An et al. presents the detailed molecular chemistry of two samples collected from the Qomolangma Station in the Himalayas. The detailed molecular chemistry was derived from ultra-high resolution FT-ICR mass spectrometry measurements following electrospray ionization to generate positive ions. The authors discuss the molecular composition of the two samples and compare them carefully to previously published studies using similar approaches. Specifically, they found an increased degree of unsaturation of the prominent species in their study. As the authors suggest, these molecules may contribute to aerosol absorption.

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“…The fRA of aliphatic and olefinic compounds in PM2.5 also exceeds 90%. The high fraction of aliphatic and olefinic and the low fraction of aromatic structure are also observed in aerosol and cloud water in previous studies (Brege et al, 2018;An et al, 2019), however, it is quite different with the primary emissions including biomass burning and coal combustion, of which the fraction of aromatic structures is higher (Song et al, 2018), indicating the aging processes of organics likely reduce the aromaticity of organics. In four groups of molecules in cloud water, CHON has the most (2.5-20.8% in fRA) aromatic structures, consistent with the high DBE values (unsaturation) of CHON.…”

Section: Aromaticitymentioning

confidence: 65%

Measurement report: Molecular characteristics of cloud water in southern China and insights into aqueous-phase processes from Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

Sun

Zhang

et al. 2021

Preprint

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Abstract. Characterizing the molecular composition of cloud water could provide unique insight into the aqueous chemistry. Field measurement was conducted at Mt. Tianjing in southern China during May, 2018. Thousands of formulas (C5-30H4-55O1-15N0-2S0-2) were identified in cloud water by Fourier transform-ion cyclotron resonance mass spectrometry (FT-ICR MS). CHON represents the dominant component (43.6–65.3 % of relative abundance), followed by CHO (13.8–52.1 %). S-containing formulas constitute the remaining ~10–20 %. Molecules have O/C of 0.45–0.56 and the double-bond equivalent of 5.10–5.70. More than 90 % are assigned as aliphatic and olefinic species. No statistical difference of oxidation state is observed between cloud water and interstitial PM2.5. CHON with aromatic structures are abundant in cloud water, suggesting their enhanced in-cloud formation. Other organics in cloud water are mainly from biomass burning and oxidation of biogenic volatile organic compounds. The cloud water contains more abundant CHON and CHOS at night, which are mainly contributed by –N2O5 function and organosulfates, demonstrating the enhanced formation in dark aqueous or multi-phase reactions. While more abundant CHO are observed during the daytime, likely due to the photochemical oxidation and photolysis of N-/S-containing formulas. The results provide an improved understanding on the in-cloud aqueous-phase reactions.

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Molecular characterization of organic aerosol in Himalayas: insight from ultra-high resolution mass spectrometry

Cited by 10 publications

References 5 publications

On the similarities and differences between the products of oxidation of hydrocarbons under simulated atmospheric conditions and cool flames

On the similarities and differences between the products of oxidation of hydrocarbons under simulated atmospheric conditions and cool flames

Review of An et al.

Measurement report: Molecular characteristics of cloud water in southern China and insights into aqueous-phase processes from Fourier Transform Ion Cyclotron Resonance Mass Spectrometry

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