Highly Oxygenated Organic Molecules (HOM) from Gas-Phase Autoxidation Involving Peroxy Radicals: A Key Contributor to Atmospheric Aerosol

Chemical Reviews, Journal Year: 2019, Volume and Issue: 119(6), P. 3472 - 3509

Published: Feb. 25, 2019

Highly oxygenated organic molecules (HOM) are formed in the atmosphere via autoxidation involving peroxy radicals arising from volatile compounds (VOC). HOM condense on pre-existing particles and can be involved new particle formation. thus contribute to formation of secondary aerosol (SOA), a significant ubiquitous component atmospheric known affect Earth's radiation balance. were discovered only very recently, but interest these has grown rapidly. In this Review, we define describe currently available techniques for their identification/quantification, followed by summary current knowledge mechanisms physicochemical properties. A main aim is provide common frame quite fragmented literature studies. Finally, highlight existing gaps our understanding suggest directions future research.

Language: Английский

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Secondary organic aerosol reduced by mixture of atmospheric vapours

Nature, Journal Year: 2019, Volume and Issue: 565(7741), P. 587 - 593

Published: Jan. 30, 2019

Language: Английский

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Evaluating the performance of five different chemical ionization techniques for detecting gaseous oxygenated organic species

Atmospheric measurement techniques, Journal Year: 2019, Volume and Issue: 12(4), P. 2403 - 2421

Published: April 17, 2019

Abstract. The impact of aerosols on climate and air quality remains poorly understood due to multiple factors. One the current limitations is incomplete understanding contribution oxygenated products, generated from gas-phase oxidation volatile organic compounds (VOCs), aerosol formation. Indeed, atmospheric gaseous chemical processes yield thousands (highly) species, spanning a wide range formulas, functional groups and, consequently, volatilities. While recent mass spectrometric developments have allowed extensive on-line detection myriad playing central role in chemistry, detailed quantification characterization this diverse group extremely challenging. To address challenge, we evaluated capability state-of-the-art spectrometers equipped with different ionization sources detect products formed α-Pinene ozonolysis under various conditions. Five were deployed simultaneously for chamber study. Two pressure interface time-of-flight (CI-APi-TOF) nitrate amine reagent ion chemistries an iodide spectrometer (TOF-CIMS) used. Additionally, proton transfer reaction (PTR-TOF 8000) new “vocus” PTR-TOF also deployed. In study, compared around 1000 between each five instruments, aim determining which VOCs (OVOCs) methods sensitive identifying regions where two or more instruments able species similar molecular formulae. We utilized large variability conditions (including VOCs, ozone, NOx OH scavenger concentrations) our newly constructed simulation comprehensive correlation analysis all instruments. This analysis, combined estimated concentrations identified molecules instrument, yielded both expected surprising results. As anticipated based earlier studies, PTR only ones measure precursor VOC, TOF-CIMS efficiently detected many semi-volatile (SVOCs) three oxygen atoms, CI-APi-TOF was mainly highly (O > 5) (HOMs). addition, vocus showed good agreement SVOC, including organonitrates. agreed well HOM dimers. However, loadings experiments caused be considerably depleted, causing nonlinear responses monomers. study explores highlights benefits currently available spectrometry instrumentation characterizing variety OVOCs atmosphere. specifically shown case ozonolysis, expect general findings valid other VOC–oxidant systems. discussed no single instrument configuration can deemed better worse than others, as optimal particular ultimately depends specific target

Language: Английский

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Accretion Product Formation from Ozonolysis and OH Radical Reaction of α-Pinene: Mechanistic Insight and the Influence of Isoprene and Ethylene

Environmental Science & Technology, Journal Year: 2018, Volume and Issue: 52(19), P. 11069 - 11077

Published: Sept. 7, 2018

α-Pinene (C10H16) represents one of the most important biogenic emissions in atmosphere. Its oxidation products can significantly contribute to secondary organic aerosol (SOA) formation. Here, we report on formation mechanism C19 and C20 accretion from α-pinene oxidation, which are believed be efficient SOA precursors. Measurements have been performed a free-jet flow system. Detection RO2 radicals was carried out by recent mass spectrometric techniques using different ionization schemes. Observed C10-RO2 ozonolysis were O,O-C10H15(O2) xO2 with x = 0, 1, 2, 3 OH radical reaction HO-C10H16(O2)αO2 α 2. All detected explained via + R'O2 → ROOR' O2 starting measured radicals. We speculate that formed an analogous way assuming CH2O elimination. Addition isoprene (C5H8), producing C5-RO2 radicals, leads C15 cross-reactions This process is competing C19/C20 pure oxidation. A similar behavior has observed for ethylene additives form C12 products. In atmosphere, complex product spectrum self- available expected. Modeling atmospheric conditions revealed only reduced factor 1.2 or 3.6 isoprene-dominated environments 2- 15-fold concentration over α-pinene, respectively, as present forested areas.

Language: Английский

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Quantitative constraints on autoxidation and dimer formation from direct probing of monoterpene-derived peroxy radical chemistry

Proceedings of the National Academy of Sciences, Journal Year: 2018, Volume and Issue: 115(48), P. 12142 - 12147

Published: Nov. 9, 2018

Organic peroxy radicals (RO 2 ) are key intermediates in the atmospheric degradation of organic matter and fuel combustion, but to date, few direct studies specific RO complex reaction systems exist, leading large gaps our understanding their fate. We show, using direct, speciated measurements a suite gas-phase dimers from O 3 -initiated oxidation α-pinene, that ∼150 gaseous (C 16–20 H 24–34 4–13 primarily formed through cross-reactions, with typical rate constant 0.75–2 × 10 −12 cm molecule −1 s lower-limit dimer formation branching ratio 4%. These findings imply yield varies strongly nitric oxide (NO) concentrations, at least 0.2–2.5% by mole (0.5–6.6% mass) for conditions forested regions low moderate anthropogenic influence (i.e., ≤50-parts per trillion NO). Given very volatility, C provide potentially important medium initial particle formation, alone can explain 5–60% α-pinene secondary aerosol mass yields measured atmospherically relevant loadings. The responses , dimers, highly oxygenated multifunctional compounds (HOM) reacted concentration NO an average ∼20% primary OH 10% ozonolysis autoxidize 3–10 ≥1 respectively, confirming both pathways produce HOM efficiently, even higher concentrations urban areas. Thus, autoxidation ubiquitous sources low-volatility capable driving growth.

Language: Английский

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Peroxy radical chemistry and the volatility basis set

Atmospheric chemistry and physics, Journal Year: 2020, Volume and Issue: 20(2), P. 1183 - 1199

Published: Jan. 31, 2020

Abstract. Gas-phase autoxidation of organics can generate highly oxygenated organic molecules (HOMs) and thus increase secondary aerosol production enable new-particle formation. Here we present a new implementation the volatility basis set (VBS) that explicitly resolves peroxy radical (RO2) products formed via autoxidation. The model includes strong temperature dependence for as well explicit termination RO2, including reactions with NO, HO2, other RO2. RO2 cross-reactions produce dimers (ROOR). We explore NOx this chemistry, showing strongly influences intrinsic distribution NO suppress under conditions typically found in atmosphere.

Language: Английский

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Multi-generation OH oxidation as a source for highly oxygenated organic molecules from aromatics

Atmospheric chemistry and physics, Journal Year: 2020, Volume and Issue: 20(1), P. 515 - 537

Published: Jan. 15, 2020

Abstract. Recent studies have recognised highly oxygenated organic molecules (HOMs) in the atmosphere as important formation of secondary aerosol (SOA). A large number focused on HOM from oxidation biogenically emitted monoterpenes. However, anthropogenic vapours has so far received much less attention. Previous identified importance aromatic volatile compounds (VOCs) for SOA formation. In this study, we investigated several compounds, benzene (C6H6), toluene (C7H8), and naphthalene (C10H8), their potential to form HOMs upon reaction with hydroxyl radicals (OH). We performed flow tube experiments all three VOCs detail Jülich Plant Atmosphere Chamber (JPAC). JPAC, also response NOx seed aerosol. Using a nitrate-based chemical ionisation mass spectrometer (CI-APi-TOF), observed reactor first OH attack. naphthalene, which were injected at lower concentrations, multi-generation seemed impact composition. tested more system allowed studying longer residence times. The results showed that apparent molar yield under our experimental conditions varied 4.1 % 14.0 %, strong dependence concentration, indicating majority formed through multiple OH-oxidation steps. composition spectrum supported hypothesis. By injecting only phenol into chamber, found cannot be solely responsible experiments. When was added changed many nitrogen-containing products CI-APi-TOF. Upon injection, loss rate higher than predicted by irreversible condensation, suggesting some undetected intermediates condensed onto aerosol, is line hypothesis oxidation. Based results, conclude systems strongly depend VOC concentration are needed fully understand effect and, consequently, SOA. suggest chamber may explain part variability yields reported literature advise monitoring future studies.

Language: Английский

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Fast Peroxy Radical Isomerization and OH Recycling in the Reaction of OH Radicals with Dimethyl Sulfide

The Journal of Physical Chemistry Letters, Journal Year: 2019, Volume and Issue: 10(21), P. 6478 - 6483

Published: Oct. 7, 2019

Dimethyl sulfide (DMS), produced by marine organisms, represents the most abundant, biogenic sulfur emission into Earth's atmosphere. The gas-phase degradation of DMS is mainly initiated reaction with OH radical forming first CH3SCH2O2 radicals from dominant H-abstraction channel. It experimentally shown that these peroxy undergo a two-step isomerization process finally product consistent formula HOOCH2SCHO. accompanied recycling. rate-limiting step, → CH2SCH2OOH, followed O2 addition, proceeds k = (0.23 ± 0.12) s-1 at 295 2 K. Competing bimolecular reactions NO, HO2, or RO2 are less important for trace-gas conditions over oceans. Results atmospheric chemistry simulations demonstrate predominance (≥95%) isomerization. rapid isomerization, not yet considered in models, substantially changes understanding DMS's processes

Language: Английский

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Radical chemistry in oxidation flow reactors for atmospheric chemistry research

Chemical Society Reviews, Journal Year: 2020, Volume and Issue: 49(9), P. 2570 - 2616

Published: Jan. 1, 2020

We summarize the studies on chemistry in oxidation flow reactor and discuss its atmospheric relevance.

Language: Английский

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Chemical characterization of oxygenated organic compounds in the gas phase and particle phase using iodide CIMS with FIGAERO in urban air

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(11), P. 8455 - 8478

Published: June 3, 2021

Abstract. The atmospheric processes under polluted environments involving interactions of anthropogenic pollutants and natural emissions lead to the formation various complex secondary products. Therefore, characterization oxygenated organic compounds in urban areas remains a pivotal issue our understanding evolution carbon. Here, we describe measurements an iodide chemical ionization time-of-flight mass spectrometer installed with Filter Inlet for Gases AEROsols (FIGAERO-I-CIMS) both gas phase particle at site Guangzhou, typical megacity southern China, during autumn 2018. Abundant containing two five oxygen atoms were observed, including acids, multi-functional typically emitted from biomass burning, oxidation products biogenic hydrocarbons aromatics. Photochemistry played dominant roles gaseous acids isoprene-derived nitrates, while nighttime chemistry contributed significantly monoterpene-derived nitrates inorganics. Nitrogen-containing occupied significant fraction total signal phases, elevated fractions higher molecular weights. Measurements by FIGAERO-I-CIMS explained 24 ± 0.8 % aerosol measured (AMS), increased more aged aerosol. systematical interpretation spectra area Guangzhou provides holistic view numerous atmosphere, which can serve as reference future field regions.

Language: Английский

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