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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New Particle Formation in the Atmosphere: From Molecular Clusters to Global Climate

Journal of Geophysical Research Atmospheres, Journal Year: 2019, Volume and Issue: 124(13), P. 7098 - 7146

Published: June 25, 2019

Abstract New particle formation (NPF) represents the first step in complex processes leading to of cloud condensation nuclei. Newly formed nanoparticles affect human health, air quality, weather, and climate. This review provides a brief history, synthesizes recent significant progresses, outlines challenges future directions for research relevant NPF. developments include emergence state‐of‐the‐art instruments that measure prenucleation clusters newly nucleated down about 1 nm; systematic laboratory studies multicomponent nucleation systems, including collaborative experiments conducted Cosmics Leaving Outdoor Droplets chamber at CERN; observations NPF different types forests, extremely polluted urban locations, coastal sites, polar regions, high‐elevation sites; improved theories parameterizations account atmospheric models. The lack understanding fundamental chemical mechanisms responsible aerosol growth under diverse environments, effects SO 2 NO x on NPF, contribution anthropogenic organic compounds It is also critical develop can detect composition particles from 3 20 nm improve represent over wide range conditions precursor, temperature, humidity.

Language: Английский

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Accretion Product Formation from Self‐ and Cross‐Reactions of RO₂ Radicals in the Atmosphere

Angewandte Chemie International Edition, Journal Year: 2018, Volume and Issue: 57(14), P. 3820 - 3824

Published: Feb. 1, 2018

Abstract Hydrocarbons are emitted into the Earth's atmosphere in very large quantities by human and biogenic activities. Their atmospheric oxidation processes almost exclusively yield RO 2 radicals as reactive intermediates whose fate is not yet fully unraveled. Herein, we show that gas‐phase reactions of two produce accretion products composed carbon backbone both reactants. The rates for product formation high bearing functional groups, competing with those corresponding NO HO . This pathway, which has been considered modelling processes, can be important, or even dominant, all areas atmosphere. Moreover, vapor pressure formed remarkably low, characterizing them an effective source secondary organic aerosol.

Language: Английский

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Recent Progress and Prospects in Catalytic Water Treatment

Chemical Reviews, Journal Year: 2021, Volume and Issue: 122(3), P. 2981 - 3121

Published: Dec. 7, 2021

Presently, conventional technologies in water treatment are not efficient enough to completely mineralize refractory contaminants. In this context, the implementation of catalytic processes could be an alternative. Despite advantages provided terms kinetics transformation, selectivity, and energy saving, numerous attempts have yet led at industrial scale. This review examines investigations different scales for which controversies limitations must solved bridge gap between fundamentals practical developments. Particular attention has been paid development solar-driven some other emerging processes, such as microwave assisted catalysis, plasma-catalytic or biocatalytic remediation, taking into account their specific drawbacks. Challenges a better understanding related complexity systems coexistence various solid-liquid-gas interfaces identified.

Language: Английский

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Atmospheric autoxidation is increasingly important in urban and suburban North America

Proceedings of the National Academy of Sciences, Journal Year: 2017, Volume and Issue: 115(1), P. 64 - 69

Published: Dec. 18, 2017

Gas-phase autoxidation-regenerative peroxy radical formation following intramolecular hydrogen shifts-is known to be important in the combustion of organic materials. The relevance this chemistry oxidation organics atmosphere has received less attention due, part, lack kinetic data at relevant temperatures. Here, we combine computational and experimental approaches investigate rate autoxidation for radicals (RO

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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Formation of Highly Oxidized Radicals and Multifunctional Products from the Atmospheric Oxidation of Alkylbenzenes

Environmental Science & Technology, Journal Year: 2017, Volume and Issue: 51(15), P. 8442 - 8449

Published: July 6, 2017

Aromatic hydrocarbons contribute significantly to tropospheric ozone and secondary organic aerosols (SOA). Despite large efforts in elucidating the formation mechanism of aromatic-derived SOA, current models still substantially underestimate SOA yields when comparing field measurements. Here we present a new, up now undiscovered pathway for highly oxidized products from OH-initiated oxidation alkyl benzenes based on theoretical experimental investigations. We propose that unimolecular H-migration followed by O2-addition, so-called autoxidation step, can take place bicyclic peroxy radicals (BPRs), which are important intermediates aromatic compounds. These steps lead multifunctional compounds (HOMs), able form SOA. Our calculations suggest intramolecular BPRs substituted could be fast enough compete with bimolecular reactions HO2 or NO under atmospheric conditions. The findings experimentally supported flow tube studies using chemical ionization mass spectrometry detect radical closed-shell products. This new BPR route HOMs gas phase enhances our understanding mechanism, contributes better urban areas.

Language: Английский

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Aerosol characteristics and particle production in the upper troposphere over the Amazon Basin

Atmospheric chemistry and physics, Journal Year: 2018, Volume and Issue: 18(2), P. 921 - 961

Published: Jan. 25, 2018

Abstract. Airborne observations over the Amazon Basin showed high aerosol particle concentrations in upper troposphere (UT) between 8 and 15 km altitude, with number densities (normalized to standard temperature pressure) often exceeding those planetary boundary layer (PBL) by 1 or 2 orders of magnitude. The measurements were made during German–Brazilian cooperative aircraft campaign ACRIDICON–CHUVA, where ACRIDICON stands for Aerosol, Cloud, Precipitation, Radiation Interactions Dynamics Convective Cloud Systems CHUVA is acronym Processes Main Precipitation Brazil: A Contribution Resolving Modeling GPM (global precipitation measurement), on German High Altitude Long Range Research Aircraft (HALO). took place September–October 2014, objective studying tropical deep convective clouds rainforest their interactions atmospheric trace gases, particles, radiation. Aerosol enhancements observed consistently all flights which UT was probed, using several metrics, including condensation nuclei (CN) cloud (CCN) chemical species mass concentrations. particles differed sharply composition size distribution from PBL, ruling out transport combustion-derived (BL) as a source. air immediate outflow depleted whereas strongly enhanced small (< 90 nm diameter) found regions that had experienced convection preceding 5–72 h. We also elevated larger (> nm) UT, consisted mostly organic matter nitrate very effective CCN. Our findings suggest conceptual model, production new takes continental biogenic volatile material brought up converted condensable UT. Subsequently, downward mixing tropospheric can be source they increase compound (BVOC) oxidation products. This may an important Amazonian nucleation formation have not been observed. propose this dominant process supplying secondary pristine atmosphere, making control both removal particles.

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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Anthropogenic enhancements to production of highly oxygenated molecules from autoxidation

Proceedings of the National Academy of Sciences, Journal Year: 2019, Volume and Issue: 116(14), P. 6641 - 6646

Published: March 18, 2019

Atmospheric oxidation of natural and anthropogenic volatile organic compounds (VOCs) leads to secondary aerosol (SOA), which constitutes a major often dominant component atmospheric fine particulate matter (PM2.5). Recent work demonstrates that rapid autoxidation peroxy radicals (RO2) formed during VOC results in highly oxygenated molecules (HOM) efficiently form SOA. As NOx emissions decrease, the chemical regime atmosphere changes one RO2 becomes increasingly important, potentially increasing PM2.5, while oxidant availability driving formation rates simultaneously declines, possibly slowing regional PM2.5 formation. Using suite situ aircraft observations laboratory studies HOM, together with detailed molecular mechanism, we show although an archetypal biogenic system more competitive as decreases, absolute HOM production decrease due reductions, leading overall positive coupling between localized SOA from autoxidation. This effect is observed Atlanta, Georgia, urban plume where enhanced presence elevated NO, predictions for Guangzhou, China, HOM-RO2 coincides increases NO 1990 2010. These suggest added benefits abatement strategies come emission reductions have implications aerosol-climate interactions global resulting since preindustrial era.

Language: Английский

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