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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Recent advances in understanding secondary organic aerosol: Implications for global climate forcing

Reviews of Geophysics, Journal Year: 2017, Volume and Issue: 55(2), P. 509 - 559

Published: May 18, 2017

Abstract Anthropogenic emissions and land use changes have modified atmospheric aerosol concentrations size distributions over time. Understanding preindustrial conditions in organic due to anthropogenic activities is important because these features (1) influence estimates of radiative forcing (2) can confound the historical response climate increases greenhouse gases. Secondary (SOA), formed atmosphere by oxidation gases, represents a major fraction global submicron‐sized aerosol. Over past decade, significant advances understanding SOA properties formation mechanisms occurred through measurements, yet current models typically do not comprehensively include all processes. This review summarizes some developments during decade formation. We highlight importance processes that growth particles sizes relevant for clouds forcing, including extremely low volatility organics gas phase, acid‐catalyzed multiphase chemistry isoprene epoxydiols, particle‐phase oligomerization, physical such as viscosity. Several highlighted this are complex interdependent nonlinear effects on properties, formation, evolution SOA. Current neglect complexity nonlinearity thus less likely accurately predict project future sensitivity Efforts also needed rank most influential process‐related interactions, so be represented chemistry‐climate models.

Language: Английский

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The role of low-volatility organic compounds in initial particle growth in the atmosphere

Nature, Journal Year: 2016, Volume and Issue: 533(7604), P. 527 - 531

Published: May 25, 2016

Abstract About half of present-day cloud condensation nuclei originate from atmospheric nucleation, frequently appearing as a burst new particles near midday 1 . Atmospheric observations show that the growth rate often accelerates when diameter is between one and ten nanometres 2,3 In this critical size range, are most likely to be lost by coagulation with pre-existing 4 , thereby failing form typically 50 100 across. Sulfuric acid vapour involved in nucleation but too scarce explain subsequent 5,6 leaving organic vapours plausible alternative, at least planetary boundary layer 7,8,9,10 Although recent studies 11,12,13 predict low-volatility contribute during initial growth, direct evidence has been lacking. The accelerating may result increased photolytic production condensable species afternoon 2 presence possible Kelvin (curvature) effect, which inhibits on smallest (the nano-Köhler theory) 2,14 so far remained ambiguous. Here we present experiments performed large chamber under conditions investigate role nucleated absence inorganic acids bases such sulfuric or ammonia amines, respectively. Using data same set experiments, it shown 15 alone can drive nucleation. We focus find have extremely low volatilities (saturation concentration less than 10 −4.5 micrograms per cubic metre). As increase barrier falls, primarily due more abundant slightly higher volatility concentrations −0.5 particle model quantitatively reproduces our measurements. Furthermore, implement parameterization first steps global aerosol change substantially response, is, up cent comparison previously assumed parameterizations.

Language: Английский

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Atmospheric new particle formation and growth: review of field observations

Environmental Research Letters, Journal Year: 2018, Volume and Issue: 13(10), P. 103003 - 103003

Published: Sept. 6, 2018

This review focuses on the observed characteristics of atmospheric new particle formation (NPF) in different environments global troposphere. After a short introduction, we will present theoretical background that discusses methods used to analyze measurement data NPF and associated terminology. We update our current understanding regional NPF, i.e. taking simultaneously place over large spatial scales, complement with full reported growth rates during events. shortly at sub-regional scales. Since newly-formed particles into larger sizes is great interest, briefly discuss observation-based which gaseous compounds contribute particles, what implications this have cloud condensation nuclei formation. finish summary main findings future outlook outlines remaining research questions needs for additional measurements.

Language: Английский

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New particle formation in the free troposphere: A question of chemistry and timing

Science, Journal Year: 2016, Volume and Issue: 352(6289), P. 1109 - 1112

Published: May 26, 2016

From neutral to new Many of the particles in troposphere are formed situ, but what fraction all tropospheric do they constitute and how exactly made? Bianchi et al. report results from a high-altitude research station. Roughly half were newly by condensation highly oxygenated multifunctional compounds. A combination laboratory results, field measurements, model calculations revealed that nucleation is more than 10 times faster ion-induced nucleation, particle growth rates size-dependent, formation occurs during limited time window. Science , this issue p. 1109

Language: Английский

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Causes and importance of new particle formation in the present‐day and preindustrial atmospheres

Journal of Geophysical Research Atmospheres, Journal Year: 2017, Volume and Issue: 122(16), P. 8739 - 8760

Published: July 10, 2017

Abstract New particle formation has been estimated to produce around half of cloud‐forming particles in the present‐day atmosphere, via gas‐to‐particle conversion. Here we assess importance new (NPF) for both and preindustrial atmospheres. We use a global aerosol model with parametrizations NPF from previously published CLOUD chamber experiments involving sulfuric acid, ammonia, organic molecules, ions. find that produces 67% cloud condensation nuclei at 0.2% supersaturation (CCN0.2%) level low clouds atmosphere (estimated uncertainty range 45–84%) 54% present day 38–66%). Concerning causes, biogenic volatile compounds (BVOCs) CCN is greater than thought. Removing BVOCs hence all secondary our reduces low‐cloud‐level concentrations by 26% 41% preindustrial. Around three quarters this reduction due tiny fraction oxidation products have sufficiently volatility be involved early growth. Furthermore, estimate 40% CCN0.2% are formed ion‐induced NPF, compared 27% day, although caution poorly measured present. Our suggests effect changes cosmic ray intensity on small unlikely comparable large variations natural primary emissions.

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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Hydroxyl radical-induced formation of highly oxidized organic compounds

Nature Communications, Journal Year: 2016, Volume and Issue: 7(1)

Published: Dec. 2, 2016

Abstract Explaining the formation of secondary organic aerosol is an intriguing question in atmospheric sciences because its importance for Earth’s radiation budget and associated effects on health ecosystems. A breakthrough was recently achieved understanding from ozone reactions biogenic emissions by rapid highly oxidized multifunctional compounds via autoxidation. However, important daytime hydroxyl radical have been considered to be less this process. Here we report measurements reaction radicals with α- β-pinene applying improved mass spectrometric methods. Our laboratory results prove that products proceeds considerably higher yields than previously reported. Field support these findings. allow a better description diurnal behaviour product subsequent atmosphere.

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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Formation of highly oxygenated organic molecules from aromatic compounds

Atmospheric chemistry and physics, Journal Year: 2018, Volume and Issue: 18(3), P. 1909 - 1921

Published: Feb. 9, 2018

Abstract. Anthropogenic volatile organic compounds (AVOCs) often dominate the urban atmosphere and consist to a large degree of aromatic hydrocarbons (ArHCs), such as benzene, toluene, xylenes, trimethylbenzenes, e.g., from handling combustion fuels. These are important precursors for formation secondary aerosol. Here we show that oxidation aromatics with OH leads subsequent autoxidation chain reaction forming highly oxygenated molecules (HOMs) an O : C ratio up 1.09. This is exemplified five single-ring ArHCs (benzene, o-/m-/p-xylene, mesitylene (1,3,5-trimethylbenzene) ethylbenzene), well two conjugated polycyclic (naphthalene biphenyl). We report elemental composition HOMs differences in patterns these ArHCs. A potential pathway presented discussed. hypothesize AVOCs may contribute substantially new particle events have been detected areas.

Language: Английский

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