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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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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Ion-induced nucleation of pure biogenic particles

Nature, Journal Year: 2016, Volume and Issue: 533(7604), P. 521 - 526

Published: May 25, 2016

Abstract Atmospheric aerosols and their effect on clouds are thought to be important for anthropogenic radiative forcing of the climate, yet remain poorly understood 1 . Globally, around half cloud condensation nuclei originate from nucleation atmospheric vapours 2 It is that sulfuric acid essential initiate most particle formation in atmosphere 3,4 , ions have a relatively minor role 5 Some laboratory studies, however, reported organic without intentional addition acid, although contamination could not excluded 6,7 Here we present evidence aerosol particles highly oxidized biogenic absence large chamber under conditions. The oxygenated molecules (HOMs) produced by ozonolysis α-pinene. We find Galactic cosmic rays increase rate one two orders magnitude compared with neutral nucleation. Our experimental findings supported quantum chemical calculations cluster binding energies representative HOMs. Ion-induced pure constitutes potentially widespread source terrestrial environments low pollution.

Language: Английский

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Atmospheric new particle formation from sulfuric acid and amines in a Chinese megacity

Science, Journal Year: 2018, Volume and Issue: 361(6399), P. 278 - 281

Published: July 19, 2018

Atmospheric new particle formation (NPF) is an important global phenomenon that nevertheless sensitive to ambient conditions. According both observation and theoretical arguments, NPF usually requires a relatively high sulfuric acid (H2SO4) concentration promote the of particles low preexisting aerosol loading minimize sink particles. We investigated in Shanghai were able observe precursor vapors initial clusters at molecular level megacity. High rates observed coincide with several familiar markers suggestive H2SO4-dimethylamine (DMA)-water (H2O) nucleation, including dimers H2SO4-DMA clusters. In cluster kinetics simulation, was enough explain growth ~3 nanometers under very condensation sink, whereas subsequent higher rate beyond this size believed result from added contribution condensing organic species. These findings will help understanding urban its air quality climate effects, as well formulating policies mitigate secondary China.

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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Resonance-stabilized hydrocarbon-radical chain reactions may explain soot inception and growth

Science, Journal Year: 2018, Volume and Issue: 361(6406), P. 997 - 1000

Published: Sept. 6, 2018

Mystery surrounds the transition from gas-phase hydrocarbon precursors to terrestrial soot and interstellar dust, which are carbonaceous particles formed under similar conditions. Although polycyclic aromatic hydrocarbons (PAHs) known high-temperature carbonaceous-particle formation, molecular pathways that initiate particle formation unknown. We present experimental theoretical evidence for rapid clustering-reaction involving radicals with extended conjugation. These react other species form covalently bound complexes promote further growth clustering by regenerating resonance-stabilized through low-barrier hydrogen-abstraction hydrogen-ejection reactions. Such radical-chain reaction may lead clusters of PAHs would otherwise be too small condense at high temperatures, thus providing key mechanistic steps surface chemisorption.

Language: Английский

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Global distribution of particle phase state in atmospheric secondary organic aerosols

Nature Communications, Journal Year: 2017, Volume and Issue: 8(1)

Published: April 21, 2017

Secondary organic aerosols (SOA) are a large source of uncertainty in our current understanding climate change and air pollution. The phase state SOA is important for quantifying their effects on quality, but its global distribution poorly characterized. We developed method to estimate glass transition temperatures based the molar mass molecular O:C ratio components, we used chemistry model EMAC with aerosol module ORACLE predict atmospheric SOA. For planetary boundary layer, simulations indicate that mostly liquid tropical polar high relative humidity, semi-solid mid-latitudes solid over dry lands. find middle upper troposphere should be glassy state. Thus, slow diffusion water, oxidants molecules could kinetically limit gas-particle interactions free troposphere, promote ice nucleation facilitate long-range transport reactive toxic pollutants embedded

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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Multicomponent new particle formation from sulfuric acid, ammonia, and biogenic vapors

Science Advances, Journal Year: 2018, Volume and Issue: 4(12)

Published: Dec. 7, 2018

Atmospheric aerosol formation from biogenic vapors is strongly affected by air pollutants, like NO x , SO 2 and NH 3 .

Language: Английский

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