The viscosity of atmospherically relevant organic particles

Nature Communications, Год журнала: 2018, Номер 9(1)

Опубликована: Фев. 28, 2018

The importance of organic aerosol particles in the environment has been long established, influencing cloud formation and lifetime, absorbing scattering sunlight, affecting atmospheric composition impacting on human health. Conventionally, ambient were considered to exist as liquids. Recent observations field measurements studies laboratory suggest that they may instead highly viscous semi-solids or amorphous glassy solids under certain conditions, with important implications for chemistry, climate air quality. This review explores our understanding particle phase, particularly identified by viscosity particles, phase state.

Язык: Английский

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The Role of Organic Aerosol in Atmospheric Ice Nucleation: A Review

ACS Earth and Space Chemistry, Год журнала: 2018, Номер 2(3), С. 168 - 202

Опубликована: Янв. 19, 2018

Predicting the formation of ice in atmosphere presents one great challenges physical sciences with important implications for chemistry and composition Earth's atmosphere, hydrological cycle, climate. Among atmospheric processes, heterogeneous nucleation proceeds on aerosol particles ranging from a few nanometers to micrometers size, commonly referred as nucleating (INPs). Research over last two decades has demonstrated that organic matter (OM) is ubiquitous present (OA) or coatings other particle types. The physicochemical properties OM make predicting how can contribute INP population challenging. This review focuses role INPs, summarizing highlighting recent advances our understanding process gained theoretical, laboratory, field studies. Examination residuals INPs analytical techniques demonstrates participates crystal formation. Molecular dynamic simulations provide insight into microscopic processes initiate nucleation. amorphous phase state supercooled metastable regime identified key factor assessing particles' pathways rates. A theoretical model advanced, based water activity, holistically predict changes rates coated by OM. goal this synthesize current propose future research directions needed fully evaluate OA atmosphere.

Язык: Английский

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Submicrometer Particles Are in the Liquid State during Heavy Haze Episodes in the Urban Atmosphere of Beijing, China

Environmental Science & Technology Letters, Год журнала: 2017, Номер 4(10), С. 427 - 432

Опубликована: Сен. 19, 2017

The particle phase state is a key factor for determining gas partitioning, reactive uptake, and multiphase chemical reactions, with associated links to secondary aerosol formation. In this study, the was investigated by measuring rebound fraction f in highly polluted atmosphere of Beijing, China. sensitive ambient relative humidity (RH). particles changed from rebounding adhering when RH increased above 60%, suggesting transition semisolid liquid state. This below deliquescence both (NH4)2SO4 NH4NO3. Submicrometer were during heavy haze episodes. might be because elevated inorganic resulted an increase water content. state, marking beginning episode, kick off positive feedback loop. readily take up pollutants that then react form inorganics, thereby further increasing rate uptake. We propose facilitates mass transfer reactions particles, accelerating growth over North China Plain.

Язык: Английский

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Increasing Isoprene Epoxydiol-to-Inorganic Sulfate Aerosol Ratio Results in Extensive Conversion of Inorganic Sulfate to Organosulfur Forms: Implications for Aerosol Physicochemical Properties

Environmental Science & Technology, Год журнала: 2019, Номер 53(15), С. 8682 - 8694

Опубликована: Июнь 7, 2019

Acid-driven multiphase chemistry of isoprene epoxydiols (IEPOX), key oxidation products, with inorganic sulfate aerosol yields substantial amounts secondary organic (SOA) through the formation organosulfur compounds. The extent and implications inorganic-to-organic conversion, however, are unknown. In this article, we demonstrate that extensive consumption occurs, which increases IEPOX-to-inorganic concentration ratio (IEPOX/Sulfinorg), as determined by laboratory measurements. Characterization total sulfur observed at Look Rock, Tennessee, from 2007 to 2016 shows mass fractions will likely continue increase ongoing declines in anthropogenic Sulfinorg, consistent our findings. We further compounds greatly modify critical properties, such acidity, morphology, viscosity, phase state. These new mechanistic insights changes SO2 emissions, especially isoprene-dominated environments, significantly alter biogenic SOA physicochemical properties. Consequently, IEPOX/Sulfinorg play an important role understanding historical climate determining future impacts on global air quality.

Язык: Английский

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New Multiphase Chemical Processes Influencing Atmospheric Aerosols, Air Quality, and Climate in the Anthropocene

Accounts of Chemical Research, Год журнала: 2020, Номер 53(10), С. 2034 - 2043

Опубликована: Сен. 14, 2020

ConspectusAtmospheric aerosols and fine particulate matter (PM2.5) are strongly affecting human health climate in the Anthropocene, that is, current era of globally pervasive rapidly increasing influence on planet Earth. Poor air quality associated with high aerosol concentrations is among leading risks worldwide, causing millions attributable excess deaths years life lost every year. Besides their impact, also influencing through interactions clouds solar radiation an estimated negative total effective radiative forcing may compensate about half positive carbon dioxide but exhibits a much larger uncertainty. Heterogeneous multiphase chemical reactions surface bulk solid, semisolid, liquid particles have been recognized to formation transformation thus environmental effects. However, atmospheric chemistry not well understood because its intrinsic complexity dealing multiple phases difficulties distinguishing effect from gas phase reactions.Recently, research received boost growing interest understanding severe haze very PM2.5 polluted megacities densely populated regions. State-of-the-art models suggest reactions, however, capturing rapid increase observed during events, suggesting gap our mechanisms formation. These events characterized by humidity, especially favoring chemistry. In this Account, we review recent advances made, as challenges future perspectives for processes involved transformation. We focus following questions: what key reaction pathways under conditions, relative importance versus gas-phase chemistry, implications development efficient reliable control strategies? particular, discuss related different regimes sulfate, nitrate, secondary organic (SOAs) synthesize new insights into water content, pH, state, nanoparticle size Overall, there evidence plays important role events. contrast photochemical which self-buffered against heavy pollution, feedback mechanism, where higher particle levels accelerate production, further increases concentration resulting series record-breaking pollution fill involve physical nanoscale regional global scales. A synthetic approach combining laboratory experiments, field measurements, instrument development, model simulations suggested roadmap advance research.

Язык: Английский

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Heterogeneous N₂O₅ Uptake During Winter: Aircraft Measurements During the 2015 WINTER Campaign and Critical Evaluation of Current Parameterizations

Journal of Geophysical Research Atmospheres, Год журнала: 2018, Номер 123(8), С. 4345 - 4372

Опубликована: Март 31, 2018

Abstract Nocturnal dinitrogen pentoxide (N 2 O 5 ) heterogeneous chemistry impacts regional air quality and the distribution lifetime of tropospheric oxidants. Formed from oxidation nitrogen oxides, N is heterogeneously lost to aerosol with a highly variable reaction probability, γ ), dependent on composition ambient conditions. Reaction products include soluble nitrate (HNO 3 or NO − nitryl chloride (ClNO ). We report first‐ever derivations wintertime aircraft measurements in critically important nocturnal residual boundary layer. Box modeling 2015 Wintertime INvestigation Transport, Emissions, Reactivity (WINTER) campaign over eastern United States derived 2,876 individual values median value 0.0143 range × 10 −5 0.1751. WINTER exhibited strongest correlation water content, but weak correlations other variables, such as organics, suggesting complex, nonlinear dependence multiple factors, an additional nonobserved factor. This factor may be related phase, morphology (i.e., core shell), mixing state, none which are commonly measured during field studies. Despite general agreement previous laboratory observations, comparison data 14 literature parameterizations (used predict chemical transport models) confirms that current methods reproduce full values. Nine within 2. Presented here first field‐based, empirical parameterization fit data, based functional form parameterizations.

Язык: Английский

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Predicting the glass transition temperature and viscosity of secondary organic material using molecular composition

Atmospheric chemistry and physics, Год журнала: 2018, Номер 18(9), С. 6331 - 6351

Опубликована: Май 4, 2018

Abstract. Secondary organic aerosol (SOA) accounts for a large fraction of submicron particles in the atmosphere. SOA can occur amorphous solid or semi-solid phase states depending on chemical composition, relative humidity (RH), and temperature. The transition between occurs at glass temperature (Tg). We have recently developed method to estimate Tg pure compounds containing carbon, hydrogen, oxygen atoms (CHO compounds) with molar mass less than 450 g mol−1 based their atomic O : C ratio. In this study, we refine extend CH CHO up ∼ 1100 using number atoms. predict viscosity from Tg-scaled Arrhenius plot fragility (viscosity vs. Tg∕T) as function parameter D. compiled D values literature found that approaches lower limit 10 (±1.7) increases. estimated α-pinene isoprene RH by accounting hygroscopic growth applying Gordon–Taylor mixing rule, reproducing previously published experimental measurements very well. Sensitivity studies were conducted evaluate impacts Tg, D, hygroscopicity (κ), constant predictions. toluene was predicted elemental composition obtained high-resolution spectrometry (HRMS), resulting good agreement measured viscosity. also biomass burning HRMS two different ionization techniques: electrospray (ESI) atmospheric pressure photoionization (APPI). Due differences detected signal intensity, viscosities low ESI APPI differ 2–5 orders magnitude. Complementary are desired further constrain RH-dependent future studies.

Язык: Английский

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Temperature effect on phase state and reactivity controls atmospheric multiphase chemistry and transport of PAHs

Science Advances, Год журнала: 2018, Номер 4(3)

Опубликована: Март 2, 2018

Atmospheric refrigerator increases the global transport and health risks of carcinogenic PAHs.

Язык: Английский

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Modeling the formation and growth of atmospheric molecular clusters: A review

Journal of Aerosol Science, Год журнала: 2020, Номер 149, С. 105621 - 105621

Опубликована: Июль 3, 2020

Язык: Английский

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The South Asian monsoon—pollution pump and purifier

Science, Год журнала: 2018, Номер 361(6399), С. 270 - 273

Опубликована: Июнь 14, 2018

Air pollution is growing fastest in monsoon-affected South Asia. During the dry winter monsoon, fumes disperse toward Indian Ocean, creating a vast haze, but their fate during wet summer monsoon has been unclear. We performed atmospheric chemistry measurements by aircraft Oxidation Mechanism Observations campaign, sampling outflow upper troposphere between Mediterranean and Ocean. The measurements, supported model calculations, show that sustains remarkably efficient cleansing mechanism which contaminants are rapidly oxidized deposited to Earth's surface. However, some pollutants lofted above clouds chemically processed reactive reservoir before being redistributed globally, including stratosphere.

Язык: Английский

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