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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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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Non-methane organic gas emissions from biomass burning: identification, quantification, and emission factors from PTR-ToF during the FIREX 2016 laboratory experiment

Atmospheric chemistry and physics, Journal Year: 2018, Volume and Issue: 18(5), P. 3299 - 3319

Published: March 7, 2018

Abstract. Volatile and intermediate-volatility non-methane organic gases (NMOGs) released from biomass burning were measured during laboratory-simulated wildfires by proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF). We identified NMOG contributors to more than 150 PTR ion masses using gas chromatography (GC) pre-separation with electron ionization, H3O+ chemical NO+ an extensive literature review, time series correlation, providing higher certainty for identifications has been previously available. Our interpretation of the PTR-ToF spectrum accounts nearly 90 % detected across all fuel types. The relative contributions different NMOGs individual exact are mostly similar many fires measurements compared corresponding open-path Fourier transform infrared spectroscopy (OP-FTIR), broadband cavity-enhanced (ACES), iodide ionization (I− CIMS) where possible. majority comparisons have slopes near 1 values linear correlation coefficient, R2, > 0.8, including compounds that not frequently reported PTR-MS such as ammonia, hydrogen cyanide (HCN), nitrous acid (HONO), propene. exceptions include methylglyoxal known be difficult measure one or deployed instruments. fire-integrated emission ratios CO factors 18 types provided. Finally, we provide overview characteristics species. Non-aromatic oxygenated most abundant. Furans aromatics, while less abundant, comprise a large portion OH reactivity. reactivity, its major contributors, volatility distribution emissions can change considerably over course fire.

Language: Английский

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

ACS Earth and Space Chemistry, Journal Year: 2018, Volume and Issue: 2(3), P. 168 - 202

Published: Jan. 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.

Language: Английский

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Molecular Characterization of Brown Carbon in Biomass Burning Aerosol Particles

Environmental Science & Technology, Journal Year: 2016, Volume and Issue: 50(21), P. 11815 - 11824

Published: Oct. 5, 2016

Emissions from biomass burning are a significant source of brown carbon (BrC) in the atmosphere. In this study, we investigate molecular composition freshly emitted organic aerosol (BBOA) samples collected during test burns sawgrass, peat, ponderosa pine, and black spruce. We demonstrate that both BrC absorption chemical light-absorbing compounds depend significantly on type fuels. Common chromophores selected BBOA include nitro-aromatics, polycyclic aromatic hydrocarbon derivatives, polyphenols spanning wide range weights, structures, light properties. A number biofuel-specific observed, indicating some them may be used as source-specific markers BrC. On average, ∼50% solvent-extractable fraction can attributed to limited strong chromophores. The coefficients affected by solar photolysis. Specifically, under typical atmospheric conditions, 300 nm absorbance decays with half-life ∼16 h. "molecular corridor" analysis volatility distribution suggests many fresh have low saturation mass concentration (<1 μg m–3) will retained particle phase atmospherically relevant conditions.

Language: Английский

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Multi-instrument comparison and compilation of non-methane organic gas emissions from biomass burning and implications for smoke-derived secondary organic aerosol precursors

Atmospheric chemistry and physics, Journal Year: 2017, Volume and Issue: 17(2), P. 1471 - 1489

Published: Jan. 31, 2017

Abstract. Multiple trace-gas instruments were deployed during the fourth Fire Lab at Missoula Experiment (FLAME-4), including first application of proton-transfer-reaction time-of-flight mass spectrometry (PTR-TOFMS) and comprehensive two-dimensional gas chromatography–time-of-flight (GC × GC-TOFMS) for laboratory biomass burning (BB) measurements. Open-path Fourier transform infrared spectroscopy (OP-FTIR) was also deployed, as well whole-air sampling (WAS) with one-dimensional chromatography–mass (GC-MS) analysis. This combination provided an unprecedented level detection chemical speciation. The composition emission factors (EFs) determined by these four analytical techniques compared representative fuels. results demonstrate that are highly complementary, each covering some unique important ranges compositional space, thus demonstrating need multi-instrument approaches to adequately characterize BB smoke emissions. Emission overlapping compounds generally within experimental uncertainty, despite outliers, monoterpenes. Data from all measurements synthesized into a single EF database includes over 500 non-methane organic gases (NMOGs) provide picture speciated, gaseous identified assessed function volatility; 6–11 % total NMOG associated intermediate-volatility (IVOCs). These atmospherically relevant historically have been unresolved in largely missing inventories. Additionally, screened published secondary aerosol (SOA) yields. Of reactive carbon (defined scaled OH rate constant number compound) emissions, 55–77 which SOA yields unknown or understudied. best candidates future smog chamber experiments based on relative abundance ubiquity understudied compounds, they included furfural, 2-methyl furan, 2-furan methanol, 1,3-cyclopentadiene. Laboratory study will facilitate modeling efforts.

Language: Английский

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

Atmospheric chemistry and physics, Journal Year: 2018, Volume and Issue: 18(9), P. 6331 - 6351

Published: May 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.

Language: Английский

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High- and low-temperature pyrolysis profiles describe volatile organic compound emissions from western US wildfire fuels

Atmospheric chemistry and physics, Journal Year: 2018, Volume and Issue: 18(13), P. 9263 - 9281

Published: July 3, 2018

Abstract. Biomass burning is a large source of volatile organic compounds (VOCs) and many other trace species to the atmosphere, which can act as precursors secondary pollutants such ozone fine particles. Measurements performed with proton-transfer-reaction time-of-flight mass spectrometer during FIREX 2016 laboratory intensive were analyzed positive matrix factorization (PMF), in order understand instantaneous variability VOC emissions from biomass burning, simplify description these types emissions. Despite complexity emissions, we found that solution including just two emission profiles, are spectral representations relative abundances emitted VOCs, explained on average 85 % across various fuels representative western US (including coniferous chaparral fuels). In addition, profiles remarkably similar almost all fuel tested. For example, correlation coefficient r2 each profile between ponderosa pine (coniferous tree) manzanita (chaparral) higher than 0.84. The compositional differences appear be related pyrolysis processes biopolymers at high low temperatures. These thought main “High-temperature” “low-temperature” do not correspond exactly commonly used “flaming” “smoldering” categories described by modified combustion efficiency (MCE). atmospheric properties (e.g., OH reactivity, volatility, etc) high- low-temperature significantly different. We also describe previously reported data for field burns.

Language: Английский

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Secondary organic aerosol formed by condensing anthropogenic vapours over China’s megacities

Nature Geoscience, Journal Year: 2022, Volume and Issue: 15(4), P. 255 - 261

Published: April 1, 2022

Language: Английский

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Infrared-absorbing carbonaceous tar can dominate light absorption by marine-engine exhaust

npj Climate and Atmospheric Science, Journal Year: 2019, Volume and Issue: 2(1)

Published: May 9, 2019

Abstract Ship engines in the open ocean and Arctic typically combust heavy fuel oil (HFO), resulting light-absorbing particulate matter (PM) emissions that have been attributed to black carbon (BC) conventional, soluble brown (brC). We show here neither BC nor brC is major (LAC) species HFO-combustion PM. Instead, “tar brC” dominates. This tar brC, previously identified only open-biomass-burning emissions, shares key defining properties with BC: it insoluble, refractory, substantially absorbs visible near-infrared light. Relative BC, has a higher Angstrom absorption exponent (AAE) (2.5–6, depending on considered wavelengths), moderately-high mass efficiency (up 50% of BC), lower ratio sp 2 - 3 -bonded carbon. Based our results, we present refined classification atmospheric LAC into two sub-types brC. apply this demonstrate common analytical techniques for must be interpreted care when applied tar-containing aerosols. The global significance results indicated by field observations which suggest already contributes snow darkening, an effect may magnified over upcoming decades as shipping continues intensify.

Language: Английский

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