Multigeneration Chemistry in Secondary Organic Aerosol Formation from Nitrate Radical Oxidation of Isoprene

ACS Earth and Space Chemistry, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 26, 2025

The nitrate radical (NO3) oxidation of isoprene is an important contributor to secondary organic aerosol (SOA). Isoprene has two double bonds which allow for multigeneration occur. effects chemistry on the gas- and particle-phase product distributions + NO3 system are not fully understood. In this study, we conduct chamber experiments by varying ratio N2O5 (precursor NO3) concentration from 1:1 14:1 investigate formation products in both phases under different levels. Multigeneration leads gas-phase then partition into particle phase depending volatility; first-generation (15–36% total SOA) such as C5H9NO5 C10H16N2O9 have volatility (log10C* = 1.0–3.0 using partitioning method log10C* 2.6–4.5 formula method) 1–5 orders magnitude higher than second-generation (37–57% SOA, −0.8–2.1 −3.7–1.8 C5H8,10N2O8, C5H9N3O10, C10H17N3O13. fast reaction rate constants (estimated be order 10–13 cm3 molecules–1 s–1 at 295 K) lower result increased SOA yields when availability increases enhanced. Specifically, increase up 300% yield observed N2O5/isoprene 3:1; 5.7% (organic mass concentration, ΔMo 4.2 μg/m3) 16.3% (ΔMo 11.9 reacted 25 ppb 3.1% 1.2 12.4% 5.4 15 ppb. maximum occurs greater or equal 3:1 a combined peroxy radicals (RO2) fate. We encourage future studies consider factors, can vary laboratory ambient conditions, comparing better understand any differences observed. Our results highlight that updated parameters including distribution should considered enable more comprehensive representation prediction atmospheric models.

Language: Английский

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Highly oxygenated organic molecule (HOM) formation in the isoprene oxidation by NO<sub>3</sub> radical

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(12), P. 9681 - 9704

Published: June 29, 2021

Abstract. Highly oxygenated organic molecules (HOM) are found to play an important role in the formation and growth of secondary aerosol (SOA). SOA is type with significant impact on air quality climate. Compared oxidation volatile compounds by ozone (O3) hydroxyl radical (OH), HOM nitrate (NO3), oxidant at nighttime dawn, has received less attention. In this study, reaction isoprene NO3 was investigated SAPHIR chamber (Simulation Atmospheric PHotochemistry a large Reaction chamber). A number HOM, including monomers (C5), dimers (C10), trimers (C15), both closed-shell open-shell peroxy radicals (RO2), were identified classified into various series according their formula. Their pathways proposed based observed known mechanisms literature, which further constrained time profiles after sequential addition differentiate first- second-generation products. containing one three N atoms (1–3N-monomers) formed, starting carbon double bond, forming radicals, followed autoxidation. 1N-monomers formed direct first-generation 2N-monomers (e.g., C5H8N2On(n=7–13), C5H10N2On(n=8–14)) likely termination products C5H9N2On⚫, C5-hydroxynitrate (C5H9NO4), product bond. 2N-monomers, products, dominated accounted for ∼34 % all indicating + under our experimental conditions. H shift alkoxy form subsequent autoxidation (“alkoxy–peroxy” pathway) be pathway formation. mostly accretion monomer RO2 via reactions dimer possibly C5–RO2 isoprene. RO2. The concentrations different showed distinct during reaction, linked pathway. either typical profile or combination both, multiple and/or isomers. Total molar yield estimated 1.2 %-0.7%+1.3%, corresponded ∼3.6 assuming molecular weight C5H9NO6 as lower limit. This suggests that may contribute fraction NO3.

Language: Английский

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A systematic re-evaluation of methods for quantification of bulk particle-phase organic nitrates using real-time aerosol mass spectrometry

Atmospheric measurement techniques, Journal Year: 2022, Volume and Issue: 15(2), P. 459 - 483

Published: Jan. 27, 2022

Abstract. Organic nitrate (RONO2) formation in the atmosphere represents a sink of NOx (NOx = NO + NO2) and termination NOx/HOx (HOx HO2 OH) ozone radical propagation cycles, can act as reservoir transporting reactive nitrogen, contributes to secondary organic aerosol formation. While some fraction RONO2 is thought reside particle phase, particle-phase nitrates (pRONO2) are infrequently measured thus poorly understood. There an increasing prevalence mass spectrometer (AMS) instruments, which have shown promise for determining quantitative total functional group contribution aerosols. A simple approach that relies on relative intensities NO+ NO2+ ions AMS spectrum, calibrated NOx+ ratio NH4NO3, inferred pRONO2 has been proposed way apportion signal NH4NO3 pRONO2. This method increasingly being applied field laboratory data. However, methods largely inconsistent characterized, and, therefore, detailed evaluation timely. Here, we compile extensive survey ratios various compounds mixtures from multiple groups, measurements. All data analysis presented here use with standard vaporizer. We show that, absence standards, be estimated using referenced ratio, so-called “Ratio-of-Ratios” (RoR 2.75 ± 0.41). systematically explore basis quantifying (and NH4NO3) RoR ground aircraft measurements conducted over large range conditions. The compared another (positive matrix factorization, PMF) other related (e.g., gas RONO2) measurements, generally showing good agreement/correlation. broad shows pervasive trend higher fractional lower concentrations, corresponds shifts urban-influenced rural/remote regions. Compared campaigns, observations all campaigns showed substantially contributions at midranges (0.01–0.1 up 2–5 µg m−3), suggesting balance effects controlling lifetimes – such humidity, temperatures, greater dilution, different sources, acidity, hydrolysis (possibly accelerated by acidity) favors those environments altitudes sampled.

Language: Английский

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Highly time-resolved chemical speciation and source apportionment of organic aerosol components in Delhi, India, using extractive electrospray ionization mass spectrometry

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(11), P. 7739 - 7761

Published: June 15, 2022

Abstract. In recent years, the Indian capital city of Delhi has been impacted by very high levels air pollution, especially during winter. Comprehensive knowledge composition and sources organic aerosol (OA), which constitutes a substantial fraction total particulate mass (PM) in Delhi, is central to formulating effective public health policies. Previous source apportionment studies identified key primary OA (POA) showed that secondary (SOA) played major role but were unable resolve specific SOA sources. We address latter through first field deployment an extractive electrospray ionization time-of-flight spectrometer (EESI-TOF) together with high-resolution (AMS). Measurements conducted winter 2018/19, positive matrix factorization (PMF) was used separately on AMS EESI-TOF datasets apportion OA. PMF analysis yielded three two factors attributed hydrocarbon-like (HOA), biomass burning (BBOA-1 BBOA-2), more oxidized oxygenated (MO-OOA), less (LO-OOA). On average, 40 % apportioned factors. The contribution varied greatly between daytime (76.8 %, 10:00–16:00 local time (LT)) nighttime (31.0 21:00–04:00 LT). higher chemical resolution data allowed identification individual six factors, (primary cooking-related OA). remaining four predominantly origin: aromatic SOA, biogenic aged mixed urban SOA. Due uncertainties ion sensitivities, concentrations SOA-dominated related (i.e. MO-OOA + LO-OOA) multiple linear regression (MLR). Aromatic component daytime, 55.2 (42.4 Its however, decreased 25.4 (7.9 OA) nighttime. This factor oxidation light compounds emitted mostly from traffic. Biogenic accounted for 18.4 (14.2 36.1 (11.2 Aged 15.2 11.0 (11.7 8.5 mass), respectively, 15.4 22.9 (4.8 7.1 A simple dilution–partitioning model applied all estimate observed resulting photochemical production or emissions (POA). burning, found be dominated production, likely locally volatile (VOCs). contrast, diffuse regional isoprene monoterpenes. findings this study show are caused POA led traffic accounting largest fraction. Because possibly toxic than OA, its dominance suggests increased toxicity health-related consequences general public.

Language: Английский

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Elucidating Secondary Organic Aerosol Processes through High-Resolution Aerosol Mass Spectrometry in Beijing

Advances in Atmospheric Sciences, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 24, 2025

Language: Английский

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Organic aerosol volatility and viscosity in the North China Plain: contrast between summer and winter

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(7), P. 5463 - 5476

Published: April 8, 2021

Abstract. Volatility and viscosity have substantial impacts on gas–particle partitioning, formation evolution of aerosol hence the predictions aerosol-related air quality climate effects. Here volatility at a rural site (Gucheng) an urban (Beijing) in North China Plain (NCP) summer winter were investigated by using thermodenuder coupled with high-resolution mass spectrometer. The effective saturation concentration (C*) organic (OA) was smaller than that (0.55 µg m−3 vs. 0.71–0.75 m−3), indicating OA NCP is more volatile due to enhanced primary emissions from coal combustion biomass burning. distributions varied largely different among factors. In particular, we found hydrocarbon-like (HOA) contained nonvolatile compounds compared coal-combustion-related OA. oxidized oxygenated (MO-OOA) showed overall lower less OOA (LO-OOA) both winter, yet MO-OOA be relative humidity (RH) dependent showing properties higher RH. Our results demonstrated composition chemical pathways under RH levels. glass transition temperature (Tg) are estimated recently developed parameterization formula. Tg Beijing (291.5 K) (289.7–290.0 K), while it greatly suggested existed mainly as solid (RH = 29 ± 17 %), but semisolids 48 25 %) Gucheng 68 24 %). These important implication kinetically limited partitioning may need considered when simulating secondary NCP.

Language: Английский

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Low-Molecular-Weight Carboxylic Acids in the Southeastern U.S.: Formation, Partitioning, and Implications for Organic Aerosol Aging

Environmental Science & Technology, Journal Year: 2021, Volume and Issue: 55(10), P. 6688 - 6699

Published: April 27, 2021

While carboxylic acids are important components in both particle and gas phases the atmosphere, their sources partitioning not fully understood. In this study, we present real-time measurements of particle- gas-phase concentrations for five most common abundant low-molecular-weight (LMWCA) a rural region southeastern U.S. Fall 2016. Through comparison with secondary organic aerosol (SOA) tracers, find that isoprene was local precursor all LMWCA but via different pathways. We propose monocarboxylic (formic acetic acids) were mainly formed through photochemical reactions, while dicarboxylic (oxalic, malonic, succinic predominantly from aqueous processing. Unexpectedly high particle-phase formic (in form formate acetate, respectively) observed likely long-range transport (OA), decoupled counterparts. addition, an extraordinarily strong correlation (R2 = 0.90) between particulate aged SOA, which tentatively attribute to boundary layer dynamics.

Language: Английский

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Characterization of thermal decomposition of oxygenated organic compounds in FIGAERO-CIMS

Aerosol Science and Technology, Journal Year: 2021, Volume and Issue: 55(12), P. 1321 - 1342

Published: June 22, 2021

The Filter Inlet for Gases and AEROsols coupled with a chemical ionization mass spectrometer (FIGAERO-CIMS) measures particle-phase organics via temperature-programmed thermal desorption, though the extent to which different compounds undergo decomposition is not well characterized. We study effect of functional groups on degree pathways (decarboxylation dehydration) in FIGAERO-CIMS using atmospherically relevant alcohols, monoacids, diacids, polyacids, multifunctional acids. Based their carbon oxidation state, are categorized as less-oxidized oxygenated organic aerosol (LO-OOA), (OOA), or more-oxidized OOA (MO-OOA), exhibit little, minor, considerable decomposition, respectively. result shows that leads negative biases measured elemental ratios (O:C H:C) MO-OOA, except H:C ratio those MO-OOA. develop screening criteria double bond equivalent (DBE), maximum desorption temperature (Tmax), number oxygen (nO) (DBE ≥ 2, Tmax 72 °C, nO > 4). Additionally, we find β-keto-carboxylic acids carboxyl-containing aromatic only favor decarboxylation. Lastly, investigate instrument's ramping rate (40, 13.3, 3.3 °C min−1) citric acid. recommend 13.3 40 min−1 rates but do acts distinctively from most parental compound decomposition.Copyright © 2021 American Association Aerosol Research

Language: Английский

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Synthesis and Hydrolysis of Atmospherically Relevant Monoterpene-Derived Organic Nitrates

Environmental Science & Technology, Journal Year: 2021, Volume and Issue: 55(21), P. 14595 - 14606

Published: Oct. 20, 2021

The partition of gas-phase organic nitrates (ONs) to aerosols and subsequent hydrolysis are regarded as important loss mechanisms for ON species. However, the major factors controlling lifetime not fully understood. In this work, we synthesized seven monoterpene-derived ONs systematically investigated their in bulk solutions at different pH values. lifetimes ranged from 12.9 min 8.5 h allylic primary tertiary ONs, but secondary were stable neutral pH. alkyl substitution numbers, functional groups, carbon skeletons three rates. Tertiary found hydrolyze via acid-catalyzed unimolecular (SN1) mechanism, while a competition SN1 bimolecular (SN2) accounted ONs. consistency experimental theoretical rates calculated by density theory further supported proposed mechanisms. Reversible reactions including nitration first reported explain highlighting possibility that particulate nitric acid can participate generate new nitrogen-containing compounds. These findings demonstrate is complex reaction proceeds controlled various parameters.

Language: Английский

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Recent advances in mass spectrometry techniques for atmospheric chemistry research on molecular‐level

Mass Spectrometry Reviews, Journal Year: 2023, Volume and Issue: 43(5), P. 1091 - 1134

Published: July 13, 2023

Abstract The Earth's atmosphere is composed of an enormous variety chemical species associated with trace gases and aerosol particles whose composition chemistry have critical impacts on the climate, air quality, human health. Mass spectrometry analysis as a powerful popular analytical technique has been widely developed applied in atmospheric for decades. allows effective detection, identification, quantification broad range organic inorganic high sensitivity resolution. In this review, we summarize recently mass techniques, methods, applications research past several years molecular‐level. Specifically, new developments ion‐molecule reactors, various soft ionization unique coupling separation techniques are highlighted. laboratory studies field measurements focused improving detection limits traditional emerging volatile compounds, characterizing multiphase highly oxygenated molecules, monitoring particle bulk surface compositions.

Language: Английский

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