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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Evaluating Organic Aerosol Sources and Evolution with a Combined Molecular Composition and Volatility Framework Using the Filter Inlet for Gases and Aerosols (FIGAERO)

Accounts of Chemical Research, Journal Year: 2020, Volume and Issue: 53(8), P. 1415 - 1426

Published: July 10, 2020

ConspectusThe complex array of sources and transformations organic carbonaceous material that comprises an important fraction atmospheric fine particle mass, known as aerosol, has presented a long running challenge for accurate predictions its abundance, distribution, sensitivity to anthropogenic activities. Uncertainties about changes in aerosol abundance over time translate uncertainties their impact on Earth's climate response air quality policy. One limitation our understanding been lack comprehensive measurements molecular composition volatility, which can elucidate processes affecting abundance. Herein we describe advances the development application Filter Inlet Gases Aerosols (FIGAERO) coupled field-deployable High-Resolution Time-of-Flight Chemical Ionization Mass Spectrometers (HRToF-CIMS). The FIGAERO HRToFCIMS combination broadly probes gas particulate OA by using programmed thermal desorption particles collected Teflon filter with subsequent detection speciation desorbed vapors inherently quantitative selected-ion chemical ionization. provides means obtain insights into volatility components thus physicochemical nature will govern evolution atmosphere.In this Account, discuss design operation FIGAERO, when HRToF-CIMS, characterization molecular-level effective laboratory field. We provide example gleaned from deployment, improve evolution. Specifically, connect profiles equilibrium saturation vapor concentration enthalpy vaporization detected components. also show how HRToF-CIMS environmental simulation chamber experiments field new constraints mechanisms governing secondary formation dynamic associated challenges decomposition during calibration both axis signal. illustrate additional through isothermal evaporation well ultrafine composition. conclude description future opportunities needs ability further science.

Language: Английский

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Chemical characterization of secondary organic aerosol at a rural site in the southeastern US: insights from simultaneous high-resolution time-of-flight aerosol mass spectrometer (HR-ToF-AMS) and FIGAERO chemical ionization mass spectrometer (CIMS) measurements

Atmospheric chemistry and physics, Journal Year: 2020, Volume and Issue: 20(14), P. 8421 - 8440

Published: July 17, 2020

Abstract. The formation and evolution of secondary organic aerosol (SOA) were investigated at Yorkville, GA, in late summer (mid-August to mid-October 2016). (OA) composition was measured using two online mass spectrometry instruments, the high-resolution time-of-flight spectrometer (AMS) Filter Inlet for Gases AEROsols coupled a iodide-adduct chemical ionization (FIGAERO-CIMS). Through analysis speciated organics data from FIGAERO-CIMS factorization obtained both we observed notable SOA isoprene monoterpenes during day night. Specifically, addition epoxydiol (IEPOX) uptake, identified non-IEPOX pathways nitrate via photooxidation presence NOx radical oxidation. Monoterpenes found be most important precursors We significant contributions highly oxidized acid-like compounds aged OA factor FIGAERO-CIMS. Taken together, our results showed that measurements are complementary extensively used AMS analysis, together they provide more comprehensive insights into sources composition.

Language: Английский

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Optical Properties of Secondary Organic Aerosol Produced by Nitrate Radical Oxidation of Biogenic Volatile Organic Compounds

Environmental Science & Technology, Journal Year: 2021, Volume and Issue: 55(5), P. 2878 - 2889

Published: Feb. 17, 2021

Nighttime oxidation of biogenic volatile organic compounds (BVOCs) by nitrate radicals (NO3·) represents one the most important interactions between anthropogenic and natural emissions, leading to substantial secondary aerosol (SOA) formation. The direct climatic effect such SOA cannot be quantified because its optical properties atmospheric fate are poorly understood. In this study, we generated from NO3· a series BVOCs including isoprene, monoterpenes, sesquiterpenes. were subjected comprehensive online offline chemical composition analysis using high-resolution mass spectrometry measurements novel broadband (315–650 nm) cavity-enhanced spectrometer, which covers wavelength range needed understand potential contribution radiative forcing. contained significant fraction oxygenated nitrates (ONs), consisting monomers oligomers that responsible for detected light absorption in 315–400 nm range. created β-pinene α-humulene was further photochemically aged an flow reactor. has photochemical bleaching lifetime >6.2 h, indicating some ONs may serve as atmosphere-stable nitrogen oxide sinks or reservoirs will absorb scatter incoming solar radiation during daytime.

Language: Английский

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Impact of NO<sub><i>x</i></sub> on secondary organic aerosol (SOA) formation from <i>α</i>-pinene and <i>β</i>-pinene photooxidation: the role of highly oxygenated organic nitrates

Atmospheric chemistry and physics, Journal Year: 2020, Volume and Issue: 20(17), P. 10125 - 10147

Published: Sept. 1, 2020

Abstract. The formation of organic nitrates (ONs) in the gas phase and their impact on mass secondary aerosol (SOA) was investigated a laboratory study for α-pinene β-pinene photooxidation. Focus elucidation those mechanisms that cause often observed suppression SOA by NOx, therein role highly oxygenated multifunctional molecules (HOMs). We with increasing NOx concentration (a) portion HOM (HOM-ONs) increased, (b) fraction accretion products (HOM-ACCs) decreased, (c) HOM-ACCs contained average smaller carbon numbers. Specifically, we (HOM-ONs), arising from termination reactions peroxy radicals permutation (HOM-PPs), such as ketones, alcohols, or hydroperoxides, formed other reactions. Effective uptake coefficients γeff HOMs particles were determined. more than six O atoms efficiently condensed (γeff>0.5 average), containing eight atoms, every collision led to loss. There no systematic difference HOM-ONs HOM-PPs same radicals. This similarity is attributed character HOMs: functional groups precursor radical are identical, vapor pressures should not strongly depend final group. As consequence, suppressing effect cannot be simply explained replacement terminal nitrate groups. According all will contribute bound (OrgNO3) particulate phase. However, OrgNO3 stored condensable molecular masses > 230 Da appeared substantially higher spectrometry. result suggests losses particles, probably due hydrolysis releases HNO3 into but leaves behind rest loss alone could explain particle β-pinene. Instead can attribute most reduction yields significant HOM-ACCs, which have high potentially important at low-NOx conditions.

Language: Английский

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Comprehensive isoprene and terpene gas-phase chemistry improves simulated surface ozone in the southeastern US

Atmospheric chemistry and physics, Journal Year: 2020, Volume and Issue: 20(6), P. 3739 - 3776

Published: March 30, 2020

Abstract. Ozone is a greenhouse gas and air pollutant that harmful to human health plants. During the summer in southeastern US, many regional global models are biased high for surface ozone compared observations. Past studies have suggested different solutions including need updates model representation of clouds, chemistry, deposition, emissions nitrogen oxides (NOx) or biogenic hydrocarbons. Here, due more comprehensive updated isoprene terpene chemistry added into CESM/CAM-chem (Community Earth System Model/Community Atmosphere Model with full chemistry) evaluate impact on simulated ozone. Comparisons results data collected during Studies Emissions Atmospheric Composition, Clouds Climate Coupling by Regional Surveys (SEAC4RS) field campaign from US EPA (Environmental Protection Agency) CASTNET (Clean Air Status Trends Network) monitoring stations confirm improves ozone, precursors, NOx reservoir compounds. The reduce bias daily maximum 8 h average (MDA8) up 7 ppb. In past, oxidation particular has been ignored heavily reduced chemical schemes used models, this study demonstrates needed biases. Sensitivity tests were performed order lingering uncertainties Results suggest even though higher than remaining similar impacts lower oxidation. Additionally, identifies further constraints aerosol uptake organic nitrates derived terpenes uncertainty Although greatly CAM-chem, large remains. Evaluation against SEAC4RS suggests future improvements horizontal resolution cloud parameterizations CAM-chem may be particularly important reducing bias.

Language: Английский

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Nontargeted Tandem Mass Spectrometry Analysis Reveals Diversity and Variability in Aerosol Functional Groups across Multiple Sites, Seasons, and Times of Day

Environmental Science & Technology Letters, Journal Year: 2020, Volume and Issue: 7(2), P. 60 - 69

Published: Jan. 13, 2020

Organic aerosol (OA) is a complex mixture of compounds with diverse elemental and structural features, its composition affects health environmental impacts. A detailed speciation the functional group distribution in OA important for constraining atmospheric reaction pathways products, evaluating chemical mechanisms models, understanding We used high-resolution tandem mass spectrometry to perform nontargeted analysis groups from three ambient sites across times day seasons. observed range oxygen-, nitrogen-, and/or sulfur-containing groups, including oxygenates such as hydroxyls (29–69%) carboxylic acids (19–59%), that dominated may participate hydrogen bonding thus impact physical properties (percentages indicate average ion abundance contributions campaigns). also esters (7–39%) ethers (13–42%) suggest importance oligomerization. On average, organonitrates represented only 12% identified nitrogen-containing organosulfates 21% while we many other nitrogen- structures were contributors (e.g., amines, imines, nitrophenols, sulfides). Most (81%) multifunctional likely multigenerational oxidation which typically contained two five total.

Language: Английский

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Evaluation of the chemical composition of gas- and particle-phase products of aromatic oxidation

Atmospheric chemistry and physics, Journal Year: 2020, Volume and Issue: 20(16), P. 9783 - 9803

Published: Aug. 21, 2020

Abstract. Aromatic volatile organic compounds (VOCs) are key anthropogenic pollutants emitted to the atmosphere and important for both ozone secondary aerosol (SOA) formation in urban areas. Recent studies have indicated that aromatic hydrocarbons may follow previously unknown oxidation chemistry pathways, including autoxidation can lead of highly oxidised products. In this study we evaluate gas- particle-phase ions measured by online mass spectrometry during hydroxyl radical substituted C9-aromatic isomers (1,3,5-trimethylbenzene, 1,2,4-trimethylbenzene, propylbenzene isopropylbenzene) a polyaromatic hydrocarbon (1-methylnaphthalene) under low- medium-NOx conditions. A time-of-flight chemical ionisation spectrometer (ToF-CIMS) with iodide–anion was used filter inlet gases aerosols (FIGAERO) detection products particle phase, while Vocus proton-transfer-reaction (Vocus-PTR-MS) gas phase. The signal product observed spectra were compared different precursors experimental majority spectral phases comes from which common all precursors, though distributions distinct VOCs. Gas- composition one another. Ions corresponding contained near-explicit phase Master Chemical Mechanism (MCM version 3.3.1) utilised as benchmark current scientific understanding, comparison these observations shows MCM is missing range its mechanism. bulk ring scission ions, large proportion more than reported undergone further form oxygenated molecules (HOMs). Under perturbation OH increased NOx, contribution HOM-ion signals remains elevated precursors. Up 43 % ring-retaining HOMs; most aromatics. Unique minor component systems, many dominant ion formulae concurrent other highlighting challenges utilising marker SOA.

Language: Английский

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Highly Oxygenated Organic Nitrates Formed from NO₃ Radical-Initiated Oxidation of β-Pinene

Environmental Science & Technology, Journal Year: 2021, Volume and Issue: 55(23), P. 15658 - 15671

Published: Nov. 22, 2021

The reactions of biogenic volatile organic compounds (BVOC) with the nitrate radicals (NO3) are major night-time sources nitrates and secondary aerosols (SOA) in regions influenced by BVOC anthropogenic emissions. In this study, formation gas-phase highly oxygenated molecules-organic (HOM-ON) from NO3-initiated oxidation a representative monoterpene, β-pinene, was investigated SAPHIR chamber (Simulation Atmosphere PHotochemistry large Reaction chamber). Six monomer (C = 7–10, N 1–2, O 6–16) five accretion product 17–20, 2–4, 9–22) families were identified further classified into first- or second-generation products based on their temporal behavior. time lag observed peak concentrations between peroxy containing odd even number oxygen atoms, as well corresponding termination products, provided constraints HOM-ON mechanism. can be explained unimolecular bimolecular radicals. A dominant portion carbonylnitrates detected, highlighting significance intramolecular H-shift for HOM-ON. mean molar yield estimated to 4.8% (−2.6%/+5.6%), suggesting significant contributions SOA formation.

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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