Secondary Organic Aerosol Mass Yields from NO₃ Oxidation of α-Pinene and Δ-Carene: Effect of RO₂ Radical Fate

The Journal of Physical Chemistry A, Journal Year: 2022, Volume and Issue: 126(40), P. 7309 - 7330

Published: Sept. 28, 2022

Dark chamber experiments were conducted to study the SOA formed from oxidation of α-pinene and Δ-carene under different peroxy radical (RO2) fate regimes: RO2 + NO3, RO2, HO2. mass yields <1 ∼25% strongly dependent on available OA up ∼100 μg m-3. The strong yield dependence is driven by absorptive partitioning not surface area for condensation. Yields NO3 consistently higher, ranging ∼10-50% with some <25 Explicit kinetic modeling including vapor wall losses was enable comparisons across VOC precursors regimes determine atmospherically relevant yields. Furthermore, similar each monoterpene nominal or HO2 regimes; thus, volatility basis sets (VBS) constructed independent chemical regime. Elemental O/C ratios ∼0.4-0.6 nitrate/organic ∼0.15 observed in particle phase both monoterpenes all regimes, using aerosol spectrometer (AMS) measurements. An empirical relationship estimating density AMS-derived elemental ratios, previously reported literature non-nitrate containing OA, successfully adapted organic nitrate-rich SOA. Observations an NO3- ionization (NO3-CIMS) suggest that more readily forms low-volatility gas-phase highly oxygenated molecules (HOMs) than α-pinene, which primarily volatile semivolatile species, when reacted regardless high presence HOMs, unimolecular multistep processes such as alkoxy isomerization decomposition may play a role formation NO3. scarcity peroxide functional groups (on average, 14% C10 carried group one test experiment regime) appears rule out major autoxidation (ROOH, ROOR) formation. substantially lower pathways are less this precursor. marked robust regime-independent difference two precursor suggests order accurately model production forested regions mechanism must feature distinction among monoterpenes.

Language: Английский

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Temperature-Dependent Composition of Summertime PM_2.5 in Observations and Model Predictions across the Eastern U.S.

ACS Earth and Space Chemistry, Journal Year: 2024, Volume and Issue: 8(2), P. 381 - 392

Published: Feb. 5, 2024

Throughout the U.S., summertime fine particulate matter (PM2.5) exhibits a strong temperature (T) dependence. Reducing PM2.5 enhancement with T could reduce public health burden of now and in warmer future. Atmospheric models are critical tool for probing processes components driving observed behaviors. In this work, we describe how modeled aerosol abundance composition vary present-day Eastern specific attention to two major components: sulfate (SO42–) organic carbon (OC). Observations U.S. show an average measured PM2.5-T sensitivity 0.67 μg/m3/K, CMAQv5.4 regional model predictions closely matching value. Observed SO42– OC also increase T; however, has component-specific discrepancies observations. Specifically, underestimates concentrations their while overestimating T. Here, explore series interventions aimed at correcting these deviations. We conclude that relationship is driven by inorganic systems highly coupled, it possible design simultaneously address biases component as well responses

Language: Английский

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Unexpected significance of a minor reaction pathway in daytime formation of biogenic highly oxygenated organic compounds

Science Advances, Journal Year: 2022, Volume and Issue: 8(42)

Published: Oct. 21, 2022

Secondary organic aerosol (SOA), formed by oxidation of volatile compounds, substantially influence air quality and climate. Highly oxygenated molecules (HOMs), particularly those from biogenic monoterpenes, contribute a large fraction SOA. During daytime, hydroxyl radicals initiate monoterpene oxidation, mainly addition to double bonds. Naturally, related HOM formation mechanisms should be induced that reaction route, too. However, for α-pinene, the most abundant atmospheric monoterpene, we find previously unidentified competitive pathway under atmospherically relevant conditions: is predominately via hydrogen abstraction radicals, generally minor pathway. We show observations theoretical calculations followed rearrangement alkoxy prerequisite fast daytime formation. Our analysis provides an accurate mechanism yield, demonstrating pathways can become major, here SOA growth impacts on

Language: Английский

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Identification of highly oxygenated organic molecules and their role in aerosol formation in the reaction of limonene with nitrate radical

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(17), P. 11323 - 11346

Published: Sept. 2, 2022

Abstract. Nighttime NO3-initiated oxidation of biogenic volatile organic compounds (BVOCs) such as monoterpenes is important for the atmospheric formation and growth secondary aerosol (SOA), which has significant impact on climate, air quality, human health. In SOA growth, highly oxygenated molecules (HOM) may be crucial, but their pathways role in have yet to clarified. Among monoterpenes, limonene particular interest its high emission globally yield. this work, HOM reaction with nitrate radical (NO3) was investigated SAPHIR chamber (Simulation Atmospheric PHotochemistry a large Reaction chamber). About 280 products were identified, grouped into 19 monomer families, 11 dimer 3 trimer families. Both closed-shell open-shell peroxy radicals (RO2⚫) observed, many them not been reported previously. Monomers dimers accounted 47 % concentrations, respectively, trimers making up remaining 6 %. most abundant C10H15−17NO6−14, carbonyl outnumbered hydroxyl products, indicating importance RO2⚫ termination by unimolecular dissociation. autoxidation alkoxy–peroxy found processes leading HOM. Time-dependent concentration profiles containing nitrogen showed mainly second-generation patterns. Dimers likely formed via accretion two RO2⚫, HOM-trimers between RO2⚫. Trimers are suggested play an new particle (NPF) observed our experiment. A yield 1.5%-0.7%+1.7% estimated considering only first-generation products. mass could reasonably explained condensation particles assuming irreversible uptake ultra-low volatility (ULVOCs), extremely low (ELVOCs), (LVOCs). This work provides evidence +NO3 NPF particles.

Language: Английский

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The important contribution of secondary formation and biomass burning to oxidized organic nitrogen (OON) in a polluted urban area: insights from in situ measurements of a chemical ionization mass spectrometer (CIMS)

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(15), P. 8855 - 8877

Published: Aug. 9, 2023

Abstract. To investigate the sources and formation mechanism of oxidized organic nitrogen (OON), field measurements OON were conducted using an iodide-adduct chemical ionization mass spectrometer equipped with a Filter Inlet for Gases AEROsols (FIGAERO-CIMS) during fall 2018 in megacity Guangzhou, China. Using levoglucosan as tracer biomass burning emissions, results show that (49±23 %) secondary (51±23 accounted comparable fractions to total particle-phase (pOON) but 24±25 % 76±25 gas-phase (gOON), respectively, signifying important contribution pOON gOON this urban area. Calculations production rates indicated hydroxyl radical (42 nitrate (NO3) (49 oxidation pathways potentially dominated gOON. A high concentration NO3 radicals afternoon was observed, demonstrating daytime might be more than previous recognition. Monoterpenes, found major precursors gOON, mainly from anthropogenic emissions The ratio Ox ([Ox] = [O3] + [NO2]) increased function relative humidity aerosol surface area, indicating heterogeneous reaction pathway pOON. Finally, highly 6 11 oxygen atoms highlighting complex processes ambient air. Overall, our improve understanding dynamic variation atmosphere.

Language: Английский

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Formation of highly oxygenated organic molecules from the oxidation of limonene by OH radical: significant contribution of H-abstraction pathway

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(13), P. 7297 - 7319

Published: July 4, 2023

Abstract. Highly oxygenated organic molecules (HOMs) play a pivotal role in the formation of secondary aerosol (SOA). Therefore, distribution and yields HOMs are fundamental to understand their fate chemical evolution atmosphere, it is conducive ultimately assess impact SOA on air quality climate change. In this study, gas-phase formed from reaction limonene with OH radicals photooxidation were investigated SAPHIR (Simulation Atmospheric PHotochemistry large Reaction chamber), using time-of-flight ionization mass spectrometer nitrate reagent ion (NO3--CIMS). A number HOMs, including monomers (C9–10) dimers (C17–20), detected classified into various families. Both closed-shell products open-shell peroxy (RO2) identified under low NO (0.06–0.1 ppb) high conditions (17 ppb). C10 most abundant HOM account for over 80 % total HOMs. Closed-shell two radical family, C10H15Ox⚫ (x=6–15) C10H17Ox⚫ (x=6–15), respective termination reactions NO, RO2, HO2. While likely by addition C10H16, dominant initial step plus OH, C10H15Ox⚫, via H abstraction OH. related contributed 41 42 at demonstrating that H-abstraction pathways significant Combining theoretical kinetic calculations, structure–activity relationships (SARs), data literature, observed RO2 intensities, we proposed tentative mechanisms both pathways. We further estimated molar be 1.97-1.06+2.52 0.29-0.16+0.38 respectively. Our study highlights importance provides yield oxidation simulate formation.

Language: Английский

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Chemical ionization mass spectrometry: Developments and applications for on-line characterization of atmospheric aerosols and trace gases

TrAC Trends in Analytical Chemistry, Journal Year: 2023, Volume and Issue: 168, P. 117353 - 117353

Published: Oct. 11, 2023

Language: Английский

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Impact of fossil and non-fossil fuel sources on the molecular compositions of water-soluble humic-like substances in PM_2.5 at a suburban site of Yangtze River Delta, China

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(14), P. 8305 - 8324

Published: July 25, 2023

Abstract. Atmospheric humic-like substances (HULIS) affect the global radiation balance due to their strong light absorption at ultraviolet wavelength. The potential sources and molecular compositions of water-soluble HULIS a suburban site in Yangtze River Delta from 2017 2018 were discussed, based on results radiocarbon (14C) analysis combining Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) technique this study. 14C showed that averaged non-fossil-fuel source contributions 39 ± 8 % 36 6 summer winter, respectively, indicating significant fossil fuel HULIS. Van Krevelen diagrams obtained FT-ICR-MS proportions tannin-like carbohydrate-like groups higher summer, suggesting contribution biogenic secondary organic aerosols (SOAs). condensed aromatic structures winter suggested increasing anthropogenic emissions. Molecular composition CHO, CHON, CHOS, CHONS subgroups relatively intensities high O-containing macromolecular oligomers CHO compounds further stronger SOA formation summer. High-intensity phenolic flavonoids, which related biomass burning polycyclic hydrocarbon (PAH) derivatives combustion emissions, found compounds. Besides, two high-intensity containing ring (C9H6O7 C10H5O8) identified samples similar those off-road engine samples, traffic emissions one important study site. CHON mainly composed nitro or organonitrates with significantly associated addition enhanced NOx winter. However, formulas referring N-heterocyclic compounds, produced atmospheric processes involving reduced N species (e.g., ammonium). S-containing organosulfates (OSs) derived precursors, namely long-chain alkane hydrocarbon, illustrate mixed Generally, different policies need be considered for each season seasonal (i.e., sources, both seasons, additional coal winter). Measures control motor vehicles industrial Additional measures power plants should applied These findings add our understanding interaction between

Language: Английский

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Large differences of highly oxygenated organic molecules (HOMs) and low-volatile species in secondary organic aerosols (SOAs) formed from ozonolysis of β-pinene and limonene

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(14), P. 8383 - 8402

Published: July 26, 2023

Abstract. Secondary organic aerosols (SOAs) play a key role in climate change and public health. However, the oxidation state volatility of SOAs are still not well understood. Here, we investigated highly oxygenated molecules (HOMs) formed from ozonolysis β-pinene limonene. Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) was used to characterize HOMs aerosol filter samples, scanning mobility particle sizer (SMPS) measure concentration size distribution SOA particles. The relative abundance (i.e., ratio summed peak intensity totally identified compounds) limonene 14 %–20 %, higher than (3 %–13 %), exhibiting different trends with increasing ozone concentrations. oxidation-derived exhibit yield at high concentration, accompanied by substantial formation ultra-low-volatile compounds (ULVOCs). Limonene moderate concentrations, semi-, low-, extremely low-volatile (SVOCs, LOVCs, ELVOCs) major role. Combined experimental evidence theoretical analysis indicate that oxygen-increasing-based peroxy radical chemistry is plausible mechanism for 10 carbon atoms. Our findings show species largely different. concentration-driven evolution monoterpenes suggested be considered future or exposure risk models, which may enable more accurate air quality prediction management.

Language: Английский

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Nighttime reactions of a series of unsaturated alcohols with NO3•: Kinetics, products and mechanisms study

Journal of Environmental Sciences, Journal Year: 2024, Volume and Issue: 151, P. 331 - 346

Published: April 6, 2024

Language: Английский

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