Isolating α-Pinene Ozonolysis Pathways Reveals New Insights into Peroxy Radical Chemistry and Secondary Organic Aerosol Formation

Environmental Science & Technology, Journal Year: 2021, Volume and Issue: 55(10), P. 6700 - 6709

Published: April 29, 2021

α-Pinene ozonolysis is a key process that impacts the formation of new particles and secondary organic aerosol (SOA) in atmosphere. The mechanistic understanding this chemistry has been inconclusive despite extensive research, hindering accurate simulations atmospheric processes. In work, we examine two synthesized unsaturated carbonyl isomers (C11H18O) which separately produce Criegee intermediates (CIs) would form simultaneously α-pinene ozonolysis. Direct gas-phase measurements peroxy radicals (RO2) from flowtube experiments by an iodide-adduct chemical ionization mass spectrometer suggest initial C10H15O4· RO2 CI with terminal methyl ketone undergo autoxidation 20-fold faster than aldehyde always outcompete bimolecular reactions under typical laboratory conditions. These results provide experimental constraints on detailed mechanisms for particle Further, isomer-resolved characterization SOA formed continuous-flow stirred tank reactor using ion mobility spectrometry suggests structurally different CIs predominantly unexpectedly constituents identical structures. open up possibilities diverse isomerization pathways may mutual products to large extent toward their way forming SOA. This work highlights insights into call future studies uncover mechanisms.

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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A combined gas- and particle-phase analysis of highly oxygenated organic molecules (HOMs) from α-pinene ozonolysis

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(6), P. 3707 - 3730

Published: March 28, 2023

Abstract. Highly oxygenated organic molecules (HOMs) are important for the formation of secondary aerosol (SOA), which poses serious health risks and exerts great influence on Earth's climate. However, speciation particle-phase HOMs its relationship with gas-phase HOM has been limited by lack suitable analytical techniques. Here, combining a novel particle evaporation inlet, VIA (Vaporization Inlet Aerosols), nitrate chemical ionization mass spectrometer (NO3-CIMS), gas- products α-pinene ozonolysis were studied under different conditions. Within 50 min residence time our Teflon chamber, we observed enhancement C16–C19 dimers in particles compared to that condensing. In particular, dimer was considerably suppressed experiments addition CO or NO, but still made up considerable fraction SOA. generally shorter carbon skeletons (i.e., C16–C19) gas phase (C19–C20), average O/C ratios (especially range) also decreased slightly phase. C17H26Oz compounds, have often reported previous offline measurements, dominate spectra experiments. Our results indicate these C17 compounds might be related processes within 1 h after condensation. new VIA–NO3-CIMS system used this work will require more detailed characterization better understand how thermal desorption wall effects may modify measured distributions. Nevertheless, nitrate, example, consistent measurements an Aerodyne (AMS), showing capability as promising technique measurements. Taken together, believe is combined online

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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Gas-to-Particle Partitioning of Cyclohexene- and α-Pinene-Derived Highly Oxygenated Dimers Evaluated Using COSMOtherm

The Journal of Physical Chemistry A, Journal Year: 2021, Volume and Issue: 125(17), P. 3726 - 3738

Published: April 22, 2021

Oxidized organic compounds are expected to contribute secondary aerosol (SOA) if they have sufficiently low volatilities. We estimated saturation vapor pressures and activity coefficients (at infinite dilution in water a model water-insoluble phase) of cyclohexene- α-pinene-derived accretion products, "dimers", using the COSMOtherm19 program. found that these two property estimates correlate with number hydrogen bond-donating functional groups oxygen atoms compound. In contrast, when H-bond donors is fixed, no clear differences seen either between group types (e.g., OH or OOH as donors) formation mechanisms gas-phase radical recombination vs liquid-phase closed-shell esterification). For cyclohexene-derived dimers studied here, predicts lower than SIMPOL.1 group-contribution method contrast previous COSMOtherm older parameterizations nonsystematic conformer sampling. The can be classified low, extremely ultra-low-volatility based on their mass concentrations. presence aqueous particles, all likely partition into particle phase thereby SOA formation.

Language: Английский

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Volatile-compound fingerprinting and discrimination of positional isomers in stamp-pad ink tracing using HS-GC-IMS combined with multivariate statistical analysis

Analytical and Bioanalytical Chemistry, Journal Year: 2024, Volume and Issue: 416(5), P. 1293 - 1305

Published: Jan. 8, 2024

Language: Английский

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Impact of HO₂∕RO₂ ratio on highly oxygenated α-pinene photooxidation products and secondary organic aerosol formation potential

Atmospheric chemistry and physics, Journal Year: 2024, Volume and Issue: 24(8), P. 4789 - 4807

Published: April 22, 2024

Abstract. Highly oxygenated molecules (HOMs) from the atmospheric oxidation of biogenic volatile organic compounds are important contributors to secondary aerosol (SOA). Organic peroxy radicals (RO2) and hydroperoxy (HO2) key species influencing HOM product distribution. In laboratory studies, experimental requirements often result in overemphasis on RO2 cross-reactions compared reactions with HO2. We analyzed photochemical formation HOMs α-pinene their potential contribute SOA under high (≈1/1) low (≈1/100) HO2/RO2 conditions. As > 1 is prevalent daytime atmosphere, sufficiently crucial mimic conditions prevent biases by distribution thus yield. Experiments were performed steady-state new, continuously stirred tank reactor SAPHIR-STAR at Forschungszentrum Jülich. The ratio was increased adding CO while keeping OH concentration constant. determined HOM's potential, considering its fraction remaining gas phase after seeding (NH4)2SO4 aerosol. An increase led a reduction main driver being ∼ 60 % HOM-accretion products. also observed shift HOM-monomer functionalization carbonyl hydroperoxide groups. 30 ≈1/1 ≈ 1/100. Particle-phase observations measured similar decrease mass Our study shows that too ratios atmosphere can lead an overestimation yields.

Language: Английский

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Insights into Calpain Activation and Rho-ROCK Signaling in Parkinson’s Disease and Aging

Biomedicines, Journal Year: 2024, Volume and Issue: 12(5), P. 1074 - 1074

Published: May 13, 2024

Parkinson’s disease (PD), a progressive neurodegenerative disease, has no cure, and current therapies are not effective at halting progression. The affects mid-brain dopaminergic neurons and, subsequently, the spinal cord, contributing to many debilitating symptoms associated with PD. GTP-binding protein, Rho, plays significant role in cellular pathology of downstream effector Rho-associated kinase (ROCK), multiple functions, including microglial activation induction inflammatory responses. Activated microglia have been implicated diseases, PD, that initiate responses, leading neuron death. Calpain expression activity is increased following glial activation, which triggers Rho-ROCK pathway induces T cell migration as well mediates toxic α-synuclein (α-syn) aggregation death, indicating pivotal for calpain degenerative processes Increased may represent new mechanism oxidative damage aging. This review will summarize stress α-syn aggregation, their influence on process PD aging, possible strategies research directions therapeutic intervention.

Language: Английский

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Molecular rearrangement of bicyclic peroxy radicals is a key route to aerosol from aromatics

Nature Communications, Journal Year: 2023, Volume and Issue: 14(1)

Published: Aug. 17, 2023

Abstract The oxidation of aromatics contributes significantly to the formation atmospheric aerosol. Using toluene as an example, we demonstrate existence a molecular rearrangement channel in mechanism. Based on both flow reactor experiments and quantum chemical calculations, show that bicyclic peroxy radicals (BPRs) formed OH-initiated aromatic are much less stable than previously thought, case derived ipso-BPRs, lead aerosol-forming low-volatility products with up 9 oxygen atoms sub-second timescales. Similar results predicted for ipso-BPRs from many other compounds. This reaction class is likely key route aerosol formation, including BPRs may be vital accurate modeling atmosphere.

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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