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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On the importance of multiphase photolysis of organic nitrates on their global atmospheric removal

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(10), P. 5851 - 5866

Published: May 26, 2023

Abstract. Organic nitrates (RONO2) are secondary compounds, and their fate is related to the transport removal of NOx in atmosphere. While previous research studies have focused on reactivity these molecules gas phase, condensed phases remains poorly explored despite ubiquitous presence submicron aerosols. This work investigated for first time aqueous-phase photolysis-rate constants quantum yields four RONO2 (isopropyl nitrate, isobutyl α-nitrooxyacetone, 1-nitrooxy-2-propanol). Our results showed much lower aqueous phase than phase. From alkyl polyfunctional RONO2, no significant increase was observed, even with conjugated carbonyl groups, contrast corresponding gas-phase photolysis reactions. Using new results, extrapolated other combination estimates atmospheric sinks (hydrolysis, photolysis, aqueous- ⚫OH oxidation, dry wet deposition), multiphase lifetimes were calculated 45 atmospherically relevant along relative importance each sink. Their range from a few minutes several hours depending chemical structure its water solubility. In general, lengthened when partition especially which can by up 100 %. Furthermore, our show that oxidation major sink water-soluble (KH>105 M atm−1) ranging 50 % 70 total at high liquid content (LWC) (0.35 g m−3). These highlight investigating understand how it affects ability air pollution.

Language: Английский

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Kinetics, products and mechanisms of unsaturated alcohols and NO3 radicals

Atmospheric Environment, Journal Year: 2024, Volume and Issue: 327, P. 120518 - 120518

Published: April 9, 2024

Language: Английский

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Effects of NO2 and SO2 on the secondary organic aerosol formation from β-pinene photooxidation

Journal of Environmental Sciences, Journal Year: 2022, Volume and Issue: 136, P. 151 - 160

Published: Nov. 1, 2022

Language: Английский

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Contrasting Influence of Nitrogen Oxides on the Cloud Condensation Nuclei Activity of Monoterpene‐Derived Secondary Organic Aerosol in Daytime and Nighttime Oxidation

Geophysical Research Letters, Journal Year: 2023, Volume and Issue: 50(4)

Published: Feb. 22, 2023

Abstract Anthropogenic nitrogen oxides may influence the cloud condensation nuclei (CCN) activity of biogenic secondary organic aerosols (SOA) in both daytime photooxidation and nighttime NO 3 oxidation, which has significant implications for climatic impact SOA. We investigated x on CCN monoterpene‐derived SOA OH oxidation oxidation. In had little hygroscopic parameter κ aerosol ( Org ), was attributed to minor fraction nitrates (ON) (<24%), resulted from low branching ratio RO 2 + form ON. contrast, much reduced compared OH/O due a dominant report MT‐derived ON formed photo‐oxidation (0.029–0.052) first time our knowledge, be used improve model simulations concentrations.

Language: Английский

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Continuous Measurement and Molecular Compositions of Atmospheric Water‐Soluble Brown Carbon in the Nearshore Marine Boundary Layer of Northern China: Secondary Formation and Influencing Factors

Journal of Geophysical Research Atmospheres, Journal Year: 2023, Volume and Issue: 128(12)

Published: June 12, 2023

Abstract Understanding the evolution of brown carbon (BrC) in atmosphere is essential for investigating its climate effects. This study deployed a novel in‐situ BrC continuous observation system to firstly measure water‐soluble absorption (Abs WS‐BrC ) an offshore island over Bohai Sea winter 2020. The Abs abundance before cold wave (BCW) was more than twice higher that after (ACW). mainly ascribed substantially suppressed formation secondary (WS‐BrC sec ). Diurnal patterns exhibited nighttime peaks, which derived from enhanced primary emissions and strong aqueous‐phase processes. Photochemical processes bleached daytime during BCW, while peaks emerged ACW due weakened photobleaching effect. Statistical analysis indicated ambient temperature relative humidity as well total oxidized nitrogen (NO 2 + NO 3 − reduced (NH 4 NH were dominant factors promoting . Moderate aerosol pH (>2.5) also facilitated no obvious dependences on gas‐particle partitioning ammonia, O , sulfur precursors found. At molecular level, chromophores with identified compositions, oxidation state, O/C, H/C, spectra compared between two periods. Characteristics CHO‐ CHON‐BrC origin contributed significantly ACW. highlights advantage high resolution measurement probing dynamic influencing factors.

Language: Английский

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Influence of anthropogenic emissions on the composition of highly oxygenated organic molecules in Helsinki: a street canyon and urban background station comparison

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(20), P. 12965 - 12983

Published: Oct. 16, 2023

Abstract. Condensable vapors, including highly oxygenated organic molecules (HOMs), govern secondary aerosol formation and thereby impact the quantity, composition, properties (e.g., toxicity) of particles. These vapors are mainly formed in atmosphere through oxidation volatile compounds (VOCs). Urban environments contain a variety VOCs from both anthropogenic biogenic sources, as well other species, for instance nitrogen oxides (NOx), that can greatly influence pathways condensable like HOMs. During last decade, our understanding HOM composition has increased dramatically, with most experiments performed forests or heavily polluted urban areas. However, studies on main sources aerosols (SOAs) biogenically influenced areas, such suburbs small cities, have been limited. Here, we studied measured two nitrate-based chemical ionization mass spectrometers analyzed using positive matrix factorization (PMF), during late spring at locations Helsinki, Finland. Comparing concentrations street canyon site nearby background station, found strong NOx stations, agreement previous conducted Even though stations dominated by VOCs, identified originated precursors. This implies Helsinki activities effect VOC oxidation. At groups (monoterpenes sesquiterpenes), while canyon, only precursor was monoterpenes. also observed products aliphatic which were not station. The factors clearly correlate (temporally composition-wise) between contained monoterpene-derived dimers. suggests mechanisms strongly dependent localized emissions oxidative environment these they change considerably within distances 1 km environment. further should be careful when extrapolating single-point measurements an setting to representative district city scales.

Language: Английский

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Technical note: Gas-phase nitrate radical generation via irradiation of aerated ceric ammonium nitrate mixtures

Atmospheric chemistry and physics, Journal Year: 2023, Volume and Issue: 23(21), P. 13869 - 13882

Published: Nov. 7, 2023

Abstract. We present a novel photolytic source of gas-phase NO3 suitable for use in atmospheric chemistry studies that has several advantages over traditional sources utilize NO2 + O3 reactions and/or thermal dissociation dinitrogen pentoxide (N2O5). The method generates via irradiation aerated aqueous solutions ceric ammonium nitrate (CAN, (NH4)2Ce(NO3)6) and nitric acid (HNO3) or sodium (NaNO3). experimental model characterization the formation potential irradiated CAN / HNO3 NaNO3 mixtures containing [CAN] = 10−3 to 1.0 M, [HNO3] 6.0 [NaNO3] 4.8 photon fluxes (I) ranging from 6.9 × 1014 1016 photons cm−2 s−1, wavelengths 254 421 nm. mixing ratios parts per billion million by volume were achieved using this method. At solubility limit, maximum [NO3] was ≈ 3.0 M UVA radiation (λmax⁡ 369 nm) ≥ UVC mixtures. Other reactive nitrogen (NO2, N2O4, N2O5, N2O6, HNO2, HNO3, HNO4) oxygen (HO2, H2O2) species obtained measured NOx analyzer an iodide-adduct high-resolution time-of-flight chemical ionization mass spectrometer (HR-ToF-CIMS). To assess applicability NO3-initiated oxidative aging processes, we generated composition oxygenated volatile organic compounds (OVOCs) secondary aerosol (SOA) β-pinene reaction Filter Inlet Gases AEROsols (FIGAERO) coupled HR-ToF-CIMS.

Language: Английский

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Nitrate Radicals Suppress Biogenic New Particle Formation from Monoterpene Oxidation

Environmental Science & Technology, Journal Year: 2024, Volume and Issue: 58(3), P. 1601 - 1614

Published: Jan. 8, 2024

Highly oxygenated organic molecules (HOMs) are a major source of new particles that affect the Earth's climate. HOM production from oxidation volatile compounds (VOCs) occurs during both day and night can lead to particle formation (NPF). However, NPF involving vapors has been reported much more often daytime than nighttime. Here, we show nitrate radicals (NO3), which arise predominantly at night, inhibit monoterpenes based on three lines observational evidence: experiments in CLOUD (Cosmics Leaving OUtdoor Droplets) chamber CERN (European Organization for Nuclear Research), radical chemistry using an flow reactor, field observations wetland occasionally exhibits nocturnal NPF. Nitrooxy-peroxy formed NO3 suppress ultralow-volatility (ULVOCs) responsible biogenic NPF, covalently bound peroxy (RO2) dimer association products. The ULVOC yield α-pinene presence is one-fifth resulting ozone alone. Even trace amounts radicals, sub-parts per trillion level, rate by factor 4. Ambient further confirm when involved, monoterpene completely turned off. Our results explain frequent absence (α-pinene)-rich environments.

Language: Английский

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Resolving Atmospheric Oxygenated Organic Molecules in Urban Beijing Using Online Ultrahigh-Resolution Chemical Ionization Mass Spectrometry

Environmental Science & Technology, Journal Year: 2024, Volume and Issue: unknown

Published: Sept. 27, 2024

Gaseous oxygenated organic molecules (OOMs) are crucial precursors of atmospheric aerosols. OOMs in urban atmospheres have complex compositions, posing challenges to understanding their formation, evolution, and influences. In this study, we identify 2403 gaseous Beijing using online nitrate-based chemical ionization Orbitrap mass spectrometry based on one-year measurements. We find that can be identified with higher accuracy wider coverage, compared previously used spectrometry. With optimized OOM resolving capabilities, previous knowledge expanded. First, clear homologous oxygen-addition characteristics the revealed. Second, lower concentrations or masses characterized high confidence, e.g., above 350 Da. particular, dimers (e.g., C

Language: Английский

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