Secondary organic aerosol formed by condensing anthropogenic vapours over China’s megacities

Nature Geoscience, Journal Year: 2022, Volume and Issue: 15(4), P. 255 - 261

Published: April 1, 2022

Language: Английский

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Chemical characterization of oxygenated organic compounds in the gas phase and particle phase using iodide CIMS with FIGAERO in urban air

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(11), P. 8455 - 8478

Published: June 3, 2021

Abstract. The atmospheric processes under polluted environments involving interactions of anthropogenic pollutants and natural emissions lead to the formation various complex secondary products. Therefore, characterization oxygenated organic compounds in urban areas remains a pivotal issue our understanding evolution carbon. Here, we describe measurements an iodide chemical ionization time-of-flight mass spectrometer installed with Filter Inlet for Gases AEROsols (FIGAERO-I-CIMS) both gas phase particle at site Guangzhou, typical megacity southern China, during autumn 2018. Abundant containing two five oxygen atoms were observed, including acids, multi-functional typically emitted from biomass burning, oxidation products biogenic hydrocarbons aromatics. Photochemistry played dominant roles gaseous acids isoprene-derived nitrates, while nighttime chemistry contributed significantly monoterpene-derived nitrates inorganics. Nitrogen-containing occupied significant fraction total signal phases, elevated fractions higher molecular weights. Measurements by FIGAERO-I-CIMS explained 24 ± 0.8 % aerosol measured (AMS), increased more aged aerosol. systematical interpretation spectra area Guangzhou provides holistic view numerous atmosphere, which can serve as reference future field regions.

Language: Английский

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Oxidation Flow Reactor Results in a Chinese Megacity Emphasize the Important Contribution of S/IVOCs to Ambient SOA Formation

Environmental Science & Technology, Journal Year: 2021, Volume and Issue: 56(11), P. 6880 - 6893

Published: Dec. 13, 2021

Oxygenated volatile organic compounds (OVOCs) and secondary aerosol (SOA) formation potential of ambient air in Guangzhou, China was investigated using a field-deployed oxidation flow reactor (OFR). The OFR used to mimic hours weeks atmospheric exposure hydroxyl (OH) radicals within the 2–3 min residence time. A comprehensive investigation on variation VOCs OVOCs as function OH is shown. Substantial acids nitrogen-containing OVOC species were observed. Maximum SOA observed following 1–4 equiv days' exposure. produced from known/measured VOC/IVOC precursors such single-ring aromatics long-chain alkanes can account for 52–75% measured under low NOx 26–60% high conditions based laboratory yield parametrizations. To our knowledge, this first time that contribution (8–20%) (C8–C20) alkane quantified direct measurement. By additionally estimating unmeasured semivolatile intermediate volatility (S/IVOCs) are committed with C8–C20 alkanes, 64–100% be explained, signifying important S/IVOCs large cyclic SOA.

Language: Английский

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Atmospheric organic vapors in two European pine forests measured by a Vocus PTR-TOF: insights into monoterpene and sesquiterpene oxidation processes

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(5), P. 4123 - 4147

Published: March 18, 2021

Abstract. Atmospheric organic vapors play essential roles in the formation of secondary aerosol. Source identification these is thus fundamental to understanding their emission sources and chemical evolution atmosphere further impact on air quality climate change. In this study, a Vocus proton-transfer-reaction time-of-flight mass spectrometer (PTR-TOF) was deployed two forested environments, Landes forest southern France boreal Finland, measure atmospheric vapors, including both volatile compounds (VOCs) oxidation products. For first time, we performed binned positive matrix factorization (binPMF) analysis complex spectra acquired with PTR-TOF identified various as well processes atmosphere. Based separate low- high-mass ranges, 15 PMF factors nine Finnish were resolved, showing high similarity between sites. Particularly, terpenes terpene reaction products separated into individual varying degrees, such lightly oxidized from monoterpene sesquiterpene oxidation, monoterpene-derived nitrates, more compounds. Factors representing monoterpenes dominated biogenic VOCs forests, lower contributions isoprene factors. products, nitrates monoterpenes/sesquiterpenes accounted for 8 %–12 % measured gas-phase forests. interpretation results relating processes, insights gained regarding reactions. example, strong relative humidity (RH) dependence found behavior High concentrations only occur at RH; yet similar not observed

Language: Английский

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In-situ synthesis of Z-Scheme MIL-100(Fe)/α-Fe2O3 heterojunction for enhanced adsorption and Visible-light photocatalytic oxidation of O-xylene

Chemical Engineering Journal, Journal Year: 2021, Volume and Issue: 416, P. 129112 - 129112

Published: Feb. 25, 2021

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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Formation of condensable organic vapors from anthropogenic and biogenic volatile organic compounds (VOCs) is strongly perturbed by NO<sub><i>x</i></sub> in eastern China

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(19), P. 14789 - 14814

Published: Oct. 6, 2021

Abstract. Oxygenated organic molecules (OOMs) are the crucial intermediates linking volatile compounds (VOCs) to secondary aerosols (SOAs) in atmosphere, but comprehensive understanding of characteristics OOMs and their formation from VOCs is still missing. Ambient observations using recently developed mass spectrometry techniques limited, especially polluted urban atmospheres where oxidants extremely variable complex. Here, we investigate OOMs, measured by a nitrate-ion-based chemical ionization spectrometer at Nanjing eastern China, through performing positive matrix factorization on binned spectra (binPMF). The binPMF analysis reveals three factors about anthropogenic VOC (AVOC) daytime chemistry, isoprene-related factors, biogenic (BVOC) nighttime nitrated phenols. All influenced NOx different ways extents. Over 1000 non-nitro have been identified then reconstructed selected solution binPMF, 72 % total signals contributed nitrogen-containing mostly regarded as nitrates formed peroxy radicals terminated nitric oxide or nitrate-radical-initiated oxidations. Moreover, multi-nitrates account for 24 signals, indicating significant presence multiple generations, isoprene (e.g., C5H10O8N2 C5H9O10N3). Additionally, distribution OOM concentration carbon number confirms precursors driven AVOCs mixed with enhanced BVOCs during summer. Our results highlight decisive role densely populated areas, encourage more studies dramatic interactions between emissions.

Language: Английский

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Composition of Ultrafine Particles in Urban Beijing: Measurement Using a Thermal Desorption Chemical Ionization Mass Spectrometer

Environmental Science & Technology, Journal Year: 2021, Volume and Issue: 55(5), P. 2859 - 2868

Published: Feb. 12, 2021

Ultrafine particles (UFPs) dominate the particle number population in urban atmosphere and revealing their chemical composition is important. The thermal desorption ionization mass spectrometer (TDCIMS) can semicontinuously measure UFP at molecular level. We modified a TDCIMS deployed it Beijing. Radioactive materials for aerosol charging were replaced by soft X-ray ionizers so that be operated countries with tight regulations on radioactive materials. Protonated N-methyl-2-pyrrolidone ions used as positive reagent ion, which selectively detects ammonia low-molecular weight-aliphatic amines amides vaporized from phase. With superoxide negative wide range of inorganic organic compounds observed, including nitrate, sulfate, aliphatic acids carbon numbers up to 18, highly oxygenated CHO, CHON, CHOS compounds. latter two attributed parent or decomposition products organonitrates organosulfates/organosulfonates, respectively. Components both primary emissions secondary formation UFPs identified. Compared measured forest marine sites, those Beijing contain more nitrogen-containing sulfur-containing These observations illustrate unique features environment provide insights into origins.

Language: Английский

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Quantification of solid fuel combustion and aqueous chemistry contributions to secondary organic aerosol during wintertime haze events in Beijing

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(12), P. 9859 - 9886

Published: July 1, 2021

Abstract. In recent years, intense haze events in megacities such as Beijing have received significant attention. Although secondary organic aerosol (SOA) has been identified a major contributor to events, knowledge of its sources and formation mechanisms remains uncertain. We investigate this question through the first field deployment extractive electrospray ionisation time-of-flight mass spectrometer (EESI-TOF) Beijing, together with an Aerodyne long-time-of-flight (L-TOF AMS). Measurements were performed during autumn winter 2017, capturing transition from non-heating heating seasons. Source apportionment resolved four factors related primary aerosols (traffic, cooking, biomass burning, coal combustion), well SOA. Of SOA factors, two solid fuel combustion (SFC), one generated aqueous chemistry, mixed/indeterminate sources. The SFC spectral signatures corresponding aromatic oxidation products, while factor was characterised by small acids diacids unusually low CO+/CO2+ fragment ratios measured AMS. Solid dominant source season. However, comparably event also observed season dominated factor. During event, chemistry promoted combination high relative humidity air masses passing over high-NOx regions south east leading particulate nitrate. resulting liquid water content highly correlated concentration These results highlight strong compositional variability between different indicating need consider multiple pathways precursor describe Beijing.

Language: Английский

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Chemical characterisation of benzene oxidation products under high- and low-NO<sub><i>x</i></sub> conditions using chemical ionisation mass spectrometry

Atmospheric chemistry and physics, Journal Year: 2021, Volume and Issue: 21(5), P. 3473 - 3490

Published: March 5, 2021

Abstract. Aromatic hydrocarbons are a class of volatile organic compounds associated with anthropogenic activity and make up significant fraction urban compound (VOC) emissions that contribute to the formation secondary aerosol (SOA). Benzene is one most abundant species emitted from vehicles, biomass burning industry. An iodide time-of-flight chemical ionisation mass spectrometer (ToF-CIMS) nitrate ToF-CIMS were deployed at Jülich Plant Atmosphere Chamber as part series experiments examining benzene oxidation by OH under high- low-NOx conditions, where range products detected. The scheme detects many high masses, ranging intermediate (IVOCs) extremely low (ELVOCs), including C12 dimers. In comparison, very few C≥6 O≥8 detected scheme, which more IVOCs semi-volatile (SVOCs) but ELVOCs (LVOCs). A total 132 195 CHO CHON in low- high-NOx respectively. Ring-breaking dominant signal 21 26 listed Master Chemical Mechanism (MCM) time highly oxidised (O≥6) ring-retaining (C6 double-bond equivalent = 4) equilibrate quickly, characterised square form profile, compared MCM ring-breaking increase throughout oxidation, exhibiting sawtooth profiles. Under all formulae attributed radical termination reactions first-generation products, auto-oxidation observed. Several N-containing either or also observed conditions. Hierarchical cluster analysis finds four clusters, two describe photo-oxidation. Cluster 2 shows negative dependency on NO2/NOx ratio, indicating it sensitive NO concentration thus likely contain addition alkoxy-derived products. This has highest average carbon state (OSC‾) lowest number. Where nitrogen present member 2, oxygen number even, expected for contrast, 1 no ratio so NO2 peroxy-derived contains fewer fragmented species, higher OSC‾ lower than an odd atoms. suggests clustering have features pertaining distinct regimes, example, perturbations, coupled priori knowledge, can provide insight into identification potential functionality.

Language: Английский

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