Evolution of the light-absorption properties of combustion brown carbon aerosols following reaction with nitrate radicals

Aerosol Science and Technology, Год журнала: 2020, Номер 54(7), С. 849 - 863

Опубликована: Фев. 7, 2020

Polycyclic aromatic hydrocarbons (PAHs) are important constituents of brown carbon (BrC) that subject to atmospheric processing by gas-phase oxidants such as the hydroxyl radical (OH) and nitrate (NO3). While OH oxidation BrC has been investigated extensively, studies NO3 limited. Here, we generated from combustion toluene containing a complex mixture light-absorbing PAHs changes in their chemical composition light-absorption properties following exposure an flow reactor. Three types were studied, with varying classified terms imaginary part refractive index (k) as: light (k at 532 nm, k532 = 0.008), medium (k532 0.026), dark 0.091). Exposure led ∼30% increase ∼5% decrease BrC. This discrepancy is attributed two competing effects: 1) addition chromophoric functional groups NO3-induced heterogeneous 2) condensation PAH + products less-absorbing than particulate PAHs. Analysis aerosol evolution revealed effect (2) was more experiments. We performed optical calculations isolate (1) showed ∼50% for all types. These results indicate darkens some BrC, which can counterbalance bleaching effects induced oxidation.Copyright © 2020 American Association Aerosol Research

Язык: Английский

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Determining the Sources and Transport of Brown Carbon Using Radionuclide Tracers and Modeling

Journal of Geophysical Research Atmospheres, Год журнала: 2021, Номер 126(9)

Опубликована: Май 3, 2021

Abstract The isotope tracer technique plays a key role in identifying the sources and atmospheric processes affecting pollution. of brown carbon (BrC) at Guangzhou during 2017–2018 were characterized by positive matrix factorization with radiocarbon constraints multiple linear regression analysis. primary emission factors fossil fuel combustion (FF) biomass burning (BB) accounted for 34% 27% dissolved BrC absorption λ = 365 nm (Abs ), respectively. total mean light contributed secondary was 39%. FF‐origin Abs changed insignificantly throughout year dominant summer monsoon period, whereas from BB nitrate formation increased larger fractions winter period. Transported estimated using an index 7 Be/( Be + n 210 Pb). Higher values generally accompanied lower , associated higher indicating that aerosols transported upper‐atmosphere is than near surface. Based on correlations between Pb non‐fossil organic we contribution invasive (include ground level) to period elevated ∼50%. likely related processes. This study supports radionuclides as novel method characterizing transport can be applied future research.

Язык: Английский

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Secondary Formation of Aerosols Under Typical High‐Humidity Conditions in Wintertime Sichuan Basin, China: A Contrast to the North China Plain

Journal of Geophysical Research Atmospheres, Год журнала: 2021, Номер 126(10)

Опубликована: Май 21, 2021

Abstract The Sichuan Basin is one of the regions suffering from severe haze pollution in southwest China. However, secondary aerosol formation this region poorly understood. In study, chemical compositions PM 2.5 and molecular water‐soluble organics wintertime were measured to investigate sources under typical high relative humidity (RH) conditions. Strong correlations between , carbonaceous aerosols K + suggested influence biomass burning. impacts burning also supported by dominance primarily emitted reduced/less oxidized nitrogen‐containing as well peak intensities secondarily formed nitrocatechols methyl‐nitrocatechols. High (average RH = 80%) liquid water (ALW) facilitated sulfate, nitrate, organic (SOA). average sulfate oxidation ratio nitrogen 3.1 times those winter Beijing 27%). This higher potentials SO 2 NO x form nitrate high‐RH abundant aqueous‐SOA was organosulfates (OSs) nitrooxy‐OSs mass spectra organics, while OSs quite limited. more OS attributed much RH, ALW, acidity, which favored acidic sulfate‐catalyzed aqueous‐phase reactions for formation. Higher concentrations biogenic volatile compounds additional reasons than Beijing.

Язык: Английский

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Mixing state of black carbon at different atmospheres in north and southwest China

Atmospheric chemistry and physics, Год журнала: 2022, Номер 22(16), С. 10861 - 10873

Опубликована: Авг. 26, 2022

Abstract. Large uncertainties remain when estimating the radiative forcing by black carbon (BC) because corresponding microphysical properties have not been well addressed. In this study, BC size distributions were studied based on three different field campaigns at an urban site, a suburban and background site in China using single particle soot photometer (SP2) tandem with differential mobility diameter. Measurement results indicate that particles composed of either thinly or thickly coated aerosols. The mean number fractions aerosols 51 %, 67 21 % for urban, suburban, sites, respectively. (thinly coated) core mass median diameters 187 (154), 182 (146), 238 (163) nm, diameter BC-containing was larger than aerosols, while smaller About 10 are attached to other non-BC components, which mainly generated coagulation between components. measurement our study can be further used modeling studies help constraining effects.

Язык: Английский

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Molecular characterization of nitrogen-containing organic compounds in the winter North China Plain

The Science of The Total Environment, Год журнала: 2022, Номер 838, С. 156189 - 156189

Опубликована: Май 23, 2022

Язык: Английский

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Measurement report: Changes in light absorption and molecular composition of water-soluble humic-like substances during a winter haze bloom-decay process in Guangzhou, China

Atmospheric chemistry and physics, Год журнала: 2023, Номер 23(2), С. 963 - 979

Опубликована: Янв. 20, 2023

Abstract. Water-soluble humic-like substances (HULIS) absorb light in near-UV and visible wavelengths exert significant influence on the atmospheric environment climate. However, knowledge HULIS evolution during haze bloom-decay process is limited. Herein, PM2.5 samples were obtained a winter event Guangzhou, China, absorption molecular composition of investigated by UV–Vis spectrophotometry ultrahigh-resolution mass spectrometry. Compared with clean days, coefficients (Abs365) days significantly higher but efficiencies (MAE365) relatively low, suggesting diverse dynamic properties episodes. The CHO CHON compounds most abundant components HULIS, followed CHOS, CHONS, CHN. Haze presented comparatively high weight; lower aromaticity index (AImod); O/Cw, O/Nw, O/Sw ratios, indicating that fractions undergo oxidation compared to days. Moreover, AImod major potential chromophores contributed absorption. It worth noting proportions these decreased events, mainly owing their Besides, accumulated contribution organic emitted from vehicles formed reactions biogenic volatile (bio-VOCs) also diluted light-absorbing HULIS. These findings help us understand processes subtropic region China.

Язык: 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, Год журнала: 2023, Номер 23(15), С. 8855 - 8877

Опубликована: Авг. 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.

Язык: Английский

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Enhancing characterization of organic nitrogen components in aerosols and droplets using high-resolution aerosol mass spectrometry

Atmospheric measurement techniques, Год журнала: 2024, Номер 17(2), С. 423 - 439

Опубликована: Янв. 22, 2024

Abstract. This study aims to enhance the understanding and application of Aerodyne high-resolution aerosol mass spectrometer (HR-AMS) for comprehensive characterization organic nitrogen (ON) compounds in particles atmospheric droplets. To achieve this goal, we analyzed 75 N-containing compounds, representing a diverse range ambient non-organonitrate ON (NOON) types, including amines, amides, amino acids, N heterocycles, protein, humic acids. Our results show that NOON can produce significant levels NHx+ NOx+ ion fragments, which are typically recognized as ions representative inorganic species. We also identified presence CH2N+ at m/z = 28.0187, an fragment rarely quantified datasets due substantial interference from N2+. As result, utilization updated calibration factor 0.79 is necessary accurate quantification via HR-AMS. assessed relative ionization efficiencies (RIEs) various species found average RIE (1.52 ± 0.58) aligns with commonly used default value 1.40 aerosol. Moreover, through careful examination HR-AMS spectral features propose fingerprint series aid speciation analysis. For instance, CnH2n+2N+ closely linked CH4N+ indicating primary C2H6N+ suggesting secondary C3H8N+ tertiary amines. CnH2nNO+ (especially n values 1–4) very likely derived amides. The co-existence three ions, C2H4NO2+, C2H3NO+, CH4NO+, serves indicator Additionally, CxHyN2+ indicates occurrence 2N-heterocyclic compounds. Notably, elevated abundance NH4+ distinct signature amines ammonium salts only negligible amounts Finally, contents submicron (PM1) fog water Fresno, California, PM1 New York City (NYC). revealed both Fresno NYC aerosols, whereas concurrently collected contained broader species, aromatic heterocycle (e.g., imidazoles) These findings highlight potential employing widespread measurements aerosols droplets our sources, transformation processes, environmental impacts associated atmosphere.

Язык: Английский

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Measurement report: Strong light absorption induced by aged biomass burning black carbon over the southeastern Tibetan Plateau in pre-monsoon season

Atmospheric chemistry and physics, Год журнала: 2021, Номер 21(11), С. 8499 - 8510

Опубликована: Июнь 7, 2021

Abstract. During the pre-monsoon season, biomass burning (BB) activities are intensive in southern Asia. Facilitated by westerly circulation, those BB plumes can be transported to Tibetan Plateau (TP). Black carbon (BC), main aerosol species emissions, is an important climate warming agent, and its absorbing property strongly depends on size distribution mixing state. To elucidate influence of TP, a field campaign was conducted southeast edge TP during season. It found that substantially increased number concentration atmospheric BC particles factor 13 greatly elevated fraction thickly coated from 52 % up 91 %. Those had slightly larger core much thicker coatings than background particles. However, coating mass not evenly distributed with different sizes. The smaller cores were have shell / ratios cores. Besides, affected vertical variation BC's abundance state, resulting higher concentration, fraction, aging degree upper atmosphere. Resulting both increase loading degree, eventually enhanced total light absorption 15, which 21 contributed aging, 79 mass. Particularly, enhancement induced process long-range transport has far exceeded absorption, implicates significant over region.

Язык: Английский

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Unexpected High Absorption of Atmospheric Aerosols Over a Western Tibetan Plateau Site in Summer

Journal of Geophysical Research Atmospheres, Год журнала: 2021, Номер 126(7)

Опубликована: Март 12, 2021

Abstract The assessment of atmospheric aerosol radiative effects in the Tibetan Plateau (TP) suffers from large uncertainties due to limited understanding physicochemical properties. To quantify optical properties, size distributions, and chemical compositions western TP, an intensive field campaign was carried out at Shiquanhe National Reference Climatological Station July 8 August 2, 2019. Unexpected low single scattering albedo (SSA) 870 nm found for fine aerosols with average value 0.73 ± 0.18. SSA even lower than 0.60 morning when peaked, indicating high absorption induced by anthropogenic activities. Coarse mode accounted 70.58% 14.98% total volume concentration mineral dust most abundant species suspended particles a mass fraction 48.7%. Fine concentrations showed little dependence on wind speed while coarse metallic element exhibited strong positive correlations speed, importance wind‐blown particles. present study first time quantified key parameters TP unexpected were over site summer. Our results suggest need carefully consider caused region.

Язык: Английский

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