Molecular insights into the composition, sources, and aging of atmospheric brown carbon

Chemical Society Reviews, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

The light-absorbing chemical components of atmospheric organic aerosols are commonly referred to as Brown Carbon (BrC), reflecting the characteristic yellowish brown appearance aerosol.

Language: Английский

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Measurement report: Optical properties and sources of water-soluble brown carbon in Tianjin, North China – insights from organic molecular compositions

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(10), P. 6449 - 6470

Published: May 19, 2022

Abstract. Brown carbon (BrC) aerosols exert vital impacts on climate change and atmospheric photochemistry due to their light absorption in the wavelength range from near-ultraviolet (UV) visible light. However, optical properties formation mechanisms of ambient BrC remain poorly understood, limiting estimation radiative forcing. In present study, fine particles (PM2.5) were collected during 2016–2017 a day/night basis over urban Tianjin, megacity northern China. Light fluorescence water extracts PM2.5 investigated obtain seasonal diurnal patterns water-soluble BrC. There obvious seasonal, but no evident diurnal, variations winter, showed much stronger light-absorbing ability, with mass efficiency at 365 nm (MAE365) winter (1.54±0.33 m2 gC−1) that was 1.8 times larger than MAE365 summer (0.84±0.22 gC−1). Direct effects by relative black UV 54.3±16.9 % 44.6±13.9 summer, respectively. addition, five fluorescent components BrC, including three humic-like fluorophores two protein-like identified excitation–emission matrix spectrometry parallel factor (PARAFAC) analysis. The less oxygenated contributed more nighttime samples, while increased daytime samples. higher humification index (HIX), together lower biological (BIX) (FI), suggests chemical compositions associated high aromaticity degree photobleaching. Fluorescent indicate wintertime predominantly affected primary emissions fresh secondary organic aerosol (SOA), ones influenced aging processes. Results source apportionments using molecular same set reveal fossil fuel combustion processes, bioaerosol emission, biomass burning, biogenic anthropogenic SOA main sources Biomass burning nighttime, daytime. particular, our study highlights emission is an important Tianjin summer.

Language: Английский

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Research progress of catalysts for catalytic steam reforming of high temperature tar:A review

Fuel, Journal Year: 2022, Volume and Issue: 331, P. 125790 - 125790

Published: Sept. 1, 2022

Language: Английский

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Significant coal combustion contribution to water-soluble brown carbon during winter in Xingtai, China: Optical properties and sources

Journal of Environmental Sciences, Journal Year: 2022, Volume and Issue: 124, P. 892 - 900

Published: Feb. 26, 2022

Language: Английский

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Connecting the Light Absorption of Atmospheric Organic Aerosols with Oxidation State and Polarity

Environmental Science & Technology, Journal Year: 2022, Volume and Issue: 56(18), P. 12873 - 12885

Published: Sept. 9, 2022

The light-absorbing organic aerosol (OA) constitutes an important fraction of absorbing components, counteracting major cooling effect aerosols to climate. mechanisms in linking the complex and changeable chemistry OA with its properties remain be elucidated. Here, by using solvent extraction, ambient from urban environment was fractionated according polarity, which further nebulized online characterized compositions properties. Water extracted high-polar compounds a significantly higher oxygen carbon ratio (O/C) than methanol extracts. A transition O/C about 0.6 found, below above enhancement reduction absorptivity were observed increasing O/C, occurring on less polar high compounds, respectively. In particular, co-increase nitrogen elements suggests role nitrogen-containing functional groups enhancing (e.g., forming aromatics), while oxidation (O/C > 0.6) likely led fragmentation bleaching chromophores. results here may reconcile previous observations darkening or whitening chromophores brown carbon, parametrization has potential link changing polarity

Language: 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, Journal Year: 2023, Volume and Issue: 23(2), P. 963 - 979

Published: Jan. 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.

Language: Английский

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Atmospheric aerosol size distribution impacts radiative effects over the Himalayas via modulating aerosol single-scattering albedo

npj Climate and Atmospheric Science, Journal Year: 2023, Volume and Issue: 6(1)

Published: May 30, 2023

Abstract The single-scattering albedo (SSA) of atmospheric aerosols is a key parameter that controls aerosol radiative effects. variation SSA thought to be mainly regulated by absorption in the Himalayas and South Asia, but observations contradict this idea. In situ field campaigns conducted over two Himalayan sites revealed was strongly dependent on scattering weakly correlated with absorption. Observational results combined Mie theory further illustrated primarily modulated size distribution rather than Aerosol Robotic Network (AERONET) data showed similar impacts forcing efficiencies were significantly SSA. therefore considerably affects modulating Himalayas. This study highlighted influence Himalayas, which has important implications for understanding effects globally.

Language: Английский

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Insight into the Role of NH₃/NH₄⁺ and NO_x/NO₃^– in the Formation of Nitrogen-Containing Brown Carbon in Chinese Megacities

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

Published: Feb. 23, 2024

Particulate brown carbon (BrC) plays a crucial role in the global radiative balance due to its ability absorb light. However, effect of molecular formation on light absorption properties BrC remains poorly understood. In this study, atmospheric samples collected from six Chinese megacities winter and summer were characterized through ultrahigh-performance liquid chromatography coupled with Orbitrap mass spectrometry (UHPLC-Orbitrap MS) measurements. The average values coefficient at wavelength 365 nm (babs365) approximately 4.0 times higher than those summer. Nitrogen-containing organic molecules (CHNO) identified as critical components light-absorbing substances both seasons, underscoring importance N-addition BrC. These nitrogen-containing chromophores more closely related nitro-containing compounds originating biomass burning nitrogen oxides (NOx)/nitrate (NO3–) reactions winter. summer, they reduced N-containing formed ammonia (NH3)/ammonium (NH4+) reactions. NH3/NH4+-mediated contributed secondary winter, particularly southern cities. Compared O/Cw, lower molecule conjugation indicator (double bond equivalent, DBE), babs365 suggest possible bleaching mechanism during oxidation process. findings strengthen connection between composition BrC, providing insights into mechanisms across northern cities different seasons.

Language: Английский

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Winter brown carbon over six of China's megacities: light absorption, molecular characterization, and improved source apportionment revealed by multilayer perceptron neural network

Atmospheric chemistry and physics, Journal Year: 2022, Volume and Issue: 22(22), P. 14893 - 14904

Published: Nov. 23, 2022

Abstract. Brown carbon (BrC) constitutes a large fraction of organic and exhibits strong light absorption properties, thus affecting the global radiation budget. In this study, we investigated chemical functional bonds, sources BrC in six megacities China, namely Beijing, Harbin, Xi'an, Chengdu, Guangzhou, Wuhan. The average values coefficient mass efficiency at 365 nm northern cities were higher than those southern by 2.5 1.8 times, respectively, demonstrating abundance present China's megacities. Fourier transform infrared (FT-IR) spectra revealed sharp intense peaks 1640, 1458–1385, 1090–1030 cm−1, which ascribed to aromatic phenols, confirming contribution primary emission (e.g., biomass burning coal combustion) BrC. addition, noted 860, 1280–1260, 1640 attributed organonitrate oxygenated phenolic groups, indicating that secondary also existed Positive matrix factorization (PMF) coupled with multilayer perceptron (MLP) neural network analysis was used apportion absorption. results showed emissions burning, tailpipe emissions, made major However, formation processes greater (17.9 %–21.2 %) (2.1 %–10.2 %). These can provide basis for more effective control reduce its impacts on regional climates human health.

Language: Английский

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Source profiles of molecular structure and light absorption of PM2.5 brown carbon from residential coal combustion emission in Northwestern China

Environmental Pollution, Journal Year: 2022, Volume and Issue: 299, P. 118866 - 118866

Published: Jan. 22, 2022

Language: Английский

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