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, Год журнала: 2022, Номер 22(22), С. 14893 - 14904

Опубликована: Ноя. 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.

Язык: Английский

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Optical properties and molecular composition of wintertime atmospheric water-soluble organic carbon in different coastal cities of eastern China

The Science of The Total Environment, Год журнала: 2023, Номер 892, С. 164702 - 164702

Опубликована: Июнь 9, 2023

Язык: Английский

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Impact of fossil and non-fossil fuel sources on the molecular compositions of water-soluble humic-like substances in PM_2.5 at a suburban site of Yangtze River Delta, China

Atmospheric chemistry and physics, Год журнала: 2023, Номер 23(14), С. 8305 - 8324

Опубликована: Июль 25, 2023

Abstract. Atmospheric humic-like substances (HULIS) affect the global radiation balance due to their strong light absorption at ultraviolet wavelength. The potential sources and molecular compositions of water-soluble HULIS a suburban site in Yangtze River Delta from 2017 2018 were discussed, based on results radiocarbon (14C) analysis combining Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS) technique this study. 14C showed that averaged non-fossil-fuel source contributions 39 ± 8 % 36 6 summer winter, respectively, indicating significant fossil fuel HULIS. Van Krevelen diagrams obtained FT-ICR-MS proportions tannin-like carbohydrate-like groups higher summer, suggesting contribution biogenic secondary organic aerosols (SOAs). condensed aromatic structures winter suggested increasing anthropogenic emissions. Molecular composition CHO, CHON, CHOS, CHONS subgroups relatively intensities high O-containing macromolecular oligomers CHO compounds further stronger SOA formation summer. High-intensity phenolic flavonoids, which related biomass burning polycyclic hydrocarbon (PAH) derivatives combustion emissions, found compounds. Besides, two high-intensity containing ring (C9H6O7 C10H5O8) identified samples similar those off-road engine samples, traffic emissions one important study site. CHON mainly composed nitro or organonitrates with significantly associated addition enhanced NOx winter. However, formulas referring N-heterocyclic compounds, produced atmospheric processes involving reduced N species (e.g., ammonium). S-containing organosulfates (OSs) derived precursors, namely long-chain alkane hydrocarbon, illustrate mixed Generally, different policies need be considered for each season seasonal (i.e., sources, both seasons, additional coal winter). Measures control motor vehicles industrial Additional measures power plants should applied These findings add our understanding interaction between

Язык: Английский

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The Sources and Atmospheric Processes of Strong Light‐Absorbing Components in Water Soluble Brown Carbon: Insights From a Multi‐Proxy Study of PM_2.5 in 10 Chinese Cities

Journal of Geophysical Research Atmospheres, Год журнала: 2024, Номер 129(2)

Опубликована: Янв. 17, 2024

Abstract Humic‐like substances (HULIS) are significant contributor to the light absorption of water‐soluble brown carbon (WSBrC), which contains certain strong light‐absorbing chemical components that not well understood, impeding assessment WSBrC's climate impact. China as hotspot regions with high loading WSBrC characterized by capacity, here, we investigated sources and atmospheric processes (δ 13 C–Δ 14 C), molecular composition (Fourier transform ion cyclotron resonance mass spectrometry), properties (UV spectrophotometry) HULIS in PM 2.5 from 10 Chinese cities. HULIS‐C was major coefficient (70.5 ± 6.6%) at 365 nm, more enriched fossil (48.0 9.0% vs. 30.3 13.9%) but depleted C C: −25.6 0.9‰ −22.4 1.0‰) relative non‐HULIS‐C. This suggests recalcitrant oxidative aging exhibit higher while non‐fossil organic is likely be oxidatively bleached into small, colorless, highly polar molecules (i.e., non‐HULIS). Aromatic HULIS, dominantly originating coal combustion (>77%). Non‐negative matrix factorization model showed aromatic have weight lower oxidation levels than biomass burning, potentially making them photo‐recalcitrant compounds. Our finding combustion‐derived BrC maybe persistent atmosphere has greater long‐term impact on derived burning an important consideration models mitigation policies.

Язык: Английский

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Significant role of biomass burning in heavy haze formation in Nanjing, a megacity in China: molecular-level insights from intensive PM_2.5 sampling on winter hazy days

Atmospheric chemistry and physics, Год журнала: 2025, Номер 25(1), С. 73 - 91

Опубликована: Янв. 7, 2025

Abstract. Reports on the molecular-level characterization of primary and secondary constituents in PM2.5 at high temporal resolution, particularly during haze events, are still limited. This study employed comprehensive analytical methods to examine molecular composition source contributions PM2.5, with samples collected approximately every 2 h hazy winter days. Results show that organic matter was predominant species, followed by nitrate (NO3-). Radiocarbon analysis carbonaceous fractions reveals fossil fuels account for 61 %–82 % water-soluble carbon (WSOC), likely resulting from increased fuel consumption cold heating months. Interestingly, contribution non-fossil sources WSOC enhanced worsening pollution, coinciding significantly intensified biomass burning (BB). BB identified as largest contributor (OC) both concentration proportion, due intensive emissions surrounding areas, especially heavily polluted For sources, naphthalene-derived (SOC) contributed more OC (0.27 %–2.46 %) compared biogenic SOC (0.05 %–1.10 %), suggesting anthropogenic volatile compounds (VOCs), such those combustion, play a major role formation urban aerosols winter. In addition promoting aerosol formation, could also enhance other evidenced significant correlations between tracers various tracers. These findings highlight contributing heavy haze.

Язык: Английский

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Oxidized Nitrogen‐Containing Organic Compounds Formation Enhanced the Light Absorption of PM_2.5 Brown Carbon

Journal of Geophysical Research Atmospheres, Год журнала: 2025, Номер 130(3)

Опубликована: Фев. 6, 2025

Abstract Brown carbon (BrC) is known to have a great impact on atmospheric radiative forcing, but its absorption characteristics at the molecular level not well understood. This study investigated seasonal variations of light and composition BrC in Xi'an, China. Results showed that exhibited higher capacity cold (autumn winter) than warm seasons (spring summer). Nitrogen‐containing organic compounds were identified as important chromophores. Oxidized‐N originated from biomass burning emissions NO x /NO 3 − mediated oxidation reactions predominant seasons, whereas reduced‐N mainly formed NH /NH 4 + abundant seasons. These results contribute better understanding formation mechanisms nitrogen‐containing chromophores PM 2.5 .

Язык: Английский

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Characterizing optical properties of HULIS versus WSOC in cloud water of Eastern China - Insights into secondary formation in cloud processes

Atmospheric Research, Год журнала: 2025, Номер unknown, С. 108091 - 108091

Опубликована: Март 1, 2025

Язык: Английский

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Using machine learning to quantify sources of light-absorbing water-soluble humic-like substances (HULISws) in Northeast China

Atmospheric Environment, Год журнала: 2022, Номер 291, С. 119371 - 119371

Опубликована: Сен. 9, 2022

Язык: Английский

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Water-soluble organic matter with various polarities in PM2.5 over Xi'an, China: Abundance, functional groups, and light absorption

Particuology, Год журнала: 2023, Номер 84, С. 281 - 289

Опубликована: Июль 22, 2023

Язык: Английский

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Characterization and sources of water-soluble organic species in PM2.5 in a remote mountain environment in Southeastern China

Atmospheric Environment, Год журнала: 2023, Номер 313, С. 120057 - 120057

Опубликована: Авг. 30, 2023

Язык: Английский

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