Concentration, optical characteristics, and emission factors of brown carbon emitted by on-road vehicles

The Science of The Total Environment, Год журнала: 2021, Номер 810, С. 151307 - 151307

Опубликована: Ноя. 5, 2021

Язык: Английский

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Characterizing water-soluble brown carbon in fine particles in four typical cities in northwestern China during wintertime: integrating optical properties with chemical processes

Atmospheric chemistry and physics, Год журнала: 2023, Номер 23(19), С. 12609 - 12630

Опубликована: Окт. 10, 2023

Abstract. Brown carbon (BrC) aerosol could impact atmospheric radiative forcing and play a crucial role in photochemistry. In this study, fine particulate matter (PM2.5) filter samples were collected synchronously four major cities northwestern China during the winter season (December 2019–January 2020): Lanzhou (LZ), Xining (XN), Yinchuan (YC), Ürümqi (UR), which are represented as energy-producing heavy manufacturing China. The primary aim of study is to explore optical properties, sources, chemical processes water-soluble BrC (WS-BrC). average mass absorption efficiency at 365 nm (MAE365) WS-BrC these was 1.24 ± 0.19 m2 g−1 1.19 0.12 1.07 0.23 0.78 0.16 (UR). properties further investigated by an acid–base titration experiment. results showed that MAE365 values all increased with higher pH (2–11), while fluorescence intensities water extracts fluctuated values, being stronger under both highly acidic basic conditions. sensitivity variation most pronounced from YC LZ, indicating important contribution acid or base functional group compounds locations. Additionally, revealed significant photo-enhancement (LZ) photo-bleaching (YC UR) phenomena different cities. These suggest sources and/or varied among explored combination parallel factor analysis (PARAFAC) on excitation–emission matrix (EEM) spectra positive factorization (PMF) high-resolution organic (WSOA). Six PARAFAC components identified, including three humic-like substances (HULIS; two less oxygenated (LO) HULIS one (HO) HULIS), protein-like phenol-like (PLS), undefined substance. Four PMF factors OA (WS-POA), oxidized associated coal combustion-induced WSOA (LO-OOA), OAs resulting photochemical oxidation aqueous-phase transformations (HO-OOA1 HO-OOA2). WS-POA determined be source light absorption, accounting for 30 %–60 % based multiple linear regression models, it correlation PLS LO-HULIS components. loss found occur through its conversion LO-OOA HO-OOAs aqueous reactions, significantly correlated HO-HULIS component. can clearly illustrated integrating composition using Van Krevelen diagram EEM plot.

Язык: Английский

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Temporal and Spatial Trends in Particulate Matter and the Responses to Meteorological Conditions and Environmental Management in Xi’an, China

Atmosphere, Год журнала: 2021, Номер 12(9), С. 1112 - 1112

Опубликована: Авг. 30, 2021

Particulate matter contributes much to the haze pollution in China. Meteorological conditions and environmental management significantly influenced accumulation, deposition, transportation, diffusion, emission intensity of particulate matter. In this study, temporal spatial variations PM10 PM2.5—and responses meteorological factors regulation intensity—were explored Xi’an, The concentrations were higher than those PM2.5, especially spring winter. mean annual PM2.5 markedly decreased from 2013 2017, but decreasing trend has plateaued since 2015. exhibited seasonal differences, with winter being highest summer lowest. Air quality monitoring stations did not reveal significant variability concentrations. by precipitation, relative humidity, atmospheric temperature. impact wind speed was prominent autumn winter, while direction obvious. Additionally, SO2, smoke dust could be effectively increasing intensity, This study provide a scientific framework for management.

Язык: Английский

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Humic-like substances (HULIS) in springtime aerosols at a high-altitude background station in the western North Pacific: Source attribution, abundance, and light-absorption

The Science of The Total Environment, Год журнала: 2021, Номер 809, С. 151180 - 151180

Опубликована: Окт. 25, 2021

Язык: Английский

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Triplet-Excited Dissolved Organic Matter Efficiently Promoted Atmospheric Sulfate Production: Kinetics and Mechanisms

Separations, Год журнала: 2023, Номер 10(6), С. 335 - 335

Опубликована: Май 30, 2023

Photochemical generation is an important pathway for atmospheric sulfate formation. However, the roles of co-existing photosensitive dissolved organic matter (DOM) in formation are still unclear. The experimental results this work provide evidence that photosensitizers produce active intermediates to oxidize S(IV) into S(VI) under illumination. Quenching experiments eight model compounds (PS) demonstrate their triplet-excited states (3PS*) dominate photosensitizing with a contribution over 90%, and 1O2 plays role using humic acid (HA) water-soluble carbon vehicle exhaust particles (WSOC) as representatives further verify DOM (3DOM*) main reactive species formation, which consistent PS. Our findings new insights photochemical pathways sulfate.

Язык: Английский

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Distribution, chemical, and molecular composition of high and low molecular weight humic-like substances in ambient aerosols

Atmospheric chemistry and physics, Год журнала: 2024, Номер 24(6), С. 3769 - 3783

Опубликована: Март 27, 2024

Abstract. Humic-like substances (HULIS) encompass a continuum of molecular weight (MW) ranges, yet our understanding how HULIS characteristics vary with MW is still limited and not well established. In this study, combination ultrafiltration solid-phase extraction protocols was employed to fractionate the high (HMW; > 1 kDa) low (LMW; < fractions from ambient aerosols collected during summer winter at rural site. Subsequently, comprehensive characterization using total organic carbon, high-performance size exclusion chromatography (HPSEC), UV-visible (UV-vis) fluorescence spectroscopy, Fourier transform infrared spectroscopy (FTIR), negative electrospray ionization high-resolution mass spectrometry (ESI–HRMS) were conducted. The results revealed that HMW dominated by larger-sized chromophores, substantially constituting higher fraction carbon UV absorption 254 nm than LMW HULIS. While both shared similar fluorophore types functional groups, former exhibited levels humification greater presence polar groups (e.g., −COOH; C=O). HRMS analysis further unveiled formulas within generally featured smaller sizes but degrees unsaturation aromaticity compared those fractions. This observation suggests possibility small molecules assembling form through intermolecular weak forces. Moreover, contained proportion CHON fewer CHO compounds HULIS, unique primarily characterized lignin-like species, displayed prevalence N-enriched highly aromatic species. Additionally, more lipid-like compounds, while distinct tannin-like compounds. These findings provide valuable insights into distribution, optical properties, molecular-level in atmospheric aerosols, thereby advancing their sources, composition, environmental implications.

Язык: Английский

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Atmospheric humic-like substances (HULIS) in Chongqing, Southwest China: Abundance, light absorption properties, and potential sources

Atmospheric Research, Год журнала: 2023, Номер 295, С. 107016 - 107016

Опубликована: Сен. 13, 2023

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

Опубликована: Июль 20, 2022

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 lower, suggesting diverse dynamic properties episodes. The CHO CHON compounds most abundant components HULIS, followed CHOS, CHONS, CHN. Haze presented comparatively weight, lower aromaticity index (AImod), O/Cw, O/Nw, O/Sw ratios, indicating that fractions undergo oxidation than days. Moreover, high AImod major potential chromophores contributed to absorption. It's worth noting proportions these decreased event, mainly owing their longer aging period episode. Besides, accumulated contribution organic emitted from vehicles formed stronger reactions bio-VOCs also diluted light-absorbing HULIS. These findings help understand subtropic region China.

Язык: Английский

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Distribution, chemical and molecular composition of high and low-molecular-weight humic-like substances in ambient aerosols

Опубликована: Окт. 5, 2023

Abstract. Humic-like Substances (HULIS) encompass a continuum of molecular weight (MW) ranges, yet our understanding how HULIS characteristics vary with MW is still limited and not well-established. In this study, combination ultrafiltration solid-phase extraction protocols was employed to fractionate the high (HMW, >1 kDa) low (LMW, < 1kDa) fractions from ambient aerosols collected during summer winter at rural site. Subsequently, comprehensive characterization by using total organic carbon, high-performance size exclusion chromatography (HPSEC), UV-vis fluorescence spectroscopy, Fourier-transform infrared spectroscopy (FTIR), negative electrospray ionization resolution mass spectrometry (ESI- HRMS) were conducted. The results revealed that HMW dominated larger-sized chromophores, substantially constituting higher fraction carbon UV absorption 254 nm than LMW HULIS. While both shared similar fluorophore types functional groups, former exhibited levels humification greater presence polar groups (e.g., -COOH, >C=O). HRMS analysis further unveiled formulas within generally featured smaller sizes but degrees unsaturation aromaticity compared those fractions. This observation suggests possibility small molecules assembling form through intermolecular weak forces. Moreover, contained proportion CHON fewer CHO compounds HULIS, unique primarily characterized lignin-like species, displayed prevalence N-enriched highly aromatic species. Additionally, more lipids-like compounds, while distinct tannin-like compounds. These findings provide valuable insights into distribution, optical properties, molecular-level in atmospheric aerosols, thereby advancing their sources, composition, environmental implications.

Язык: Английский

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Supplementary material to "Distribution, chemical and molecular composition of high and low-molecular-weight humic-like substances in ambient aerosols"

Опубликована: Окт. 5, 2023

Язык: Английский

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