Application of parallel factor analysis model to decompose excitation-emission matrix fluorescence spectra for characterizing sources of water-soluble brown carbon in PM2.5

Wang, Huanbo; Zhang, Leiming; Huo, Tingting; Wang, Bin; Yang, Fumo; Chen, Yang; Tian, Mi; Qiao, Baoqing; Peng, Chao

doi:10.1016/j.atmosenv.2019.117192

Cited by 29 publications

(14 citation statements)

References 71 publications

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“…Component 3 (C3) showed one signal of 360/398 nm. The signals for C1 were similar to those reported for highly oxygenated HULIS of terrestrial and dust origin, which were found in aerosol samples from urban areas and organic matter dissolved in water samples (Fu et al, 2015;Yan and Kim, 2017;Qin et al, 2018;Wang et al, 2020). Moreover, Wen et al (2021) applied the PARAFAC model to samples collected from three sites with different environments in northern China.…”

Section: Analysis Of Pm 25 By Fluorescence Spectroscopysupporting

confidence: 74%

Chemical Composition, Optical Properties and Sources of PM2.5 From a Highly Urbanized Region in Northeastern Mexico

Askar

González

Mendoza

et al. 2022

Front. Environ. Sci.

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Here, we report the chemical composition and optical properties of the fine particles (PM2.5) and water-soluble organic carbon (WSOC) of these particles. Additionally, the potential sources of WSOC emission were determined through the study on fluorescence excitation–emission matrix spectra and parallel factor analysis (EEM-PARAFAC). Samples were collected in an urban site of the Monterrey Metropolitan Area in Mexico during summer and winter and characterized using attenuated total reflectance-Fourier-transform infrared spectroscopy (ATR-FTIR), ultraviolet-visible-near infrared-diffuse reflectance spectroscopy (UV–Vis-NIR-DRS), fluorescence spectroscopy, X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) techniques. The ATR-FTIR analyses allowed the identification of inorganic ions (e.g., CO32−, SO42−, and NO3−), organic functional groups [e.g., carbonyls (C=O), organic hydroxyl (C-OH), carboxylic acid (COOH)], and aromatic and unsaturated aliphatic hydrocarbons. The results obtained by XRD and XPS revealed the presence of organic and inorganic chemical species in PM2.5. The diffuse reflectance spectra of PM2.5 provided the absorption bands in the UV region for CaSO4, CaCO3, and aluminosilicates. The absorption coefficient at 365 nm (Abs365) and Ångström absorption exponent (AAE) values obtained for the aqueous extracts suggest that many of the water-soluble organic compounds corresponded to brown carbon (BrC) chromophores. The mass absorption efficiency values at 365 nm (MAE365) were higher in the winter than summer samples, suggesting the presence of more BrC compounds in the winter samples. The fluorescence indices combined with EEM-PARAFAC analysis showed that the WSOC fraction was mainly composed of humic-like substances (HULIS) which are both of terrestrial and microbial origin.

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Section: Analysis Of Pm 25 By Fluorescence Spectroscopysupporting

confidence: 74%

Chemical Composition, Optical Properties and Sources of PM2.5 From a Highly Urbanized Region in Northeastern Mexico

Askar

González

Mendoza

et al. 2022

Front. Environ. Sci.

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“…where x represents the fluorescence intensity; f is the number of components resolved by PARAFAC; a is proportional to the concentration of the f th component; b and c are the scaled estimation of the emission and excitation spectra; the subscript i is the sample number; and j and k represent the emission and excitation wavelength, respectively. Before performing PARAFAC, all EEM data were normalized to unit norm to reduce concentration-related collinearity and avoid extremely different leverages (Wang et al, 2020). The Tucker congruence coefficient (TCC) was determined for each excitation spectrum and emission spectrum, and a threshold of 0.95 was applied to confirm the spectral congruence.…”

Section: Parafacmentioning

confidence: 99%

Measurement report: Particle-size-dependent fluorescence properties of water-soluble organic compounds (WSOCs) and their atmospheric implications for the aging of WSOCs

et al. 2022

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Abstract. Water-soluble organic compounds (WSOCs) play important roles in atmospheric particle formation, migration, and transformation processes. Size-segregated atmospheric particles were collected in a rural area of Beijing. Three-dimensional fluorescence spectroscopy was used to investigate the optical properties of WSOCs as a means of inferring information about their atmospheric sources. Sophisticated analysis on fluorescence data was performed to characteristically estimate the connections among particles of different sizes. WSOC concentrations and the average fluorescence intensity (AFI) showed a monomodal distribution in winter and a bimodal distribution in summer, with the dominant mode in the 0.26–0.44 µm size range in both seasons. The excitation–emission matrix (EEM) spectra of WSOCs varied with particle size, likely due to changing sources and/or the chemical transformation of organics. Size distributions of the fluorescence regional integration (regions III and V) and humification index (HIX) indicate that the humification degree or aromaticity of WSOCs was the highest in the particle size range of 0.26–0.44 µm. The Stokes shift (SS) and the harmonic mean of the excitation and emission wavelengths (WH) reflected that π-conjugated systems were high in the same particle size range. The parallel factor analysis (PARAFAC) results showed that humic-like substances were abundant in fine particles (< 1 µm) and peaked at 0.26–0.44 µm. All evidence supported the fact that the humification degree of WSOCs increased with particle size in the submicron mode (< 0.44 µm) and then decreased gradually with particle size, which implied that the condensation of organics occurred in submicron particles, resulting in the highest degree of humification in the particle size range of 0.26–0.44 µm rather than in the < 0.26 µm range. Synthetically analyzing three-dimensional fluorescence data could efficiently reveal the secondary transformation processes of WSOCs.

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“…Footnote of i is the sample number, footnotes j and k represent emission and excitation wavelengths, respectively. Before performing PARAFAC, all EEM data were normalized to unit norm to reducing concentration-related collinearity and avoid extremely different leverages (Wang et al 2020).…”

Section: Parafacmentioning

confidence: 99%

Particle size-dependent fluorescence properties of water-soluble organic compounds (WSOC) and their atmospheric implications on the aging of WSOC

Qin

Tan

Zhou

et al. 2021

Preprint

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Abstract. Water-soluble organic compounds (WSOC) are essential in atmospheric particle formation, migration, and transformation processes. Size-segregated atmospheric particles were collected in a rural area of Beijing. Excitation-emission matrix (EEM) fluorescence spectroscopy was used to investigate the sources and optical properties of WSOC. Sophisticated data analysis on EEM data was performed to characteristically estimate the underlying connections among aerosol particles in different sizes. The WSOC concentrations and average fluorescence intensity (AFI) showed monomodal distribution in winter and bimodal distribution in summer, with dominant mode between 0.26 to 0.44 µm for both seasons. The EEM spectra of size-segregated WSOC were different among variant particle sizes, which could be the results of changing sources and/or chemical transformation of organics. Size distributions of fluorescence regional intensity (region Ⅲ and Ⅴ) and HIX indicate that humification degree or aromaticity of WSOC was highest between 0.26 to 0.44 µm. The Stokes shift (SS) and the harmonic mean of the excitation and emission wavelengths (WH) reflected that π-conjugated systems were high between 0.26 to 0.44 µm as well. The parallel factor analysis (PARAFAC) results showed that humic-like substances were abundant in fine particles (< 1 µm) and peaked at 0.26–0.44 µm. All evidence supported that the humification degree of WSOC increased in submicron mode (< 0.44 µm) and decreased gradually. Thus, it was conjectured that condensation of organics still goes on in submicron mode, resulting in the highest humification degree exhibit in particle size between 0.26 to 0.44 µm rather than < 0.26 µm. Synthetically analyzing 3-dimensional fluorescence data could efficiently present the secondary transformation processes of WSOC.

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Application of parallel factor analysis model to decompose excitation-emission matrix fluorescence spectra for characterizing sources of water-soluble brown carbon in PM2.5

Cited by 29 publications

References 71 publications

Chemical Composition, Optical Properties and Sources of PM2.5 From a Highly Urbanized Region in Northeastern Mexico

Chemical Composition, Optical Properties and Sources of PM2.5 From a Highly Urbanized Region in Northeastern Mexico

Measurement report: Particle-size-dependent fluorescence properties of water-soluble organic compounds (WSOCs) and their atmospheric implications for the aging of WSOCs

Particle size-dependent fluorescence properties of water-soluble organic compounds (WSOC) and their atmospheric implications on the aging of WSOC

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