The Sources, Molecular Compositions, and Light Absorption Properties of Water‐Soluble Organic Carbon in Marine Aerosols From South China Sea to the Eastern Indian Ocean

Mo, Yangzhi; Zhong, Guangcai; Liu, Xin; Jiang, Hongxing; Tang, Junyan; Jiang, Bin; Liao, Yuhong; Cheng, Zhu; Zhang, Gan

doi:10.1029/2021jd036168

Cited by 12 publications

(4 citation statements)

References 116 publications

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“…Therefore, most of the literature cited above has chosen the similar wavelength bands to make the comparisons more reliable. In a previous study, Mo et al (2022) reported a good linear correlation between MAE 365 and AAE, despite fitting AAE with different wavelength. This indicates that the aromatic component in WSOC is a crucial factor in determining its light absorption capacity.…”

Section: Uv-vis Light Absorption Properties Of Ws-brcmentioning

confidence: 87%

“…As shown in Supplementary Figure S1, during the autumn campaign, most air masses originated from the northern continent, but in summer, only a small fraction originated from the continent, while the majority came from the ocean. Continent-influenced air masses carried substances that absorb light stronger than marine-influenced air masses (Mo et al, 2022;Tang et al, 2024).…”

Section: Uv-vis Light Absorption Properties Of Ws-brcmentioning

confidence: 99%

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Seasonal changes in water-soluble brown carbon (BrC) at Nanling background station in South China

Zhang,

Tang,

Geng

et al. 2024

Front. Environ. Sci.

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Brown carbon (BrC) is an important light-absorbing component of organic carbon (OC), causing large uncertainty in aerosol radiative forcing evaluation and being related to health issues as well. Knowledge of BrC in an atmospheric background station is beneficial to understand its role in a changing climate. A year-long sampling campaign was conducted at Nanling background station to get a comprehensive knowledge of WS-BrC, a total of seventy-two PM2.5 samples throughout a year were used. Light absorption and fluorescence spectra of WSOC were analyzed synchronously using a fluorescence spectrophotometer. The low levels of PM2.5, OC, and elemental carbon (EC) conferred a background site. The optical properties of WS-BrC were characterized using excitation-emission matrix (EEM) fluorescence spectroscopy. The WS-BrC made a significant contribution (365 nm, 18% ± 10%) to total carbonaceous aerosol absorption. The mass absorption efficiency (MAE) of WS-BrC is 0.81 ± 0.34 m2 gC–1, and varies among seasons due to the different sources or atmospheric processing. Three EEM fluorescent components were identified by parallel factor (PAFAFAC) analysis, including two humic-like substances (HULIS, C1, C2), and one phenolic-like component. The HULIS components accounted for approximately 70% of the total fluorescence intensities. Primary combustion emissions showed enhanced activity during the winter and spring seasons, but there were no significant influences on WS-BrC in spring. Secondary sources contributed significantly to WS-BrC during winter, summer, and autumn (all exceeding 50%), except for spring. Photooxidation is a significant process in the formation of secondary WS-BrC in winter and autumn, but there may be another formation pathway in summer, i.e., the ammonia pathway. This study contributes to our understanding of BrC in the background atmosphere.

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Section: Uv-vis Light Absorption Properties Of Ws-brcmentioning

confidence: 87%

Section: Uv-vis Light Absorption Properties Of Ws-brcmentioning

confidence: 99%

Seasonal changes in water-soluble brown carbon (BrC) at Nanling background station in South China

Zhang,

Tang,

Geng

et al. 2024

Front. Environ. Sci.

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“…Field blanks were subtracted from the spectra of the extracts. The light‐absorption coefficients of WSOC and MSOC at 365 nm (Abs 365,WSOC and Abs 365,MSOC ) were used as BrC proxies according to previous studies, and the detailed calculations are presented in Text S2 of Supporting Information (Hecobian et al., 2010; Mo et al., 2022). Water‐insoluble organic carbon (WISOC) was then defined as the difference between MSOC and WSOC.…”

Section: Methodsmentioning

confidence: 99%

Aqueous‐Phase Secondary Processes and Meteorological Change Promote the Brown Carbon Formation and Transformation During Haze Events

Jiang,

Cai,

Feng

et al. 2023

JGR Atmospheres

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The evolution and the impacts of meteorological conditions on brown carbon (BrC) absorption are not understood, which hinders the assessment of BrC radiative forcing. To address this issue, 1‐hour time‐resolved PM2.5 samples collected during three haze events in the North China Plain prior to the COVID‐19 pandemic were used to measure the optical properties of BrC. By coupling excitation‐emission matrix spectroscopy, chemical tracer analysis with multiple model analysis including positive matrix factorization and a deweather‐random forest model, we found that a higher proportion of highly oxidized chromophoric components was present in water‐soluble BrC than in methanol‐soluble BrC, indicating the conversion of low‐oxidized water‐insoluble BrC into highly oxidized water‐soluble BrC during the day. The results of the positive matrix factorization and the deweather‐random forest model showed that aqueous secondary processes were the major contributor to the BrC absorption (68±38%), and the changes in meteorological conditions such as relative humidity (RH) could significantly lead to the changes in the light‐absorbing capacity of BrC, especially the enhancement for water‐soluble BrC and bleaching for methanol‐soluble BrC during the noon and afternoon. We further found that the BrC absorption capacity increased as RH increases to a maximum of ∼65%, and then decreased when RH>65%, highlighting the important role of RH in the generation of water‐soluble BrC.

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“…Water‐soluble organic carbon (WSOC) typically constitutes up to 70% of total OC and 53%–66% of total absorption at 300–400 nm (Chen et al., 2017; Mo et al., 2022), excluding BC interference. When biomass combustion is absent, WSOC is usually considered as a surrogate for SOA (Weber et al., 2007).…”

Section: Introductionmentioning

confidence: 99%

Long‐Emission‐Wavelength Humic‐Like Component (L‐HULIS) as a Secondary Source Tracer of Brown Carbon in the Atmosphere

Tang,

Xu,

Zhao

et al. 2024

JGR Atmospheres

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The optical properties of secondary brown carbon (BrC) aerosols are poorly understood, hampering quantitative assessments of their impact. We propose a new method for estimating secondary source of BrC using excitation‐emission matrix (EEM) fluorescence spectroscopy, combined with parallel factor analysis (PARAFAC) and partial least squares regression (PLSR). Experiments were conducted on a collection of PM2.5 samples from urban areas in five Chinese cities during winter and summer. The humic‐like component with long‐emission wavelengths (L‐HULIS) was identified as a secondary source tracer of BrC. This was confirmed by correlating PARAFAC components with secondary organic aerosol tracers and molecular oxidation indices obtained from Fourier transform ion cyclotron resonance mass spectrometry analysis. Using L‐HULIS as a secondary tracer of BrC, it was determined that the contribution of secondary sources to water‐soluble BrC (WS‐BrC) in source emission samples is significantly smaller than in PM2.5 from five Chinese cities, supporting our method. In the five cities, secondary source derived via L‐HULIS contributes a dominant potion (80% ± 3.5%) of WS‐BrC at 365 nm during the summer, which is approximately twice as high as during the winter (45% ± 4.9%). Radiocarbon isotope (14C) analysis provides additional constraints to the sources of L‐HULIS‐derived secondary WS‐BrC in urban PM2.5, suggesting that aged biomass burning is the dominant contributor to secondary WS‐BrC in winter, and biogenic emission is dominant during summer. This study is the first report on identification of secondary sources of BrC using the fluorescence technique. It demonstrates the potential of this method in characterizing non‐fossil source secondary BrC in the atmosphere.

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The Sources, Molecular Compositions, and Light Absorption Properties of Water‐Soluble Organic Carbon in Marine Aerosols From South China Sea to the Eastern Indian Ocean

Cited by 12 publications

References 116 publications

Seasonal changes in water-soluble brown carbon (BrC) at Nanling background station in South China

Seasonal changes in water-soluble brown carbon (BrC) at Nanling background station in South China

Aqueous‐Phase Secondary Processes and Meteorological Change Promote the Brown Carbon Formation and Transformation During Haze Events

Long‐Emission‐Wavelength Humic‐Like Component (L‐HULIS) as a Secondary Source Tracer of Brown Carbon in the Atmosphere

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