Size-resolved fluorescence properties of water-soluble organic carbon in atmospheric aerosols in coastal China

IF 7.3 2区环境科学与生态学 Q1 ENVIRONMENTAL SCIENCES

Environmental Pollution Pub Date : 2025-07-24 DOI:10.1016/j.envpol.2025.126871

Sen Zhao, Jianhua Qi

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Abstract

Water-soluble organic carbon (WSOC) is widely regarded as an important driving factor to climate change due to its light absorption properties. This research examined the seasonal, size-resolved fluorescence properties of WSOC in Qingdao, China, utilizing excitation-emission matrices (EEMs) and parallel factor analysis (PARAFAC). We identified two humus-like substances (HULIS) and one protein-like substance (PRLIS), observing their highest fluorescence intensities during winter and the lowest in summer. In summer, fine particles (<2.1 μm) exhibited a greater proportion of more-oxygenated HULIS due to intensive photochemical aging processes, whereas winter's coarse particles (>2.1 μm) contained predominantly less-oxygenated HULIS. Additionally, the PRLIS proportion increased with particle sizeand peaked in summer (37.7%). Biological and humification indices indicated that fine particles demonstrated greater aromaticity and aging compared to coarser particles, which displayed more freshness and biogenic contributions. Dust and rainfall significantly influenced WSOC's aging and size distribution, enhancing humification in coarse particles during dust events and reducing aromaticity in smaller particles during rainfall episodes. Correlation and random forest interpretable analyses suggested that secondary sources majorly influence WSOC (75.0%) and more-oxygenated HULIS (84.5%), while PRLIS (43.3%) and less-oxygenated HULIS (39.5%) were also significantly affected by primary sources.

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中国沿海大气气溶胶中水溶性有机碳的尺寸分辨荧光特性

水溶性有机碳（WSOC）由于其光吸收特性而被广泛认为是气候变化的重要驱动因子。本研究利用激发-发射矩阵（EEMs）和平行因子分析（PARAFAC）对青岛WSOC的季节性、尺寸分辨荧光特性进行了研究。我们鉴定了两种腐殖质样物质（HULIS）和一种蛋白质样物质（PRLIS），观察到它们的荧光强度在冬季最高，夏季最低。在夏季，由于强烈的光化学老化过程，细颗粒（<2.1 μm）表现出更多含氧的HULIS，而冬季粗颗粒（>2.1 μm）则主要含有较少含氧的HULIS。PRLIS比例随粒径的增大而增大，夏季最高（37.7%）。生物和腐殖化指标表明，细颗粒比粗颗粒具有更强的芳香性和老化性，表现出更大的新鲜度和生物成因贡献。沙尘和降雨显著影响了WSOC的老化和粒径分布，沙尘增强了粗颗粒的腐殖化，降雨降低了小颗粒的芳香性。相关分析和随机森林解释分析表明，次生源主要影响WSOC（75.0%）和高氧HULIS(84.5%)，而PRLIS（43.3%）和低氧HULIS（39.5%）也受到一次源的显著影响。

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来源期刊

Environmental Pollution 环境科学-环境科学

CiteScore

16.00

自引率

6.70%

发文量

2082

审稿时长

2.9 months

期刊介绍： Environmental Pollution is an international peer-reviewed journal that publishes high-quality research papers and review articles covering all aspects of environmental pollution and its impacts on ecosystems and human health. Subject areas include, but are not limited to: • Sources and occurrences of pollutants that are clearly defined and measured in environmental compartments, food and food-related items, and human bodies; • Interlinks between contaminant exposure and biological, ecological, and human health effects, including those of climate change; • Contaminants of emerging concerns (including but not limited to antibiotic resistant microorganisms or genes, microplastics/nanoplastics, electronic wastes, light, and noise) and/or their biological, ecological, or human health effects; • Laboratory and field studies on the remediation/mitigation of environmental pollution via new techniques and with clear links to biological, ecological, or human health effects; • Modeling of pollution processes, patterns, or trends that is of clear environmental and/or human health interest; • New techniques that measure and examine environmental occurrences, transport, behavior, and effects of pollutants within the environment or the laboratory, provided that they can be clearly used to address problems within regional or global environmental compartments.