Aqueous photochemical aging of water-soluble smoke particles from crop straws burning

IF 4.2 2区环境科学与生态学 Q2 ENVIRONMENTAL SCIENCES

Atmospheric Environment Pub Date : 2024-10-29 DOI:10.1016/j.atmosenv.2024.120897

Zhaolian Ye , Dandan Hu , Zixuan Wang , Hui Wang , Xinlei Ge

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引用次数: 0

Abstract

Most aqueous oxidation studies focus on single model precursors, while the photochemical aging of actual water soluble organic matter (WSOM) in particles emitted from biomass burning remains poorly understood. In this study, gas chromatography-mass spectrometry (GC/MS) was first used to analyze the WSOM in smoke particles emitted from three crop straws burning. The results show that the dominant WSOM in three crop straws (CS) smoke are phenolic substances with small differences. Aqueous photochemical aging of WSOM in CS smoke was investigated under simulated sunlight exposure. High-resolution aerosol mass spectrometry (HR-AMS) analyzed aqueous secondary organic aerosol (aqSOA) and it was found that the oxidation degree of aqSOA increased with prolonged aging. No obvious increase in the abundance of N-containing organic ions was observed over the course of aqueous aging. As aqueous aging progresses, the pH of the solution gradually decreases, accompanied by the continuous generation of organic acids. Studies on dithiothreitol (DTT) activity indicate that the impact of aqueous photochemical aging on health is not significant.

The solution after photoaging shows relatively lower light absorption ability than the initial solution. The aqueous photochemical aging also led to a gradual reduction of fluorescence at excitation/emission = 250–260 nm/350 nm (protein-like substances) for CS smoke WSOM, suggesting the significant degradation of chromophores. However, three-dimensional excitation-emission matrix (EEM) fluorescence combined with parallel factor analysis (PARAFAC) revealed that aqueous aged CS smoke WSOM contains compounds with high humification index, confirming that the fluorophore composition is altered by aqueous aging. The humic-like substance (HULIS) concentration increased for the first 3 h and then decreased, closely matching the pattern of a new fluorescence peak. Finally, GC/MS analysis of the products indicated that there was obvious decline in proportion of methoxyphenol. The results of this study are important for understanding the aqueous-phase oxidation reactions of CS smoke WSOM in the atmosphere and their light-absorption characteristics and health impacts.

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农作物秸秆燃烧产生的水溶性烟雾颗粒的水光化学老化

大多数水氧化研究都集中在单一的模型前体上，而对生物质燃烧排放的颗粒中实际水溶性有机物（WSOM）的光化学老化仍然知之甚少。本研究首次采用气相色谱-质谱法（GC/MS）分析了三种农作物秸秆燃烧排放的烟雾颗粒中的水溶性有机物。结果表明，三种农作物秸秆（CS）烟雾中最主要的 WSOM 是酚类物质，且差异较小。在模拟太阳光照射下，研究了农作物秸秆（CS）烟雾中 WSOM 的水光化学老化。高分辨率气溶胶质谱（HR-AMS）分析了水溶液二次有机气溶胶（aqSOA），发现随着老化时间的延长，aqSOA 的氧化程度增加。在水老化过程中，没有观察到含 N 有机离子丰度的明显增加。随着水老化的进行，溶液的 pH 值逐渐降低，同时不断产生有机酸。对二硫苏糖醇（DTT）活性的研究表明，水体光化学老化对健康的影响不大。水体光化学老化还导致 CS 烟雾 WSOM 在激发/发射 = 250-260 纳米/350 纳米（类蛋白物质）处的荧光逐渐减弱，表明发色团发生了显著降解。然而，三维激发-发射矩阵（EEM）荧光结合平行因子分析（PARAFAC）发现，水性老化的 CS 烟雾 WSOM 含有高腐殖化指数的化合物，这证实了荧光团的组成会因水性老化而改变。类腐殖质（HULIS）的浓度在最初的 3 小时内有所增加，随后有所减少，这与新荧光峰的形态非常吻合。最后，对产品进行的气相色谱/质谱分析表明，甲氧基苯酚的比例明显下降。这项研究的结果对于了解 CS 烟雾 WSOM 在大气中的水相氧化反应及其光吸收特性和对健康的影响具有重要意义。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Atmospheric Environment 环境科学-环境科学

CiteScore

9.40

自引率

8.00%

发文量

458

审稿时长

53 days

期刊介绍： Atmospheric Environment has an open access mirror journal Atmospheric Environment: X, sharing the same aims and scope, editorial team, submission system and rigorous peer review. Atmospheric Environment is the international journal for scientists in different disciplines related to atmospheric composition and its impacts. The journal publishes scientific articles with atmospheric relevance of emissions and depositions of gaseous and particulate compounds, chemical processes and physical effects in the atmosphere, as well as impacts of the changing atmospheric composition on human health, air quality, climate change, and ecosystems.