低NO类氧化途径对受污染的城市空气中的二次有机气溶作出了重大贡献
Chenshuo Ye1,2, Ying Liu1, Bin Yuan3
1State Key Joint Laboratory of Environmental Simulation and Pollution Control (SKL-ESPC), College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China.
Environmental science & technology
|September 5, 2023
概括
氧化 (NO/NO2) 的比率显著影响城市空气中的二次有机气溶 (SOA) 组成. 低NO/NO2条件有利于非化合物,而高NO/NO2则有利于有机酸盐和酸.
科学领域:
- 大气化学 大气化学
- 环境科学 环境科学
- 气溶科学 气溶科学
背景情况:
- 人为污染物严重影响城市环境中的二次有机气溶 (SOA) 形成和组成.
- 了解SOA的分子组成对于评估其对空气质量和气候的影响至关重要.
研究的目的:
- 在广州,在不同氧化 (NO/NO2) 比率下,在PM2.5中研究不同类型的SOA分子标记物.
- 阐明NO/NO2比对SOA形成路径和化学特征的影响.
主要方法:
- 使用气体和AEROsols的过器入口与化物电离质谱仪 (FIGAERO-I-CIMS) 配合用于粒子相规格有机分析.
- 进行有机化合物的源分析,以确定与不同SOA类型和形成条件相关的分子标记物.
- 分析了数据,考虑了不同的NO/NO2比率,臭氧积累,气溶中的水含量和气溶酸度.
主要成果:
- 低NOx路径 (NO/NO2 < 0.2) 主导区域运输周期 (约75%的FIGAERO-OA),以氧化C4-C6非化合物为特征.
- 在局部污染事件中,高NOx化学物质 (38%) 是显著的,导致有机酸盐 (ONs) 和酸的增加,气溶中的水和酸盐含量更高.
- 夜间NO3启动的氧化贡献了FIGAERO-OA的10-12%,主要是通过单烯衍生的ONs.
- 有机硫酸盐 (OSs),特别是碳基衍生物,在酸性条件下优先形成,与低NOx SOA相关,突出显示水相贡献.
结论:
- NO/NO2比率是SOA组成的关键决定因素,影响不同氧化和功能化途径的流行.
- 气溶中的水含量,酸度和无机盐在可凝结的有机化合物的气体-颗粒分离中起着重要作用,影响SOA的形成.
- 该研究提供了关于SOA形成机制的分子层面见解,这对于改善空气质量模型和缓解策略至关重要.
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