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多相硫化学在寒冷和黑暗的城市环境中促进粒子生长

Jingqiu Mao¹, Kunal Bali¹, James R Campbell¹

¹Geophysical Institute and Department of Chemistry and Biochemistry, University of Alaska Fairbanks, Fairbanks, AK, USA. jmao2@alaska.edu.

Faraday discussions

|March 18, 2025

概括

费尔班克斯严重的冬季空气污染是由快速的二次硫酸盐形成引起的,主要来自有机硫和化物. 控制化物对于减轻这些事件及其对粒子生长的影响至关重要.

科学领域:

大气化学大气化学
气溶科学气溶科学
环境科学环境科学

背景情况:

在费尔班克斯的冬季,硫酸盐占环境PM2.5的很大一部分 (20%).
之前的研究缺乏污染事件期间气溶成分的小时分辨率.

研究的目的:

调查冬季污染期间气溶成分和尺寸分布的实时演变.
为了确定化学途径和前体,负责快速硫酸盐的形成.

主要方法:

在ALPACA 2022活动期间部署气溶质谱仪 (AMS),气溶化学特异监测仪 (ACSM) 和扫描移动性颗粒尺寸仪 (SMPS).
在零度以下温度 (-25至-35°C) 的强烈污染事件中分析小时数据.
将AMS-硫酸盐测量与在线粒子转液样机离子染色学 (PILS-IC) 数据进行比较.

主要成果:

观察到硫酸盐质量急剧增加 (5-40μg m-3),导致PM2.5增加的比例高达50%.
颗粒大小分布从<100 nm到>100 nm直径发生了变化,表明二次气溶形成.
有机硫约占观察到的硫酸盐增加的80%,与有机硫化合物有关.
快速的硫酸盐形成与环境中阿尔德海德 (甲,乙) 度和S(IV) 种类的增加相关.
化物-SO2反应在稀释的气溶中可能形成甲硫酸盐 (HMS) 和其他化物-S(IV) 添加物.

结论:

涉及化物和SO2的多相化学是费尔班克斯冬季严重PM2.5污染的关键驱动因素.
控制化物排放对于减轻空气污染事件及其对颗粒生长的影响至关重要.
这些发现强调了二次气溶形成对粒子生长和潜在的气溶云相互作用的重要性.

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