纳夫他林衍生颗粒氧化产物的光降解
Félix Sari Doré1, Cecilie Carstens1, Jens Top2
1Université Claude Bernard Lyon1, CNRS, IRCELYON, UMR 5256 69100 Villeurbanne France.
概括
光化学老化迅速降解高分子量纳二次有机气溶 (SOA),减少粒子质量并释放挥发性化合物. 这种光降解会改变SOA.
科学领域:
- 大气化学 大气化学
- 环境科学 环境科学
- 有机地化学 有机地化学
背景情况:
- 光化学老化显著影响二次有机气溶 (SOA) 的性能.
- 人为产生的SOA的光降解,特别是来自纳夫他林的光降解,尚不清楚.
- 了解这些过程对于大气模型和空气质量评估至关重要.
研究的目的:
- 为了研究不同氧化 (NOx) 条件下的乙烯衍生SOA的光降解.
- 描述光降解过程中气体和粒子阶段的分子变化.
- 为了确定光降解对SOA物理性质的影响,例如挥发性.
主要方法:
- 由基引发的甲烯氧化形成SOA.
- SOA在不同阶段 (形成和生长) 暴露于模拟的太阳辐射.
- 先进的质谱技术 (提取电喷射电离MS,化学电离MS) 用于分子特征.
主要成果:
- 高分子量化合物在粒子相SOA中的快速光降解 (>30分钟).
- 在低NOx条件下,C20物种的显著减少 (2/3) 和~12%的粒子质量损失.
- 短链寡合物的形成和挥发性产品 (酸,甲) 的释放到气相中.
结论:
- 光降解是一个关键的过程,它改变了甲衍生SOA的分子组成.
- 在SOA产品中的光性功能组在紫外线下加速降解.
- 光降解会导致SOA挥发率和其他物理性质的变化,影响大气的行为.
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