Laboratory of Environmental Chemistry, Paul Scherrer Institute, Villigen, Switzerland.
Institute for Atmospheric and Climate Science, ETH Zurich, Zurich, Switzerland.
Nat Commun. 2021 Mar 19;12(1):1769. doi: 10.1038/s41467-021-21913-x.
In viscous, organic-rich aerosol particles containing iron, sunlight may induce anoxic conditions that stabilize reactive oxygen species (ROS) and carbon-centered radicals (CCRs). In laboratory experiments, we show mass loss, iron oxidation and radical formation and release from photoactive organic particles containing iron. Our results reveal a range of temperature and relative humidity, including ambient conditions, that control ROS build up and CCR persistence in photochemically active, viscous organic particles. We find that radicals can attain high concentrations, altering aerosol chemistry and exacerbating health hazards of aerosol exposure. Our physicochemical kinetic model confirmed these results, implying that oxygen does not penetrate such particles due to the combined effects of fast reaction and slow diffusion near the particle surface, allowing photochemically-produced radicals to be effectively trapped in an anoxic organic matrix.
在含有铁的粘性、富含有机物的气溶胶颗粒中，阳光可能会导致缺氧条件，从而稳定活性氧（ROS）和碳中心自由基（CCR）。在实验室实验中，我们展示了含有铁的光活性有机颗粒中质量损失、铁氧化和自由基形成和释放。我们的结果揭示了一系列温度和相对湿度范围，包括环境条件，这些条件控制着光化学反应活性、粘性有机颗粒中 ROS 的积累和 CCR 的持久性。我们发现自由基可以达到很高的浓度，改变气溶胶化学性质，并加剧气溶胶暴露的健康危害。我们的物理化学动力学模型证实了这些结果，这意味着由于快速反应和靠近颗粒表面的缓慢扩散的综合作用，氧气不会穿透这些颗粒，从而使光化学产生的自由基能够有效地被困在缺氧的有机基质中。
