Bhandari Janarjan, China Swarup, Chandrakar Kamal Kant, Kinney Greg, Cantrell Will, Shaw Raymond A, Mazzoleni Lynn R, Girotto Giulia, Sharma Noopur, Gorkowski Kyle, Gilardoni Stefania, Decesari Stefano, Facchini Maria Cristina, Zanca Nicola, Pavese Giulia, Esposito Francesco, Dubey Manvendra K, Aiken Allison C, Chakrabarty Rajan K, Moosmüller Hans, Onasch Timothy B, Zaveri Rahul A, Scarnato Barbara V, Fialho Paulo, Mazzoleni Claudio
Atmospheric Sciences Program and Department of Physics, Michigan Technological University, Houghton, MI, USA.
Pacific Northwest National Laboratory, Richland, WA, USA.
Sci Rep. 2019 Aug 14;9(1):11824. doi: 10.1038/s41598-019-48143-y.
Soot particles form during combustion of carbonaceous materials and impact climate and air quality. When freshly emitted, they are typically fractal-like aggregates. After atmospheric aging, they can act as cloud condensation nuclei, and water condensation or evaporation restructure them to more compact aggregates, affecting their optical, aerodynamic, and surface properties. Here we survey the morphology of ambient soot particles from various locations and different environmental and aging conditions. We used electron microscopy and show extensive soot compaction after cloud processing. We further performed laboratory experiments to simulate atmospheric cloud processing under controlled conditions. We find that soot particles sampled after evaporating the cloud droplets, are significantly more compact than freshly emitted and interstitial soot, confirming that cloud processing, not just exposure to high humidity, compacts soot. Our findings have implications for how the radiative, surface, and aerodynamic properties, and the fate of soot particles are represented in numerical models.
碳质材料燃烧过程中会形成煤烟颗粒，其会影响气候和空气质量。新排放的煤烟颗粒通常呈类分形聚集体。经过大气老化后，它们可充当云凝结核，水的凝结或蒸发会将它们重构为更致密的聚集体，从而影响其光学、空气动力学和表面特性。在此，我们调查了来自不同地点以及不同环境和老化条件下的环境煤烟颗粒的形态。我们使用电子显微镜观察并发现，经过云处理后煤烟会大量压实。我们还进行了实验室实验，以在可控条件下模拟大气云处理过程。我们发现，云滴蒸发后采集的煤烟颗粒比新排放的和间隙煤烟致密得多，这证实了云处理而非仅仅是暴露于高湿度环境会使煤烟压实。我们的研究结果对数值模型中煤烟颗粒的辐射、表面和空气动力学特性以及归宿的表示方式具有重要意义。
