Mixing state of regionally transported soot particles and the coating effect on their size and shape at a mountain site in Japan
Mixing state of regionally transported soot particles and the coating effect on their size and shape at a mountain site in Japan
复制标题
DOI：
10.1002/2013jd020880
复制
发表时间：
2014-05
期刊：
影响因子：
--
通讯作者：
K. Adachi;Y. Zaizen;M. Kajino;Y. Igarashi
中科院分区：
文献类型：
--
作者：
K. Adachi;Y. Zaizen;M. Kajino;Y. Igarashi
烟尘颗粒通过与阳光的相互作用影响全球气候。当烟尘颗粒与其他吸湿性气溶胶成分混合时，烟尘颗粒上的涂层通过增加其吸收截面和云凝结核的活性来增加它们的光吸收。因此，重要的是要了解烟尘如何在内部与其他材料混合，以便在气候模型中准确模拟其影响。在这项研究中，我们使用了带有自动颗粒分析系统的透射电子显微镜(TEM)，它能够比传统的TEM分析更多的颗粒。利用透射电子显微镜，从日本偏远山区采集的样品中，测定了有涂层和无涂层的碳烟颗粒大小和形状(形状因子)。结果表明，在空气动力学直径为60~350 nm的气溶胶粒子中，约有10%的粒子含有或由碳烟粒子组成，约75%的碳烟粒子与不挥发的硫酸铵或其他物质在内部混合。与涂层改变碳烟形状的假设相反，内部和外部混合的碳烟颗粒具有相似的形状和尺寸分布。较大的气溶胶粒子具有较高的碳烟混合比，即直径<1µm的气溶胶粒子中有40%以上含有碳烟包裹体，而直径为<；1µm的气溶胶粒子中有20%包含碳烟。我们的结果表明，对于内部和外部混合的烟尘，气候模式可以使用相同的尺寸分布和形状；但是，改变不同气溶胶尺寸箱中的烟尘混合比例是必要的。
Soot particles influence the global climate through interactions with sunlight. A coating on soot particles increases their light absorption by increasing their absorption cross section and cloud condensation nuclei activity when mixed with other hygroscopic aerosol components. Therefore, it is important to understand how soot internally mixes with other materials to accurately simulate its effects in climate models. In this study, we used a transmission electron microscope (TEM) with an auto particle analysis system, which enables more particles to be analyzed than a conventional TEM. Using the TEM, soot particle size and shape (shape factor) were determined with and without coating from samples collected at a remote mountain site in Japan. The results indicate that ~10% of aerosol particles between 60 and 350 nm in aerodynamic diameters contain or consist of soot particles and ~75% of soot particles were internally mixed with nonvolatile ammonium sulfate or other materials. In contrast to an assumption that coatings change soot shape, both internally and externally mixed soot particles had similar shape and size distributions. Larger aerosol particles had higher soot mixing ratios, i.e., more than 40% of aerosol particles with diameters >1 µm had soot inclusions, whereas <20% of aerosol particles with diameters <1 µm included soot. Our results suggest that climate models may use the same size distributions and shapes for both internally and externally mixed soot; however, changing the soot mixing ratios in the different aerosol size bins is necessary.