The dependence of the specific attenuation cross-section on black carbon mass fraction and particle size
The dependence of the specific attenuation cross-section on black carbon mass fraction and particle size
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DOI：
10.1016/s1352-2310(96)00245-2
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发表时间：
1997-03
影响因子：
5
通讯作者：
A. Petzold;C. Kopp;R. Niessner
中科院分区：
文献类型：
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作者：
A. Petzold;C. Kopp;R. Niessner
比衰减截面σ ATN将颗粒负载石英纤维过滤器对光的衰减与沉积细尘的黑碳（BC）含量联系起来，是使用酒精计进行光学BC测定的最重要参数。提出了一个简单的模型来描述光散射颗粒的影响上的特定衰减截面。发现σ ATN随BC占总质量的比例f的变化符合δATN= σabs+（f−1− 1）σ scat。平均比散射截面σ scat取决于细粉尘颗粒的光散射干分数，而比吸收截面σ abs则取决于吸收光的BC颗粒。该模型的应用程序外部混合BC-NaCl气溶胶显示出良好的协议之间提出的理论和我们的实验。概述的模型的适用性证实了从几个测量站点在德国的衰减数据集的分析。对于检查的数据集，环境BC的平均衰减截面σ ATN在8 m2 g −1（农村站点）和19 m2 g −1（街道交叉口）之间变化。这些变化可以通过假设一个与地点无关的BC吸收截面σabs= 4 m2 g − 1（来自BC测试气溶胶的实验）和将σ scat值从0.45 m2 g −1（农村地区）变化到1.2-1.4 m2 g −1（城市地区）来解释。最后，研究了0.05 μm ~ 1.1 μm粒径范围内比吸收截面σ ab的粒径依赖性。正如BC颗粒的分形性质所表明的那样，没有发现σ abs与所使用的BC测试气溶胶的尺寸相关性。
The specific attenuation cross-section σATNwhich relates the attenuation of light by a particleloaden quartz fiber filter to the black carbon (BC) content of deposited fine dust is the most important parameter far optical BC determination using an aethalometer. A simple model is presented to describe the effects of light scattering particles on the specific attenuation cross-section. It is found that σATNvaries with the BC fraction of total mass f according to δATN= σabs+ (f−1− 1)σscatThe average specific scattering cross-section σscatdepends on the light scattering dry fraction of fine dust particles, while the specific absorption cross-section σabsis determined by the light absorbing BC particles. The application of the model to an externally mixed BC-NaCl aerosol shows excellent agreement between the proposed theory and our experiments. The suitability of the outlined model is confirmed by analyses of attenuation data sets obtained from several measuring sites in Germany. For the examined data sets the average attenuation cross-section σATNof ambient BC varies between 8 m2g−1(rural sites) and 19 m2g−1(street crossing). These variations can be explained by assuming a site-independent BC absorption cross-section σabs= 4 m2g−1which is derived from experiments with a BC test aerosol, and by varying the σscatvalue from 0.45 m2g−1(rural sites) to 1.2–1.4 m2g−1(urban areas). Finally, the particle size dependence of the specific absorption cross-section σabsis examined for a particle size range from 0.05 μm to 1.1 μm. As it is suggested by the fractal nature of BC particles no size dependence of σabswith respect to the used BC test aerosol is found.