Stabilization of the Mass Absorption Cross Section of Black Carbon for Filter-Based Absorption Photometry by the use of a Heated Inlet
Stabilization of the Mass Absorption Cross Section of Black Carbon for Filter-Based Absorption Photometry by the use of a Heated Inlet
复制标题
DOI：
10.1080/02786820902889879
复制
发表时间：
2009-05
影响因子：
5.2
通讯作者：
Y. Kondo;L. Sahu;M. Kuwata;Y. Miyazaki;N. Takegawa;N. Moteki;J. Imaru;S. Han;T. Nakayama;N. Oanh;Min Hu;Y. J. Kim;K. Kita
中科院分区：
文献类型：
--
作者：
Y. Kondo;L. Sahu;M. Kuwata;Y. Miyazaki;N. Takegawa;N. Moteki;J. Imaru;S. Han;T. Nakayama;N. Oanh;Min Hu;Y. J. Kim;K. Kita
原则上，黑碳（BC）的质量浓度（MBC）可以通过测量BC的光吸收系数来估计。基于过滤器的方法已经广泛用于测量MBC，所述基于过滤器的方法根据通过负载有颗粒的过滤器的透射率的变化来量化吸收系数（B abs）。然而，由于质量吸收截面（C abs）的大的可变性，可靠地测定MBC是非常困难的，质量吸收截面（C abs）是从B abs到MBC的转换因子。挥发性化合物对BC的包覆和光散射颗粒的共存导致了C abs的变化。为了克服这一困难，在过滤器上收集BC颗粒之前，通过将入口的一部分加热到400°C来去除挥发性气溶胶组分。在亚洲的6个地点，我们用两种类型的光度计（颗粒烟尘吸收光度计（PSAP）和连续烟尘监测系统（COSMOS））同时测量B abs，并用EC-OC分析仪测量MBC，以确定C abs。在565 nm波长处，碳绝对值稳定在10.5 ± 0.7 m2 g −1，这是受到车辆排放和生物质燃烧强烈影响的BC。稳定的绝对碳值为COSMOS和PSAP估算百万吨级碳酸盐浓度提供了坚实的基础，准确度约为10%。为了定量解释C abs与模型计算的C abs* 的比率，我们在实验室中测量了单分散苯胺黑颗粒的C abs。在100-200 nm直径下，C abs/C abs* 比率为1.4-1.9，解释了环境BC的比率为1.8。
In principle, mass concentrations of black carbon (BC) (M BC) can be estimated by the measurement of the light absorption coefficient of BC. Filter-based methods, which quantify the absorption coefficient (b abs) from the change in transmission through a filter loaded with particles, have been widely used to measure M BC. However, reliable determination of M BC has been very difficult because of the large variability in the mass absorption cross section (C abs), which is the conversion factor from b abs to M BC. Coating of BC by volatile compounds and the co-existence of light-scattering particles contribute to the variability of C abs. In order to overcome this difficulty, volatile aerosol components were removed before collection of BC particles on filters by heating a section of the inlet to 400°C. We made simultaneous measurements of b abs by two types of photometers (Particle Soot Absorption Photometer (PSAP) and Continuous Soot Monitoring System (COSMOS)) together with M BC by an EC-OC analyzer to determine C abs at 6 locations in Asia. C abs was stable at 10.5 ± 0.7 m2 g −1 at a wavelength of 565 nm for BC strongly impacted by emissions from vehicles and biomass burning. The stable C abs value provides a firm basis for its use in estimating M BC by COSMOS and PSAP with an accuracy of about 10%. For the quantitative interpretation of the ratio of the C abs to the model-calculated C abs*, we measured C abs for mono-disperse nigrosin particles in the laboratory. The C abs/C abs* ratio was 1.4–1.9 at the 100–200 nm diameters, explaining the ratio of 1.8 for ambient BC.