1. Stabilization of the Mass Absorption Cross Section of Black Carbon for Filter-Based Absorption Photometry by the use of a Heated Inlet.
- Author
-
Kondo, Y., Sahu, L., Kuwata, M., Miyazaki, Y., Takegawa, N., Moteki, N., Imaru, J., Han, S., Nakayama, T., Oanh, N. T. Kim, Hu, M., Kim, Y. J., and Kita, K.
- Subjects
LIGHT absorption ,CARBON ,MASS attenuation coefficients ,VOLATILE organic compounds ,LIGHT scattering ,AEROSOLS ,EXHAUST gas from spark ignition engines ,EMISSIONS (Air pollution) ,BIOMASS - Abstract
In principle, mass concentrations of black carbon (BC) (MBC) can be estimated by the measurement of the light absorption coefficient of BC. Filter-based methods, which quantify the absorption coefficient (babs) from the change in transmission through a filter loaded with particles, have been widely used to measure MBC. However, reliable determination of MBC has been very difficult because of the large variability in the mass absorption cross section (Cabs), which is the conversion factor from babs to MBC. Coating of BC by volatile compounds and the co-existence of light-scattering particles contribute to the variability of Cabs. 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 babs by two types of photometers (Particle Soot Absorption Photometer (PSAP) and Continuous Soot Monitoring System (COSMOS)) together with MBC by an EC-OC analyzer to determine Cabs at 6 locations in Asia. Cabs 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 Cabs value provides a firm basis for its use in estimating MBC by COSMOS and PSAP with an accuracy of about 10%. For the quantitative interpretation of the ratio of the Cabs to the model-calculated Cabs*, we measured Cabs for mono-disperse nigrosin particles in the laboratory. The Cabs/Cabs* ratio was 1.4-1.9 at the 100-200 nm diameters, explaining the ratio of 1.8 for ambient BC. [ABSTRACT FROM AUTHOR]
- Published
- 2009
- Full Text
- View/download PDF