Modified thermal-optical analysis using spectral absorption selectivity to distinguish black carbon from pyrolized organic carbon

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Black carbon (BC), a main component of combustion-generated soot, is a strong absorber of sunlight and contributes to climate change. Measurement methods for BC are uncertain, however. This study presents a method for analyzing the BC mass loading on a quartz fiber filter using a modified thermal-optical analysis method, wherein light transmitted through the sample is measured over a spectral region instead of at a single wavelength as the sample is heated. Evolution of the spectral light transmission signal depends on the relative amounts of light-absorbing BC and char, the latter of which forms when organic carbon in the sample ... continued below

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Hadley, Odelle; Hadley, O.L.; Corrigan, C.E. & Kirchstetter, T.W. April 14, 2008.

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Black carbon (BC), a main component of combustion-generated soot, is a strong absorber of sunlight and contributes to climate change. Measurement methods for BC are uncertain, however. This study presents a method for analyzing the BC mass loading on a quartz fiber filter using a modified thermal-optical analysis method, wherein light transmitted through the sample is measured over a spectral region instead of at a single wavelength as the sample is heated. Evolution of the spectral light transmission signal depends on the relative amounts of light-absorbing BC and char, the latter of which forms when organic carbon in the sample pyrolyzes during heating. Absorption selectivities of BC and char are found to be distinct and are used to apportion the amount of light attenuated by each component in the sample. Light attenuation is converted to mass concentration based on derived mass attenuation efficiencies (MAE) of BC and char. The fraction of attenuation due to each component are scaled by their individual MAE values and added together as the total mass of light absorbing carbon (LAC). An iterative algorithm is used to find the MAE values for both BC and char that provide the best fit to the carbon mass remaining on the filter (derived from direct measurements of thermally evolved CO{sub 2}) at temperatures higher than 480 C. This method was applied to measure the BC concentration in precipitation samples collected from coastal and mountain sites in Northern California. The uncertainty in measured BC concentration of samples that contained a high concentration of organics susceptible to char ranged from 12 to 100 percent, depending on the mass loading of BC on the filter. The lower detection limit for this method was approximately 0.35 {micro}g BC and uncertainty approached 20 percent for BC mass loading greater than 1.0 {micro}g BC.

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  • Journal Name: Environmental Science and Technology

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  • Report No.: LBNL-450E
  • Grant Number: DE-AC02-05CH11231
  • Office of Scientific & Technical Information Report Number: 934734
  • Archival Resource Key: ark:/67531/metadc895025

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Office of Scientific & Technical Information Technical Reports

Reports, articles and other documents harvested from the Office of Scientific and Technical Information.

Office of Scientific and Technical Information (OSTI) is the Department of Energy (DOE) office that collects, preserves, and disseminates DOE-sponsored research and development (R&D) results that are the outcomes of R&D projects or other funded activities at DOE labs and facilities nationwide and grantees at universities and other institutions.

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  • April 14, 2008

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  • Sept. 27, 2016, 1:39 a.m.

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  • Jan. 4, 2017, 5:39 p.m.

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Hadley, Odelle; Hadley, O.L.; Corrigan, C.E. & Kirchstetter, T.W. Modified thermal-optical analysis using spectral absorption selectivity to distinguish black carbon from pyrolized organic carbon, article, April 14, 2008; Berkeley, California. (digital.library.unt.edu/ark:/67531/metadc895025/: accessed December 12, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.