Measurement methods for fine particle carbon were compared under field sampling conditions. Sampling methods included filtration, impaction, and adsorptioncorrected filtration. Systems were operated side-by-side for nine consecutive days in the Los Angeles Basin. Analytical M methods were compared separately. For organic carbon and total carbon, ambient measurements showed greater variability than could be accounted for by differences in analytical methods, and these differences are attributed to sampling methodology. The highest reported concentrations were obtained by quartz filter sampling; the lowest were from the sum of the impactor stages (excluding the quartz alterfilters). Positive artifact from the adsorption of gaseous vapors on quartz fiber filters was significant. However, correction for vapor adsorption by subtraction of the carbon value on the second of two filters in series did not completely elimenate the dependence of the apparent total aerosol carbon concentration on filter face velocity or sample duration.
Bibliographical noteFunding Information:
(Rosemead, CA) who provided the electrical power, is gratefully acknowledged. Funding for the participant groups in this study came from ARB (contract nos. A415832A (AIHL), A402893 (UCD), and A514932 (OGC)), the US Environmental Protection Agency (contract 68024084, EMSI), the Coordinating Research Council (contract AP13-1/86,UM), and the Electric Power Research Institute (contract 1630-11, AV). Support for the project management and data analysis was provided by ARB contract A515432.