Dept. of Environmental Science
Oregon Graduate Center
This dissertation has three sections which cover analytical measurements, source apportionment, and visibility impact of carbonaceous aerosols. The samples from 46 urban and 20 rural National Air Surveillance Network (NASN) sites were analyzed for organic, elemental, and carbonate carbon to establish a data base for carbonaceous aerosol. Exploratory data analysis was performed on the NASN results to gain an understanding of the nature, magnitude, and relationship of carbon with other constituents of ambient aerosol. Urban centers with high carbonaceous aerosol concentration were Burbank, Chicago, Dallas, East Chicago, Gary, Houston, Los Angeles, New York City, Pasadena, Phoenix, San Bernardino, Santa Ana, and Torrance. The chemical element balance (CEB) and multiple linear regression (MLR) receptor models were evaluated for source apportionment of carbonaceous aerosol measured at Portland, Oregon, during 1977-78. The chemical element balance method on an average accounted for 87% of the fine mass and 83% of the carbon for each filter. The major sources of carbonaceous aerosol were vegetative burning and automobile exhaust. The results of receptor models were compared with the carbonaceous aerosol emission inventory (EI). The agreement between the chemical element balance method and the emission inventory shows that well constructed EI's can be used for seasonal or annual source apportionment. The automotive contribution by MLR agreed with that of the CEB; however, the residual oil combustion and vegetative burning contributions were significantly different. The correlation between vanadium and vegetative burning and the inability of potassium to represent vegetative burning in the MLR were the primary reasons for the discrepancy between MLR and CEB. Because the MLR method relies solely on tracers, the presence of sources without good tracers limits MLR's ability to perform accurate source apportionment. A regression model was applied to the Portland Aerosol Characterization Study data set to determine the sources of visibility degradation. The contributions of chemical species to the scattering coefficient were studied by a linear model, and it was found that all the major chemical components had to be included for the scattering efficiency evaluation. Sulfates, nitrates, and carbon were found to be equally efficient scatterers with a scattering efficiency of around 5 m [superscript 2]/g. This is in contrast to other cities where sulfates have been found to be the most efficient scatterers.
Shah, Jitendra J., "Measurements of carbonaceous aerosol across the U.S. sources and role in visibility degradation" (1981). Scholar Archive. 100.