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Energy & Fuels 2002, 16, 222-260
Review of PM2.5 and PM10 Apportionment for Fossil Fuel Combustion and Other Sources by the Chemical Mass Balance Receptor Model Judith C. Chow* and John G. Watson Desert Research Institute, 2215 Raggio Parkway, Reno, Nevada 89512 Received July 17, 2001. Revised Manuscript Received November 5, 2001
This review examines how the Chemical Mass Balance (CMB) receptor model has been used to quantify source contributions from fossil fuel combustion and other sources to ambient concentrations of PM2.5 and PM10 for urban and regional scales. Nonfossil fuel sources, such as fugitive dust, cooking, vegetative burning, and natural or human-caused biogenics must be considered together with fossil-fuel sources in a CMB analysis to obtain closure for PM2.5 and PM10 mass. CMB analyses in 22 different studies have found fossil fuel combustion to be a large contributor to PM2.5 and PM10 concentrations, with most of the primary contributions originating form diesel- and gasoline-powered vehicle exhaust. Primary contributions from ducted sources, such as coal- and oil-fired power stations, are negligible when these facilities have been modernized with effective pollution controls, but they have been shown to be large contributors without these controls. Secondary sulfates and nitrates from fossil fuel combustion are recognized, but their attribution to specific precursor gas emitters is uncertain using either the CMB or source-oriented chemical transport models. Using source and receptor models together improves source contribution estimates and the confidence in those estimates.
Introduction Fossil fuel combustion results in large quantities of primary particle emissions to the atmosphere, as well as gaseous compounds that convert to particles within hours to days after emission. Coal, raw and refined petroleum products, and natural gas are burned throughout the world to create electricity, refine metals and organic materials, heat buildings, cook food, and provide transportation. Fossil fuel combustion is also a major emitter of sulfur dioxide (SO2) and oxides of nitrogen (NOx), gases that react with other constituents in the atmosphere to create secondary sulfate and nitrate particles.1 Much of the sulfate found in the air of the eastern United States,2 in national parks with poor visibility,3 in waterways and snowpacks with high acidity,4 and in remote regions of Asia5 and Europe6 is believed to arise from fossil fuel sulfur emissions, especially coal combustion. In addition to direct emissions from stacks, chimneys, and tailpipes, fossil fuels * Author to whom correspondence should be addressed. (1) Seinfeld, J. H.; Pandis, S. N. Atmospheric Chemistry and Physics: From Air Pollution to Climate Change; John Wiley & Sons: New York, 1998. (2) Mueller, P. K.; Hidy, G. M.; Baskett, R. L.; Fung, K. K.; Henry, R. C.; Lavery, T. F.; Nordi, N. J.; Lloyd, A. C.; Thrasher, J. W.; Warren, K. K.; Watson, J. G. “Sulfate Regional Experiment (SURE): Report of findings”; Report No. EA-1901. Prepared by Electric Power Research Institute: Palo Alto, CA, 1983. (3) Eldred, R. A.; Cahill, T. A.; Flocchini, R. G. JAWMA 1997, 47 (2), 194-203. (4) Turk, J. T.; Campbell, D. H.; Spahr, N. E. Water, Air, Soil Pollut. 1993, 67, 415-431. (5) Kim, B. G.; Han, J. S.; Park, S. U. Atmos. Environ. 2001, 35 (4), 727-737. (6) Nova´k, I. J.; Prechova´, E. Environ. Sci. Technol. 2001, 35 (2), 255-260.
also result in fugitive dust from mining and extraction activities as well as disposal of noncombustible ash and pollution control residues that remain after combustion. Effective methods have been developed and applied that use improved fuels, better combustion methods, and after-combustor treatment to reduce primary particles and precursor gases from fossil fuel combustion.7-9 These technologies are often costly and technologically challenging to implement; their initial applications need to be targeted at those emitters that have the highest contributions to ambient concentrations, especially in areas that exceed PM2.5 and PM10 (mass of particles with aerodynamic diameters
