Beijing (China) Aerosol Characterization Study:Influence of Coal Burning
【摘要】：Coal is expected to surpass petroleum as the world's most used fuel within the next20years. Coal currently generates more than half of U.S. electricity, and this percentage is predicted to increase. Coal usage may grow by a factor of two or three in the next decade. China's main energy source is coal, which provides76%of china's energy. Coal burning is one of major sources of air pollution in China. The burning of100million tons of coal per year in China probably also contributes greatly to the global greenhouse effect.
The purpose of this research was to determine the impact of industrial and residential coal burning on air quality in Beijing, China. PM2.5(the aero-diameters of particles collected are smaller than2.5μm) samples were collected at two sites from April30,1989to May16,1989and May20,1989to May14,1990separately. The samples were analyzed by thermal-optical carbon analysis at Oregon Graduate Institute (OGI) for organic (OC) and elemental carbon (EC) and X-ray fluorescence at Desert Research Institute for32elements and components. A variety of different data analysis approaches including multiple linear regression and CMB modeling were used to determine the sources of PM2.5and the role of coal burning in Beijing air pollution.
The results indicate that organic and elemental carbon are important components of aerosol throughout the year in Beijing. During the autumn, winter, and spring, combustion appears to be the main source of particulate organic carbon. The eleven sources of aerosol included in honeycomb coal burning when closed mode (HONEYC), residential boilers (BOILER), industrial burning (INDST), power station coal burning (POWER), heavy duty diesel emission (MVHDDS), secondary sulfate, soil, urban dust, plant dust, cement dust, and cooking emissions. Based on the low chi-squared, high R-squared and high fraction of mass accounted for, the results of the CMB on Beijing data can be considered good. In the winter at the west site in Beijing the total coal burning contribution was43%; in the summer it was18%. The average winter HONEYC and BOILER contributions were6%and14%, while the INDST and POWER were10%and13%respectively. MVHDDS is an another important source as its annual average contribution was over30%. The average dust contributions were as high as34%and32%in the spring and summer, but17%and10%in the autumn and winter. Those sources and their contributions were supported by east site results in Beijing.
The source profiles of honeycomb and ball coal were compared with piece coal including their smoke, ash and coal. For open-vent burning the source profiles of honeycomb and ball coal are very similar. The EC content of honeycomb coal open-vent burning and ash are much less than that of ball coal. Thus, the coal shape might be an important factor for coal burning pollution control and energy saving. Honeycomb and ball coals and their ashes show less sulfate and chloride and much less EC content than piece coal's ash. That implies that research of honeycomb, ball and other kind of coal may be important for new clean and cheap fuel in power station, industry and residential usage. The source libraries and CMB modeling from the U.S. are good tools for studying other countries' air pollution control strategies. Therefore, this project is an example for other countries' air pollution research.