Optical characterization of ambient and source particulates

摘要: The high optical absorptivity of urban particulates is used as a tracer for the" graphitic" component of the carbonaceous aerosol. The results of the analyses of over 900 ambient samples collected over a wide range of atmospheric conditions show a strong correlation between the" graphitic" and the total carbon content of the aerosol. No systematic difference in the correlation is observed under conditions of high or low ozone, indicating that ozone-related reactions do not produce substantial quantities of secondary particulates. A comparison between these measurements and similar measurements on sources indicates that a major component of the urban carbonaceous aerosol is due to primary emissions.