Characterization of Atmospheric Coarse Particles in the Los Angeles Basin

Abstract

Size-selective coarse particle samples were collected during the 1986 Los Angeles Carbonaceous Species Methods Comparison Study (CSMCS) with a rotary inertial impactor. In addition to particle mass distribution information, chemical analysis of sulfate and nitrate were also obtained. Both short-term (approximately 30 minutes) and long-term (12-hour) samples were obtained, from which 24-hour average concentrations were determined. A least square error best-fit method was used to estimate the total coarse particle mass (> 1 μm), mass median diameter (MMD), and σg. The results were compared to samples collected by a high-volume sampler with a Sierra-Anderson 321A size-selective PM10 inlet. On the average, 28% of the total particulate mass (fine and coarse) and 16% of the total particulate nitrate was not collected by the PM10 sampler. Only 3% of the particulate sulfate was contributed by particles greater than 10 urn. More total coarse particle and nitrate mass were generated during the day than at night. No...