THE SOURCES AND SIZE DISTRIBUTIONS OF ALIPHATIC AND CARBONYL CARBON IN LOS-ANGELES AEROSOL

Size distributions of aerosol phase aliphatic and carbonyl groups were measured during the Southern California Air Quality Study. Samples were collected using a low pressure impactor equipped with ZnSe disks and the aerosol samples were analyzed directly using infrared (i.r.) spectroscopy. For the carbonyl absorbance, the ambient samples showed maxima in the 0.12-0.26 μm and the 0.5-1.0 μm size fractions. For the aliphatic carbon absorbance, the ambient samples generally showed maxima in the 0.076-0.12 μm size fraction. Factors contributing to these two absorbances were examined using principal component analysis. The results indicate that the carbonyl absorbance can be almost entirely attributed to products of atmospheric reactions and the aliphatic absorbances in particles smaller than 0.12 μm is correlated with automotive emissions. © 1990.