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Published February 1, 2003 | public
Journal Article

Air Quality Model Evaluation Data for Organics. 6. C_3−C_(24) Organic Acids


The atmospheric concentrations of 47 carboxylic acids in the semivolatile and particle phases are quantified in the Los Angeles area, as part of a larger study of the vapor-phase, semivolatile, and particle-phase organic compounds. Variations in the spatial and temporal distributions of acid concentrations are analyzed to determine whether atmospheric formation or primary emissions are responsible for the observed levels. Relatively low molecular weight aliphatic dicarboxylic acids (e.g., butanedioic acid, hexanedioic acid, and propanedioic acid) and some n-alkanoic acids (e.g., n-octanoic acid and n-nonanoic acid) are found at an offshore sampling location at levels comparable to urban area concentrations indicating that these compounds or their atmospheric precursors may be derived from long-range transport or natural background sources. Some aromatic carboxylic acids (e.g., benzoic acid and 1,2-benzenedicarboxylic acid) have spatial and temporal distributions suggesting that formation from anthropogenic emissions of gaseous precursors dominates their atmospheric concentrations. Additionally, the distributions of aliphatic carboxylic acid concentrations known to be emitted from primary sources (e.g., hexadecanoic acid and octadecanoic acid) are consistent with direct emissions as the dominant source of these compounds.

Additional Information

© 2003 American Chemical Society. Received for review September 6, 2002. Revised manuscript received November 14, 2002. Accepted November 18, 2002. Publication Date (Web): December 18, 2002. This research was supported by the Electric Power Research Institute under agreement RP3189-03 and by the Caltech Center for Air Quality Analysis.

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