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Air quality model evaluation data for organics. 6. C3-C24 organic acids.
M P Fraser1, G R Cass, B R T Simoneit
1Environmental Engineering Science Program, California Institute of Technology, Pasadena, California 91125, USA. mpf@rice.edu
Environmental Science & Technology
|March 13, 2003
Summary
Atmospheric carboxylic acids in Los Angeles show varied sources. Some acids suggest long-range transport, while others indicate formation from human-made emissions or direct release.
Area of Science:
- Atmospheric Chemistry
- Environmental Science
Background:
- Carboxylic acids are significant atmospheric organic compounds.
- Understanding their sources (emissions vs. formation) is crucial for air quality.
Purpose of the Study:
- Quantify atmospheric concentrations of 47 carboxylic acids in Los Angeles.
- Differentiate between primary emissions and atmospheric formation as sources.
Main Methods:
- Collected samples in the Los Angeles area for vapor, semivolatile, and particle phases.
- Analyzed spatial and temporal variations in acid concentrations.
Main Results:
- Low molecular weight aliphatic and some n-alkanoic acids at offshore sites suggest long-range transport or natural sources.
- Aromatic carboxylic acids indicate formation from anthropogenic gaseous precursors.
- Long-chain aliphatic acids align with primary emission sources.
Conclusions:
- Carboxylic acid sources in Los Angeles are diverse, including long-range transport, atmospheric formation, and direct emissions.
- Source attribution varies significantly among different carboxylic acid types.