Mathematical modeling of urban organic aerosol: properties measured by high-resolution gas chromatography

Primary fine aerosol emissions from a variety of urban have been quantitatively characterized via high-resolution chromatography to obtain organic mass fingerprints. To assess the degree of secondary aerosol formation in urban areas, a model is used to predict the distribution of organic aerosol characteristics that would exist various sites in the Los Angeles Basin if the primary emissions were transported without chemical . Comparisons between the model predictions and measurements show substantial agreement for nonpolar organics, suggesting that ambient concentrations this organic fraction result directly from primary . In contrast, ambient concentrations of fine organic aerosols are significantly underpredicted the model, indicating that secondary formation is for acidic organics. On the basis of the observed between model predictions and measured of acidic organics, it is estimated, using monthly , that up to 18-27 % of the elutable organic aerosol in the Los Angeles atmosphere may be secondary origin.