Preliminary assessment of the anthropogenic and biogenic contributions to secondary organic aerosols at two industrial cities in the upper Midwest

Limitations were found in the current version of the model. Approximately half of the water soluble organic carbon unrelated to biomass burning (NB-WSOC) during spring, summer and early fall could not be apportioned by the CMB model with the SOC markers available during this study. This suggested that additional sources not included in the CMB model used in this study contributed to SOC, or that models using markers measured in chamber oxidations are not entirely representative of the study sites. The unapportioned OC did not correlate particularly well with any of the known OC sources. While performance of the model is limited due to uncertainties in the source profiles, the apportionments calculated still give a preliminary insight into the relative contributions to SOC from anthropogenic and biogenic emissions.