Abstract. Little is known regarding levels and source strength of carbonaceous aerosols in Scandinavia. In the present study, ambient aerosol (PM 10 and PM 2.5 ) concentrations of elemental carbon (EC), organic carbon (OC), waterinsoluble organic carbon (WINSOC), and water-soluble organic carbon (WSOC) are reported for a curbside site, an urban background site, and a suburban site in Norway in order to investigate their spatial and seasonal variations. Aerosol filter samples were collected using tandem filter sampling to correct for the positive sampling artefact introduced by volatile and semivolatile OC. Analyses were performed using the thermal optical transmission (TOT) instrument from Sunset Lab Inc., which corrects for charring during analysis. Finally, we estimated the relative contribution of OC from wood burning based on the samples content of levoglucosan.Levels of EC varied by more than one order of magnitude between sites, likely due to the higher impact of vehicular traffic at the curbside and the urban background sites. In winter, the level of particulate organic carbon (OC p ) at the suburban site was equal to (for PM 10 ) or even higher (for PM 2.5 ) than the levels observed at the curbside and the urban background sites. This finding was attributed to the impact of residential wood burning at the suburban site in winter, which was confirmed by a high mean concentration of levoglucosan (407 ng m −3 ). This finding indicates that exposure to primary combustion derived OC p could be equally high in residential areas as in a city center. It is demonstrated that OC p from wood burning (OC wood ) accounted for almost all OC p at the suburban site in winter, allowing a new estimate of the ratio TC p /levoglucosan for both PM 10 and PM 2.5 . Particulate carbonaceous material (PCM=Organic matter+Elemental matter) accounted for 46-83% of PM 10 at the sites studied, thus being the major fraction.

Little is known regarding levels and source strength of carbonaceous aerosols in Scandinavia. In the present study, ambient aerosol (PM 10 and PM 2.5 ) concentrations of elemental carbon (EC), organic carbon (OC), water-insoluble organic carbon (WINSOC), and water-soluble organic carbon (WSOC) are reported for a curbside site, an urban Abstract Introduction Conclusions References Tables Figures Back CloseFull Screen / Esc Printer-friendly VersionInteractive Discussion 20 of OC also allows for a much better evaluation of atmospheric models than simple comparison with total OC allows. For example, Simpson et al. (2007) clearly showed that increased knowledge of the wood-burning (and other) contributions to measured OC levels could explain many apparent discrepancies between modelled and measured wintertime OC. While quantification of single organic molecules can be useful for 25 the purpose of source apportionment, this approach becomes an insurmountable task when it comes to mass closure studies due to the great number of organic molecules associated with the carbonaceous aerosol. Thus, implementation of operational definiAbstract Introduction Conclusions References Tables urban background site is situated in a park in the central part of Oslo, at which sampling 19490 ACPD Abstract Introduction Conclusions References Tables 25 Aerosol sampling was performed using tandem filter set-ups (McDow and Huntzicker, 1990) in order to correct for the positive sampling artefact introduced by semi 19491 ACPD Abstract Introduction Conclusions References Tables 25 acid impregnated cellulose filter (Whatman 40) (EMEP, 1995). Potassium was obtained 19492 ACPD Abstract Introduction Conclusions References Tables Abstract Introduction Conclusions References Tables ACPD Abstract Introduction Conclusions References Tables Abstract Introduction Conclusions References Tables ACPD Abstract Introduction Conclusions References Tables ACPD Abstract Introduction Conclusions References Tables ACPD Abstract Introduction Conclusions References Tables Abstract Introduction Conclusions References Tables Abstract Introduction Conclusions References Tables ACPD Abstract 25 19502 Abstract Introduction Conclusions References Tables ACPD Abstract Introduction Conclusions References Tables Abstract Introduction Conclusions References Tables Abstract Introduction Conclusions References Tables and Letters and Statoil) project number 6143, the Norwegian Research Council project number 171691/S30 (SORGA), the EU project number 036833-2 (EUCAARI) within the 6th Framework 25 Programme, and UNECE