 |
| Titel |
Better constraints on sources of carbonaceous aerosols using a combined 14C – macro tracer analysis in a European rural background site |
| VerfasserIn |
S. Gilardoni, E. Vignati, F. Cavalli, J. P. Putaud, B. R. Larsen, M. Karl, K. Stenström, J. Genberg, S. Henne, F. Dentener |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1680-7316
|
| Digitales Dokument |
URL |
| Erschienen |
In: Atmospheric Chemistry and Physics ; 11, no. 12 ; Nr. 11, no. 12 (2011-06-20), S.5685-5700 |
| Datensatznummer |
250009853
|
| Publikation (Nr.) |
 copernicus.org/acp-11-5685-2011.pdf |
|
|
|
|
|
| Zusammenfassung |
The source contributions to carbonaceous PM2.5 aerosol were investigated
at a European background site at the edge of the Po Valley, in Northern
Italy, during the period January–December 2007. Carbonaceous aerosol was
described as the sum of 8 source components: primary (1) and secondary
(2) biomass burning organic carbon, biomass burning elemental carbon (3),
primary (4) and secondary (5) fossil organic carbon, fossil fuel burning
elemental carbon (6), primary (7) and secondary (8) biogenic organic carbon.
The mass concentration of each component was quantified using a set of macro
tracers (organic carbon OC, elemental carbon EC, and levoglucosan), micro
tracers (arabitol and mannitol), and 14C measurements. This was the
first time that 14C measurements covered a full annual cycle with daily
resolution. This set of 6 tracers, together with assumed uncertainty ranges
of the ratios of OC-to-EC, and the reference fraction of modern carbon in the
8 source categories, provides strong constraints to the source contributions
to carbonaceous aerosol. The uncertainty of contributions was assessed with a
Quasi-Monte Carlo (QMC) method accounting for the variability of OC and EC
emission factors, the uncertainty of reference fractions of modern carbon,
and the measurement uncertainty.
During winter, biomass burning composed 64 % (±15 %) of the total carbon
(TC) concentration, while in summer secondary biogenic OC accounted for 50 %
(±16 %) of TC. The contribution of primary biogenic aerosol particles was
negligible during the entire year. Moreover, aerosol associated with fossil
sources represented 27 % (±16 %) and 41 % (±26 %) of TC in winter
and summer, respectively. The contribution of secondary organic aerosol (SOA)
to the organic mass (OM) was significant during the entire year. SOA
accounted for 30 % (±16 %) and 85 % (±12 %) of OM during winter and
summer, respectively. While the summer SOA was dominated by biogenic sources,
winter SOA was mainly due to biomass burning and fossil sources. This
indicates that the oxidation of semi-volatile and intermediate volatility
organic compounds co-emitted with primary organics is a significant source of
SOA, as suggested by recent model results and Aerosol Mass Spectrometer
measurements. Comparison with previous global model simulations, indicates a
strong underestimate of wintertime primary aerosol emissions in this region.
The comparison of source apportionment results in different urban and rural
areas showed that the sampling site was mainly affected by local aerosol
sources during winter and regional air masses from the nearby Po Valley in
summer. This observation was further confirmed by back-trajectory analysis
applying the Potential Source Contribution Function method to identify
potential source regions. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|