Chemistry Reference
In-Depth Information
Fig. 7 Modelled source attribution on a sectorial basis for the Spain as function of total modelled
PM10 mass. For each concentration bin, the number of occurrences is given. Note that desert dust
is incorporated as boundary conditions in the simulations, explaining the large contribution of
boundary conditions for Spain
5 Concluding Remarks
The chemical composition of PM10 on various measurement sites in the
Netherlands, Germany and Belgium shows a considerable conformity. Always,
SIA is the major constituent (
40%) followed by the carbonaceous compounds
(
25%). Contributions of sea salt and mineral dust vary between 10% and 15%
depending on location (distance to the North Sea) or presence of local sources. The
unidentified mass is only in the order of 15% showing that the composition of PM10
in the region is rather well known.
PM10 concentrations are systematically higher at urban sites. Roughly, every
constituent in PM10 appears higher in the urban area. The reduced dispersion in
urban areas and the presence of dominating (anthropogenic) sources are the main
reasons. However, the locations and distance between the rural and urban site may
also have influenced the analysis. For instance, the higher urban concentrations of
sea salt are induced by a closer proximity to the coast, though a small gradient in
salt may be explained by the resuspension of road salt in winter. Elementary carbon
in cities primarily originates from diesel emissions. The organic mass is a very
complex group with anthropogenic and natural sources. Although Robinson et al.
[
28
] showed that photo-oxidation of diesel emissions rapidly generates organic
aerosol ten Brink et al. [
13
], indicated that only one-third of the OC in a Dutch city
was due to fossil fuel combustion. Hence, the origin of OM remains unclear.
