Chemistry Reference
In-Depth Information
Fig. 4 Modelled distribution of PM10 across Europe for 2007-2009 excluding mineral dust
the model does not include a relevant process description. The uncertainties in the
process description including secondary organic aerosol formation and the semi-
volatile nature of OM are so large that they are not considered robust enough to
incorporate in a source apportionment study. Model to observation comparison
shows no significant biases for sulphate, ammonium and sea salt. Hence, the source
apportionment presented here covers about 60% of the observed PM mass.
The source apportionment is performed for each component separately. Figure
5
shows the source attribution per sector for the most important PM components
averaged across the Netherlands. Some components are dominated by a few sectors.
Agriculture is by far the most important source of ammonium, causing over 90% of
the emissions and concentration of this substance in the Netherlands. The mineral
dust concentration in the Netherlands originates for about 25% from outside the
model domain which is mainly associated with a few desert dust episodes. The
remaining mineral dust is equally divided between agriculture and road transport.
The unspecified primary particulate mass is dominated by industrial process
emissions. Nitrate, sulphate and EC concentrations originate mainly from sectors
in which fuel combustion is important (e.g. transport, industrial combustion and
power generation). For the other components, the sector origin is more diffuse.
Summing all separate contributions allows to assess the origin of the modelled
total mass. The most important contributions to total PM10 mass in this region are
associated with agriculture, on-road and off-road transport and natural sources.
Together these explain about 75% of the modelled mass. Secondary contributions
