English Abstract The statistical atmospheric transport model TREND has
been applied for the calculation of concentrations and depositions of
ammonia (NH3) and ammonium (NH4). The model is capable of describing
dispersion, conversion and deposition from both local sources and from more
distant sources. Detailed calculations have been made for the Netherlands
(5x5 km2 grid), Belgium, the F.R.G. and Denmark and less detailed
calculations for the rest of Europe (75x75 km2). Model results show that in
areas with relatively high emission densities dry deposition is the
dominating form of deposition, whereas in areas with lower emission
densities - most of Europe as well as at sea -, wet deposition is more
important. An extensive comparison of model results with available
measurements in the Netherlands as well as in Europe has been carried out.
In general the model results agree well with the measurements. It is shown,
that for a correct reproduction of measured NH3 concentrations a very
detailed emission inventory (on a 5x5 km2 grid or better) is required.
Predictions of NH4 concentrations and wet depositions are less sensitive to
the spatial resolution of the emission inventory used. About 80% of the
total deposition of NH3 and NH4 in the Netherlands is caused by domestic
sources and the Netherlands exports 3.8 times as much NH3+NH4 as it
imports.
