National scale modelling of the concentration and deposition of reduced nitrogen and its application to Poland

The relative contribution of reduced nitrogen in acid and eutrophic deposition in Europe has been recently increasing as a result of SO2 and NOx emissions abatements. For Poland, the main source of spatial information on dry and wet deposition of NHx is the EMEP model with a coarse 50 km x 50 km grid which may be insufficient for national scale studies, as the NHx emissions, concentrations and depositions vary considerably over a short distance. The FRAME model is used to calculate the spatial patterns of annual average NHx air concentrations and depositions with a 5 km x 5 km grid. The results correlate well with available measurement and with spatial patterns of concentrations and depositions of NHx reported with the EMEP, but show higher spatial variability. The differences in deposition budgets calculated with FRAME and EMEP are less than 17% for wet and 6% for dry deposition. The differences between FRAME and the Polish Chief Inspectorate of Environmental Protection interpolation based wet deposition budget is 3%. Up to 93% of dry and 53% of wet deposition of NHx comes from national activities. The western part of Poland and the mountains in the south are strongly influenced by the NHx deposition from transboundary transport.