The impact of precipitation on wet deposition of sulphur and nitrogen compounds

Atmospheric transport model FRAME has been used in this study to estimate the influence of precipitation on the patterns of wet deposition of oxidised sulphur, oxidised nitrogen and reduced nitrogen in Poland during the years 1981-2005. A constant wind and emission data and year-specific spatially interpolated precipitation data was used in the model. The results show that the correlation coefficient between mean annual precipitation totals and mean wet deposition is above 0.9 for all examined compounds. The spatial patterns of pollutant deposition are similar for all years, with the north-western part of Poland receiving the lowest and the southern, mountainous part, the highest pollutant load. The largest precipitation-induced changes in wet deposition budgets are observed for oxidised sulphur (53% of the average amount between wet and dry year), and smaller for oxidised and reduced nitrogen (30%). Inter-annual precipitation changes cause large variations in the amount of wet deposition of pollutants. This means that the emission abatements may not cause immediate environmental effects, eg reductions in deposition of pollutants and, further ecosystems areas of exceeded critical loads.