Long-term trends in emissions and transboundary transport of acidifying air pollution in Europe

Abstract

The time evolution of the atmospheric emissions and depositions of sulphur and nitrogen compounds in Europe have been studied in this paper. Source-receptor matrices, which quantify the transboundary transport between the European countries, are presented. The temporal evolution of exceedances of the critical loads have also been analysed. The present (1995) emission and deposition levels are also presented. The database utilized in this study is the one presently employed under the 1979 Geneva Convention on Long Range Transboundary Air Pollution. The emission data reported to EMEP indicate that the European sulphur emissions declined by approximately 50% during the period 1980-1995. Larger reductions were found in the area of the Former Soviet Union and western Europe than in central eastern Europe. For oxidized and reduced nitrogen the overall European reductions were approximately 15% from 1980 to 1995. Both oxidized and reduced nitrogen emissions fell more in eastern Europe than in western Europe. The corresponding declines in total deposition to all grid cells in the the EMEP domain have been calculated with a two-dimensional trajectory model for the period 1985-1995. The percent reductions were 34, 9 and 12% for sulphur, oxidized and reduced nitrogen, respectively. The deposition reductions are 5, 1 and 6% smaller than the emission reductions during this period for sulphur oxidized and reduced nitrogen. We have further found that the total area affected by exceedances of acidifying sulphur and nitrogen was about 20% in the mid eighties, but it has dropped to approximately 10% in 1995. The area affected by exceedances of eutrophying nitrogen has, on the other hand, remained approximately at a little less than 30% throughout the whole period. The reductions in the total area of exceedance are consistent with the emission trends. The two-dimensional trajectory model has also been used to derive source-receptor matrices for the European countries for the period 1985-1995. The matrices clearly show that the atmospheric transport over distances of 1000-2000 km are very significant in particular for sulphur and oxidized nitrogen, and many countries in Europe receive most of the acidifying compounds from emissions in other countries.