Air and Precipitation Quality and Trends in Europe Results of the EMEP Network

Summary

Results of the EMEP network consisting of 87 background stations in 24 countries are summarized in this presentation. The large-scale spatial distribution of S and N compounds is shown in maps for 1985. The areas of maximum concentrations of SO₂ and NO₂ compare well with major emission areas in Europe. Wet deposition patterns of non-marine sulfate, nitrate and ammonium are mainly governed by their concentration fields and less by the precipitation amount.

After international agreements on sulfur and oxidized nitrogen emission reduction have been signed by most European countries it is important to investigate how the changes in emissions affect concentration and deposition levels observed. By a single station statistic looking at averages or frequency distributions no significant trend could be observed. First a stratification of the data from different stations into subsets with back trajectories from a common area made it possible to relate a downward trend in concentration to a reduction in emission. In western Europe sulfur concentrations in air and precipitation have decreased.