Long-term trends in chemistry of precipitation after longscale transport-effects of atmospheric rehabilitation in East-Germany

Components in precipitation are dominantly dependent on structure and quantity of emissions on the course of the rainy air masses. It can be proved after meso-and long-range transport. Starting in 1982, precipitation is collected in 4-hour-periods at sites far from industry in East-Germany. For regions with specific geographical or uniform emission features arrival sectors are established, e. g. former GDR, Scandinavia, Poland, or Czech. The classification of the samples is done by back-trajectories. From the former GDR the anthropogenical components were most significantly raised before the political change, but acidity remained on an average level. After the change, the most emission products decline considerably —except NO_X. Consequently, those lead to essential changes of pollutants in precipitation. The reduction is not uniformly. The report represents long-term data and discusses clear differences between components in deposition from sectors of the former GDR and West-Germany. The effects of atmospheric rehabilitation are analysed. Specially starting in 1993 the acidity of rain from the former GDR increases very strikingly up to now threefold more than from West-Germany (average ≤pH 4 at some sites). An explanation in terms of emission components only is devious, a complex consideration of change of dust composition as neutralizing factors and of processes of cloud formation and dispersal is necessary. It must be mentioned, that the acidity of precipitation from West-Germany and Scandinavia declines slightly in recent period. Therefore only sector-classified data show the real range of acidity.