ATMOSPHERIC RESEARCH-PROGRAM FOR STUDYING CHANGING EMISSION PATTERNS AFTER GERMAN UNIFICATION

A dramatic decrease in emission of sulphur dioxide (SO2, 60%), dust (8 2%), nitrogen oxide (NO, 30%) and other pollutants (hydrochloric acid (HCl); ammonia (NH3)) has been observed in East Germany after German u nification in 1989. The smaller decrease in total NO is due to signifi cant increase of NO from traffic. Air-pollutant concentrations in both parts of Germany before and after 1989 will be compared and their dev elopment will be discussed, based on precipitation and cloud chemistry data from long-term continuous record. Sectoral rain data, based on b ackward trajectory calculations, clearly show that the significant dec line in annual volume weighted precipitation ions (sulphate, calcium, ammonium,chloride) in rain water from sector ''East'' since 1989 and p articularly since about 1992 is roughly correlated with a similar perc entage decline in SO2, dust and NH3 emissions for the region East Germ any. The acidity of the precipitation from sector ''East'' has increas ed very strikingly from 1993 up to 1995 threefold more than from secto r ''West''. Despite the strong decrease in SO2 emission, this decrease of the atmospheric neutralising capacity was caused by the much steep er decline in atmospheric base cations in that region. Precipitation d ata from all transport directions show high variation, but no signific ant trend in the annual average H+ ion concentration. At Mt. Brocken t he annual average volume weighted cloud-water acidity during frost-fre e periods increased by a factor of three between 1992 and 1995. This r esult, confirmed also by the annual frequency distributions of the pH values, reflects the atmospheric pollutant loading also from all entry sectors. After 1995 this trend is reversed. Detailed classification o f the cloud-water data by entry sector, and by meteorological and espe cially microphysical factors is currently being carried out and prelim inary results are presented. (C) 1998 Elsevier Science Ltd. All rights reserved.