Atmospheric research program for studying changing emission patterns after German unification

A dramatic decrease in emission of sulphur dioxide (SO2, 60%), dust (82%), nitrogen oxide (NO, 30%) and other pollutants (hydrochloric acid (HCl); ammonia (NH3)) has been observed in East Germany after German unification in 1989. The smaller decrease in total NO is due to significant increase of NO from traffic. Air-pollutant concentrations in both parts of Germany before and after 1989 will be compared and their development will be discussed, based on precipitation and cloud chemistry data from long-term continuous record. Sectoral rain data, based on backward trajectory calculations, clearly show that the significant decline in annual volume weighted precipitation ions (sulphate, calcium, ammonium, chloride) in rain water from sector “East” since 1989 and particularly since about 1992 is roughly correlated with a similar percentage decline in SO2, dust and NH3 emissions for the region East Germany. The acidity of the precipitation from sector “East” has increased very strikingly from 1993 up to 1995 threefold more than from sector “West”. Despite the strong decrease in SO2 emission, this decrease of the atmospheric neutralising capacity was caused by the much steeper decline in atmospheric base cations in that region. Precipitation data from all transport directions show high variation, but no significant trend in the annual average H+ ion concentration. At Mt. Brocken the annual average volume weighted cloud-water acidity during frost-free periods increased by a factor of three between 1992 and 1995. This result, 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 of the cloud-water data by entry sector, and by meteorological and especially microphysical factors is currently being carried out and preliminary results are presented.