DETERMINATION OF ACIDIC SULFATE AEROSOLS IN URBAN ATMOSPHERES IN ERFURT (FRG) AND SOKOLOV (FORMER CSSR)

Acidic sulfate aerosols were sampled from the atmosphere with the Harv ard Impactor-Honeycomb Denuder System. This sampler incorporates a cit ric-acid-coated denuder to remove NH3 and an impactor with a 50% size cutoff of 2.5 mu m (d(a)). Fine particles were collected on a Teflon f ilter. The sampling (24 h) lasted from December 1990 until June 1992. The sampling sites were in Erfurt and Sokolov, two eastern European ci ties with high SO2 concentrations. At the same time approximately 230 asthmatic children and adults were followed by daily peak flow measure ments and symptom diaries. Despite the high SO2 pollution with daily a verages of 62 mu g m(-3) and peaks of nearly 500 mu g m(-3), the mean SO42- concentration for Erfurt, 9.8 mu g m(-3), and that for Sokolov, 8.9 mu g m(-3), were moderate. In addition, the average H+ concentrati on over the entire period was low in Erfurt (0.3 mu g m(-3), H+ as H2S O4) as well as in Sokolov (0.4 mu g m(-3)). H+ concentrations tended, however, to be higher during the cold winter months and the hot summer months. In Sokolov, there were three episodes in the winter when meas urements exceeded 3.5 mu g m(-3). The measurements suggest that the en vironmental conditions in Erfurt and Sokolov produce a low SO2 oxidati on rate and have a high H2SO4 neutralization potential. Daily PM(10) c oncentrations (59.90 mu g m(-3) in Erfurt and 53.8 mu g m(-3) in Sokol ov) were in the same range for both cities with higher values in winte r. Of note was the decrease of all pollutants during the period of obs ervation.