Determination of acidic sulfate aerosols in urban atmospheres in Erfurt (F.R.G.) and Sokolov (Former C.S.S.R.)

Abstract

Acidic sulfate aerosols were sampled from the atmosphere with the Harvard Impactor-Honeycomb Denuder System. This sampler incorporates a citric-acid-coated denuder to remove NH 3 and an impactor with a 50% size cutoff of 2.5 μm ( d a). Fine particles were collected on a Teflon filter. The sampling (24 h) lasted from December 1990 until June 1992. The sampling sites were in Erfurt and Sokolov, two eastern European cities with high SO 2 concentrations. At the same time approximately 230 asthmatic children and adults were followed by daily peak flow measurements and symptom diaries. Despite the high SO 2 pollution with daily averages of 62 μg m −3 and peaks of nearly 500 jug m −3, the mean SO 4 −2 concentration for Erfurt, 9.8 μg m −3, and that for Sokolov, 8.9 μg m −3, were moderate. In addition, the average H + concentration over the entire period was low in Erfurt (0.3 μg m −3, H + as H 2SO 4) as well as in Sokolov (0.4 μg 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 measurements exceeded 3.5 μg m −3. The measurements suggest that the environmental conditions in Erfurt and Sokolov produce a low SO 2 oxidation rate and have a high H 2SO 4 neutralization potential. Daily PM 10 concentrations (59.90 μg m −3 in Erfurt and 53.8 μg m −3 in Sokolov) were in the same range for both cities with higher values in winter. Of note was the decrease of all pollutants during the period of observation.