The Berlin smog project—Description and summary of results

Abstract

The composition of ambient air pollution, emphasising the ambient particulate matter, has been investigated for 14 wintertime smog periods (SO 2 and/or suspended particulate concentrations exceeding 400 μg m −3) in Berlin (West). The total aerosol mass concentration, the SO 2, CO, NO and NO 2 and pertinent meteorological parameters were measured. For chemical characterization the aerosol was collected by hi-volume, low-volume samplers and cascade impactors. The samples were analysed for the metals Pb, Cd, Mn, Ni; the water soluble ions: NH 4 +, SO 4 2−, NO 3 −; and the PAH's: Fl, Py, Per, BaP, BghiP and Cor. The aerosol size distribution (0,01 < d p < 20 μm) was measured by a combination of electrical and optical analysers with a time resolution of 10 min. The smog periods lasted from 6 to 100 h and occured during anticyclonic conditions with restricted vertical mixing and low to moderate wind velocities. The smog producing pollutants originated either in the city of Berlin or in the industrial regions 100–200 km away. Ambient air quality standards were exceeded by SO 2 (highest 24-h concentration: 760 μg m −3), NO x (320), TSP (930) and SO 4 2− (190). BaP levels of up to 92 μg m −3 were measured. The total sulfate level increases with the SO 2 concentration and exceeds 100 μg m −3 for SO 2 levels above 600 μg m −3. In 40% of all cases the aerosol sulfate seems to be more acidic than (NH 4)HSO 4. The secondary aerosol fraction, i.e. the sum of SO 4 2−, NH 4 + and NO 2 − ranges from 23 up to 65% of TSP and is related to the age of the pollutants. The composition of the pollutants reflects the different emission patterns of the various source regions and chemical conversions during the trip from the sources to the measuring station. Therefore, the patterns of the composition of the pollutants provide a means to apportion the pollutants among contributing source regions. Thus, it seems possible to develop a scheme to determine during an ongoing smog condition the major contributing source region on the basis of real time measurements of selected physical and chemical parameters of ambient pollutants.