PARTICLE SIZE-DEPENDENT CONCENTRATIONS OF POLYCYCLIC AROMATIC-HYDROCARBONS

Particle size-dependent concentrations of PAHs from outdoor air sampli ng were measured. Size-segregated samples were collected at the outski rts of Munich in October 1994, A five-stage high-volume cascade impact or (HVS, particle diameter D-P < 10 mu m, 810 l min(-1)) and two Berne r-type low-pressure cascade impactors (LPI, 79 l min(-1), six-stage, D -P = 0.04-21 mu m and 291 min(-1), nine-stage, D-P = 0.06-16 mu m) wer e used. Eleven PAHs were quantified by HPLC with fluorescence detectio n. The concentrations of lead, bromine, zinc, sulfur and iron were mea sured by PIXE analysis, Particle number-concentrations in the range D- P = 0.01-1 mu m were measured with a differential mobility analyser (D MA), The concentrations of the PAHs in particulate matter were in the range 0.8-3.8 ng m(-3). The concentrations found in the LPI samples al ways were higher than those in the samples taken with the HVS, The dif ferences were in the range 30-63%, The results for the two LPI were in good agreement, The size-dependent PAH concentrations were similar wi th all three samplers, With the HVS, about 60 % of the PAHs were found on the back-up filter (D-P < 0.66 mu m). In the LPI samples 40% of th e total PAHs were found on particles with Dp = 0.13-0.50 mu m. Lead, b romine, zinc and sulfur showed the same distribution as the PAHs where as iron had its maximum concentration at D-P = 2-4 mu m. The measureme nts with the DMA gave unimodal distributions with the maximum in parti cle mass at D-P = 0.22-0.28 mu m.