Size-segregated aerosol samples were collected with a high-volume 6-stage cascade impactor at Sodankylä, Finland, 100 km north of the Arctic Circle. The (210)Pb content of the samples were determined with radiochemical separation of in-grown (210)Po followed by alpha spectrometry. Most of the (210)Pb activity was incorporated in accumulation mode aerosol particles. The activity median aerodynamic diameter (AMAD) ranged from 0.53 µm to 0.98 µm 38-61 per cent of (210)Pb activity was found to be associated with aerosol particles smaller than 0.69 µm. A slight downward tendency of (210)Pb activity median aerodynamic diameter was observed as a function of increasing (210)Pb activity concentration. This is related to the continental origin of airborne (210)Pb on one hand, and various aerosol particle growth processes on the other hand. Also a clear tendency towards a higher (7)Be/(210)Pb activity ratio as a function of increasing aerosol particle diameter was observed. This, in turn, reflects the different origin of (210)Pb, exhalation of (222)Rn from the soil into the air, and (7)Be, formation by cosmic radiation in the upper troposphere and the stratosphere.
