ATMOSPHERIC AEROSOL IN THE FINNISH ARCTIC - PARTICLE NUMBER CONCENTRATIONS, CHEMICAL CHARACTERISTICS, AND SOURCE ANALYSIS

Atmospheric aerosols have been measured in Finnish Lapland from Januar y 1992 to June 1994. A seasonal cycle in particle number concentration , measured using a condensation particle counter, is observed. Aerosol samples have been collected by a virtual impactor (VI) in two size ra nges. The filters have been changed every 48 hours. Most fine particle samples are acidic: 91% of the measured anions (neq/m(3)) to measured cations (neq/m(3)) ratios are above one. According to a trajectory st atistical analysis, high sulphate concentrations come to Finnish Lapla nd from all of continental Europe. The source areas of the highest obs erved ammonium concentrations are in Western Europe.