During austral summer 1998, aerosol particles were sampled at the Finnish station Aboa in continental Antarctica. The collected aerosol samples were analyzed for major inorganic ions, methane sulphonate, and dicarboxylates. Measured ions composed on average about one third of the total gravimetric mass in fine particulate matter (particle diameter 80--90%) were shown to be smaller than ~0.1 μm in diameter. ¿ 2000 American Geophysical Union