On the Composition and Origin of Large and Giant Particles Observed at Syowa Station,Antarctica

Large and giant aerosol particles were collected by means of a single-stage impactor at Syowa Station and their composition was examined with scanning electron and optical microscopes, X-ray diffraction and phase transition methods. Large and giant particles in the winter season were found to consist mainly of NaCl, Na_2SO_4・10H_2O, MgSO_4・6H_2O, CaSO_4・2H_2O, etc. These components must be of sea salt origin. The increase of these sea salt particles was accompanied by cyclonic snowstorms (blizzard). On the other hand, their concentrations were smaller in the summer season than in the winter season, and another component besides those of the sea salt origin was found in the summer antarctic atmosphere. From the results of X-ray diffraction of the summer samples, this component is considered to be ammonium sulfate