Chemistry of sea-salt particles and sea-salt fractionation in Antarctic region

Abstract

Observations of aerosol constituents and acidic gases were carried out at Syowa Station (1997-1998 and 2003-2006; JARE-38～ 39, and JARE-44～ 47) and Dome Fuji Station (1997, JARE-38). Seasonal variations and size distribution of sea-salt particles were compared between coastal and inland stations. Seasonal variations of the concentrations of sea-salt particles showed a minimum in the austral summer and higher during the winter at both stations due to strong winds and long-range transport. Sea-salt particles were mostly distributed in fine (D_p: 0.2-2.0 μm) and ultra-fine (D_p and below the detection limit (BDL)-1.5 nmol m^, respectively. Sea-salt fractionation (SO_4^ depletion) due to Mirabilite formation was identified not only at Syowa Station but also at Dome Fuji Station. Seasonal variation of molar ratio of Mg^ Na^+ showed higher ratios at lower temperature. The range and temperature dependence of Mg^ Na^+ strongly suggested that other sea-salt fractionation (e.g., formation of gypsum and hydrohalite) occurred in the Antarctic coasts in addition to Mirabilite formation. Because of different seasonal variation and range of Mg^ Na^+ between Dome Fuji and Syowa Stations, sea-salt fractionation may proceed even in the inland area.