Chemistry of sea‐salt particles and inorganic halogen species in Antarctic regions: Compositional differences between coastal and inland stations

Observations of aerosol constituents and acidic gases in the Antarctic area were carried out at Syowa (39.58°E, 69.00°S) in 1997 and 1998 and Dome Fuji stations (39.62°E, 77.37°S) in 1997. Sea‐salt concentrations decreased to background levels in the summer at both Syowa (Na + , ≤4 nmol m −3 ) and Dome Fuji (Na + , ∼0.44 nmol m −3 on average). During the winter, blizzard and strong wind may cause an increase of sea‐salt particles at Syowa, whereas long‐range transport from the boundary layer at midlatitudes and coastal Antarctic regions may contribute significantly to the increase in sea‐salt particles observed at Dome Fuji. Particulate Cl − and Br − are liberated preferentially from sea‐salt particles at Syowa and Dome Fuji in the summer. The molar ratio of Cl − /Na + and Br − /Na + at Syowa decreased to ∼0.5 and ≈0, respectively, in summer. At Dome Fuji more Cl − tend to be liberated from sea‐salt particles thorough heterogeneous NO 3 − formation. The concentrations of gaseous chlorine species (mostly HCl) and bromine species ranged from 0.2 to 5.3 nmol m −3 and below detection limit (BDL) to 1.5 nmol m −3 , respectively, corresponding to sea‐salt modification. In the present study, SO 4 2− depletion due to mirabilite formation was observed not only at Syowa but also at Dome Fuji. This evidence suggests that SO 4 2− depletion might occur through sublimation on snow surfaces in addition to seawater freezing. At Syowa, sea‐salt fractionation relating to Mg 2+ , K + , and Ca 2+ was also observed mostly under strong wind conditions.