Chemistry of south polar snow

The chemical composition of trace impurities present in recent Antarctic snow is reviewed and interpreted. In coastal areas, sea salt is found to be important, while at the South Pole this contribution is much lower (10–15% of the bulk deposition). Insoluble impurities play a negligible role. Gas-derived ions (SO4, NO3, NH4, Cl) are the major components deposited in central Antarctica, the anions forming the more important fraction. When considering the ionic budget of these impurities, the proton is dominant. The Antarctic snow meltwater can therefore be described as a very diluted mixture of natural acids (most likely H2SO4 and HNO3) containing a small amount of neutral salts. The possible sources of all these chemical species are briefly discussed.