SPATIAL AND TEMPORAL VARIATIONS OF METHANESULFONIC-ACID AND NON-SEASALT SULFATE IN ANTARCTIC ICE

A simultaneous glaciochemical study of methanesulfonic acid (MSA) and non-seasalt sulfate (nss-SO4-) has been conducted on the Antarctic plateau (South Pole, Vostok) and in more coastal regions. The objective was to investigate marine sulfur emissions in very remote areas. Firstly, our data suggest that MSA and nss-SO4 present in antarctic ice are mainly marine in origin and that DMS emissions have been significantly modulated by short term (eg. El Nino Southern Oscillation events) as well as long term climatic changes in the past. Secondly, our study of spatial variations of these two sulfur species seems to indicate that the atmosphere of coastal antarctic regions are mainly supplied by local DMS emissions whereas the atmosphere of the high plateau is also influenced by DMS emissions from more temperate marine latitudes. Thirdly, our study of the partitioning between MSA and nss-SO4 suggest that the temperature could have been an important parameter controlling the final composition of the high southern latitude atmosphere over the last climatic cycle ; colder temperature favoring the formation of MSA. However, our data also support a possible role played by changes in the transport pattern of marine air to the high antarctic plateau.