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Author |
Benassai, S., S. Becagli, R.Gragnani, O. Magand, M. Proposito, I. Fattori, R.Traversi, R. Udisti |
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Abstract |
Sea-salt markers (Na+, Mg2+ and Cl-) were analyzed in recent snow collected at more than 600 sites located in coastal and central areas of East Antarctica (northern Victoria Land Dome C Wilkes Land), in order to understand the effect of site remoteness, transport efficiency and depositional and post-depositional processes on the spatial distribution of the primary marine aerosol. Firn-core, snow-pit and 1 m integrated superficial snow samples were collected in the framework of the International Trans-Antarctic Scientific Expeditions (ITASE) project during recent Italian Antarctic Campaigns (1992 2002). The sampling sites were mainly distributed along coast inland traverses (northern Victoria Land Dome C) and an east west transect following the 2100 m contour line (Wilkes Land). At each site, the snow ionic composition was determined. Here, we discuss the distribution of sea-spray components (Na+, Mg2+ and Cl-) as a function of distance from the sea, altitude and accumulation rate, in order to discover the pulling-down rate, possible fractionating phenomena and alternative sources moving inland from coastal areas. Sea-spray depositional fluxes decrease as a function of distance from the sea and altitude. A two-order-of-magnitude decrease occurs in the first 200 km from the sea, corresponding to about 2000 ma.s.l. Correlations of Mg2+ and Cl- with Na+ and trends of Mg2+/Na+ and Cl-/Na+ ratios showed that chloride has other sources than sea spray (HCl) and is affected by post-depositional processes. Accumulation rate higher than 80 kg m-2a-1 preserves the chloride record in the snow. Seaspray atmospheric scavenging is dominated by wet deposition in coastal and inland sites. |
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