Spatial and Temporal Variations of Snow Chemistry in Terre Adélie (East Antarctica) release_y5gctqk76bhzzhvtma2fpfogie

Abstract

The chemistry of recently deposited snow sampled in 1982–83 along a 430 km coast-interior traverse in Terre Adelie, East Antarctica, is reported. In addition, three firn samples, covering the same time period (1959 to 1969) and collected on the traverse at D 55, D 80 and Dome C stations, respectively at 200, 430 and 1070 km from the sea, are also studied. Concentrations of major soluble impurities (H<jats:sup>+</jats:sup>, <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:href="S0260305500005851_inline1" xlink:type="simple" />, Na<jats:sup>+</jats:sup>, K<jats:sup>+</jats:sup>, Cl<jats:sup>−</jats:sup>, <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:href="S0260305500005851_inline2" xlink:type="simple" /> and <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:href="S0260305500005851_inline3" xlink:type="simple" />) were determined by ion chromatography (except H<jats:sup>+</jats:sup> which was titrated) on more than 200 samples. Conditions of sampling and analysis were carefully controlled in order to avoid contamination problems. A balanced ionic budget was generally obtained for each of the samples. For stations occupying an intermediary position between the coastal areas and the central Antarctic plateau, our results demonstrate that the two major impurities are H<jats:sub>2</jats:sub>SO<jats:sub>4</jats:sub> and HNO<jats:sub>3</jats:sub>. HCl is also present, but at a lower level of concentration; the sea-salt contribution is dominant only at the most coastal sites (within 40 km) of the sea. The degree of neutralization of the snow acidity by NH<jats:sub>3</jats:sub> is always very low as indicated by the values of <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" mime-subtype="gif" xlink:href="S0260305500005851_inline1" xlink:type="simple" /> content. The mean concentrations of H<jats:sub>2</jats:sub>SO<jats:sub>4</jats:sub> along the traverse are relatively constant whereas an increase of the HNO<jats:sub>3</jats:sub> concentrations is observed when going inland. It decreases, however, in most central areas. These results are discussed in relation to the glaciochemical data published for other locations on the Antarctic plateau, in particular the sulphate concentrations which depend strongly on explosive volcanic activity.
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