Abstract:

Following completion of the inland survey 35th Chinese National Antarctic Research Expedition, samples from four snow pits along the route from the Zhongshan Station to Dome A section in East Antarctica were analyzed using ion chromatography and major anions and cations concentrations were obtained. Stratigraphic dating (1962–2018) was attempted for a snow pit in Dome A based on seasonal variations of volcanic markers. Temporal and spatial analysis of snow pit ion concentrations show that Cl^– and Na⁺ concentrations in coastal areas were higher because they were affected by marine sources. A gradual increase of the Cl^–/Na⁺ ratio from the coast to inland areas indicates that Cl^– had other sources or was affected by volatile HCl deposition. The high concentrations of  SO₄^2– inland may be associated with the low accumulation of snow or the long-distance input of SO₄^2– from mid-and low-latitude regions. Non-sea salt sulfate (nssSO₄^2–) accounted for over 90% of SO₄^2– in snow pits above 2000 m, which indicates that long-distance input of nssSO₄^2– was the main source of SO₄^2– in high altitude areas. NO₃^– concentrations were complex and showed a large spatial heterogeneity because of accumulation rate, downwind and post-deposition effects. The high NO₃^– concentration in a snow pit 800 km away from the coast was presumed to be caused by landforms, solar radiation area and 800 km from the coast showed different seasonal characteristics, but there were no obvious seasonal trends in samples from the 520 km or the inland area, which is considered the result of a combination of source, downwind, and post-deposition effects and the accumulation rate. The formation of high salinity “frost flower” and blowing salty snow on sea ice may be a plausible mechanism behind the increase of sea salt ion content in the coastal area.

Key words:

Zhongshan Station-Dome A transect, snow pit, snow chemistry, ionic concentration, seasonal variations