Spatial Variability of Glaciochemistry along a Transect from Zhongshan Station to LGB69, Antarctica

Weilong Huang,Cunde Xiao,Robert Mulvaney,Zuoqin Qian,Yujia Zhang,Ming Yan,Chunlei An,Leibao Liu

doi:10.3390/atmos12030393

Abstract

The spatial glaciochemical variability of snow samples collected along a transect from Zhongshan Station to Lambert Glacier Basin 69 (LGB69) in Antarctica was investigated. Sea-salt ion concentrations exponentially decreased with increasing distance from the coast and/or altitude. The observed high sea-salt ion concentrations within 20.6 km of the coast may be related to preferential wet or dry deposition of sea-salt aerosols. Methanesulfonic acid (MSA), non-sea-salt sulfate (nssSO42−), and calcium (Ca2+) concentrations decreased along the transect. The mean MSA/nssSO42− value of the surface snow samples (0.34 ± 0.08) indicates that coastal sea areas are their likely source regions. The non-sea-salt Ca2+ (nssCa2+)/Ca2+ percentages of the surface snow and LGB69 snow pit samples reveal that continental dust is the primary Ca2+ source. The δD and δ18O values decreased from the coast inland. The variation of deuterium excess (d-excess) along the transect was stable and d-excess values in the two snow pit samples were low and similar, which indicates that the moisture source region between Zhongshan Station and LGB69 is a coastal sea area. These results reveal the spatial distribution patterns and sources of ions and stable isotopes, as well as factors that influence the deposition of ions and the composition of stable isotopes, which provide important insight for further studies of ice cores drilled in Antarctic coastal regions.

Highlights

The ionic and isotopic compositions of Antarctic snow can serve as important indicators of environmental and climatic information [1]
When the abnormally negative and high Methanesulfonic acid (MSA)/nssSO42− ratios within 20.6 km were removed, the mean MSA/nssSO42− value of the surface snow samples from Zhongshan Station to Lambert Glacier Basin 69 (LGB69) was 0.34 ± 0.08 (Figure 6), which was in agreement with the MSA/nssSO42− ratios observed in the marine atmospheric boundary layer near coastal Antarctica, implying that the source regions of the MSA and nssSO42− from Zhongshan Station to LGB69 are likely coastal sea areas
This study reports the spatial distribution patterns and sources of ions and stable isotopes as well as factors that influence the deposition of major ions and the composition of stable isotopes in surface snow and snow pit samples obtained along a transect from Zhongshan Station to LGB69, East Antarctica

Summary

Introduction

The ionic and isotopic compositions of Antarctic snow can serve as important indicators of environmental and climatic information [1]. Previous investigations of stable isotopes from surface snow samples along the transect from Zhongshan Station to Dome A showed that δD and δ18O values negatively correlated with distance from the coast and altitude and that the δD/δ18O ratio was lower than that of the Global Meteoric Water Line (GMWL) and the mean value for Antarctica (7.75) [24,26]. This study fills in a gap of snow chemistry investigation within 20.6 km distance from the coast along the transect from Zhongshan Station to Dome A, and contributes to the interpretation of long-term chemical records obtained from ice cores drilled in the coastal regions of Princess Elizabeth Land. L156 LH404 LH397 LH386 LGB72 LT987 LT981 LT976 LT971 LT966 LT961 LT956 LT951 LT946 LT941

Sample Analysis

Results and Discussion

Conclusions