Measurement report: Spatial variations in ionic chemistry and water-stable isotopes in the snowpack on glaciers across Svalbard during the 2015–2016 snow accumulation season

Abstract

The Svalbard archipelago, located at the Arctic sea-ice edge between 74 and 81◦ N, is ∼ 60 % covered by glaciers. The region experiences rapid variations in atmo-spheric flow during the snow season (from late September to May) and can be affected by air advected from both lower and higher latitudes, which likely impact the chemical com-position of snowfall. While long-term changes in Svalbard snow chemistry have been documented in ice cores drilled from two high-elevation glaciers, the spatial variability of the snowpack composition across Svalbard is comparatively poorly understood. Here, we report the results of the most comprehensive seasonal snow chemistry survey to date, car-ried out in April 2016 across 22 sites on seven glaciers across the archipelago. At each glacier, three snowpits were sampled along the altitudinal profiles and the collected samples were analysed for major ions (Ca2+, K+, Na+, Mg2+, NH , SO24−, Br−, Cl−, and NO ) and stable water isotopes (δ18O, δ2H). The main aims were to investigate the natural and an-thropogenic processes influencing the snowpack and to bet-ter understand the influence of atmospheric aerosol trans-port and deposition patterns on the snow chemical compo-sition. The snow deposited in the southern region of Sval-bard is characterized by the highest total ionic loads, mainly attributed to sea-salt particles. Both NO and NH in the seasonal snowpack reflect secondary aerosol formation and post-depositional changes, resulting in very different spatial deposition patterns: NO has its highest loading in north-western Spitsbergen and NH in the south-west. The Br−enrichment in snow is highest in north-eastern glacier sites closest to areas of extensive sea-ice coverage. Spatial corre-lation patterns between Na+ and δ18O suggest that the influ-ence of long-range transport of aerosols on snow chemistry is proportionally greater above 600–700 m a.s.l.