ABSTRACT: Supraglacial sulphur springs supporting a diverse microbial rcosystem, Borup Fiord Pass, Ellesmere Island.

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Abstract

Borup Fiord Pass (81°N, 81°W) is home to unique sulfur-rich springs which discharge onto the surface of glacial ice, releasing H2S and forming deposits of elemental sulfur (S°), calcite, and gypsum, as well as the rare carbonate mineral vaterite. Springs occur on the southern end of a prominent valley glacier, but discharge sites vary significantly from year to year. Stratified layers of elemental sulphur are observed in proglacial icings suggesting that spring discharge may be perennial. Springs are Na-Cl rich saline waters (7000 mg/l TDS) that discharge at up to 8.4 l/s. The measured level of dissolved H2S, 143 mg/l, is one of the highest reported for any sulphur spring in Canada. A thriving microbial community has been detected in the spring water and mineral deposits, with rapid cycling of sulfur between three oxidation states, as well as measured changes in S-isotopic signatures in the spring waters, indicating a complex series of biologically mediated redox reactions. Sulphur isotope data indicate that evaporites of the Otto Fiord Formation are the likely source of sulphur in the system, necessitating deep groundwater circulation under glaciated mountains in a region of over 500 m permafrost. Preliminary analysis of the clone library generated shows that some of the 16s rRNA sequences correlate well with known groups of sulfate-reducing microorganisms (e.g. classes of delta-Proteobacteria), while a small fraction of the total sequences do not correspond with any in the public databases. The large-scale annual precipitation of S° on the ice provide a geochemical biosignature extensive enough to be detected from orbital measurements.

Bibliography of Canadian Geomorphology