The ephemeral nature of the Antarctic Cotton Glacier fluvial system provides a unique environment where recalcitrant carbon does not accumulate over time as in other water bodies, making it a natural laboratory to examine the formation and conditioning of dissolved organic matter (DOM) over time. For two austral summer seasons we studied the ecology and biogeochemistry of a supraglacial stream on the Cotton Glacier. Using high pressure size exclusion chromatography (HPSEC), Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS), and excitation emission matrix fluorescence spectroscopy (EEMs) we show evidence of the formation of humic-like molecules over time. Evidence for compositional shifts in molecular formulae (chemical species containing combinations of CcHhNnOoSs), an increase in molecular size, and the appearance of humic-like fluorescence after ageing will be presented, with discussion of the underlying chemical reactions that govern the role of these materials in major biogeochemical cycles.

Transformations in autochthonous DOM: An Antarctic supraglacial case study

249th National Meeting (2015)

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