Stable isotope evidence for the biogeochemical transformation of ancient organic matter beneath Suess Glacier, Antarctica

Joel D. Barker, Andréa G. Grottoli, W. Berry Lyons

Research output: Contribution to journalArticlepeer-review

Abstract

Glaciers overrun organic matter (OM) during periods of advance, making this overrun OM available as a metabolic substrate for subglacial microbes. The biogeochemical fate of this overrun OM remains poorly understood, ultimately limiting our understanding of subglacial biogeochemical cycling, particularly for cold-based glaciers. This study presents evidence for the biogeochemical transformation of algal mat material that was overrun by a cold-based glacier (Suess Glacier, Taylor Valley, Antarctica) during its advance 4840–3570 years BP. We use a suite of stable isotope analyses to show that active nitrogen cycling has depleted N-isotope values to amongst the lowest reported in Taylor Valley (-15.59 ‰) from an initial value of ~-1.88 ‰, while potentially depleting C-isotope values by 2.46 ‰. While this study examines biogeochemical conditions beneath a single glacier, all glaciers export meltwater during the melt season that may host algae and other OM in proglacial streams and lakes that may be overridden during glacier advance. As such, subglacial nitrogen cycling detected here may represent processes that occur in cold zones beneath glaciers generally.

Original languageEnglish (US)
Article numbere1448643
JournalArctic, Antarctic, and Alpine Research
Volume50
Issue number1
DOIs
StatePublished - Jan 1 2018
Externally publishedYes

Bibliographical note

Funding Information:
Figure 1. The location of the PM sampling site at Suess Glacier, Taylor Valley, Antarctica (77° 38.70′S, 162° 42.61′E). Antarctica base map courtesy of the National Science Foundation (2017).

Keywords

  • McMurdo Dry Valleys
  • basal ice
  • nitrogen cycling
  • stable isotopes
  • subglacial biogeochemistry

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