Carbon dating reveals a seasonal progression in the source of particulate organic carbon exported from the Greenland Ice Sheet

T. J. Kohler*, J. D. Žárský, J. C. Yde, G. Lamarche-Gagnon, J. R. Hawkings, A. J. Tedstone, J. L. Wadham, J. E. Box, Alex D Beaton, Marek Stibal

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

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Abstract

Surface melt from the Greenland Ice Sheet (GrIS) collects particulate organic carbon (POC) as it drains into subglacial environments and transports it downstream where it serves as a microbial substrate. We hypothesized that older POC is entrained by meltwaters as the subglacial drainage network expands upglacier over the summer. To test this, POC samples were collected from a meltwater river exiting the GrIS over an ablation season and 14C dated. Resulting values were compared with meltwater hydrochemistry and satellite observations of the catchment area. We found that POC ages increased from ~5000 to ~9000 years B.P. until peak discharge and catchment size. Afterward, significant fluctuations in POC age were observed, interpreted to result from periods of high and low subglacial hydrological pressure and sediment supply and subsequent exhaustion. These observations suggest a seasonal progression in the source of POC exported from the GrIS and provide evidence for a seasonally evolving subglacial drainage system.

Original languageEnglish
Pages (from-to)6209-6217
Number of pages9
JournalGeophysical Research Letters
Volume44
Issue number12
Early online date22 Jun 2017
DOIs
Publication statusPublished - 28 Jun 2017

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Keywords

  • glacial hydrology
  • Kangerlussuaq
  • Leverett Glacier
  • meltwater export
  • particulate organic carbon
  • subglacial drainage system

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