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

Kohler, T.J.; Žárský, JD.; Yde, J.C.; Lamarche-Gagnon, G.; Hawkings, J.R.; Tedstone, A.J.; Wadham, J.L.; Box, J. .; Beaton, A.D.; Stibal, M.. 2017 Carbon dating reveals a seasonal progression in the source of particulate organic carbon exported from the Greenland Ice Sheet. Geophysical Research Letters, 44 (12). 6209-6217. 10.1002/2017GL073219

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Abstract/Summary

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.

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1002/2017GL073219
ISSN: 00948276
Additional Keywords: meltwater export; particulate organic carbon; glacial hydrology; subglacial drainage system; Kangerlussuaq; Leverett Glacier
Date made live: 22 Aug 2017 09:30 +0 (UTC)
URI: http://nora.nerc.ac.uk/id/eprint/517652

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