Greenland Ice Sheet exports labile organic carbon to the Arctic oceans
Runoff from small glacier systems contains dissolved organic carbon (DOC) rich in protein-like, low molecular weight (LMW) compounds, designating glaciers as an important source of bioavailable carbon for downstream heterotrophic activity. Fluxes of DOC and particulate organic carbon (POC) exported...
| Main Authors: | , , , , , , , , , |
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| Format: | Article |
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Copernicus Publications
2014
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| Online Access: | https://eprints.nottingham.ac.uk/27608/ |
| _version_ | 1848793400710529024 |
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| author | Lawson, Emily C. Wadham, Jemma L. Tranter, Martyn Stibal, Marek Lis, Greg P. Butler, Catriona E.H. Laybourn-Parry, Johanna Nienow, Peter Chandler, David Dewsbury, Paul |
| author_facet | Lawson, Emily C. Wadham, Jemma L. Tranter, Martyn Stibal, Marek Lis, Greg P. Butler, Catriona E.H. Laybourn-Parry, Johanna Nienow, Peter Chandler, David Dewsbury, Paul |
| author_sort | Lawson, Emily C. |
| building | Nottingham Research Data Repository |
| collection | Online Access |
| description | Runoff from small glacier systems contains dissolved organic carbon (DOC) rich in protein-like, low molecular weight (LMW) compounds, designating glaciers as an important source of bioavailable carbon for downstream heterotrophic activity. Fluxes of DOC and particulate organic carbon (POC) exported from large Greenland catchments, however, remain unquantified, despite the Greenland Ice Sheet (GrIS) being the largest source of global glacial runoff (ca. 400 km3 yr−1). We report high and episodic fluxes of POC and DOC from a large (> 600 km2) GrIS catchment during contrasting melt seasons. POC dominates organic carbon (OC) export (70–89% on average), is sourced from the ice sheet bed, and contains a significant bioreactive component (9% carbohydrates). A major source of the “bioavailable” (free carbohydrate) LMW–DOC fraction is microbial activity on the ice sheet surface, with some further addition of LMW–DOC to meltwaters by biogeochemical processes at the ice sheet bed. The bioavailability of the exported DOC (26–53%) to downstream marine microorganisms is similar to that reported from other glacial watersheds. Annual fluxes of DOC and free carbohydrates during two melt seasons were similar, despite the approximately two-fold difference in runoff fluxes, suggesting production-limited DOC sources. POC fluxes were also insensitive to an increase in seasonal runoff volumes, indicating a supply limitation in suspended sediment in runoff. Scaled to the GrIS, the combined DOC (0.13–0.17 TgC yr−1 (±13 %)) and POC fluxes (mean = 0.36–1.52 TgC yr−1 (±14 %)) are of a similar order of magnitude to a large Arctic river system, and hence may represent an important OC source to the near-coastal North Atlantic, Greenland and Labrador seas. |
| first_indexed | 2025-11-14T18:59:42Z |
| format | Article |
| id | nottingham-27608 |
| institution | University of Nottingham Malaysia Campus |
| institution_category | Local University |
| last_indexed | 2025-11-14T18:59:42Z |
| publishDate | 2014 |
| publisher | Copernicus Publications |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | nottingham-276082020-05-04T16:50:13Z https://eprints.nottingham.ac.uk/27608/ Greenland Ice Sheet exports labile organic carbon to the Arctic oceans Lawson, Emily C. Wadham, Jemma L. Tranter, Martyn Stibal, Marek Lis, Greg P. Butler, Catriona E.H. Laybourn-Parry, Johanna Nienow, Peter Chandler, David Dewsbury, Paul Runoff from small glacier systems contains dissolved organic carbon (DOC) rich in protein-like, low molecular weight (LMW) compounds, designating glaciers as an important source of bioavailable carbon for downstream heterotrophic activity. Fluxes of DOC and particulate organic carbon (POC) exported from large Greenland catchments, however, remain unquantified, despite the Greenland Ice Sheet (GrIS) being the largest source of global glacial runoff (ca. 400 km3 yr−1). We report high and episodic fluxes of POC and DOC from a large (> 600 km2) GrIS catchment during contrasting melt seasons. POC dominates organic carbon (OC) export (70–89% on average), is sourced from the ice sheet bed, and contains a significant bioreactive component (9% carbohydrates). A major source of the “bioavailable” (free carbohydrate) LMW–DOC fraction is microbial activity on the ice sheet surface, with some further addition of LMW–DOC to meltwaters by biogeochemical processes at the ice sheet bed. The bioavailability of the exported DOC (26–53%) to downstream marine microorganisms is similar to that reported from other glacial watersheds. Annual fluxes of DOC and free carbohydrates during two melt seasons were similar, despite the approximately two-fold difference in runoff fluxes, suggesting production-limited DOC sources. POC fluxes were also insensitive to an increase in seasonal runoff volumes, indicating a supply limitation in suspended sediment in runoff. Scaled to the GrIS, the combined DOC (0.13–0.17 TgC yr−1 (±13 %)) and POC fluxes (mean = 0.36–1.52 TgC yr−1 (±14 %)) are of a similar order of magnitude to a large Arctic river system, and hence may represent an important OC source to the near-coastal North Atlantic, Greenland and Labrador seas. Copernicus Publications 2014-07-31 Article PeerReviewed Lawson, Emily C., Wadham, Jemma L., Tranter, Martyn, Stibal, Marek, Lis, Greg P., Butler, Catriona E.H., Laybourn-Parry, Johanna, Nienow, Peter, Chandler, David and Dewsbury, Paul (2014) Greenland Ice Sheet exports labile organic carbon to the Arctic oceans. Biogeosciences, 11 (14). pp. 4015-4028. ISSN 1726-4170 Glacier carbon bioavailable microbes Greenland Ice Sheet http://www.biogeosciences.net/11/4015/2014/bg-11-4015-2014.html doi:10.5194/bg-11-4015-2014 doi:10.5194/bg-11-4015-2014 |
| spellingShingle | Glacier carbon bioavailable microbes Greenland Ice Sheet Lawson, Emily C. Wadham, Jemma L. Tranter, Martyn Stibal, Marek Lis, Greg P. Butler, Catriona E.H. Laybourn-Parry, Johanna Nienow, Peter Chandler, David Dewsbury, Paul Greenland Ice Sheet exports labile organic carbon to the Arctic oceans |
| title | Greenland Ice Sheet exports labile organic carbon to the Arctic oceans |
| title_full | Greenland Ice Sheet exports labile organic carbon to the Arctic oceans |
| title_fullStr | Greenland Ice Sheet exports labile organic carbon to the Arctic oceans |
| title_full_unstemmed | Greenland Ice Sheet exports labile organic carbon to the Arctic oceans |
| title_short | Greenland Ice Sheet exports labile organic carbon to the Arctic oceans |
| title_sort | greenland ice sheet exports labile organic carbon to the arctic oceans |
| topic | Glacier carbon bioavailable microbes Greenland Ice Sheet |
| url | https://eprints.nottingham.ac.uk/27608/ https://eprints.nottingham.ac.uk/27608/ https://eprints.nottingham.ac.uk/27608/ |