Sources, cycling and export of nitrogen on the Greenland Ice Sheet
Fjord and continental shelf environments in the polar regions are host to some of the planet's most productive ecosystems and support economically important fisheries. Their productivity, however, is often critically dependent upon nutrient supply from upstream terrestrial environments deli...
| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2016-11-01
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| Series: | Biogeosciences |
| Online Access: | https://www.biogeosciences.net/13/6339/2016/bg-13-6339-2016.pdf |
| _version_ | 1818944816152576000 |
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| author | J. L. Wadham J. Hawkings J. Telling D. Chandler J. Alcock E. O'Donnell P. Kaur E. Bagshaw M. Tranter A. Tedstone P. Nienow |
| author_facet | J. L. Wadham J. Hawkings J. Telling D. Chandler J. Alcock E. O'Donnell P. Kaur E. Bagshaw M. Tranter A. Tedstone P. Nienow |
| author_sort | J. L. Wadham |
| collection | DOAJ |
| description | Fjord and continental shelf environments in the polar regions are host to
some of the planet's most productive ecosystems and support economically
important fisheries. Their productivity, however, is often critically
dependent upon nutrient supply from upstream terrestrial environments
delivered via river systems. In glacially fed coastal ecosystems, riverine
nutrients are largely sourced from melting snow and ice. The largest and
most extensive glacially fed coastal ecosystem in the Arctic is that
bordering the Greenland Ice Sheet. The future primary productivity of this
ecosystem, however, is uncertain. A potential increase in primary
productivity driven by reduced sea ice extent and associated increased light
levels may be curtailed by insufficient nutrient supply, and specifically
nitrogen. Research on small valley glaciers indicates that glaciers are
important sources of nitrogen to downstream environments. However, no data
exist from ice sheet systems such as Greenland. Time series of nitrogen
concentrations in runoff are documented from a large Greenland glacier,
demonstrating seasonally elevated fluxes to the ocean. Fluxes are highest in
mid-summer, when nitrogen limitation is commonly reported in coastal waters.
It is estimated that approximately half of the glacially exported nitrogen
is sourced from microbial activity within glacial sediments at the surface
and bed of the ice sheet, doubling nitrogen fluxes in runoff. Summer
dissolved inorganic nitrogen fluxes from the Greenland Ice Sheet (30–40 Gg)
are a similar order of magnitude to those from a large Arctic river
(Holmes et al., 2012). Nitrogen yields from the ice sheet (236 kg TDN km<sup>−2</sup> a<sup>−1</sup>), however, are approximately double those from Arctic
riverine catchments. We assert that this ice sheet nitrogen subsidy to
Arctic coastal ecosystems may be important for understanding coastal
biodiversity, productivity and fisheries and should be considered in future
biogeochemical modelling studies of coastal marine productivity in the
Arctic regions. |
| first_indexed | 2024-12-20T07:49:14Z |
| format | Article |
| id | doaj.art-264f18c7c780425687eda74d8e509d08 |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-20T07:49:14Z |
| publishDate | 2016-11-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-264f18c7c780425687eda74d8e509d082022-12-21T19:47:52ZengCopernicus PublicationsBiogeosciences1726-41701726-41892016-11-01136339635210.5194/bg-13-6339-2016Sources, cycling and export of nitrogen on the Greenland Ice SheetJ. L. Wadham0J. Hawkings1J. Telling2D. Chandler3J. Alcock4E. O'Donnell5P. Kaur6E. Bagshaw7M. Tranter8A. Tedstone9P. Nienow10Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UKBristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UKBristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UKBristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UKBristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UKSchool of Geoscience, University of Edinburgh, Edinburgh, EH8 9XP, UKBristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UKBristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UKBristol Glaciology Centre, School of Geographical Sciences, University of Bristol, University Road, Bristol, BS8 1SS, UKSchool of Geography, University of Nottingham, NG7 2RD, UKSchool of Geography, University of Nottingham, NG7 2RD, UKFjord and continental shelf environments in the polar regions are host to some of the planet's most productive ecosystems and support economically important fisheries. Their productivity, however, is often critically dependent upon nutrient supply from upstream terrestrial environments delivered via river systems. In glacially fed coastal ecosystems, riverine nutrients are largely sourced from melting snow and ice. The largest and most extensive glacially fed coastal ecosystem in the Arctic is that bordering the Greenland Ice Sheet. The future primary productivity of this ecosystem, however, is uncertain. A potential increase in primary productivity driven by reduced sea ice extent and associated increased light levels may be curtailed by insufficient nutrient supply, and specifically nitrogen. Research on small valley glaciers indicates that glaciers are important sources of nitrogen to downstream environments. However, no data exist from ice sheet systems such as Greenland. Time series of nitrogen concentrations in runoff are documented from a large Greenland glacier, demonstrating seasonally elevated fluxes to the ocean. Fluxes are highest in mid-summer, when nitrogen limitation is commonly reported in coastal waters. It is estimated that approximately half of the glacially exported nitrogen is sourced from microbial activity within glacial sediments at the surface and bed of the ice sheet, doubling nitrogen fluxes in runoff. Summer dissolved inorganic nitrogen fluxes from the Greenland Ice Sheet (30–40 Gg) are a similar order of magnitude to those from a large Arctic river (Holmes et al., 2012). Nitrogen yields from the ice sheet (236 kg TDN km<sup>−2</sup> a<sup>−1</sup>), however, are approximately double those from Arctic riverine catchments. We assert that this ice sheet nitrogen subsidy to Arctic coastal ecosystems may be important for understanding coastal biodiversity, productivity and fisheries and should be considered in future biogeochemical modelling studies of coastal marine productivity in the Arctic regions.https://www.biogeosciences.net/13/6339/2016/bg-13-6339-2016.pdf |
| spellingShingle | J. L. Wadham J. Hawkings J. Telling D. Chandler J. Alcock E. O'Donnell P. Kaur E. Bagshaw M. Tranter A. Tedstone P. Nienow Sources, cycling and export of nitrogen on the Greenland Ice Sheet Biogeosciences |
| title | Sources, cycling and export of nitrogen on the Greenland Ice Sheet |
| title_full | Sources, cycling and export of nitrogen on the Greenland Ice Sheet |
| title_fullStr | Sources, cycling and export of nitrogen on the Greenland Ice Sheet |
| title_full_unstemmed | Sources, cycling and export of nitrogen on the Greenland Ice Sheet |
| title_short | Sources, cycling and export of nitrogen on the Greenland Ice Sheet |
| title_sort | sources cycling and export of nitrogen on the greenland ice sheet |
| url | https://www.biogeosciences.net/13/6339/2016/bg-13-6339-2016.pdf |
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