Nutrient cycling in the Arctic and Subarctic oceans: a stable isotope study
Anthropogenic global warming is actively changing nutrient supply and the food web of the Arctic Ocean and the subpolar regions. This study uses the stable isotopes of dissolved silicon and nitrate, two vital nutrients for marine life, to investigate the marine biogeochemical cycling of nutrients in...
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The University of Edinburgh
2023
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Online Access: | https://hdl.handle.net/1842/39796 https://doi.org/10.7488/era/3044 |
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ftunivedinburgh:oai:era.ed.ac.uk:1842/39796 2023-07-30T03:59:57+02:00 Nutrient cycling in the Arctic and Subarctic oceans: a stable isotope study Debyser, Margot Ganeshram, Raja Pichevin, Laetitia Tuerena, Robyn UKRI Changing Arctic Ocean program SAGES 2023-02-02 application/pdf https://hdl.handle.net/1842/39796 https://doi.org/10.7488/era/3044 en eng The University of Edinburgh Tuerena, R. E., Mahaffey, C., Henley, S. F., de la Vega, C., Norman, L., Brand, T., Sanders, T., Debyser, M., Dähnke, K., Braun, J. and März, C.: Nutrient pathways and their susceptibility to past and future change in the Eurasian Arctic Ocean, Ambio, 355–369, doi:10.1007/s13280-021-01673-0, 2021c https://hdl.handle.net/1842/39796 http://dx.doi.org/10.7488/era/3044 2024-02-02 nutrient isotope biogeochemistry Arctic Ocean polar Thesis or Dissertation Doctoral PhD Doctor of Philosophy 2023 ftunivedinburgh https://doi.org/10.7488/era/304410.1007/s13280-021-01673-0 2023-07-09T20:35:35Z Anthropogenic global warming is actively changing nutrient supply and the food web of the Arctic Ocean and the subpolar regions. This study uses the stable isotopes of dissolved silicon and nitrate, two vital nutrients for marine life, to investigate the marine biogeochemical cycling of nutrients in these regions. This work analyses datasets acquired from 7 oceanographic expeditions in three key regions: the Laptev Sea shelf, polar outflow waters of the Fram Strait (79˚N) and a full transect across the subpolar North Atlantic (50-60˚N). Hydrographic data, alongside concentrations of nitrate (NO3), dissolved silicon (DSi) and their isotopic composition (d15N-NO3, d18O-NO3, d30Si(OH)4) is presented to provide spatially and temporally integrated information on biogeochemical cycling in these regions. The overall objective of this work is to determine the processes which control nutrient budgets and cycling in the Arctic Ocean, export to the subpolar regions and the sensitivity of these processes to ongoing climate change. On the shallow Eurasian shelves of the Arctic Ocean, nitrogen is strongly depleted. This results from intense biological utilisation and significant benthic denitrification in the coastal regions, coupled with nitrogen-poor freshwater sources. Primary production in these regions is limited by N availability as a result of this. This puts a biological control on the extent of DSi utilisation in surface waters and modulates its export to the central Arctic Ocean. Over 40% of riverine DSi supplied by the Lena river is consumed and buried into the sediments of the Laptev shelf, enabled by vigorous recycling of nitrogen. Extrapolating these burial rates to the Eurasian shelf leads to an excess riverine DSi export of 3.10 ± 0.71 kmol/s through the Transpolar Drift to the central Arctic Ocean and outflowing currents. Consequently, Eurasian rivers significantly contribute to the DSi inventory of outflow polar surface waters, providing 40 ± 4% of the total DSi. By contrast, Pacific sources, which were ... Doctoral or Postdoctoral Thesis Arctic Arctic Arctic Ocean Climate change Fram Strait Global warming laptev Laptev Sea lena river North Atlantic Subarctic Edinburgh Research Archive (ERA - University of Edinburgh) Arctic Arctic Ocean Laptev Sea Pacific |
institution |
Open Polar |
collection |
Edinburgh Research Archive (ERA - University of Edinburgh) |
op_collection_id |
ftunivedinburgh |
language |
English |
topic |
nutrient isotope biogeochemistry Arctic Ocean polar |
spellingShingle |
nutrient isotope biogeochemistry Arctic Ocean polar Debyser, Margot Nutrient cycling in the Arctic and Subarctic oceans: a stable isotope study |
topic_facet |
nutrient isotope biogeochemistry Arctic Ocean polar |
description |
Anthropogenic global warming is actively changing nutrient supply and the food web of the Arctic Ocean and the subpolar regions. This study uses the stable isotopes of dissolved silicon and nitrate, two vital nutrients for marine life, to investigate the marine biogeochemical cycling of nutrients in these regions. This work analyses datasets acquired from 7 oceanographic expeditions in three key regions: the Laptev Sea shelf, polar outflow waters of the Fram Strait (79˚N) and a full transect across the subpolar North Atlantic (50-60˚N). Hydrographic data, alongside concentrations of nitrate (NO3), dissolved silicon (DSi) and their isotopic composition (d15N-NO3, d18O-NO3, d30Si(OH)4) is presented to provide spatially and temporally integrated information on biogeochemical cycling in these regions. The overall objective of this work is to determine the processes which control nutrient budgets and cycling in the Arctic Ocean, export to the subpolar regions and the sensitivity of these processes to ongoing climate change. On the shallow Eurasian shelves of the Arctic Ocean, nitrogen is strongly depleted. This results from intense biological utilisation and significant benthic denitrification in the coastal regions, coupled with nitrogen-poor freshwater sources. Primary production in these regions is limited by N availability as a result of this. This puts a biological control on the extent of DSi utilisation in surface waters and modulates its export to the central Arctic Ocean. Over 40% of riverine DSi supplied by the Lena river is consumed and buried into the sediments of the Laptev shelf, enabled by vigorous recycling of nitrogen. Extrapolating these burial rates to the Eurasian shelf leads to an excess riverine DSi export of 3.10 ± 0.71 kmol/s through the Transpolar Drift to the central Arctic Ocean and outflowing currents. Consequently, Eurasian rivers significantly contribute to the DSi inventory of outflow polar surface waters, providing 40 ± 4% of the total DSi. By contrast, Pacific sources, which were ... |
author2 |
Ganeshram, Raja Pichevin, Laetitia Tuerena, Robyn UKRI Changing Arctic Ocean program SAGES |
format |
Doctoral or Postdoctoral Thesis |
author |
Debyser, Margot |
author_facet |
Debyser, Margot |
author_sort |
Debyser, Margot |
title |
Nutrient cycling in the Arctic and Subarctic oceans: a stable isotope study |
title_short |
Nutrient cycling in the Arctic and Subarctic oceans: a stable isotope study |
title_full |
Nutrient cycling in the Arctic and Subarctic oceans: a stable isotope study |
title_fullStr |
Nutrient cycling in the Arctic and Subarctic oceans: a stable isotope study |
title_full_unstemmed |
Nutrient cycling in the Arctic and Subarctic oceans: a stable isotope study |
title_sort |
nutrient cycling in the arctic and subarctic oceans: a stable isotope study |
publisher |
The University of Edinburgh |
publishDate |
2023 |
url |
https://hdl.handle.net/1842/39796 https://doi.org/10.7488/era/3044 |
geographic |
Arctic Arctic Ocean Laptev Sea Pacific |
geographic_facet |
Arctic Arctic Ocean Laptev Sea Pacific |
genre |
Arctic Arctic Arctic Ocean Climate change Fram Strait Global warming laptev Laptev Sea lena river North Atlantic Subarctic |
genre_facet |
Arctic Arctic Arctic Ocean Climate change Fram Strait Global warming laptev Laptev Sea lena river North Atlantic Subarctic |
op_relation |
Tuerena, R. E., Mahaffey, C., Henley, S. F., de la Vega, C., Norman, L., Brand, T., Sanders, T., Debyser, M., Dähnke, K., Braun, J. and März, C.: Nutrient pathways and their susceptibility to past and future change in the Eurasian Arctic Ocean, Ambio, 355–369, doi:10.1007/s13280-021-01673-0, 2021c https://hdl.handle.net/1842/39796 http://dx.doi.org/10.7488/era/3044 |
op_rights |
2024-02-02 |
op_doi |
https://doi.org/10.7488/era/304410.1007/s13280-021-01673-0 |
_version_ |
1772810639868166144 |