Elevated sources of cobalt in the Arctic Ocean
<p>Cobalt (Co) is an important bioactive trace metal that is the metal cofactor in cobalamin (vitamin B<span class="inline-formula"><sub>12</sub></span>) which can limit or co-limit phytoplankton growth in many regions of the ocean. Total dissolved and labile...
| Main Authors: | , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
2020-10-01
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| Series: | Biogeosciences |
| Online Access: | https://bg.copernicus.org/articles/17/4745/2020/bg-17-4745-2020.pdf |
| _version_ | 1818400825174654976 |
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| author | R. M. Bundy R. M. Bundy A. Tagliabue N. J. Hawco N. J. Hawco P. L. Morton B. S. Twining M. Hatta A. E. Noble A. E. Noble M. R. Cape M. R. Cape S. G. John J. T. Cullen M. A. Saito |
| author_facet | R. M. Bundy R. M. Bundy A. Tagliabue N. J. Hawco N. J. Hawco P. L. Morton B. S. Twining M. Hatta A. E. Noble A. E. Noble M. R. Cape M. R. Cape S. G. John J. T. Cullen M. A. Saito |
| author_sort | R. M. Bundy |
| collection | DOAJ |
| description | <p>Cobalt (Co) is an important bioactive trace metal that is the metal
cofactor in cobalamin (vitamin B<span class="inline-formula"><sub>12</sub></span>) which can limit or co-limit
phytoplankton growth in many regions of the ocean. Total dissolved and
labile Co measurements in the Canadian sector of the Arctic Ocean during the
U.S. GEOTRACES Arctic expedition (GN01) and the Canadian International Polar
Year GEOTRACES expedition (GIPY14) revealed a dynamic biogeochemical cycle
for Co in this basin. The major sources of Co in the Arctic were from shelf
regions and rivers, with only minimal contributions from other freshwater
sources (sea ice, snow) and eolian deposition. The most striking feature
was the extremely high concentrations of dissolved Co in the upper 100 m,
with concentrations routinely exceeding 800 pmol L<span class="inline-formula"><sup>−1</sup></span> over the shelf
regions. This plume of high Co persisted throughout the Arctic basin and
extended to the North Pole, where sources of Co shifted from primarily
shelf-derived to riverine, as freshwater from Arctic rivers was entrained in
the Transpolar Drift. Dissolved Co was also strongly organically complexed
in the Arctic, ranging from 70 % to 100 % complexed in the surface and deep
ocean, respectively. Deep-water concentrations of dissolved Co were
remarkably consistent throughout the basin (<span class="inline-formula">∼55</span> pmol L<span class="inline-formula"><sup>−1</sup></span>), with concentrations reflecting those of deep Atlantic water and
deep-ocean scavenging of dissolved Co. A biogeochemical model of Co cycling
was used to support the hypothesis that the majority of the high surface Co
in the Arctic was emanating from the shelf. The model showed that the high
concentrations of Co observed were due to the large shelf area of the
Arctic, as well as to dampened scavenging of Co by manganese-oxidizing (Mn-oxidizing)
bacteria due to the lower temperatures. The majority of this scavenging
appears to have occurred in the upper 200 m, with minimal additional
scavenging below this depth. Evidence suggests that both dissolved Co (dCo) and labile Co (LCo) are increasing over time on the Arctic shelf, and these limited temporal results are consistent
with other tracers in the Arctic. These
elevated surface concentrations of Co likely lead to a net flux of Co out of
the Arctic, with implications for downstream biological uptake of Co in the
North Atlantic and elevated Co in North Atlantic Deep Water. Understanding
the current distributions of Co in the Arctic will be important for
constraining changes to Co inputs resulting from regional intensification of
freshwater fluxes from ice and permafrost melt in response to ongoing
climate change.</p> |
| first_indexed | 2024-12-14T07:42:43Z |
| format | Article |
| id | doaj.art-c8710e4963d74742898ed37918c57f3a |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-14T07:42:43Z |
| publishDate | 2020-10-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-c8710e4963d74742898ed37918c57f3a2022-12-21T23:10:59ZengCopernicus PublicationsBiogeosciences1726-41701726-41892020-10-01174745476710.5194/bg-17-4745-2020Elevated sources of cobalt in the Arctic OceanR. M. Bundy0R. M. Bundy1A. Tagliabue2N. J. Hawco3N. J. Hawco4P. L. Morton5B. S. Twining6M. Hatta7A. E. Noble8A. E. Noble9M. R. Cape10M. R. Cape11S. G. John12J. T. Cullen13M. A. Saito14Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USAnow at: School of Oceanography, University of Washington, Seattle, WA, USASchool of Environmental Sciences, University of Liverpool, Liverpool, United KingdomDepartment of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USADepartment of Oceanography, University of Hawai`i at Manoa, Honolulu, HI, USANational High Magnetic Field Laboratory, Tallahassee, FL, USABigelow Laboratory for Ocean Sciences, East Boothbay, ME, USADepartment of Oceanography, University of Hawai`i at Manoa, Honolulu, HI, USADepartment of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USAnow at: California Department of Toxic Substances Control, Sacramento, CA, USADepartment of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USAnow at: School of Oceanography, University of Washington, Seattle, WA, USADepartment of Earth Sciences, University of Southern California, Los Angeles, CA, USASchool of Earth and Ocean Sciences, University of Victoria, Victoria, BC, CanadaDepartment of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution, Woods Hole, MA, USA<p>Cobalt (Co) is an important bioactive trace metal that is the metal cofactor in cobalamin (vitamin B<span class="inline-formula"><sub>12</sub></span>) which can limit or co-limit phytoplankton growth in many regions of the ocean. Total dissolved and labile Co measurements in the Canadian sector of the Arctic Ocean during the U.S. GEOTRACES Arctic expedition (GN01) and the Canadian International Polar Year GEOTRACES expedition (GIPY14) revealed a dynamic biogeochemical cycle for Co in this basin. The major sources of Co in the Arctic were from shelf regions and rivers, with only minimal contributions from other freshwater sources (sea ice, snow) and eolian deposition. The most striking feature was the extremely high concentrations of dissolved Co in the upper 100 m, with concentrations routinely exceeding 800 pmol L<span class="inline-formula"><sup>−1</sup></span> over the shelf regions. This plume of high Co persisted throughout the Arctic basin and extended to the North Pole, where sources of Co shifted from primarily shelf-derived to riverine, as freshwater from Arctic rivers was entrained in the Transpolar Drift. Dissolved Co was also strongly organically complexed in the Arctic, ranging from 70 % to 100 % complexed in the surface and deep ocean, respectively. Deep-water concentrations of dissolved Co were remarkably consistent throughout the basin (<span class="inline-formula">∼55</span> pmol L<span class="inline-formula"><sup>−1</sup></span>), with concentrations reflecting those of deep Atlantic water and deep-ocean scavenging of dissolved Co. A biogeochemical model of Co cycling was used to support the hypothesis that the majority of the high surface Co in the Arctic was emanating from the shelf. The model showed that the high concentrations of Co observed were due to the large shelf area of the Arctic, as well as to dampened scavenging of Co by manganese-oxidizing (Mn-oxidizing) bacteria due to the lower temperatures. The majority of this scavenging appears to have occurred in the upper 200 m, with minimal additional scavenging below this depth. Evidence suggests that both dissolved Co (dCo) and labile Co (LCo) are increasing over time on the Arctic shelf, and these limited temporal results are consistent with other tracers in the Arctic. These elevated surface concentrations of Co likely lead to a net flux of Co out of the Arctic, with implications for downstream biological uptake of Co in the North Atlantic and elevated Co in North Atlantic Deep Water. Understanding the current distributions of Co in the Arctic will be important for constraining changes to Co inputs resulting from regional intensification of freshwater fluxes from ice and permafrost melt in response to ongoing climate change.</p>https://bg.copernicus.org/articles/17/4745/2020/bg-17-4745-2020.pdf |
| spellingShingle | R. M. Bundy R. M. Bundy A. Tagliabue N. J. Hawco N. J. Hawco P. L. Morton B. S. Twining M. Hatta A. E. Noble A. E. Noble M. R. Cape M. R. Cape S. G. John J. T. Cullen M. A. Saito Elevated sources of cobalt in the Arctic Ocean Biogeosciences |
| title | Elevated sources of cobalt in the Arctic Ocean |
| title_full | Elevated sources of cobalt in the Arctic Ocean |
| title_fullStr | Elevated sources of cobalt in the Arctic Ocean |
| title_full_unstemmed | Elevated sources of cobalt in the Arctic Ocean |
| title_short | Elevated sources of cobalt in the Arctic Ocean |
| title_sort | elevated sources of cobalt in the arctic ocean |
| url | https://bg.copernicus.org/articles/17/4745/2020/bg-17-4745-2020.pdf |
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