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Carbon sequestration in the deep Atlantic enhanced by Saharan dust

Carbon sequestration in the deep Atlantic enhanced by Saharan dust
Carbon sequestration in the deep Atlantic enhanced by Saharan dust
Enhanced atmospheric input of dust-borne nutrients and minerals to the remote surface ocean can potentially increase carbon uptake and sequestration at depth. Nutrients can enhance primary productivity, and mineral particles act as ballast, increasing sinking rates of particulate organic matter. Here we present a two-year time series of sediment trap observations of particulate organic carbon flux to 3,000 m depth, measured directly in two locations: the dust-rich central North Atlantic gyre and the dust-poor South Atlantic gyre. We find that carbon fluxes are twice as high and a higher proportion of primary production is exported to depth in the dust-rich North Atlantic gyre. Low stable nitrogen isotope ratios suggest that high fluxes result from the stimulation of nitrogen fixation and productivity following the deposition of dust-borne nutrients. Sediment traps in the northern gyre also collected intact colonies of nitrogen-fixing Trichodesmium species. Whereas ballast in the southern gyre is predominantly biogenic, dust-derived mineral particles constitute the dominant ballast element during the enhanced carbon fluxes in the northern gyre. We conclude that dust deposition increases carbon sequestration in the North Atlantic gyre through the fertilization of the nitrogen-fixing community in surface waters and mineral ballasting of sinking particles.
1752-0894
189–194
Pabortsava, Katsiaryna
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Lampitt, Richard S.
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Benson, Jeff
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Crowe, Christian
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McLachlan, Robert
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Le Moigne, Frederick A.C.
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Moore, C. Mark
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Pebody, Corinne
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Provost, Paul
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Rees, Andrew
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Tilstone, Gavin
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Woodward, E. Malcolm S.
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Pabortsava, Katsiaryna
bb9c573c-918c-4bc5-ad41-f85e47a6a580
Lampitt, Richard S.
dfc3785c-fc7d-41fa-89ee-d0c6e27503ad
Benson, Jeff
8669360f-d201-48f8-9479-d3075bda1d1f
Crowe, Christian
6109e138-9c24-4141-909a-13790ddfb150
McLachlan, Robert
92a12465-2824-4382-bc42-b008ce5c4587
Le Moigne, Frederick A.C.
f809fb0e-04ac-46fb-aae8-e04326555d7e
Moore, C. Mark
7ec80b7b-bedc-4dd5-8924-0f5d01927b12
Pebody, Corinne
21c75802-0b16-4ad9-8ec4-5649ce4055b0
Provost, Paul
f5d31a56-f5e4-4c7b-8ee3-0cf248a6f900
Rees, Andrew
97833d72-87b4-4c51-ba38-301bf9b1fd16
Tilstone, Gavin
b48d90ea-3039-4f2a-a1a5-967e1109bf4d
Woodward, E. Malcolm S.
e90435b9-a070-40a0-a2ef-89b35a7b7541

Pabortsava, Katsiaryna, Lampitt, Richard S., Benson, Jeff, Crowe, Christian, McLachlan, Robert, Le Moigne, Frederick A.C., Moore, C. Mark, Pebody, Corinne, Provost, Paul, Rees, Andrew, Tilstone, Gavin and Woodward, E. Malcolm S. (2017) Carbon sequestration in the deep Atlantic enhanced by Saharan dust. Nature Geoscience, 10 (3), 189–194. (doi:10.1038/ngeo2899).

Record type: Article

Abstract

Enhanced atmospheric input of dust-borne nutrients and minerals to the remote surface ocean can potentially increase carbon uptake and sequestration at depth. Nutrients can enhance primary productivity, and mineral particles act as ballast, increasing sinking rates of particulate organic matter. Here we present a two-year time series of sediment trap observations of particulate organic carbon flux to 3,000 m depth, measured directly in two locations: the dust-rich central North Atlantic gyre and the dust-poor South Atlantic gyre. We find that carbon fluxes are twice as high and a higher proportion of primary production is exported to depth in the dust-rich North Atlantic gyre. Low stable nitrogen isotope ratios suggest that high fluxes result from the stimulation of nitrogen fixation and productivity following the deposition of dust-borne nutrients. Sediment traps in the northern gyre also collected intact colonies of nitrogen-fixing Trichodesmium species. Whereas ballast in the southern gyre is predominantly biogenic, dust-derived mineral particles constitute the dominant ballast element during the enhanced carbon fluxes in the northern gyre. We conclude that dust deposition increases carbon sequestration in the North Atlantic gyre through the fertilization of the nitrogen-fixing community in surface waters and mineral ballasting of sinking particles.

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Pabortsava et al_2017 - Accepted Manuscript
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Accepted/In Press date: 20 January 2017
e-pub ahead of print date: 27 February 2017
Published date: 27 February 2017
Organisations: Marine Biogeochemistry, National Oceanography Centre

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Local EPrints ID: 406410
URI: http://eprints.soton.ac.uk/id/eprint/406410
ISSN: 1752-0894
PURE UUID: 8abc01a5-332d-4c70-b9a3-d2de974c743c

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Date deposited: 10 Mar 2017 10:46
Last modified: 29 Aug 2020 04:01

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Contributors

Author: Katsiaryna Pabortsava
Author: Richard S. Lampitt
Author: Jeff Benson
Author: Christian Crowe
Author: Robert McLachlan
Author: Frederick A.C. Le Moigne
Author: C. Mark Moore
Author: Corinne Pebody
Author: Paul Provost
Author: Andrew Rees
Author: Gavin Tilstone
Author: E. Malcolm S. Woodward

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