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Attenuation of sinking particulate organic carbon flux through the mesopelagic ocean

Attenuation of sinking particulate organic carbon flux through the mesopelagic ocean
Attenuation of sinking particulate organic carbon flux through the mesopelagic ocean
The biological carbon pump, which transports particulate organic carbon (POC) from the surface to the deep ocean, plays an important role in regulating atmospheric carbon dioxide (CO2) concentrations. We know very little about geographical variability in the remineralization depth of this sinking material and less about what controls such variability. Here we present previously unpublished profiles of mesopelagic POC flux derived from neutrally buoyant sediment traps deployed in the North Atlantic, from which we calculate the remineralization length scale for each site. Combining these results with corresponding data from the North Pacific, we show that the observed variability in attenuation of vertical POC flux can largely be explained by temperature, with shallower remineralization occurring in warmer waters. This is seemingly inconsistent with conclusions drawn from earlier analyses of deep-sea sediment trap and export flux data, which suggest lowest transfer efficiency at high latitudes. However, the two patterns can be reconciled by considering relatively intense remineralization of a labile fraction of material in warm waters, followed by efficient downward transfer of the remaining refractory fraction, while in cold environments, a larger labile fraction undergoes slower remineralization that continues over a longer length scale. Based on the observed relationship, future increases in ocean temperature will likely lead to shallower remineralization of POC and hence reduced storage of CO2 by the ocean.
biological carbon pump, particulate organic carbon, remineralization, mesopelagic
0027-8424
1089-1094
Marsay, Chris M.
f18098e4-e58c-4799-a7fc-5d6f8ec95677
Sanders, Richard J.
02c163c1-8f5e-49ad-857c-d28f7da66c65
Henson, Stephanie A.
d6532e17-a65b-4d7b-9ee3-755ecb565c19
Pabortsava, Katsiaryna
bb9c573c-918c-4bc5-ad41-f85e47a6a580
Achterberg, Eric P.
685ce961-8c45-4503-9f03-50f6561202b9
Lampitt, Richard S.
dfc3785c-fc7d-41fa-89ee-d0c6e27503ad
Marsay, Chris M.
f18098e4-e58c-4799-a7fc-5d6f8ec95677
Sanders, Richard J.
02c163c1-8f5e-49ad-857c-d28f7da66c65
Henson, Stephanie A.
d6532e17-a65b-4d7b-9ee3-755ecb565c19
Pabortsava, Katsiaryna
bb9c573c-918c-4bc5-ad41-f85e47a6a580
Achterberg, Eric P.
685ce961-8c45-4503-9f03-50f6561202b9
Lampitt, Richard S.
dfc3785c-fc7d-41fa-89ee-d0c6e27503ad

Marsay, Chris M., Sanders, Richard J., Henson, Stephanie A., Pabortsava, Katsiaryna, Achterberg, Eric P. and Lampitt, Richard S. (2015) Attenuation of sinking particulate organic carbon flux through the mesopelagic ocean. Proceedings of the National Academy of Sciences, 112 (4), 1089-1094. (doi:10.1073/pnas.1415311112).

Record type: Article

Abstract

The biological carbon pump, which transports particulate organic carbon (POC) from the surface to the deep ocean, plays an important role in regulating atmospheric carbon dioxide (CO2) concentrations. We know very little about geographical variability in the remineralization depth of this sinking material and less about what controls such variability. Here we present previously unpublished profiles of mesopelagic POC flux derived from neutrally buoyant sediment traps deployed in the North Atlantic, from which we calculate the remineralization length scale for each site. Combining these results with corresponding data from the North Pacific, we show that the observed variability in attenuation of vertical POC flux can largely be explained by temperature, with shallower remineralization occurring in warmer waters. This is seemingly inconsistent with conclusions drawn from earlier analyses of deep-sea sediment trap and export flux data, which suggest lowest transfer efficiency at high latitudes. However, the two patterns can be reconciled by considering relatively intense remineralization of a labile fraction of material in warm waters, followed by efficient downward transfer of the remaining refractory fraction, while in cold environments, a larger labile fraction undergoes slower remineralization that continues over a longer length scale. Based on the observed relationship, future increases in ocean temperature will likely lead to shallower remineralization of POC and hence reduced storage of CO2 by the ocean.

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Accepted/In Press date: 9 December 2014
e-pub ahead of print date: 5 January 2015
Published date: 27 January 2015
Keywords: biological carbon pump, particulate organic carbon, remineralization, mesopelagic
Organisations: Ocean and Earth Science, Marine Biogeochemistry

Identifiers

Local EPrints ID: 372725
URI: http://eprints.soton.ac.uk/id/eprint/372725
ISSN: 0027-8424
PURE UUID: c6e20037-4bff-43aa-b912-41d828f853ed

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Date deposited: 15 Dec 2014 13:17
Last modified: 27 Apr 2022 04:12

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Contributors

Author: Chris M. Marsay
Author: Richard J. Sanders
Author: Katsiaryna Pabortsava
Author: Richard S. Lampitt

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