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Factors regulating the Great Calcite Belt in the Southern Ocean and its biogeochemical significance

Factors regulating the Great Calcite Belt in the Southern Ocean and its biogeochemical significance
Factors regulating the Great Calcite Belt in the Southern Ocean and its biogeochemical significance
The Great Calcite Belt (GCB) is a region of elevated surface reflectance in the Southern Ocean (SO) covering ~16% of the global ocean and is thought to result from elevated, seasonal concentrations of coccolithophores. Here we describe field observations and experiments from two cruises that crossed the GCB in the Atlantic and Indian sectors of the SO. We confirm the presence of coccolithophores, their coccoliths, and associated optical scattering, located primarily in the region of the subtropical, Agulhas, and Subantarctic frontal regions. Coccolithophore-rich regions were typically associated with high-velocity frontal regions with higher seawater partial pressures of CO2 (pCO2) than the atmosphere, sufficient to reverse the direction of gas exchange to a CO2 source. There was no calcium carbonate (CaCO3) enhancement of particulate organic carbon (POC) export, but there were increased POC transfer efficiencies in high-flux particulate inorganic carbon regions. Contemporaneous observations are synthesized with results of trace-metal incubation experiments, 234Th-based flux estimates, and remotely sensed observations to generate a mandala that summarizes our understanding about the factors that regulate the location of the GCB.
coccolithophores, trace metals, carbonate chemistry, Southern Ocean, Subantarctic Front, Subtropical Front
0886-6236
1124-1144
Balch, William M.
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Bates, Nicholas R.
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Lam, Phoebe J.
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Twining, Benjamin S.
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Rosengard, Sarah Z.
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Bowler, Bruce C.
ad482df4-39b8-410d-a036-12830ceed822
Drapeau, Dave T.
d37d0b57-1a63-44c7-b937-68d2f51f2f4b
Garley, Rebecca
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Lubelczyk, Laura C.
bf238cfa-0ac4-4b43-a443-22d954ef22d6
Mitchell, Catherine
57498eaa-7fe4-4a6a-aff4-d389153b2743
Rauschenberg, Sara
cb420d73-e9a1-4319-a119-7b8cecda0dec
Balch, William M.
18270567-fc45-4bc9-bd82-253d473e9564
Bates, Nicholas R.
954a83d6-8424-49e9-8acd-e606221c9c57
Lam, Phoebe J.
edd6ad71-e42a-4157-bb1d-ef0ec23e8210
Twining, Benjamin S.
480e107b-8504-4251-b650-d0a3ffccd9db
Rosengard, Sarah Z.
6fc88766-1f80-4876-8896-06642240d53f
Bowler, Bruce C.
ad482df4-39b8-410d-a036-12830ceed822
Drapeau, Dave T.
d37d0b57-1a63-44c7-b937-68d2f51f2f4b
Garley, Rebecca
1030a064-03e4-43d6-ba49-29675db70184
Lubelczyk, Laura C.
bf238cfa-0ac4-4b43-a443-22d954ef22d6
Mitchell, Catherine
57498eaa-7fe4-4a6a-aff4-d389153b2743
Rauschenberg, Sara
cb420d73-e9a1-4319-a119-7b8cecda0dec

Balch, William M., Bates, Nicholas R., Lam, Phoebe J., Twining, Benjamin S., Rosengard, Sarah Z., Bowler, Bruce C., Drapeau, Dave T., Garley, Rebecca, Lubelczyk, Laura C., Mitchell, Catherine and Rauschenberg, Sara (2016) Factors regulating the Great Calcite Belt in the Southern Ocean and its biogeochemical significance. Global Biogeochemical Cycles, 30 (8), 1124-1144. (doi:10.1002/2016GB005414).

Record type: Article

Abstract

The Great Calcite Belt (GCB) is a region of elevated surface reflectance in the Southern Ocean (SO) covering ~16% of the global ocean and is thought to result from elevated, seasonal concentrations of coccolithophores. Here we describe field observations and experiments from two cruises that crossed the GCB in the Atlantic and Indian sectors of the SO. We confirm the presence of coccolithophores, their coccoliths, and associated optical scattering, located primarily in the region of the subtropical, Agulhas, and Subantarctic frontal regions. Coccolithophore-rich regions were typically associated with high-velocity frontal regions with higher seawater partial pressures of CO2 (pCO2) than the atmosphere, sufficient to reverse the direction of gas exchange to a CO2 source. There was no calcium carbonate (CaCO3) enhancement of particulate organic carbon (POC) export, but there were increased POC transfer efficiencies in high-flux particulate inorganic carbon regions. Contemporaneous observations are synthesized with results of trace-metal incubation experiments, 234Th-based flux estimates, and remotely sensed observations to generate a mandala that summarizes our understanding about the factors that regulate the location of the GCB.

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Accepted/In Press date: 23 May 2016
e-pub ahead of print date: 10 August 2016
Published date: August 2016
Keywords: coccolithophores, trace metals, carbonate chemistry, Southern Ocean, Subantarctic Front, Subtropical Front
Organisations: Ocean and Earth Science

Identifiers

Local EPrints ID: 403109
URI: https://eprints.soton.ac.uk/id/eprint/403109
ISSN: 0886-6236
PURE UUID: 85d7257f-d38a-4916-9bb7-4eac3888090d

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Date deposited: 21 Nov 2016 15:07
Last modified: 09 Jan 2018 17:42

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Contributors

Author: William M. Balch
Author: Phoebe J. Lam
Author: Benjamin S. Twining
Author: Sarah Z. Rosengard
Author: Bruce C. Bowler
Author: Dave T. Drapeau
Author: Rebecca Garley
Author: Laura C. Lubelczyk
Author: Catherine Mitchell
Author: Sara Rauschenberg

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