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Alkalinity changes in the Sargasso Sea: geochemical evidence of calcification?

Alkalinity changes in the Sargasso Sea: geochemical evidence of calcification?
Alkalinity changes in the Sargasso Sea: geochemical evidence of calcification?
Strong seasonal patterns in upper ocean total carbon dioxide (TCO2), alkalinity (TA) and calculated pCO2 were observed in a time series of water column measurements collected at the US Joint Global Ocean Flux Study (JGOFS) BATS site (31°50' N, 64°10' W) in the Sargasso Sea. TA distribution was a conservative function of salinity. However, in February 1992, a non-conservative decrease in TA was observed, with maximum depletion of 25–30 µmoles kg-1 occurring in the surface layer and at the depth of the chlorophyll maximum (~ 80–100 m). Mixed-layer TCO2 also decreased, while surface pCO2 increased by 25–30 µatm. We suggest these changes in carbon dioxide species resulted from open-ocean calcification by carbonate-secreting organisms rather than physical processes. Coccolithophore calcification is the most likely cause of this event although calcification by foraminifera or pteropods cannot be ruled out. Due to the transient increase in surface pCO2, the net annual transfer of CO2 into the ocean at BATS was reduced. These observations demonstrate the potential importance of open-ocean calcification and biological community structure in the biogeochemical cycling of carbon.
0304-4203
347-358
Bates, Nicholas R.
954a83d6-8424-49e9-8acd-e606221c9c57
Michaels, Anthony F.
f1417e33-1039-4229-8268-4a1521d1012c
Knap, Anthony H.
c5c7e8b6-3a16-47e6-bdb3-78797bca42ee
Bates, Nicholas R.
954a83d6-8424-49e9-8acd-e606221c9c57
Michaels, Anthony F.
f1417e33-1039-4229-8268-4a1521d1012c
Knap, Anthony H.
c5c7e8b6-3a16-47e6-bdb3-78797bca42ee

Bates, Nicholas R., Michaels, Anthony F. and Knap, Anthony H. (1996) Alkalinity changes in the Sargasso Sea: geochemical evidence of calcification? Marine Chemistry, 51 (4), 347-358. (doi:10.1016/0304-4203(95)00068-2).

Record type: Article

Abstract

Strong seasonal patterns in upper ocean total carbon dioxide (TCO2), alkalinity (TA) and calculated pCO2 were observed in a time series of water column measurements collected at the US Joint Global Ocean Flux Study (JGOFS) BATS site (31°50' N, 64°10' W) in the Sargasso Sea. TA distribution was a conservative function of salinity. However, in February 1992, a non-conservative decrease in TA was observed, with maximum depletion of 25–30 µmoles kg-1 occurring in the surface layer and at the depth of the chlorophyll maximum (~ 80–100 m). Mixed-layer TCO2 also decreased, while surface pCO2 increased by 25–30 µatm. We suggest these changes in carbon dioxide species resulted from open-ocean calcification by carbonate-secreting organisms rather than physical processes. Coccolithophore calcification is the most likely cause of this event although calcification by foraminifera or pteropods cannot be ruled out. Due to the transient increase in surface pCO2, the net annual transfer of CO2 into the ocean at BATS was reduced. These observations demonstrate the potential importance of open-ocean calcification and biological community structure in the biogeochemical cycling of carbon.

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Published date: 1996
Organisations: Ocean Biochemistry & Ecosystems

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Local EPrints ID: 358380
URI: http://eprints.soton.ac.uk/id/eprint/358380
ISSN: 0304-4203
PURE UUID: 93dcd5e8-0b0d-48e8-ada5-0616cee01238

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Date deposited: 04 Oct 2013 10:50
Last modified: 14 Mar 2024 15:04

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Author: Anthony F. Michaels
Author: Anthony H. Knap

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