A Caltech Library Service

On calcium-to-alkalinity anomalies in the North Pacific, Red Sea, Indian Ocean and Southern Ocean

Steiner, Zvi and Sarkar, Amit and Liu, Xuewu and Berelson, William M. and Adkins, Jess F. and Achterberg, Eric P. and Sabu, P. and Prakash, Satya and Vinaychandran, P. N. and Byrne, Robert H. and Turchyn, Alexandra V. (2021) On calcium-to-alkalinity anomalies in the North Pacific, Red Sea, Indian Ocean and Southern Ocean. Geochimica et Cosmochimica Acta, 303 . pp. 1-14. ISSN 0016-7037. doi:10.1016/j.gca.2021.03.027.

[img] PDF - Accepted Version
See Usage Policy.

[img] MS Word (Supplementary data 1) - Supplemental Material
See Usage Policy.

[img] MS Excel (Supplementary data 2) - Supplemental Material
See Usage Policy.

[img] MS Excel (Supplementary data 3) - Supplemental Material
See Usage Policy.


Use this Persistent URL to link to this item:


An important factor for predicting the effect of increased CO₂ on future acidification of the ocean is a proper understanding of the interactions controlling production and dissolution of calcium carbonate minerals (CaCO₃). The production and dissolution of CaCO₃ in the ocean can be assessed over large spatial scales by measuring seawater calcium concentrations and total alkalinity (A_T), yet past studies suggest that there could be large discrepancies between calcium and A_T-based balances of the CaCO₃ cycle in the North Pacific and Indian Oceans. Here, we analyse water column samples collected along transects in the North Pacific, Southern Ocean, tropical Indian Ocean and Red Sea for their concentrations of calcium, nutrients, and A_T. We find that there is an excess calcium over A_T anomaly in the top 1000 m of the tropical Indian Ocean water-column. The source of this anomaly is the dissolution of subsurface gypsum deposits in the Red Sea. We find no evidence for calcium-over-A_T anomalies in the North Pacific, in contrast to previous studies. Our results show that, in most cases, calcium and A_T data agree well and can be used to reconstruct the marine CaCO₃ cycle.

Item Type:Article
Related URLs:
URLURL TypeDescription
Berelson, William M.0000-0002-1526-3802
Adkins, Jess F.0000-0002-3174-5190
Turchyn, Alexandra V.0000-0002-9298-2173
Additional Information:© 2021 Elsevier Ltd. Received 29 May 2020, Revised 25 March 2021, Accepted 26 March 2021, Available online 5 April 2021. This study was funded by a Blavatnik postdoctoral fellowship to ZS, an Isaac Newton Trust grant to AVT and ZS, and ERC StG 307582 (CARBONSINK) to AVT. The cruise on board the ORV Sagar Nidhi was funded by the Indian National Centre for Ocean Information Services (INCOIS), Ministry of Earth Sciences, India, as the first cruise of the second International Indian Ocean Expedition (IIOE-2). The cruise on board the RV Kilo Moana was funded by NSF Ocean Acidification grant number OCE1220600. We would like to thank the UK Natural Environment Research Council (NERC), the UK Department of Environment, Food and Rural Affairs (DEFRA), and the UK Department of Energy and Climate Change (DECC) for funding the research cruise JR274 via the pelagic consortium of UK Ocean Acidification research programme (grant no. NE/H017348/1) and the UK Carbonate Chemistry Facility. We thank Jonathan Erez, Boaz Lazar and Murielle Dray for enabling ZS to measure AT and salinity in their labs, and Loraine Martell-Bonet for analysing total alkalinity during CDisK-IV. The manuscript benefited greatly from the comments and remarks of Alfonso Mucci and three anonymous reviewers. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Funding AgencyGrant Number
British CouncilUNSPECIFIED
Isaac Newton TrustUNSPECIFIED
European Research Council (ERC)307582
National Center for Ocean Information Services (India)UNSPECIFIED
Natural Environment Research Council (NERC)NE/H017348/1
Department of Environment, Food and Rural Affairs (United Kingdom)UNSPECIFIED
Department of Energy and Climate Change (United Kingdom)UNSPECIFIED
Carbonate Chemistry Facility (United Kingdom)UNSPECIFIED
Subject Keywords:Calcium; Alkalinity; Ocean acidification; CaCO3; Alkalinity anomaly; Carbonate cycle
Record Number:CaltechAUTHORS:20210406-143355459
Persistent URL:
Official Citation:Zvi Steiner, Amit Sarkar, Xuewu Liu, William M. Berelson, Jess F. Adkins, Eric P. Achterberg, P. Sabu, Satya Prakash, P.N. Vinaychandran, Robert H. Byrne, Alexandra V. Turchyn, On calcium-to-alkalinity anomalies in the North Pacific, Red Sea, Indian Ocean and Southern Ocean, Geochimica et Cosmochimica Acta, Volume 303, 2021, Pages 1-14, ISSN 0016-7037, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108637
Deposited By: Tony Diaz
Deposited On:07 Apr 2021 23:50
Last Modified:22 Apr 2021 21:32

Repository Staff Only: item control page