The University of Southampton
University of Southampton Institutional Repository

Cd/Ca ratios of in situ collected planktonic foraminiferal tests

Cd/Ca ratios of in situ collected planktonic foraminiferal tests
Cd/Ca ratios of in situ collected planktonic foraminiferal tests
The Cd/Ca ratios of planktonic foraminiferal tests have been used to reconstruct surface water nutrient utilization and paleoproductivity. The reliability of this proxy has hitherto not been comprehensively studied, however. To fill this gap, we present novel Cd/Ca data for in situ sampled and sedimentary planktonic foraminifers of the species Globigerinoides ruber, G. sacculifer, Globigerina bulloides, Orbulina universa, and Globorotalia truncatulinoides from the Arabian Sea and the North Atlantic. The Cd/Ca ratios obtained for G. ruber sampled from the live habitat generally display a correlation with seawater phosphate content, but no such trend is observed for G. sacculifer. This distinct behavior may reflect different ecological niches or species-specific incorporation of Cd into the calcite shells of the organisms. The Cd/Ca ratios of G. ruber, G. sacculifer, and G. bulloides from surface sediments are consistently higher than those obtained for live collected specimens of the same species. Postdepositional alteration of the tests is unlikely to be responsible for these systematic differences. Rather, they appear to reflect a combination of factors, including the formation of calcite crusts with high Cd contents, the different timescales that are represented by in situ and sedimentary foraminiferal tests, and the dominance of tests from periods of high productivity in sediments. Our results also reveal higher Cd/Ca ratios for live G. ruber than for settling tests of the same species. This suggests that planktonic foraminiferal shells are partially dissolved while they individually settle through the water column. Sedimentary tests, however, will be less affected by dissolution processes because these shells are primarily deposited in mass sinking events, which feature much higher settling velocities than those experienced by single settling shells.
planktonic foraminifers, cadmium, paleoproductivity, Cd/Ca, Atlantic, Arabian Sea
0883-8305
PA3209
Ripperger, S.
bcffc269-c8a5-4c0e-bbb3-106b69671477
Schiebel, R.
e3ee9c3f-ae96-4523-8ec2-2ed7acdfb83a
Rehkamper, M.
49b66908-35f5-404e-a08b-4895da0a187d
Halliday, A.N.
c09ccdde-ae81-4126-92e2-5a2d60e65f2d
Ripperger, S.
bcffc269-c8a5-4c0e-bbb3-106b69671477
Schiebel, R.
e3ee9c3f-ae96-4523-8ec2-2ed7acdfb83a
Rehkamper, M.
49b66908-35f5-404e-a08b-4895da0a187d
Halliday, A.N.
c09ccdde-ae81-4126-92e2-5a2d60e65f2d

Ripperger, S., Schiebel, R., Rehkamper, M. and Halliday, A.N. (2008) Cd/Ca ratios of in situ collected planktonic foraminiferal tests. Paleoceanography, 23, PA3209. (doi:10.1029/2007PA001524).

Record type: Article

Abstract

The Cd/Ca ratios of planktonic foraminiferal tests have been used to reconstruct surface water nutrient utilization and paleoproductivity. The reliability of this proxy has hitherto not been comprehensively studied, however. To fill this gap, we present novel Cd/Ca data for in situ sampled and sedimentary planktonic foraminifers of the species Globigerinoides ruber, G. sacculifer, Globigerina bulloides, Orbulina universa, and Globorotalia truncatulinoides from the Arabian Sea and the North Atlantic. The Cd/Ca ratios obtained for G. ruber sampled from the live habitat generally display a correlation with seawater phosphate content, but no such trend is observed for G. sacculifer. This distinct behavior may reflect different ecological niches or species-specific incorporation of Cd into the calcite shells of the organisms. The Cd/Ca ratios of G. ruber, G. sacculifer, and G. bulloides from surface sediments are consistently higher than those obtained for live collected specimens of the same species. Postdepositional alteration of the tests is unlikely to be responsible for these systematic differences. Rather, they appear to reflect a combination of factors, including the formation of calcite crusts with high Cd contents, the different timescales that are represented by in situ and sedimentary foraminiferal tests, and the dominance of tests from periods of high productivity in sediments. Our results also reveal higher Cd/Ca ratios for live G. ruber than for settling tests of the same species. This suggests that planktonic foraminiferal shells are partially dissolved while they individually settle through the water column. Sedimentary tests, however, will be less affected by dissolution processes because these shells are primarily deposited in mass sinking events, which feature much higher settling velocities than those experienced by single settling shells.

This record has no associated files available for download.

More information

Published date: 2008
Keywords: planktonic foraminifers, cadmium, paleoproductivity, Cd/Ca, Atlantic, Arabian Sea

Identifiers

Local EPrints ID: 54695
URI: http://eprints.soton.ac.uk/id/eprint/54695
ISSN: 0883-8305
PURE UUID: d870a8ad-27ab-4a20-9871-831f3f00150f

Catalogue record

Date deposited: 18 Jul 2008
Last modified: 15 Mar 2024 10:49

Export record

Altmetrics

Contributors

Author: S. Ripperger
Author: R. Schiebel
Author: M. Rehkamper
Author: A.N. Halliday

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×