A new boron isotope-pH calibration for Orbulina universa, with implications for understanding and accounting for ‘vital effects’

Michael J. Henehan; Gavin L. Foster; Helen C. Bostock; Rosanna Greenop; Brittney J. Marshall; Paul A. Wilson

doi:10.1016/j.epsl.2016.09.024

A new boron isotope-pH calibration for Orbulina universa, with implications for understanding and accounting for ‘vital effects’

Michael J. Henehan^*, Gavin L. Foster, Helen C. Bostock, Rosanna Greenop, Brittney J. Marshall, Paul A. Wilson

^*Corresponding author for this work

School of Earth Sciences

Research output: Contribution to journal › Article (Academic Journal) › peer-review

62 Citations (Scopus)

Abstract

Boron isotope ratios, as measured in planktic foraminifera, can be a useful tracer of past ocean pH, and hence help to discern the concentration of CO₂ in the ancient atmosphere. However, different species of planktic foraminifera demonstrate different patterns of boron isotope variation with ambient seawater pH. Therefore when applying the proxy to questions in the geological past, species-specific calibrations are preferable. Beyond the evolutionary history of a calibrated species, we must rely on our understanding of the causes of the observed “vital effects” in the modern ocean, and the applicability of that understanding to extinct species. Here we present a new open-ocean calibration of the planktic foraminifera Orbulina universa, measured via Multi-Collector Inductively Coupled Mass Spectrometry (MC-ICPMS). Unlike other symbiont-bearing foraminifera, O. universa record a δ¹¹B (and hence pH) that is lower than its surrounding seawater, but with a pH-sensitivity roughly equal to that of aqueous borate ion. We discuss the significance of this for application of the boron isotope proxy in deep time, with recommendations for best practice and future research directions.

Original language	English
Pages (from-to)	282-292
Number of pages	11
Journal	Earth and Planetary Science Letters
Volume	454
DOIs	https://doi.org/10.1016/j.epsl.2016.09.024 https://doi.org/10.1016/j.epsl.2016.09.024
Publication status	Published - 15 Nov 2016

Bibliographical note

Funding Information:
We thank Jonathan Erez for helpful comments and insights lent during drafting of this manuscript. We thank the other members of the B-Team at the University of Southampton for valuable discussion and assistance in the laboratory. We thank Lisa Northcote (NIWA) for foraminiferal assemblage counts in MOCNESS tows, Kim Currie (NIWA) for DIC and Alkalinity analyses, and the crew and research staff on board the RV Tangaroa Cruise TAN1106, including Kevin McGill and Peter Gerring for assistance with MOCNESS operations. Michal Kucera and the staff at the University of Tübingen are thanked for provision of core-top sample material from their archives. Michael Weaver (Yale) provided valuable assistance with quantification of calibration uncertainty. We acknowledge Bob Thunnell, the Fundación La Salle de Ciencias Naturales, Estación de Investigaciones Marinas Isla Margarita (EDIMAR) and the crew of the R/V Hermano Ginés for provision of CARIACO Time Series material and data. We also thank Bärbel Hönisch for enlightening discussion with regard to vital effects in the species discussed here. This work was aided by NERC PhD studentships granted to MH and RG, and NERC grant NE/D00876X/2 awarded to GF. Voyage TAN1106 was funded by the New Zealand government through NIWA core funding, and Cariaco sampling was funded through NSF award 1258991 . This research used samples from the Ocean Drilling Program. We thank J. Bijma and one anonymous reviewer for their constructive comments.

Publisher Copyright:
ï¿½ 2016 The Authors

Keywords

boron isotopes
Orbulina universa
palaeo-CO
planktic foraminifera
vital effects

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Henehan, M. J., Foster, G. L., Bostock, H. C., Greenop, R., Marshall, B. J., & Wilson, P. A. (2016). A new boron isotope-pH calibration for Orbulina universa, with implications for understanding and accounting for ‘vital effects’. Earth and Planetary Science Letters, 454, 282-292. https://doi.org/10.1016/j.epsl.2016.09.024, https://doi.org/10.1016/j.epsl.2016.09.024

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title = "A new boron isotope-pH calibration for Orbulina universa, with implications for understanding and accounting for {\textquoteleft}vital effects{\textquoteright}",

abstract = "Boron isotope ratios, as measured in planktic foraminifera, can be a useful tracer of past ocean pH, and hence help to discern the concentration of CO2 in the ancient atmosphere. However, different species of planktic foraminifera demonstrate different patterns of boron isotope variation with ambient seawater pH. Therefore when applying the proxy to questions in the geological past, species-specific calibrations are preferable. Beyond the evolutionary history of a calibrated species, we must rely on our understanding of the causes of the observed “vital effects” in the modern ocean, and the applicability of that understanding to extinct species. Here we present a new open-ocean calibration of the planktic foraminifera Orbulina universa, measured via Multi-Collector Inductively Coupled Mass Spectrometry (MC-ICPMS). Unlike other symbiont-bearing foraminifera, O. universa record a δ11B (and hence pH) that is lower than its surrounding seawater, but with a pH-sensitivity roughly equal to that of aqueous borate ion. We discuss the significance of this for application of the boron isotope proxy in deep time, with recommendations for best practice and future research directions.",

keywords = "boron isotopes, Orbulina universa, palaeo-CO, planktic foraminifera, vital effects",

author = "Henehan, \{Michael J.\} and Foster, \{Gavin L.\} and Bostock, \{Helen C.\} and Rosanna Greenop and Marshall, \{Brittney J.\} and Wilson, \{Paul A.\}",

note = "Funding Information: We thank Jonathan Erez for helpful comments and insights lent during drafting of this manuscript. We thank the other members of the B-Team at the University of Southampton for valuable discussion and assistance in the laboratory. We thank Lisa Northcote (NIWA) for foraminiferal assemblage counts in MOCNESS tows, Kim Currie (NIWA) for DIC and Alkalinity analyses, and the crew and research staff on board the RV Tangaroa Cruise TAN1106, including Kevin McGill and Peter Gerring for assistance with MOCNESS operations. Michal Kucera and the staff at the University of T{\"u}bingen are thanked for provision of core-top sample material from their archives. Michael Weaver (Yale) provided valuable assistance with quantification of calibration uncertainty. We acknowledge Bob Thunnell, the Fundaci{\'o}n La Salle de Ciencias Naturales, Estaci{\'o}n de Investigaciones Marinas Isla Margarita (EDIMAR) and the crew of the R/V Hermano Gin{\'e}s for provision of CARIACO Time Series material and data. We also thank B{\"a}rbel H{\"o}nisch for enlightening discussion with regard to vital effects in the species discussed here. This work was aided by NERC PhD studentships granted to MH and RG, and NERC grant NE/D00876X/2 awarded to GF. Voyage TAN1106 was funded by the New Zealand government through NIWA core funding, and Cariaco sampling was funded through NSF award 1258991 . This research used samples from the Ocean Drilling Program. We thank J. Bijma and one anonymous reviewer for their constructive comments. Publisher Copyright: {\"i}¿½ 2016 The Authors",

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doi = "10.1016/j.epsl.2016.09.024",

language = "English",

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AU - Henehan, Michael J.

AU - Foster, Gavin L.

AU - Bostock, Helen C.

AU - Greenop, Rosanna

AU - Marshall, Brittney J.

AU - Wilson, Paul A.

N1 - Funding Information: We thank Jonathan Erez for helpful comments and insights lent during drafting of this manuscript. We thank the other members of the B-Team at the University of Southampton for valuable discussion and assistance in the laboratory. We thank Lisa Northcote (NIWA) for foraminiferal assemblage counts in MOCNESS tows, Kim Currie (NIWA) for DIC and Alkalinity analyses, and the crew and research staff on board the RV Tangaroa Cruise TAN1106, including Kevin McGill and Peter Gerring for assistance with MOCNESS operations. Michal Kucera and the staff at the University of Tübingen are thanked for provision of core-top sample material from their archives. Michael Weaver (Yale) provided valuable assistance with quantification of calibration uncertainty. We acknowledge Bob Thunnell, the Fundación La Salle de Ciencias Naturales, Estación de Investigaciones Marinas Isla Margarita (EDIMAR) and the crew of the R/V Hermano Ginés for provision of CARIACO Time Series material and data. We also thank Bärbel Hönisch for enlightening discussion with regard to vital effects in the species discussed here. This work was aided by NERC PhD studentships granted to MH and RG, and NERC grant NE/D00876X/2 awarded to GF. Voyage TAN1106 was funded by the New Zealand government through NIWA core funding, and Cariaco sampling was funded through NSF award 1258991 . This research used samples from the Ocean Drilling Program. We thank J. Bijma and one anonymous reviewer for their constructive comments. Publisher Copyright: ï¿½ 2016 The Authors

PY - 2016/11/15

Y1 - 2016/11/15

N2 - Boron isotope ratios, as measured in planktic foraminifera, can be a useful tracer of past ocean pH, and hence help to discern the concentration of CO2 in the ancient atmosphere. However, different species of planktic foraminifera demonstrate different patterns of boron isotope variation with ambient seawater pH. Therefore when applying the proxy to questions in the geological past, species-specific calibrations are preferable. Beyond the evolutionary history of a calibrated species, we must rely on our understanding of the causes of the observed “vital effects” in the modern ocean, and the applicability of that understanding to extinct species. Here we present a new open-ocean calibration of the planktic foraminifera Orbulina universa, measured via Multi-Collector Inductively Coupled Mass Spectrometry (MC-ICPMS). Unlike other symbiont-bearing foraminifera, O. universa record a δ11B (and hence pH) that is lower than its surrounding seawater, but with a pH-sensitivity roughly equal to that of aqueous borate ion. We discuss the significance of this for application of the boron isotope proxy in deep time, with recommendations for best practice and future research directions.

AB - Boron isotope ratios, as measured in planktic foraminifera, can be a useful tracer of past ocean pH, and hence help to discern the concentration of CO2 in the ancient atmosphere. However, different species of planktic foraminifera demonstrate different patterns of boron isotope variation with ambient seawater pH. Therefore when applying the proxy to questions in the geological past, species-specific calibrations are preferable. Beyond the evolutionary history of a calibrated species, we must rely on our understanding of the causes of the observed “vital effects” in the modern ocean, and the applicability of that understanding to extinct species. Here we present a new open-ocean calibration of the planktic foraminifera Orbulina universa, measured via Multi-Collector Inductively Coupled Mass Spectrometry (MC-ICPMS). Unlike other symbiont-bearing foraminifera, O. universa record a δ11B (and hence pH) that is lower than its surrounding seawater, but with a pH-sensitivity roughly equal to that of aqueous borate ion. We discuss the significance of this for application of the boron isotope proxy in deep time, with recommendations for best practice and future research directions.

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KW - Orbulina universa

KW - palaeo-CO

KW - planktic foraminifera

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U2 - 10.1016/j.epsl.2016.09.024

DO - 10.1016/j.epsl.2016.09.024

M3 - Article (Academic Journal)

SN - 0012-821X

VL - 454

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EP - 292

JO - Earth and Planetary Science Letters

JF - Earth and Planetary Science Letters

ER -

A new boron isotope-pH calibration for Orbulina universa, with implications for understanding and accounting for ‘vital effects’

Abstract

Bibliographical note

Keywords

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