Cold-water corals as archives of seawater Zn and Cu isotopes

Susan H. Little; David J. Wilson; Mark Rehkämper; Jess F. Adkins; Laura F. Robinson; Tina van de Flierdt

doi:10.1016/j.chemgeo.2021.120304

Cold-water corals as archives of seawater Zn and Cu isotopes

Susan H. Little^*
, David J. Wilson
, Mark Rehkämper
, Jess F. Adkins
, Laura F. Robinson
, Tina van de Flierdt

^*Corresponding author for this work

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

27 Citations (Scopus)

Abstract

Traditional carbonate sedimentary archives have proven challenging to exploit for Zn and Cu isotopes, due to the high concentrations of trace metals in potential contaminants (e.g., Fe-Mn coatings) and their low concentrations in carbonate. Here, we present the first dataset of δ⁶⁶Zn_JMC-Lyon and δ⁶⁵Cu_{SRM 976} values for cold-water corals and address their potential as a seawater archive. Extensive cleaning experiments carried out on two corals with well-developed Fe-Mn rich coatings demonstrate that thorough physical and chemical cleaning can effectively remove detrital and authigenic contaminants. Next, we present metal/Ca ratios and δ⁶⁶Zn and δ⁶⁵Cu values for a geographically diverse sample set of Holocene age cold-water corals. Comparing cold-water coral δ⁶⁶Zn values to estimated ambient seawater δ⁶⁶Zn values (where Δ⁶⁶Zn_coral-sw = δ⁶⁶Zn_coral – δ⁶⁶Zn_seawater), we find Δ⁶⁶Zn_coral-sw = +0.03 ± 0.17‰ (1SD, n = 20). Hence, to a first order, cold-water corals record seawater Zn isotope compositions without fractionation. The average Holocene coral Cu isotope composition is +0.59 ± 0.23‰ (1SD, n = 15), similar to the mean of published deep seawater δ⁶⁵Cu values at +0.66 ± 0.09‰, but with considerable variability. Finally, δ⁶⁶Zn and δ⁶⁵Cu data are presented for a small subset of four glacial-age corals. These values overlap with the respective Holocene coral datasets, hinting at limited glacial-interglacial changes in oceanic Zn and Cu cycling.

Original language	English
Article number	120304
Journal	Chemical Geology
Volume	578
Early online date	2 May 2021
DOIs	https://doi.org/10.1016/j.chemgeo.2021.120304
Publication status	Published - 20 Sept 2021

Bibliographical note

Funding Information:
We would like to acknowledge Matthew Clarkson and an anonymous reviewer for thoughtful comments on a previous version of this manuscript. Many thanks to Katharina Kreissig and Barry Coles for maintaining the smooth running of the MAGIC labs at Imperial, and to Derek Vance for the use of the Neptune at ETH. Thanks also to Sophie Hines, who sub-sampled New England Seamount corals from the Adkins collection and to Tristan Horner, who provided valuable insights early on in the development of this project. This research was supported by a Leverhulme Trust early career fellowship to SHL ( ECF-2014-615 ). DJW and TvdF acknowledge support from the Natural Environment Research Council ( NE/N001141/1 ) and a NERC independent research fellowship to DJW ( NE/T011440/1 ). SHL is currently supported by a NERC independent research fellowship ( NE/P018181/2 ).

Publisher Copyright:
© 2021 The Authors

Keywords

Aragonites
Cold-water coral
Copper
Isotopes
Palaeoceanography
Zinc

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@article{bf6a709e7f864e9f9b7f83c2d5904d52,

title = "Cold-water corals as archives of seawater Zn and Cu isotopes",

abstract = "Traditional carbonate sedimentary archives have proven challenging to exploit for Zn and Cu isotopes, due to the high concentrations of trace metals in potential contaminants (e.g., Fe-Mn coatings) and their low concentrations in carbonate. Here, we present the first dataset of δ66ZnJMC-Lyon and δ65CuSRM 976 values for cold-water corals and address their potential as a seawater archive. Extensive cleaning experiments carried out on two corals with well-developed Fe-Mn rich coatings demonstrate that thorough physical and chemical cleaning can effectively remove detrital and authigenic contaminants. Next, we present metal/Ca ratios and δ66Zn and δ65Cu values for a geographically diverse sample set of Holocene age cold-water corals. Comparing cold-water coral δ66Zn values to estimated ambient seawater δ66Zn values (where Δ66Zncoral-sw = δ66Zncoral – δ66Znseawater), we find Δ66Zncoral-sw = +0.03 ± 0.17‰ (1SD, n = 20). Hence, to a first order, cold-water corals record seawater Zn isotope compositions without fractionation. The average Holocene coral Cu isotope composition is +0.59 ± 0.23‰ (1SD, n = 15), similar to the mean of published deep seawater δ65Cu values at +0.66 ± 0.09‰, but with considerable variability. Finally, δ66Zn and δ65Cu data are presented for a small subset of four glacial-age corals. These values overlap with the respective Holocene coral datasets, hinting at limited glacial-interglacial changes in oceanic Zn and Cu cycling.",

keywords = "Aragonites, Cold-water coral, Copper, Isotopes, Palaeoceanography, Zinc",

author = "Little, \{Susan H.\} and Wilson, \{David J.\} and Mark Rehk{\"a}mper and Adkins, \{Jess F.\} and Robinson, \{Laura F.\} and \{van de Flierdt\}, Tina",

note = "Funding Information: We would like to acknowledge Matthew Clarkson and an anonymous reviewer for thoughtful comments on a previous version of this manuscript. Many thanks to Katharina Kreissig and Barry Coles for maintaining the smooth running of the MAGIC labs at Imperial, and to Derek Vance for the use of the Neptune at ETH. Thanks also to Sophie Hines, who sub-sampled New England Seamount corals from the Adkins collection and to Tristan Horner, who provided valuable insights early on in the development of this project. This research was supported by a Leverhulme Trust early career fellowship to SHL ( ECF-2014-615 ). DJW and TvdF acknowledge support from the Natural Environment Research Council ( NE/N001141/1 ) and a NERC independent research fellowship to DJW ( NE/T011440/1 ). SHL is currently supported by a NERC independent research fellowship ( NE/P018181/2 ). Publisher Copyright: {\textcopyright} 2021 The Authors",

year = "2021",

month = sep,

day = "20",

doi = "10.1016/j.chemgeo.2021.120304",

language = "English",

volume = "578",

journal = "Chemical Geology",

issn = "0009-2541",

publisher = "Elsevier B.V.",

}

TY - JOUR

T1 - Cold-water corals as archives of seawater Zn and Cu isotopes

AU - Little, Susan H.

AU - Wilson, David J.

AU - Rehkämper, Mark

AU - Adkins, Jess F.

AU - Robinson, Laura F.

AU - van de Flierdt, Tina

N1 - Funding Information: We would like to acknowledge Matthew Clarkson and an anonymous reviewer for thoughtful comments on a previous version of this manuscript. Many thanks to Katharina Kreissig and Barry Coles for maintaining the smooth running of the MAGIC labs at Imperial, and to Derek Vance for the use of the Neptune at ETH. Thanks also to Sophie Hines, who sub-sampled New England Seamount corals from the Adkins collection and to Tristan Horner, who provided valuable insights early on in the development of this project. This research was supported by a Leverhulme Trust early career fellowship to SHL ( ECF-2014-615 ). DJW and TvdF acknowledge support from the Natural Environment Research Council ( NE/N001141/1 ) and a NERC independent research fellowship to DJW ( NE/T011440/1 ). SHL is currently supported by a NERC independent research fellowship ( NE/P018181/2 ). Publisher Copyright: © 2021 The Authors

PY - 2021/9/20

Y1 - 2021/9/20

N2 - Traditional carbonate sedimentary archives have proven challenging to exploit for Zn and Cu isotopes, due to the high concentrations of trace metals in potential contaminants (e.g., Fe-Mn coatings) and their low concentrations in carbonate. Here, we present the first dataset of δ66ZnJMC-Lyon and δ65CuSRM 976 values for cold-water corals and address their potential as a seawater archive. Extensive cleaning experiments carried out on two corals with well-developed Fe-Mn rich coatings demonstrate that thorough physical and chemical cleaning can effectively remove detrital and authigenic contaminants. Next, we present metal/Ca ratios and δ66Zn and δ65Cu values for a geographically diverse sample set of Holocene age cold-water corals. Comparing cold-water coral δ66Zn values to estimated ambient seawater δ66Zn values (where Δ66Zncoral-sw = δ66Zncoral – δ66Znseawater), we find Δ66Zncoral-sw = +0.03 ± 0.17‰ (1SD, n = 20). Hence, to a first order, cold-water corals record seawater Zn isotope compositions without fractionation. The average Holocene coral Cu isotope composition is +0.59 ± 0.23‰ (1SD, n = 15), similar to the mean of published deep seawater δ65Cu values at +0.66 ± 0.09‰, but with considerable variability. Finally, δ66Zn and δ65Cu data are presented for a small subset of four glacial-age corals. These values overlap with the respective Holocene coral datasets, hinting at limited glacial-interglacial changes in oceanic Zn and Cu cycling.

AB - Traditional carbonate sedimentary archives have proven challenging to exploit for Zn and Cu isotopes, due to the high concentrations of trace metals in potential contaminants (e.g., Fe-Mn coatings) and their low concentrations in carbonate. Here, we present the first dataset of δ66ZnJMC-Lyon and δ65CuSRM 976 values for cold-water corals and address their potential as a seawater archive. Extensive cleaning experiments carried out on two corals with well-developed Fe-Mn rich coatings demonstrate that thorough physical and chemical cleaning can effectively remove detrital and authigenic contaminants. Next, we present metal/Ca ratios and δ66Zn and δ65Cu values for a geographically diverse sample set of Holocene age cold-water corals. Comparing cold-water coral δ66Zn values to estimated ambient seawater δ66Zn values (where Δ66Zncoral-sw = δ66Zncoral – δ66Znseawater), we find Δ66Zncoral-sw = +0.03 ± 0.17‰ (1SD, n = 20). Hence, to a first order, cold-water corals record seawater Zn isotope compositions without fractionation. The average Holocene coral Cu isotope composition is +0.59 ± 0.23‰ (1SD, n = 15), similar to the mean of published deep seawater δ65Cu values at +0.66 ± 0.09‰, but with considerable variability. Finally, δ66Zn and δ65Cu data are presented for a small subset of four glacial-age corals. These values overlap with the respective Holocene coral datasets, hinting at limited glacial-interglacial changes in oceanic Zn and Cu cycling.

KW - Aragonites

KW - Cold-water coral

KW - Copper

KW - Isotopes

KW - Palaeoceanography

KW - Zinc

UR - https://www.scopus.com/pages/publications/85107154978

U2 - 10.1016/j.chemgeo.2021.120304

DO - 10.1016/j.chemgeo.2021.120304

M3 - Article (Academic Journal)

AN - SCOPUS:85107154978

SN - 0009-2541

VL - 578

JO - Chemical Geology

JF - Chemical Geology

M1 - 120304

ER -

Cold-water corals as archives of seawater Zn and Cu isotopes

Abstract

Bibliographical note

Keywords

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