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Experimental calibration of manganese incorporation in foraminiferal calcite

Barras, Christine ; Mouret, Aurélia ; Nardelli, Maria Pia ; Metzger, Edouard ; Petersen, Jassin ; La, Carole ; Filipsson, Helena L. LU orcid and Jorissen, Frans (2018) In Geochimica et Cosmochimica Acta 237. p.49-64
Abstract

In the context of recent climate change and increased anthropogenic activities in coastal areas, which both may have a negative impact on dissolved oxygen concentration, there is an increased interest to better understand the mechanisms and evolution leading to hypoxia in marine environments. The development of well calibrated proxies is crucial to obtain reliable environmental reconstructions of past oxygen content and of historical development of hypoxia. Manganese is a redox element of interest for this purpose because manganese oxides are reduced to soluble Mn2+ in oxygen-depleted conditions, which can be incorporated in biogenic calcite. The Mn/Ca ratio in benthic foraminiferal calcite is therefore a promising proxy to... (More)

In the context of recent climate change and increased anthropogenic activities in coastal areas, which both may have a negative impact on dissolved oxygen concentration, there is an increased interest to better understand the mechanisms and evolution leading to hypoxia in marine environments. The development of well calibrated proxies is crucial to obtain reliable environmental reconstructions of past oxygen content and of historical development of hypoxia. Manganese is a redox element of interest for this purpose because manganese oxides are reduced to soluble Mn2+ in oxygen-depleted conditions, which can be incorporated in biogenic calcite. The Mn/Ca ratio in benthic foraminiferal calcite is therefore a promising proxy to reconstruct past oxygen variations. In this study, we calibrate this proxy by measuring (with Laser Ablation ICP-MS) the Mn/Ca ratio of benthic foraminifera calcified under controlled conditions in laboratory experiments. Two benthic foraminiferal species (Ammonia tepida and Bulimina marginata) calcified in 4 different dissolved manganese concentrations (from 2.4 to 595 µmol L−1) corresponding to in situ Mn concentrations encountered in bottom and/or pore waters in low oxygen marine environments. There is a statistically significant positive linear correlation (R2 > 0.9) between Mn/Cacalcite and Mn/Caseawater. However, the two species show different partitioning coefficients (DMn of 0.086 and 0.621, for A. tepida and B. marginata, respectively), although they calcified in exactly the same stable conditions. These results highlight a strong species specific effect on Mn incorporation, which is probably due to different biological controls during biomineralisation processes. There is also ontogenetic variability (determined through a comparison of successive chambers) that is different between the two species and also varies as a function of the dissolved Mn concentration. A conceptual model is proposed to explain these data.

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author
; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Ammonia tepida, Benthic foraminifera, Biomineralisation, Bulimina marginata, Laboratory proxy calibration, Mn/Ca, Species specific effect
in
Geochimica et Cosmochimica Acta
volume
237
pages
16 pages
publisher
Elsevier
external identifiers
  • scopus:85040791882
ISSN
0016-7037
DOI
10.1016/j.gca.2018.06.009
project
Svenska kalkskaliga mikroorganismer i franska akvarier
Lund University Centre for studies of Carbon Cycle and Climate Interactions
Fält och experimentell kalibrering av marina temperaturindikatorer genom användning av bentiska foraminiferer
language
English
LU publication?
yes
id
8b124dfa-7f4e-4bff-ab3a-d1cac6b16265
date added to LUP
2018-10-18 11:56:20
date last changed
2021-10-06 01:41:52
@article{8b124dfa-7f4e-4bff-ab3a-d1cac6b16265,
  abstract     = {<p>In the context of recent climate change and increased anthropogenic activities in coastal areas, which both may have a negative impact on dissolved oxygen concentration, there is an increased interest to better understand the mechanisms and evolution leading to hypoxia in marine environments. The development of well calibrated proxies is crucial to obtain reliable environmental reconstructions of past oxygen content and of historical development of hypoxia. Manganese is a redox element of interest for this purpose because manganese oxides are reduced to soluble Mn<sup>2+</sup> in oxygen-depleted conditions, which can be incorporated in biogenic calcite. The Mn/Ca ratio in benthic foraminiferal calcite is therefore a promising proxy to reconstruct past oxygen variations. In this study, we calibrate this proxy by measuring (with Laser Ablation ICP-MS) the Mn/Ca ratio of benthic foraminifera calcified under controlled conditions in laboratory experiments. Two benthic foraminiferal species (Ammonia tepida and Bulimina marginata) calcified in 4 different dissolved manganese concentrations (from 2.4 to 595 µmol L<sup>−1</sup>) corresponding to in situ Mn concentrations encountered in bottom and/or pore waters in low oxygen marine environments. There is a statistically significant positive linear correlation (R<sup>2</sup> &gt; 0.9) between Mn/Ca<sub>calcite</sub> and Mn/Ca<sub>seawater</sub>. However, the two species show different partitioning coefficients (D<sub>Mn</sub> of 0.086 and 0.621, for A. tepida and B. marginata, respectively), although they calcified in exactly the same stable conditions. These results highlight a strong species specific effect on Mn incorporation, which is probably due to different biological controls during biomineralisation processes. There is also ontogenetic variability (determined through a comparison of successive chambers) that is different between the two species and also varies as a function of the dissolved Mn concentration. A conceptual model is proposed to explain these data.</p>},
  author       = {Barras, Christine and Mouret, Aurélia and Nardelli, Maria Pia and Metzger, Edouard and Petersen, Jassin and La, Carole and Filipsson, Helena L. and Jorissen, Frans},
  issn         = {0016-7037},
  language     = {eng},
  month        = {09},
  pages        = {49--64},
  publisher    = {Elsevier},
  series       = {Geochimica et Cosmochimica Acta},
  title        = {Experimental calibration of manganese incorporation in foraminiferal calcite},
  url          = {http://dx.doi.org/10.1016/j.gca.2018.06.009},
  doi          = {10.1016/j.gca.2018.06.009},
  volume       = {237},
  year         = {2018},
}