Sr partitioning in the benthic foraminifera Ammonia aomoriensis and Amphistegina lessonii

Langer, Gerald and Sadekov, Aleksey and Thoms, Silke and Keul, Nina and Nehrke, Gernot and Mewes, Antje and Greaves, Mervyn and Misra, Sambuddha and Reichart, Gert-Jan and de Nooijer, Lennart Jan and Bijma, Jelle and Elderfield, Henry (2016) Sr partitioning in the benthic foraminifera Ammonia aomoriensis and Amphistegina lessonii. Chemical Geology, 440. pp. 306-312. ISSN 0009-2541 DOI 10.1016/j.chemgeo.2016.07.018

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Official URL: http://doi.org/10.1016/j.chemgeo.2016.07.018

Abstract

The shallow water benthic foraminifera Ammonia aomoriensis and Amphistegina lessonii were grown at different seawater Sr/Ca and the test Sr/Ca ratio was determined by Laser Ablation - Inductively Coupled Plasma - Mass Spectrometry. A. aomoriensis test Sr/Ca is positively correlated with seawater Sr/Ca. The linear regression has a slope of 0.17, representing the overall Sr partitioning coefficient KDSr. The slope remains unchanged, if seawater Ca concentration is changed in order to change the seawater Sr/Ca. In the case of A. lessonii, the slopes of the linear regressions representing KDSr differ from one another i.e., 0.16 if the Sr concentration is changed and 0.32 if the Ca level is changed. This difference in KDSr can be explained by the, relative to A. aomoriensis, high Mg content of A. lessonii (ca. 40 mmol/mol), distorting the calcite lattice and weakening the discrimination against Sr. The Mg content of A. aomoriensis is too low (ca. 4 mmol/mol) to observe the influence on Sr partitioning. All data are compatible with a recently developed model for minor element partitioning in foraminifera (Nehrke et al., 2013; Mewes et al., 2015a). On the whole, our data confirm the model (applicability of the model to Sr and dependence of the calcite Sr/Ca on seawater Sr/Ca, as opposed to seawater Sr concentration), and improve our understanding of the model (influence of calcite Mg/Ca on Sr partitioning).

Item Type: Article
Uncontrolled Keywords: 2016AREP; IA70
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Journal or Publication Title: Chemical Geology
Volume: 440
Page Range: pp. 306-312
Identification Number: 10.1016/j.chemgeo.2016.07.018
Depositing User: Sarah Humbert
Date Deposited: 23 Jun 2017 15:52
Last Modified: 23 Jun 2017 15:52
URI: http://eprints.esc.cam.ac.uk/id/eprint/3995

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