Li Partitioning Into Coccoliths of Emiliania huxleyi : Evaluating the General Role of “Vital Effects” in Explaining Element Partitioning in Biogenic Carbonates

Langer, Gerald and Sadekov, Aleksey and Greaves, Mervyn and Nehrke, Gernot and Probert, Ian and Misra, Sambuddha and Thoms, Silke (2020) Li Partitioning Into Coccoliths of Emiliania huxleyi : Evaluating the General Role of “Vital Effects” in Explaining Element Partitioning in Biogenic Carbonates. Geochemistry, Geophysics, Geosystems, 21 (8). ISSN 1525-2027 DOI https://doi.org/10.1029/2020GC009129

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Abstract

Emiliania huxleyi cells were grown in artificial seawater of different Li and Ca concentrations and coccolith Li/Ca ratios determined. Coccolith Li/Ca ratios were positively correlated to seawater Li/Ca ratios only if the seawater Li concentration was changed, not if the seawater Ca concentration was changed. This Li partitioning pattern of E. huxleyi was previously also observed in the benthic foraminifer Amphistegina lessonii and inorganically precipitated calcite. We argue that Li partitioning in both E. huxleyi and A. lessonii is dominated by a coupled transmembrane transport of Li and Ca from seawater to the site of calcification. We present a refined version of a recently proposed transmembrane transport model for Li and Ca. The model assumes that Li and Ca enter the cell via Ca channels, the Li flux being dependent on the Ca flux. While the original model features a linear function to describe the experimental data, our refined version uses a power function, changing the stoichiometry of Li and Ca. The version presented here accurately predicts the observed dependence of D Li on seawater Li/Ca ratios. Our data demonstrate that minor element partitioning in calcifying organisms is partly mediated by biological processes even if the partitioning behavior of the calcifying organism is indistinguishable from that of inorganically precipitated calcium carbonate.

Item Type: Article
Uncontrolled Keywords: 2020AREP; IA76
Subjects: 01 - Climate Change and Earth-Ocean Atmosphere Systems
Divisions: 01 - Climate Change and Earth-Ocean Atmosphere Systems
08 - Green Open Access
Journal or Publication Title: Geochemistry, Geophysics, Geosystems
Volume: 21
Identification Number: https://doi.org/10.1029/2020GC009129
Depositing User: Sarah Humbert
Date Deposited: 13 Aug 2020 09:56
Last Modified: 14 Dec 2020 01:00
URI: http://eprints.esc.cam.ac.uk/id/eprint/4862

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