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Biogeosciences An interactive open-access journal of the European Geosciences Union
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https://doi.org/10.5194/bg-2017-4
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/bg-2017-4
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Submitted as: research article 30 Jan 2017

Submitted as: research article | 30 Jan 2017

Review status
This discussion paper is a preprint. It has been under review for the journal Biogeosciences (BG). The manuscript was not accepted for further review after discussion.

Changes in the Si / P weathering ratio and their effect on the selection of coccolithophores and diatoms

Virginia García-Bernal, Óscar Paz, and Pedro Cermeño Virginia García-Bernal et al.
  • Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM-CSIC), Passeig Marítim de la Barceloneta, 37–49, Barcelona, 08003, Spain

Abstract. The relative contribution of coccolithophores and diatoms to export production and burial influences the mechanisms of carbon (C) removal from Earth’s surface reservoirs. Whereas the supply of phosphorus (P) to the ocean basins controls export production over geological timescales, the availability of dissolved silica (Si) determines the relative contribution of diatoms to export production and increases the efficiency of the ocean’s biologically-driven C sequestration. Here we combine analyses of data from the sedimentary record and Earth system model simulations to investigate the coupling of P and Si weathering fluxes over the last 40 million years (My). Although both weathering fluxes increased on average through time, the relative increase of Si weathering over the last 20 My exceeded that of P. Our analysis suggests that the increase in P weathering under a regime of increasingly ocean turbulence allowed full utilization of increased Si supplies and links the ecological success of marine diatoms, and consequential decline of coccolithophores, to changes in the Si / P weathering ratio. These results allow us to envisage that ocean fertilization initiatives would be more effective if they were integrated within the framework of geo-engineering programs aimed at enhancing silicate weathering.

Virginia García-Bernal et al.
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AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
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Interactive discussion
Status: closed
Status: closed
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Printer-friendly Version - Printer-friendly version Supplement - Supplement
Virginia García-Bernal et al.
Virginia García-Bernal et al.
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Short summary
Marine diatoms are responsible for roughly 40 % of modern ocean primary production and contribute disproportionately to the drawdown of atmospheric carbon dioxide through the export of organic carbon into the deep sea and sediments. Over the past 40 Myr their rise to ecological prominence and consequential decline of coccolithophores is linked to the silicon to phosphorus weathering ratio, which controls the oceanic nutrient inventories and hence the competitive ability of diatoms.
Marine diatoms are responsible for roughly 40 % of modern ocean primary production and...
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