The silicon cycle impacted by past ice sheets

Hawkings, Jon R., Hatton, Jade E., Hendry, Katharine R., De Souza, Gregory F., Wadham, Jemma L., Ivanovic, Ruza, Kohler, Tyler J., Stibal, Marek, Beaton, Alexander, Lamarche-Gagnon, Guillaume, Tedstone, Andrew, Hain, Mathis P., Bagshaw, Elizabeth ORCID: https://orcid.org/0000-0001-8392-1750, Pike, Jennifer ORCID: https://orcid.org/0000-0001-9415-6003 and Tranter, Martin 2018. The silicon cycle impacted by past ice sheets. Nature Communications 9 , 3210. 10.1038/s41467-018-05689-1

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Abstract

Globally averaged riverine silicon (Si) concentrations and isotope composition (δ30Si) may be affected by the expansion and retreat of large ice sheets during glacial−interglacial cycles. Here we provide evidence of this based on the δ30Si composition of meltwater runoff from a Greenland Ice Sheet catchment. Glacier runoff has the lightest δ30Si measured in running waters (−0.25 ± 0.12‰), significantly lower than nonglacial rivers (1.25 ± 0.68‰), such that the overall decline in glacial runoff since the Last Glacial Maximum (LGM) may explain 0.06–0.17‰ of the observed ocean δ30Si rise (0.5–1.0‰). A marine sediment core proximal to Iceland provides further evidence for transient, low-δ30Si meltwater pulses during glacial termination. Diatom Si uptake during the LGM was likely similar to present day due to an expanded Si inventory, which raises the possibility of a feedback between ice sheet expansion, enhanced Si export to the ocean and reduced CO2 concentration in the atmosphere, because of the importance of diatoms in the biological carbon pump.

Item Type:	Article
Date Type:	Publication
Status:	Published
Schools:	Schools > Earth and Environmental Sciences
Additional Information:	This article is licensed under a Creative Commons Attribution 4.0 International License
Publisher:	Nature Research
ISSN:	2041-1723
Date of First Compliant Deposit:	20 July 2018
Date of Acceptance:	11 June 2018
Last Modified:	06 May 2023 02:32
URI:	https://orca.cardiff.ac.uk/id/eprint/113338

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