Silicon isotopes reveal the impact of fjordic processes on the transport of reactive silicon from glaciers to coastal regions

Wang, Tong; Ng, Hong Chin; Hatton, Jade E.; Hammond, Samantha J.; Woodward, E. Malcolm S.; Meire, Lorenz; Hendry, Katharine R. ORCID: https://orcid.org/0000-0002-0790-5895. 2024 Silicon isotopes reveal the impact of fjordic processes on the transport of reactive silicon from glaciers to coastal regions. Chemical Geology, 670, 122403. 17, pp. https://doi.org/10.1016/j.chemgeo.2024.122403

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Abstract/Summary

Accelerated mass loss from the Greenland Ice Sheet leads to retreating glaciers and enhanced freshwater runoff to adjacent coastal regions, potentially providing additional essential nutrients, such as silicon, to downstream primary producers. However, the role of fjordic sediments in modulating the supply of silicon from glacial environments to marine ecosystems remains poorly constrained, particularly for the quantification of silicon fluxes from the sediments into overlying waters in high-latitude fjordic systems. In this study, we use the concentration and stable isotopic composition of dissolved silicon in pore waters and core-top waters, and amorphous silica phases (such as glacially-derived amorphous silica) in sediments and suspended particulate matter, collected from two fjords in the southwest Greenland margin to address this knowledge gap. We combine downcore observations with core incubations and isotope mass balance approaches to assess the benthic flux of dissolved silicon and deconvolve potential contributors to this flux during early diagenesis. Our results suggest that molecular diffusion only accounts for a portion of benthic dissolved silicon transport. Relative to surrounding continental shelves and highly-productive open ocean waters, the estimated benthic dissolved silicon flux at our sites is smaller in magnitude, supporting the role of fjords as a ‘trap’ for reactive silicon in high-latitude systems.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1016/j.chemgeo.2024.122403
ISSN:	00092541
Additional Keywords:	Benthic silicon cycle, Fjords, Benthic nutrient flux, Early diagenesis, Stable silicon isotope
Date made live:	12 Sep 2024 13:08 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/538015

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.1016/j.chemgeo.2024.122403

ISSN:

00092541

Additional Keywords:

Benthic silicon cycle, Fjords, Benthic nutrient flux, Early diagenesis, Stable silicon isotope

Date made live:

12 Sep 2024 13:08 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/538015