Skip to main content

Lund University Publications

LUND UNIVERSITY LIBRARIES

Using Stable Isotopes to Disentangle Marine Sedimentary Signals in Reactive Silicon Pools

Pickering, Rebecca A. LU orcid ; Cassarino, Lucie ; Hendry, Katharine R. ; Wang, Xiangli L. ; Maiti, Kanchan and Krause, Jeffrey W. (2020) In Geophysical Research Letters 47(15).
Abstract

Many studies use sedimentary biogenic silica (bSiO2) stable isotopes (e.g., δ30Si) as paleoproxies but neglect signals from other sedimentary reactive SiO2 phases. We quantified δ30Si for multiple reactive Si pools in coastal river-plume sediments, revealing up to −5‰ difference between acid-leachable and alkaline-digestible amorphous SiO2. Thus, previous studies have missed valuable information on early diagenetic products and, in cases where sediments were not cleaned, potentially biased bSiO2 δ30Si values. Acid-leachable δ30Si, that is, from authigenic products, are the result of either multistep fractionation from a bSiO2 source or an... (More)

Many studies use sedimentary biogenic silica (bSiO2) stable isotopes (e.g., δ30Si) as paleoproxies but neglect signals from other sedimentary reactive SiO2 phases. We quantified δ30Si for multiple reactive Si pools in coastal river-plume sediments, revealing up to −5‰ difference between acid-leachable and alkaline-digestible amorphous SiO2. Thus, previous studies have missed valuable information on early diagenetic products and, in cases where sediments were not cleaned, potentially biased bSiO2 δ30Si values. Acid-leachable δ30Si, that is, from authigenic products, are the result of either multistep fractionation from a bSiO2 source or an ~2‰ fractionation (consistent with metal hydroxide formation) from slowly dissolving lithogenic SiO2. This analysis also suggests that sedimentary diatom bSiO2, which has increased regionally in the last half-century, is the critical substrate of early authigenic Si precipitates. Regional eutrophication, which has stimulated sedimentary bSiO2 accumulation, may have facilitated additional sequestration of both sedimentary Si and cations from early diagenetic products.

(Less)
Please use this url to cite or link to this publication:
author
; ; ; ; and
publishing date
type
Contribution to journal
publication status
published
subject
keywords
authigenic coatings, biogenic silica, early diagenesis, Gulf of Mexico, reactive silicon, stable silicon isotopes
in
Geophysical Research Letters
volume
47
issue
15
article number
e2020GL087877
publisher
American Geophysical Union (AGU)
external identifiers
  • scopus:85089370189
ISSN
0094-8276
DOI
10.1029/2020GL087877
language
English
LU publication?
no
additional info
Funding Information: We would like to thank the captain, crew, and science party of the RV Pelican (PE17‐20) for their assistance in sample collection, in particular, B. Ebner and W. Bam. Additionally, we thank R. Kiene, J. Lehrter, I. Marquez, A. Smith, K. Halstead, L. Linn, and A. McAlleer for laboratory and logistical support. We appreciate the help of C. D. Coath in maintaining the operation of the Neptune MC‐ICP‐MS at the Bristol Isotope Group Laboratory. We also thank the students from the University of Bristol Isotope Group and Dauphin Island Sea Lab for assistance in sample preparation and analysis. Finally, we would like to thank the two anonymous reviewers for their critical reading, thoughtful comments, and efforts toward improving our manuscript. This work was supported by the U. S. National Science Foundation (OCE‐1558957—J. W. K. and K. M.) and European Research Council Grant ICY‐LAB (678371—K. R. H.). Funding Information: We would like to thank the captain, crew, and science party of the RV Pelican (PE17-20) for their assistance in sample collection, in particular, B. Ebner and W. Bam. Additionally, we thank R. Kiene, J. Lehrter, I. Marquez, A. Smith, K. Halstead, L. Linn, and A. McAlleer for laboratory and logistical support. We appreciate the help of C.?D. Coath in maintaining the operation of the Neptune MC-ICP-MS at the Bristol Isotope Group Laboratory. We also thank the students from the University of Bristol Isotope Group and Dauphin Island Sea Lab for assistance in sample preparation and analysis. Finally, we would like to thank the two anonymous reviewers for their critical reading, thoughtful comments, and efforts toward improving our manuscript. This work was supported by the U. S. National Science Foundation (OCE-1558957?J.?W.?K. and K.?M.) and European Research Council Grant ICY-LAB (678371?K.?R.?H.). Publisher Copyright: © 2020. American Geophysical Union. All Rights Reserved.
id
349bc495-9500-4ae8-b079-796b0a047e88
date added to LUP
2021-12-28 16:13:24
date last changed
2022-04-27 07:00:46
@article{349bc495-9500-4ae8-b079-796b0a047e88,
  abstract     = {{<p>Many studies use sedimentary biogenic silica (bSiO<sub>2</sub>) stable isotopes (e.g., δ<sup>30</sup>Si) as paleoproxies but neglect signals from other sedimentary reactive SiO<sub>2</sub> phases. We quantified δ<sup>30</sup>Si for multiple reactive Si pools in coastal river-plume sediments, revealing up to −5‰ difference between acid-leachable and alkaline-digestible amorphous SiO<sub>2</sub>. Thus, previous studies have missed valuable information on early diagenetic products and, in cases where sediments were not cleaned, potentially biased bSiO<sub>2</sub> δ<sup>30</sup>Si values. Acid-leachable δ<sup>30</sup>Si, that is, from authigenic products, are the result of either multistep fractionation from a bSiO<sub>2</sub> source or an ~2‰ fractionation (consistent with metal hydroxide formation) from slowly dissolving lithogenic SiO<sub>2</sub>. This analysis also suggests that sedimentary diatom bSiO<sub>2</sub>, which has increased regionally in the last half-century, is the critical substrate of early authigenic Si precipitates. Regional eutrophication, which has stimulated sedimentary bSiO<sub>2</sub> accumulation, may have facilitated additional sequestration of both sedimentary Si and cations from early diagenetic products.</p>}},
  author       = {{Pickering, Rebecca A. and Cassarino, Lucie and Hendry, Katharine R. and Wang, Xiangli L. and Maiti, Kanchan and Krause, Jeffrey W.}},
  issn         = {{0094-8276}},
  keywords     = {{authigenic coatings; biogenic silica; early diagenesis; Gulf of Mexico; reactive silicon; stable silicon isotopes}},
  language     = {{eng}},
  month        = {{08}},
  number       = {{15}},
  publisher    = {{American Geophysical Union (AGU)}},
  series       = {{Geophysical Research Letters}},
  title        = {{Using Stable Isotopes to Disentangle Marine Sedimentary Signals in Reactive Silicon Pools}},
  url          = {{http://dx.doi.org/10.1029/2020GL087877}},
  doi          = {{10.1029/2020GL087877}},
  volume       = {{47}},
  year         = {{2020}},
}