TY - JOUR
T1 - Using Stable Isotopes to Disentangle Marine Sedimentary Signals in Reactive Silicon Pools
AU - Pickering, Rebecca A.
AU - Cassarino, Lucie
AU - Hendry, Katharine R.
AU - Wang, Xiangli L.
AU - Maiti, Kanchan
AU - Krause, Jeffrey W.
N1 - 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.
PY - 2020/8/16
Y1 - 2020/8/16
N2 - 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.
AB - 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.
KW - authigenic coatings
KW - biogenic silica
KW - early diagenesis
KW - Gulf of Mexico
KW - reactive silicon
KW - stable silicon isotopes
U2 - 10.1029/2020GL087877
DO - 10.1029/2020GL087877
M3 - Article
AN - SCOPUS:85089370189
VL - 47
JO - Geophysical Research Letters
JF - Geophysical Research Letters
SN - 1944-8007
IS - 15
M1 - e2020GL087877
ER -