TY - JOUR
T1 - Sedimentary vanadium isotope signatures in low oxygen marine conditions
AU - Wu, Fei
AU - Owens, Jeremy D.
AU - Scholz, Florian
AU - Huang, Linqing
AU - Li, Siqi
AU - Riedinger, Natascha
AU - Peterson, Larry C.
AU - German, Christopher R.
AU - Nielsen, Sune G.
N1 - Funding Information:
We would like to thank T. Them and S. Young for providing stimulating conversation on the data from this project. G. White is thanked for instrumentation troubleshooting at the MagLab. The work was funded by grants from NSF-OCE 1434785 (JDO and SGN), and NASA Exobiology NNX16AJ60 (JDO and SGN) and 80NSSC18K1532 (JDO and FW). FS wishes to thank the German Research Foundation (DFG) for funding through Emmy Noether Research Group ICONOX and Collaborative Research Centre 754. CRG acknowledges NSF grants OCE-1234827 & OCE-1235248 (US GEOTRACES). This manuscript has benefited from reviews by Tais W. Dahl, and two anonymous reviewers and the efficient editorial handling from Noah Planavsky.
Funding Information:
We would like to thank T. Them and S. Young for providing stimulating conversation on the data from this project. G. White is thanked for instrumentation troubleshooting at the MagLab. The work was funded by grants from NSF-OCE 1434785 (JDO and SGN), and NASA Exobiology NNX16AJ60 (JDO and SGN) and 80NSSC18K1532 (JDO and FW). FS wishes to thank the German Research Foundation (DFG) for funding through Emmy Noether Research Group ICONOX and Collaborative Research Centre 754. CRG acknowledges NSF grants OCE-1234827 & OCE-1235248 ( US GEOTRACES ). This manuscript has benefited from reviews by Tais W. Dahl, and two anonymous reviewers and the efficient editorial handling from Noah Planavsky.
PY - 2020/9/1
Y1 - 2020/9/1
N2 - It has been hypothesized that vanadium (V) isotopes have the potential to track sedimentary redox conditions due to multiple valence states occurring in nature, which might induce variable V isotope fractionation as a function of sedimentary redox state. These characteristica could make V isotopes a useful paleo-redox proxy. However, in order to understand the mechanisms driving V isotope fractionation, it is crucial to build a framework for the depositional and post-depositional controls on sedimentary V isotope records from a diverse set of sedimentary environments. This study, for the first time, investigates the V isotope variations of modern marine sediments deposited under a range of redox environments. Our results document that changes in local redox conditions impart a significant isotopic fractionation from seawater as recorded in the local sedimentary V isotopic signature. Importantly, there is a significant difference between the V isotope composition of sediments deposited in the open ocean setting with oxygen-deficient bottom waters compared to less reducing environments, whereby oxic sediments (benthic oxygen contents > 10 μΜ) exhibit Δoxic = −1.1 ± 0.3‰ and anoxic sediments exhibit Δanoxic = −0.7 ± 0.2‰. Combined with previous studies on seawater particulate and sediment pore fluid analysis, our results indicate that V is mainly delivered and enriched in anoxic sediments through settling particulates. Authigenic V isotope compositions in marine sediments are likely controlled by isotope fractionation between V species bound to particulates and dissolved in seawater, which likely varies with the speciation and adsorption properties of V that are strongly controlled by local redox conditions. In addition, the euxinic Cariaco Basin sediments exhibit distinctive Δeuxinic = −0.4 ± 0.2‰, which is likely influenced by the relationship between the seawater V removal rate and the seawater renewal rate. Our results highlight the direct link between authigenic marine sedimentary V isotope compositions and the overlying local redox conditions. This investigation of V isotopes in modern marine environments provides an initial framework for the utilization of V isotopes to reconstruct ancient redox fluctuations, which has the potential to track subtle redox variations of local oxygen-deficient to low oxygen environments.
AB - It has been hypothesized that vanadium (V) isotopes have the potential to track sedimentary redox conditions due to multiple valence states occurring in nature, which might induce variable V isotope fractionation as a function of sedimentary redox state. These characteristica could make V isotopes a useful paleo-redox proxy. However, in order to understand the mechanisms driving V isotope fractionation, it is crucial to build a framework for the depositional and post-depositional controls on sedimentary V isotope records from a diverse set of sedimentary environments. This study, for the first time, investigates the V isotope variations of modern marine sediments deposited under a range of redox environments. Our results document that changes in local redox conditions impart a significant isotopic fractionation from seawater as recorded in the local sedimentary V isotopic signature. Importantly, there is a significant difference between the V isotope composition of sediments deposited in the open ocean setting with oxygen-deficient bottom waters compared to less reducing environments, whereby oxic sediments (benthic oxygen contents > 10 μΜ) exhibit Δoxic = −1.1 ± 0.3‰ and anoxic sediments exhibit Δanoxic = −0.7 ± 0.2‰. Combined with previous studies on seawater particulate and sediment pore fluid analysis, our results indicate that V is mainly delivered and enriched in anoxic sediments through settling particulates. Authigenic V isotope compositions in marine sediments are likely controlled by isotope fractionation between V species bound to particulates and dissolved in seawater, which likely varies with the speciation and adsorption properties of V that are strongly controlled by local redox conditions. In addition, the euxinic Cariaco Basin sediments exhibit distinctive Δeuxinic = −0.4 ± 0.2‰, which is likely influenced by the relationship between the seawater V removal rate and the seawater renewal rate. Our results highlight the direct link between authigenic marine sedimentary V isotope compositions and the overlying local redox conditions. This investigation of V isotopes in modern marine environments provides an initial framework for the utilization of V isotopes to reconstruct ancient redox fluctuations, which has the potential to track subtle redox variations of local oxygen-deficient to low oxygen environments.
KW - Isotope fractionation
KW - Redox
KW - Stable isotopes
KW - Suboxic sediments
KW - V isotope
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U2 - 10.1016/j.gca.2020.06.013
DO - 10.1016/j.gca.2020.06.013
M3 - Article
AN - SCOPUS:85087681508
VL - 284
SP - 134
EP - 155
JO - Geochmica et Cosmochimica Acta
JF - Geochmica et Cosmochimica Acta
SN - 0016-7037
ER -