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Published VersionCC BY-NC V4.0, Open Access
Journal article
Reductive sorption of vanadium by green rust in seawater
Geochimica et Cosmochimica Acta, Vol.361, pp.171-182
2023
Abstract
Vanadium (V) is a redox-sensitive trace metal that typically exists in one of three oxidation states (+3, +4 and +5) in natural waters; a feature increasingly used in paleoredox studies of ancient marine sediments. However, our knowledge of V geochemistry in low-oxygen marine environments is still limited, especially regarding interactions of V with reduced iron minerals such as green rust. Carbonate green rusts (GRCO3) are mixed FeII/FeIII-phases found in some modern ferruginous settings, such as Lake Matano (Indonesia), and were likely abundant in ancient ferruginous marine systems where they may have played an essential role in authigenic V enrichments in sediments. Here, we present an abiotic pathway of V removal from seawater via reduction and adsorption onto amorphous GRCO3. Suspensions of the freshly precipitated GRCO3 (1 g L−1) were added to vanadate (1 mg VV L−1 initial concentration) in anoxic synthetic seawater solutions. Vanadium removal by GRCO3 was rapid and efficient, with 92–99% of V removed in under 20 seconds. Synchrotron-based X-ray absorption near edge structure (XANES) spectroscopy showed that VV adsorbed by GRCO3 was partially reduced to a mixture of VV and VIV, with the average oxidation state of adsorbed V increasing (+4.3 to +4.7) with increasing solution pH (7.5 to 8.5). Extended X-ray absorption fine structure (EXAFS) modelling indicated that V may have formed a combination of monodentate and bidentate corner-sharing surface complexes with GRCO3. Upon subsequent exposure to aerated seawater, V-bearing GRCO3 oxidized to lepidocrocite [γ–FeO(OH)] within 24 hours, with concomitant reduction of all solid-phase VV to VIV. During oxidation, V was not released back into solution; rather, EXAFS modelling indicated that VIV was incorporated into the lepidocrocite structure as octahedral vanadyl (VO2+). Our work further constrains the aqueous geochemistry of V, which has implications for understanding V cycling and removal mechanisms in both modern and ancient marine systems.
Details
- Title
- Reductive sorption of vanadium by green rust in seawater
- Authors
- Felicia J Haase (Corresponding Author) - Griffith UniversityColton J Vessey (Author) - University of AlbertaRyo Sekine (Author) - University of the Sunshine Coast, Queensland, School of Science, Technology and EngineeringDavid Welsh (Author) - Griffith UniversityJessica Hamiliton (Author) - Australian SynchrotronYun Wang (Author) - Griffith UniversityJessica White (Author) - Griffith UniversityDonald E. Canfield (Author) - University of Southern DenmarkEnzo Lombi (Author) - University of South AustraliaWilliam W. Bennett (Author) - Griffith University
- Publication details
- Geochimica et Cosmochimica Acta, Vol.361, pp.171-182
- Publisher
- Elsevier Ltd
- Date published
- 2023
- DOI
- 10.1016/j.gca.2023.07.020
- ISSN
- 1872-9533; 0016-7037
- Copyright note
- This article is made available under the CC-BY-NC 4.0 license http://creativecommons.org/licenses/by-nc/4.0/
- Grant note
- This study was supported by a Griffith University PhD Scholarship and an AINSE Ltd. Postgraduate Research Award (PGRA) to FH. In addition, DC would like to acknowledge support from the Villum Foundation (Grant 16518).
- Organisation Unit
- School of Science, Technology and Engineering
- Language
- English
- Record Identifier
- 99743798402621
- Output Type
- Journal article
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