Yan, X, Li, W, Zhu, C et al. (7 more authors) (2023) Zinc Stable Isotope Fractionation Mechanisms during Adsorption on and Substitution in Iron (Hydr)oxides. Environmental Science & Technology, 57 (16). pp. 6636-6646. ISSN 0013-936X
Abstract
The Zn isotope fingerprint is widely used as a proxy of various environmental geochemical processes, so it is crucial to determine which are the mechanisms responsible for isotopic fractionation. Iron (Fe) (hydr)oxides greatly control the cycling and fate and thus isotope fractionation factors of Zn in terrestrial environments. Here, Zn isotope fractionation and related mechanisms during adsorption on and substitution in three FeOOH polymorphs are explored. Results demonstrate that heavy Zn isotopes are preferentially enriched onto solids, with almost similar isotopic offsets (Δ⁶⁶/⁶⁴Znsolid-solution = 0.25–0.36‰) for goethite, lepidocrocite, and feroxyhyte. This is consistent with the same average Zn–O bond lengths for adsorbed Zn on these solids as revealed by Zn K-edge X-ray absorption fine structure spectroscopy. In contrast, at an initial Zn/Fe molar ratio of 0.02, incorporation of Zn into goethite and lepidocrocite by substituting for lattice Fe preferentially sequesters light Zn isotopes with Δ⁶⁶/⁶⁴Znsubstituted-stock solution of −1.52 ± 0.09‰ and −1.18 ± 0.15‰, while Zn-substituted feroxyhyte (0.06 ± 0.11‰) indicates almost no isotope fractionation. This is closely related to the different crystal nucleation and growth rates during the Zn-doped FeOOH formation processes. These results provide direct experimental evidence of incorporation of isotopically light Zn into Fe (hydr)oxides and improve our understanding of Zn isotope fractionation mechanisms during mineral–solution interface processes.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2023 American Chemical Society. This is an author produced version of an article published in Environmental Science and Technology. Uploaded in accordance with the publisher's self-archiving policy. |
Keywords: | metal (hydr)oxides; metal isotope fractionation; interface reactions; isomorphous substitution; adsorption; X-ray absorption fine-structure spectroscopy |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Earth and Environment (Leeds) > Earth Surface Science Institute (ESSI) (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 24 Apr 2023 14:27 |
Last Modified: | 12 Apr 2024 00:13 |
Published Version: | https://pubs.acs.org/doi/10.1021/acs.est.2c08028 |
Status: | Published |
Publisher: | American Chemical Society (ACS) |
Identification Number: | 10.1021/acs.est.2c08028 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:198457 |