Oxidation of Dissolved Tetravalent Selenium by Birnessite: Se Isotope Fractionation and the Effects of pH and Birnessite Structure

Dwivedi, Pranjal and Schilling, Kathrin and Wasserman, Naomi and Johnson, Thomas M. and Pallud, Celine (2022) Oxidation of Dissolved Tetravalent Selenium by Birnessite: Se Isotope Fractionation and the Effects of pH and Birnessite Structure. Frontiers in Earth Science, 10. ISSN 2296-6463

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Abstract

Redox reactions control the mobility and bioavailability of selenium (Se) in biogeochemical systems, both modern and ancient. Se isotope ratio measurements (e.g., 82Se/76Se) have been developed to enhance understanding of biogeochemical transformations and transport of Se. Stable isotope ratios of many elements are known to be powerful indicators of redox reactions, and shifts in 82Se/76Se have been observed for Se reduction reactions. However, Se isotope shifts caused by naturally relevant oxidation reactions have not been published. Here, we report Se isotope fractionation factors for oxidation of Se(IV) by birnessite. Experiments were conducted at pH = 4.0 and 5.5, with two types of birnessite of contrasting composition at two concentrations of suspended birnessite. The results are consistent with a single 82Se/76Se fractionation factor, for all times during all experiments, of 0.99767 (±0.0035 2 s.d.). Expressed as ε, the fractionation is 2.33‰ (±0.08‰).

Item Type: Article
Subjects: Archive Digital > Geological Science
Depositing User: Unnamed user with email support@archivedigit.com
Date Deposited: 11 Mar 2023 09:51
Last Modified: 03 Jan 2024 07:02
URI: http://eprints.ditdo.in/id/eprint/356

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