Vadose-zone alteration of metaschoepite and ceramic UO 2 in Savannah River Site field lysimeters.

Autor: Fallon CM; Centre for Radiochemistry Research, Department of Chemistry, The University of Manchester, Manchester M13 9PL, UK,; Research Centre for Radwaste and Decommissioning and Williamson Research Centre, Department of Earth and Environmental Sciences, The University of Manchester, Manchester M13 9PL, UK., Bower WR; Centre for Radiochemistry Research, Department of Chemistry, The University of Manchester, Manchester M13 9PL, UK,; Radiochemistry Unit, Department of Chemistry, University of Helsinki, Helsinki 00014, Finland., Powell BA; Department of Environmental Engineering and Earth Sciences, Department of Chemistry, Clemson University, Clemson, SC 29634, USA., Livens FR; Centre for Radiochemistry Research, Department of Chemistry, The University of Manchester, Manchester M13 9PL, UK,; Research Centre for Radwaste and Decommissioning and Williamson Research Centre, Department of Earth and Environmental Sciences, The University of Manchester, Manchester M13 9PL, UK., Lyon IC; Research Centre for Radwaste and Decommissioning and Williamson Research Centre, Department of Earth and Environmental Sciences, The University of Manchester, Manchester M13 9PL, UK., McNulty AE; Research Centre for Radwaste and Decommissioning and Williamson Research Centre, Department of Earth and Environmental Sciences, The University of Manchester, Manchester M13 9PL, UK., Peruski K; Department of Environmental Engineering and Earth Sciences, Department of Chemistry, Clemson University, Clemson, SC 29634, USA., Mosselmans JFW; Diamond Light Source, Harwell Science and Innovations Campus, Didcot, Oxfordshire OX11 0DE, UK., Kaplan DI; Savannah River Ecology Laboratory, University of Georgia, Aiken, SC 29808, USA., Grolimund D; Swiss Light Source, Paul Scherrer Institute, Villigen CH-5232, Switzerland., Warnicke P; Swiss Light Source, Paul Scherrer Institute, Villigen CH-5232, Switzerland., Ferreira-Sanchez D; Swiss Light Source, Paul Scherrer Institute, Villigen CH-5232, Switzerland., Kauppi MS; Radiochemistry Unit, Department of Chemistry, University of Helsinki, Helsinki 00014, Finland., Vettese GF; Radiochemistry Unit, Department of Chemistry, University of Helsinki, Helsinki 00014, Finland., Shaw S; Research Centre for Radwaste and Decommissioning and Williamson Research Centre, Department of Earth and Environmental Sciences, The University of Manchester, Manchester M13 9PL, UK., Morris K; Research Centre for Radwaste and Decommissioning and Williamson Research Centre, Department of Earth and Environmental Sciences, The University of Manchester, Manchester M13 9PL, UK., Law GTW; Radiochemistry Unit, Department of Chemistry, University of Helsinki, Helsinki 00014, Finland. Electronic address: gareth.law@helsinki.fi.
Jazyk: angličtina
Zdroj: The Science of the total environment [Sci Total Environ] 2023 Mar 01; Vol. 862, pp. 160862. Date of Electronic Publication: 2022 Dec 12.
DOI: 10.1016/j.scitotenv.2022.160862
Abstrakt: Uranium dioxide (UO 2 ) and metaschoepite (UO 3 •nH 2 O) particles have been identified as contaminants at nuclear sites. Understanding their behavior and impact is crucial for safe management of radioactively contaminated land and to fully understand U biogeochemistry. The Savannah River Site (SRS) (South Carolina, USA), is one such contaminated site, following historical releases of U-containing wastes to the vadose zone. Here, we present an insight into the behavior of these two particle types under dynamic conditions representative of the SRS, using field lysimeters (15 cm D x 72 cm L). Discrete horizons containing the different particle types were placed at two depths in each lysimeter (25 cm and 50 cm) and exposed to ambient rainfall for 1 year, with an aim of understanding the impact of dynamic, shallow subsurface conditions on U particle behavior and U migration. The dissolution and migration of U from the particle sources and the speciation of U throughout the lysimeters was assessed after 1 year using a combination of sediment digests, sequential extractions, and bulk and μ-focus X-ray spectroscopy. In the UO 2 lysimeter, oxidative dissolution of UO 2 and subsequent migration of U was observed over 1-2 cm in the direction of waterflow and against it. Sequential extractions of the UO 2 sources suggest they were significantly altered over 1 year. The metaschoepite particles also showed significant dissolution with marginally enhanced U migration (several cm) from the sources. However, in both particle systems the released U was quantitively retained in sediment as a range of different U(IV) and U(VI) phases, and no detectable U was measured in the lysimeter effluent. The study provides a useful insight into U particle behavior in representative, real-world conditions relevant to the SRS, and highlights limited U migration from particle sources due to secondary reactions with vadose zone sediments over 1 year.
Competing Interests: Declaration of competing interest The authors declare no competing interests.
(Copyright © 2022 The Authors. Published by Elsevier B.V. All rights reserved.)
Databáze: MEDLINE
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