Metaschoepite Dissolution in Sediment Column Systems-Implications for Uranium Speciation and Transport.

Autor:	Bower WR; Centre for Radiochemistry Research, School of Chemistry , The University of Manchester , Manchester , U.K. , M13 9PL.; Research Centre for Radwaste Disposal and Williamson Research Centre, School of Earth and Environmental Sciences , The University of Manchester , Manchester , U.K. , M13 9PL.; Radiochemistry Unit, Department of Chemistry , The University of Helsinki , Helsinki , Finland , 00014., Morris K; Research Centre for Radwaste Disposal and Williamson Research Centre, School of Earth and Environmental Sciences , The University of Manchester , Manchester , U.K. , M13 9PL., Livens FR; Centre for Radiochemistry Research, School of Chemistry , The University of Manchester , Manchester , U.K. , M13 9PL.; Research Centre for Radwaste Disposal and Williamson Research Centre, School of Earth and Environmental Sciences , The University of Manchester , Manchester , U.K. , M13 9PL., Mosselmans JFW; Diamond Light Source , Harwell Science and Innovation Campus , Didcot , U.K. , OX11 0DE., Fallon CM; Centre for Radiochemistry Research, School of Chemistry , The University of Manchester , Manchester , U.K. , M13 9PL.; Research Centre for Radwaste Disposal and Williamson Research Centre, School of Earth and Environmental Sciences , The University of Manchester , Manchester , U.K. , M13 9PL.; Radiochemistry Unit, Department of Chemistry , The University of Helsinki , Helsinki , Finland , 00014., Fuller AJ; Centre for Radiochemistry Research, School of Chemistry , The University of Manchester , Manchester , U.K. , M13 9PL., Natrajan L; Centre for Radiochemistry Research, School of Chemistry , The University of Manchester , Manchester , U.K. , M13 9PL., Boothman C; Research Centre for Radwaste Disposal and Williamson Research Centre, School of Earth and Environmental Sciences , The University of Manchester , Manchester , U.K. , M13 9PL., Lloyd JR; Research Centre for Radwaste Disposal and Williamson Research Centre, School of Earth and Environmental Sciences , The University of Manchester , Manchester , U.K. , M13 9PL., Utsunomiya S; Kyushu University , Department of Chemistry , 744 Motooka , Nishi-ku , Fukuoka Japan , 819-0395., Grolimund D; Swiss Light Source , Paul Scherrer Institute , Villigen , Switzerland , 5232., Ferreira Sanchez D; Swiss Light Source , Paul Scherrer Institute , Villigen , Switzerland , 5232., Jilbert T; Ecosystems and Environmental Research Programme, Faculty of Biological and Environmental Sciences , The University of Helsinki , Helsinki , Finland , 00014., Parker J; Diamond Light Source , Harwell Science and Innovation Campus , Didcot , U.K. , OX11 0DE., Neill TS; Research Centre for Radwaste Disposal and Williamson Research Centre, School of Earth and Environmental Sciences , The University of Manchester , Manchester , U.K. , M13 9PL., Law GTW; Centre for Radiochemistry Research, School of Chemistry , The University of Manchester , Manchester , U.K. , M13 9PL.; Radiochemistry Unit, Department of Chemistry , The University of Helsinki , Helsinki , Finland , 00014.
Jazyk:	angličtina
Zdroj:	Environmental science & technology [Environ Sci Technol] 2019 Aug 20; Vol. 53 (16), pp. 9915-9925. Date of Electronic Publication: 2019 Aug 01.
DOI:	10.1021/acs.est.9b02292
Abstrakt:	Metaschoepite is commonly found in U-contaminated environments and metaschoepite-bearing wastes may be managed via shallow or deep disposal. Understanding metaschoepite dissolution and tracking the fate of any liberated U is thus important. Here, discrete horizons of metaschoepite (UO 3 · n H 2 O) particles were emplaced in flowing sediment/groundwater columns representative of the UK Sellafield Ltd. site. The column systems either remained oxic or became anoxic due to electron donor additions, and the columns were sacrificed after 6- and 12-months for analysis. Solution chemistry, extractions, and bulk and micro/nano-focus X-ray spectroscopies were used to track changes in U distribution and behavior. In the oxic columns, U migration was extensive, with UO 2 2+ identified in effluents after 6-months of reaction using fluorescence spectroscopy. Unusually, in the electron-donor amended columns, during microbially mediated sulfate reduction, significant amounts of UO 2 -like colloids (>60% of the added U) were found in the effluents using TEM. XAS analysis of the U remaining associated with the reduced sediments confirmed the presence of trace U(VI), noncrystalline U(IV), and biogenic UO 2 , with UO 2 becoming more dominant with time. This study highlights the potential for U(IV) colloid production from U(VI) solids under reducing conditions and the complexity of U biogeochemistry in dynamic systems.
Databáze:	MEDLINE
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