Biomineralization of uranium-phosphates fueled by microbial degradation of isosaccharinic acid (ISA)

DOI: 10.1021/acs.est.0c03594

Authors: Gina Kuippers (University of Manchester) , Katherine Morris (University of Manchester) , Luke T. Townsend (University of Manchester) , Pieter Bots (University of Manchester; University of Strathclyde) , Kristina Kvashnina (ESRF-The European Synchrotron; Helmholtz Zentrum Dresden-Rossendorf (HZDR)) , Nicholas D. Bryan (National Nuclear Laboratory Limited) , Jonathan R. Lloyd (University of Manchester)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Environmental Science & Technology

State: Published (Approved)
Published: March 2021
Diamond Proposal Number(s): 12767 , 13599

Abstract: Geological disposal is the globally preferred long-term solution for higher activity radioactive wastes (HAW) including intermediate level waste (ILW). In a cementitious disposal system, cellulosic waste items present in ILW may undergo alkaline hydrolysis, producing significant quantities of isosaccharinic acid (ISA), a chelating agent for radionuclides. Although microbial degradation of ISA has been demonstrated, its impact upon the fate of radionuclides in a geological disposal facility (GDF) is a topic of ongoing research. This study investigates the fate of U(VI) in pH-neutral, anoxic, microbial enrichment cultures, approaching conditions similar to the far field of a GDF, containing ISA as the sole carbon source, and elevated phosphate concentrations, incubated both (i) under fermentation and (ii) Fe(III)-reducing conditions. In the ISA-fermentation experiment, U(VI) was precipitated as insoluble U(VI)-phosphates, whereas under Fe(III)-reducing conditions, the majority of the uranium was precipitated as reduced U(IV)-phosphates, presumably formed via enzymatic reduction mediated by metal-reducing bacteria, including Geobacter species. Overall, this suggests the establishment of a microbially mediated “bio-barrier” extending into the far field geosphere surrounding a GDF is possible and this biobarrier has the potential to evolve in response to GDF evolution and can have a controlling impact on the fate of radionuclides.

Journal Keywords: geological disposal; radionuclides; U(VI)-phosphates; isosaccharinic acid; U(VI) reduction

Diamond Keywords: Biomineralisation

Subject Areas: Earth Science, Chemistry, Environment


Instruments: B18-Core EXAFS

Other Facilities: ESRF

Added On: 29/03/2021 11:33

Discipline Tags:

Earth Sciences & Environment Radioactive Materials Materials Science Nuclear Waste

Technical Tags:

Spectroscopy X-ray Absorption Spectroscopy (XAS) Extended X-ray Absorption Fine Structure (EXAFS)