1
|
Montoya V, Noseck U, Mattick F, Britz S, Blechschmidt I, Schäfer T. Radionuclide geochemistry evolution in the Long-term In-situ Test (LIT) at Grimsel Test Site (Switzerland). JOURNAL OF HAZARDOUS MATERIALS 2022; 424:127733. [PMID: 34848070 DOI: 10.1016/j.jhazmat.2021.127733] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/27/2021] [Revised: 11/04/2021] [Accepted: 11/05/2021] [Indexed: 06/13/2023]
Abstract
The Long-term In-situ Test (LIT) of the Colloid Formation and Migration project (CFM) at the Grimsel Test Site, investigates the generation of bentonite colloids and, hence, radionuclide mobilization within a well-defined and controlled shear zone in a crystalline rock. In this context, the determination of radionuclide aqueous speciation is essential to understand whether radionuclides are easily transported or immobilized by precipitation or uptake processes in the bentonite barrier included in a repository concept for nuclear waste, and mimic in the LIT experiment. The objective of this work is to determine the aqueous speciation of seven radionuclides (i.e. 75Se(VI), 99Tc(VII),233U(VI), 237Np(V), 241Am(III), Th(IV) and 242Pu(IV)) by thermodynamic calculations in different water compositions representing the geochemical evolution through the LIT. A comparison of the results obtained from two different modelling groups allows the identification of the geochemical key parameters affecting radionuclide mobility in this context and the corresponding numerical and conceptual uncertainties. Particularly, silicate complexes of trivalent actinides and uranium(VI) carbonato complexes (i.e. CanUO2(CO3)3(4-2n) n = 1 or 2) seem to be crucial in these environments, even at reducing conditions. Conceptual uncertainties like inclusion/exclusion of tetravalent actinide-bearing colloids formation and polyselenides have clearly been identified.
Collapse
Affiliation(s)
- Vanessa Montoya
- Department of Environmental Informatics - Helmholtz Centre for Environmental Research (UFZ), 04318 Leipzig, Germany; Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany.
| | - Ulrich Noseck
- Gesellschaft für Anlagen, und Reaktorsicherheit (GRS), 38122 Braunschweig, Germany
| | - Felix Mattick
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany
| | - Susan Britz
- Gesellschaft für Anlagen, und Reaktorsicherheit (GRS), 38122 Braunschweig, Germany
| | - Ingo Blechschmidt
- Nagra (National Cooperative for the Disposal of Radioactive Waste), 5430 Wettingen, Switzerland
| | - Thorsten Schäfer
- Institute for Nuclear Waste Disposal (INE), Karlsruhe Institute of Technology (KIT), 76021 Karlsruhe, Germany; Friedrich-Schiller-University Jena (FSU), Institute of Geosciences - Applied Geology, 07749 Jena, Germany
| |
Collapse
|
2
|
Bader M, Moll H, Steudtner R, Lösch H, Drobot B, Stumpf T, Cherkouk A. Association of Eu(III) and Cm(III) onto an extremely halophilic archaeon. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2019; 26:9352-9364. [PMID: 30721439 DOI: 10.1007/s11356-019-04165-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Accepted: 01/03/2019] [Indexed: 06/09/2023]
Abstract
In addition to geological, geochemical, and geophysical aspects, also, microbial aspects have to be taken into account when considering the final storage of high-level radioactive waste in a deep geological repository. Rock salt is a potential host rock formation for such a repository. One indigenous microorganism, that is, common in rock salt, is the halophilic archaeon Halobacterium noricense DSM15987T, which was used in our study to investigate its interactions with the trivalent actinide curium and its inactive analogue europium as a function of time and concentration. Time-resolved laser-induced fluorescence spectroscopy was applied to characterize formed species in the micromolar europium concentration range. An extended evaluation of the data with parallel factor analysis revealed the association of Eu(III) to a phosphate compound released by the cells (F2/F1 ratio, 2.50) and a solid phosphate species (F2/F1 ratio, 1.80). The association with an aqueous phosphate species and a solid phosphate species was proven with site-selective TRLFS. Experiments with Cm(III) in the nanomolar concentration range showed a time- and pCH+-dependent species distribution. These species were characterized by red-shifted emission maxima, 600-602 nm, in comparison to the free Cm(III) aqueous ion, 593.8 nm. After 24 h, 40% of the luminescence intensity was measured on the cells corresponding to 0.18 μg Cm(III)/gDBM. Our results demonstrate that Halobacterium noricense DSM15987T interacts with Eu(III) by the formation of phosphate species, whereas for Cm(III), a complexation with carboxylic functional groups was also observed.
Collapse
Affiliation(s)
- Miriam Bader
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden - Rossendorf, Bautzner Landstraße 400, 01328, Dresden, Germany
| | - Henry Moll
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden - Rossendorf, Bautzner Landstraße 400, 01328, Dresden, Germany
| | - Robin Steudtner
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden - Rossendorf, Bautzner Landstraße 400, 01328, Dresden, Germany
| | - Henry Lösch
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden - Rossendorf, Bautzner Landstraße 400, 01328, Dresden, Germany
| | - Björn Drobot
- Max Planck Institute of Molecular Cell Biology and Genetics, Tang Lab, Pfotenhauerstrasse 108, 01307, Dresden, Germany
| | - Thorsten Stumpf
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden - Rossendorf, Bautzner Landstraße 400, 01328, Dresden, Germany
| | - Andrea Cherkouk
- Institute of Resource Ecology, Helmholtz-Zentrum Dresden - Rossendorf, Bautzner Landstraße 400, 01328, Dresden, Germany.
| |
Collapse
|
3
|
Bader M, Müller K, Foerstendorf H, Drobot B, Schmidt M, Musat N, Swanson JS, Reed DT, Stumpf T, Cherkouk A. Multistage bioassociation of uranium onto an extremely halophilic archaeon revealed by a unique combination of spectroscopic and microscopic techniques. JOURNAL OF HAZARDOUS MATERIALS 2017; 327:225-232. [PMID: 28081458 DOI: 10.1016/j.jhazmat.2016.12.053] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 12/09/2016] [Accepted: 12/26/2016] [Indexed: 06/06/2023]
Abstract
The interactions of two extremely halophilic archaea with uranium were investigated at high ionic strength as a function of time, pH and uranium concentration. Halobacterium noricense DSM-15987 and Halobacterium sp. putatively noricense, isolated from the Waste Isolation Pilot Plant repository, were used for these investigations. The kinetics of U(VI) bioassociation with both strains showed an atypical multistage behavior, meaning that after an initial phase of U(VI) sorption, an unexpected interim period of U(VI) release was observed, followed by a slow reassociation of uranium with the cells. By applying in situ attenuated total reflection Fourier-transform infrared spectroscopy, the involvement of phosphoryl and carboxylate groups in U(VI) complexation during the first biosorption phase was shown. Differences in cell morphology and uranium localization become visible at different stages of the bioassociation process, as shown with scanning electron microscopy in combination with energy dispersive X-ray spectroscopy. Our results demonstrate for the first time that association of uranium with the extremely halophilic archaeon is a multistage process, beginning with sorption and followed by another process, probably biomineralization.
Collapse
Affiliation(s)
- Miriam Bader
- Helmholtz-Zentrum Dresden - Rossendorf, Institute of Resource Ecology, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Katharina Müller
- Helmholtz-Zentrum Dresden - Rossendorf, Institute of Resource Ecology, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Harald Foerstendorf
- Helmholtz-Zentrum Dresden - Rossendorf, Institute of Resource Ecology, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Björn Drobot
- Helmholtz-Zentrum Dresden - Rossendorf, Institute of Resource Ecology, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Matthias Schmidt
- Helmholtz Centre for Environmental Research-UFZ, Department of Isotope Biogeochemistry, Permoserstraße 15, 04318 Leipzig, Germany
| | - Niculina Musat
- Helmholtz Centre for Environmental Research-UFZ, Department of Isotope Biogeochemistry, Permoserstraße 15, 04318 Leipzig, Germany
| | - Juliet S Swanson
- Los Alamos National Laboratory, Repository Science and Operations, 1400 University Drive, Carlsbad, NM, 88220, USA
| | - Donald T Reed
- Los Alamos National Laboratory, Repository Science and Operations, 1400 University Drive, Carlsbad, NM, 88220, USA
| | - Thorsten Stumpf
- Helmholtz-Zentrum Dresden - Rossendorf, Institute of Resource Ecology, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Andrea Cherkouk
- Helmholtz-Zentrum Dresden - Rossendorf, Institute of Resource Ecology, Bautzner Landstraße 400, 01328 Dresden, Germany.
| |
Collapse
|
4
|
Buried Alive: Microbes from Ancient Halite. Trends Microbiol 2016; 24:148-160. [DOI: 10.1016/j.tim.2015.12.002] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2015] [Revised: 08/26/2015] [Accepted: 12/08/2015] [Indexed: 11/20/2022]
|
5
|
Yan X, Luo X. Radionuclides distribution, properties, and microbial diversity of soils in uranium mill tailings from southeastern China. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2015; 139:85-90. [PMID: 25464044 DOI: 10.1016/j.jenvrad.2014.09.019] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 09/05/2014] [Accepted: 09/30/2014] [Indexed: 05/10/2023]
Abstract
OBJECTIVE To collect the radioactive contamination data for environmental rehabilitation in uranium mill tailings in southeastern China. METHOD The sample areas were divided into high, moderate and low concentration areas, according to the uranium concentration. For every area, 3 soil samples were collected at 0-15 cm, 15-30 cm and 30-45 cm depth respectively, with 5 repetitions for each. Total 45 (3 × 5 × 3) soil samples were collected. Physicochemical properties and enzyme activities of soils were determined as described by references. The concentrations of the radionuclides (238)U, (232)Th, (226)Ra and (40)K in soils were determined by using HPGe gamma-ray spectrometer. Soil microbial diversity was analyzed via denaturing gradient gel electrophoresis (DGGE). RESULTS Soil samples were all acidic. Physicochemical properties, like pH, content of total/available N, P and K, as well as enzyme activities were all increased along with decreased uranium concentration. The (232)Th concentration was increased with the decreased uranium concentration and was not influenced by the depth of sample sites. However, uranium concentration and depth of sample showed no significant influence on the concentrations of (226)Ra and (40)K. The concentration of (232)Th was significantly correlated with that of (226)Ra and (40)K, while the concentrations of (226)Ra and (40)K were significantly correlated. However, Pearson correlation coefficients between (238)U and other radionuclides were not significant. The microbial population in different concentration areas was different with four domain strains in low area, and two for both moderate and high areas. Furthermore, in each sample site, Proteobacteria was the most dominant flora, while environmental samples were the second according to GenBank database. Moreover, Serratia sp. of Proteobacteria was the dominant strain. CONCLUSION Radionuclides distribution in the uranium mill tailing showed a profound influence on soil properties and microbial diversity. This primarily study might provide valuable data for further research towards a better understanding of the radioactive contamination in uranium mill tailings in southeast China.
Collapse
Affiliation(s)
- Xun Yan
- College of Life Science, Northeast Forestry University, Harbin, Heilongjiang 150040, China; College of Chemistry and Chemical Engineering, Qiqihar University Qiqihar, Heilongjiang 161006, China
| | - Xuegang Luo
- Southwest University of Science and Technology Mianyang, Sichuan 621010, China.
| |
Collapse
|
6
|
Kumar R, Nongkhlaw M, Acharya C, Joshi SR. Uranium (U)-tolerant bacterial diversity from U ore deposit of Domiasiat in North-East India and its prospective utilisation in bioremediation. Microbes Environ 2012; 28:33-41. [PMID: 23080407 PMCID: PMC4070695 DOI: 10.1264/jsme2.me12074] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Uranium (U)-tolerant aerobic chemo-heterotrophic bacteria were isolated from the sub-surface soils of U-rich deposits in Domiasiat, North East India. The bacterial community explored at molecular level by amplified ribosomal DNA restriction analysis (ARDRA) resulted in 51 distinct phylotypes. Bacterial community assemblages at the U mining site with the concentration of U ranging from 20 to 100 ppm, were found to be most diverse. Representative bacteria analysed by 16S rRNA gene sequencing were affiliated to Firmicutes (51%), Gammaproteobacteria (26%), Actinobacteria (11%), Bacteroidetes (10%) and Betaproteobacteria (2%). Representative strains removed more than 90% and 53% of U from 100 μM and 2 mM uranyl nitrate solutions, respectively, at pH 3.5 within 10 min of exposure and the activity was retained until 24 h. Overall, 76% of characterized isolates possessed phosphatase enzyme and 53% had PIB-type ATPase genes. This study generated baseline information on the diverse indigenous U-tolerant bacteria which could serve as an indicator to estimate the environmental impact expected to be caused by mining in the future. Also, these natural isolates efficient in uranium binding and harbouring phosphatase enzyme and metal-transporting genes could possibly play a vital role in the bioremediation of metal-/radionuclide-contaminated environments.
Collapse
Affiliation(s)
- Rakshak Kumar
- Department of Biotechnology & Bioinformatics, North-Eastern Hill University, India
| | | | | | | |
Collapse
|
7
|
Lütke L, Moll H, Bernhard G. Insights into the uranium(vi) speciation with Pseudomonas fluorescens on a molecular level. Dalton Trans 2012; 41:13370-8. [DOI: 10.1039/c2dt31080e] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
8
|
Xu C, Santschi PH, Schwehr KA, Hung CC. Optimized isolation procedure for obtaining strongly actinide binding exopolymeric substances (EPS) from two bacteria (Sagittula stellata and Pseudomonas fluorescens Biovar II). BIORESOURCE TECHNOLOGY 2009; 100:6010-6021. [PMID: 19574036 DOI: 10.1016/j.biortech.2009.06.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Revised: 09/09/2008] [Accepted: 06/02/2009] [Indexed: 05/28/2023]
Abstract
Different chemical extractants (NaCl, EDTA, HCl and NaOH) and physical methods (ultrasonication and heating) were examined by their efficacies of extracting "attached" exopolymeric substances (EPS) secreted by marine bacterium Sagittula stellata (SS) and terrestrial bacterium Pseudomonas fluorescens Biovar II (PF). Extraction by 0.5 N HCl for 3 h was best for SS while extraction by 0.05 N NaCl for 3-5 h was regarded as optimal for PF. Improvements in EPS purification included a pre-diafiltration step to remove the broth material and reduce the solution volume, thus the usage of ethanol, and time. The EPS harvested at the optimal time and purified by the improved method were enriched in polysaccharides, with smaller amounts of proteins, thus having amphiphilic properties. Isoelectric focusing of (234)Th or (240)Pu labeled EPS showed both actinides were strongly bound to macromolecules with low pI, similar to reported marine or soil colloidal natural organic matter (NOM).
Collapse
Affiliation(s)
- Chen Xu
- Laboratory for Oceanographic and Environmental Research, Departments of Oceanography and Marine Sciences, Texas A&M University, 5007 Avenue U, Galveston, TX 77551, United States.
| | | | | | | |
Collapse
|
9
|
Ozaki T, Gillow JB, Kimura T, Ohnuki T, Yoshida Z, Francis AJ. Sorption behavior of europium(III) and curium(III) on the cell surfaces of microorganisms. RADIOCHIM ACTA 2009. [DOI: 10.1524/ract.92.9.741.55006] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
SummaryWe investigated the association of europium(III) and curium(III) with the microorganismsChlorella vulgaris,Bacillus subtilis,Pseudomonas fluorescens,Halomonassp.,Halobacterium salinarum, andHalobacterium halobium. We determined the kinetics and distribution coefficients (Kd) for Eu(III) and Cm(III) sorption at pH 3-5 by batch experiments, and evaluated the number of water molecules in the inner-sphere (NH₂O) and the degree of strength of ligand field (RE/M) for Eu(III) by time-resolved laser-induced fluorescence spectroscopy (TRLFS). Exudates fromC. vulgaris,Halomonassp., andH. halobiumhad an affinity for Eu(III) and Cm(III). The logKdof Eu(III) and Cm(III) showed that their sorption was not fully due to the exchange with three protons on the functional groups on cell surfaces. The halophilic microorganisms (Halomonassp.,Halobacterium salinarum,H. halobium) showed almost no pH dependence in logKd, indicating that an exchange with Na+on the functional groups was involved in their sorption. The Δ NH₂O(=9-NH₂O) for Eu(III) onC. vulgariswas 1-3, while that for the other microorganisms was over 3, demonstrating that the coordination of Eu(III) withC. vulgariswas predominantly an outer-spherical process. TheRE/Mfor Eu(III) on halophilic microorganisms was 2.5-5, while that for non-halophilic ones was 1-2.5. This finding suggests that the coordination environment of Eu(III) on the halophilic microorganisms is more complicated than that on the other three non-halophilic ones.
Collapse
|
10
|
Francis AJ, Gillow JB, Dodge CJ, Harris R, Beveridge TJ, Papenguth HW. Uranium association with halophilic and non-halophilic bacteria and archaea. RADIOCHIM ACTA 2009. [DOI: 10.1524/ract.92.8.481.39281] [Citation(s) in RCA: 79] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Summary
We determined the association of uranium with bacteria isolated from the Waste Isolation Pilot Plant (WIPP), Carlsbad, New Mexico, and compared this with known strains of halophilic and non-halophilic bacteria and archaea. Examination of the cultures by transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDS) showed uranium accumulation extracellularly and/or intracellularly to a varying degree. In Pseudomonas fluorescens and Bacillus subtilis uranium was associated with the cell surface and in the latter it was present as irregularly shaped grains. In Halobacterium halobium, the only archeon studied here, uranium was present as dense deposits and with Haloanaerobium praevalens as spikey deposits. Halomonas sp. isolated from the WIPP site accumulated uranium both extracellularly on the cell surface and intracellularly as electron-dense discrete granules. Extended X-ray absorption fine structure (EXAFS) analysis of uranium with the halophilic and non-halophilic bacteria and archaea showed that the uranium present in whole cells was bonded to an average of 2.4±0.7 phosphoryl groups at a distance of 3.65±0.03 Å. Comparison of whole cells of Halomonas sp. with the cell wall fragments of lysed cells showed the presence of a uranium bidentate complex at 2.91±0.03 Å with the carboxylate group on the cell wall, and uranyl hydroxide with U-U interaction at 3.71±0.03 Å due to adsorption or precipitation reactions; no U-P interaction was observed. Addition of uranium to the cell lysate of Halomonas sp. resulted in the precipitation of uranium due to the inorganic phosphate produced by the cells. These results show that the phosphates released from bacteria bind a significant amount of uranium. However, the bacterially immobilized uranium was readily solubilized by bicarbonate with concurrent release of phosphate into solution.
Collapse
|
11
|
Abstract
SummaryPlutonium has no known biological utility, yet it has the potential to interact with bacterial cellular and extracellular structures that contain metal-binding groups, to interfere with the uptake and utilization of essential elements, and to alter cell metabolism. These interactions can transform plutonium from its most common forms, solid, mineral-adsorbed, or colloidal Pu(IV), to a variety of biogeochemical species that have much different physico-chemical properties. Organic acids that are extruded products of cell metabolism can solubilize plutonium and then enhance its environmental mobility, or in some cases facilitate plutonium transfer into cells. Phosphate- and carboxylate-rich polymers associated with cell walls can bind plutonium to form mobile biocolloids or Pu-laden biofilm/mineral solids. Bacterial membranes, proteins or redox agents can produce strongly reducing electrochemical zones and generate molecular Pu(III/IV) species or oxide particles. Alternatively, they can oxidize plutonium to form soluble Pu(V) or Pu(VI) complexes. This paper reviews research on plutonium-bacteria interactions and closely related studies on the biotransformation of uranium and other metals.
Collapse
|
12
|
Abstract
Summary
The bio-sorption of neptunyl (NpO2
+) by Pseudomonas fluorescens was investigated. The overall goals of this research are to identify key interactions between neptunium and soil bacteria and to model these effects under subsurface-related conditions. Neptunyl, which is generally thought to be non-sorptive, was significantly sorbed under all conditions studied. At initial neptunyl concentrations of 4.75 µM and pH = 7, as much as 85% of the neptunium was sorbed under aerobic conditions. Kinetic studies show that neptunyl was sorbed rapidly within the first 15 minutes. The extent of sorption also increased with pH. In all cases, the sorbed neptunium was shown to be NpO2
+ by X-ray absorption near edged spectroscopy (XANES) analysis, confirming that there was no reduction to Np(IV) under the conditions of our experiment. The sorption data were modeled using Langmuir and Freundlich isotherms. A comparison of the two approaches showed a significantly better fit for the Freundlich isotherm, and the Freundlich parameter values suggest interactions between sorbed NpO2
+ molecules. These data show that bio-sorption, even for neptunyl, has a significant role in defining the speciation of neptunium and, hence, its overall mobility in the subsurface.
Collapse
|
13
|
Merroun ML, Selenska-Pobell S. Bacterial interactions with uranium: an environmental perspective. JOURNAL OF CONTAMINANT HYDROLOGY 2008; 102:285-95. [PMID: 19008016 DOI: 10.1016/j.jconhyd.2008.09.019] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Revised: 08/05/2008] [Accepted: 09/29/2008] [Indexed: 05/12/2023]
Abstract
The presence of actinides in radioactive wastes is of major concern because of their potential for migration from the waste repositories and long-term contamination of the environment. Studies have been and are being made on inorganic processes affecting the migration of radionuclides from these repositories to the environment but it is becoming increasingly evident that microbial processes are of importance as well. Bacteria interact with uranium through different mechanisms including, biosorption at the cell surface, intracellular accumulation, precipitation, and redox transformations (oxidation/reduction). The present study is intended to give a brief overview of the key processes responsible for the interaction of actinides e.g. uranium with bacterial strains isolated from different extreme environments relevant to radioactive repositories. Fundamental understanding of the interaction of these bacteria with U will be useful for developing appropriate radioactive waste treatments, remediation and long-term management strategies as well as for predicting the microbial impacts on the performance of the radioactive waste repositories.
Collapse
Affiliation(s)
- Mohamed L Merroun
- Institute of Radiochemistry, Forschungszentrum Dresden-Rossendorf, D-01314, Dresden, Germany.
| | | |
Collapse
|
14
|
Renshaw JC, Lloyd JR, Livens FR. Microbial interactions with actinides and long-lived fission products. CR CHIM 2007. [DOI: 10.1016/j.crci.2007.02.013] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
|
15
|
Boukhalfa H, Reilly SD, Neu MP. Complexation of Pu(IV) with the Natural Siderophore Desferrioxamine B and the Redox Properties of Pu(IV)(siderophore) Complexes. Inorg Chem 2007; 46:1018-26. [PMID: 17257046 DOI: 10.1021/ic061544q] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The bioavailability and mobility of Pu species can be profoundly affected by siderophores and other oxygen-rich organic ligands. Pu(IV)(siderophore) complexes are generally soluble and may constitute with other soluble organo-Pu(IV) complexes the main fraction of soluble Pu(IV) in the environment. In order to understand the impact of siderophores on the behavior of Pu species, it is important to characterize the formation and redox behavior of Pu(siderophore) complexes. In this work, desferrioxamine B (DFO-B) was investigated for its capacity to bind Pu(IV) as a model siderophore and the properties of the complexes formed were characterized by optical spectroscopy measurements. In a 1:1 Pu(IV)/DFO-B ratio, the complexes Pu(IV)(H2DFO-B)4+, Pu(IV)(H1DFO-B)3+, Pu(IV)(DFO-B)2+, and Pu(IV)(DFO-B)(OH)+ form with corresponding thermodynamic stability constants log beta1,1,2 = 35.48, log beta1,1,1 = 34.87, log beta1,1,0 = 33.98, and log beta1,1,-1 = 27.33, respectively. In the presence of excess DFO-B, the complex Pu(IV)H2(DFO-B)22+ forms with the formation constant log beta2,1,2 = 62.30. The redox potential of the complex Pu(IV)H2(DFO-B)22+ was determined by cyclic voltammetry to be E1/2 = -0.509 V, and the redox potential of the complex Pu(IV)(DFO-B)2+ was estimated to be E1/2 = -0.269 V. The redox properties of Pu(IV)(DFO-B)2+ complexes indicate that Pu(III)(siderophore) complexes are more than 20 orders of magnitude less stable than their Pu(IV) analogues. This indicates that under reducing conditions, stable Pu(siderophore) complexes are unlikely to persist.
Collapse
Affiliation(s)
- Hakim Boukhalfa
- Inorganic, Isotope and Nuclear Chemistry (C-IIC), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | | | | |
Collapse
|
16
|
|
17
|
Wang Y, Francis AJ. Evaluation of Microbial Activity for Long-Term Performance Assessments of Deep Geologic Nuclear Waste Repositories. ACTA ACUST UNITED AC 2005. [DOI: 10.14494/jnrs2000.6.43] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|