Fe(III) Reduction in the Subsurface at a Low-level Radioactive Waste Disposal Site

Wilkins, Michael J.; Livens, Francis R.; Vaughan, David J.; Lloyd, Jonathan R.; Beadle, I. R.; Small, Joe S.

doi:10.1080/01490450903456749

Cited by 7 publications

(3 citation statements)

References 26 publications

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“…The rapid expansion of an emerging nuclear industry immediately following World War II resulted in substantial volumes of low-level radioactive waste (LLRW) being generated from nuclear fuel cycle, weapons production, medical radioisotope, and radiochemical research activities. Although there was no consensus at this time, low-level waste (and in some cases more-active material) was commonly disposed of by burial in shallow trenches, as evidenced in the United States at Maxey Flats ( 1 ), Oak Ridge ( 2 ), and Hanford ( 3 , 4 ), in Canada at Chalk River ( 5 ), in the United Kingdom at Harwell ( 6 ) and at an LLRW disposal site ( 7 ), in Lithuania at Maišiagala ( 8 ), and more recently in Ukraine at Chernobyl ( 9 ), to name but a few. This was also the case for Australia's only nuclear (research) reactor at Lucas Heights.…”

Section: Introductionmentioning

confidence: 99%

Response of Microbial Community Function to Fluctuating Geochemical Conditions within a Legacy Radioactive Waste Trench Environment

Vázquez-Campos

Kinsela

Bligh

et al. 2017

Appl Environ Microbiol

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During the 1960s, small quantities of radioactive materials were codisposed with chemical waste at the Little Forest Legacy Site (Sydney, Australia) in 3-meter-deep, unlined trenches. Chemical and microbial analyses, including functional and taxonomic information derived from shotgun metagenomics, were collected across a 6-week period immediately after a prolonged rainfall event to assess the impact of changing water levels upon the microbial ecology and contaminant mobility. Collectively, results demonstrated that oxygen-laden rainwater rapidly altered the redox balance in the trench water, strongly impacting microbial functioning as well as the radiochemistry. Two contaminants of concern, plutonium and americium, were shown to transition from solid-iron-associated species immediately after the initial rainwater pulse to progressively more soluble moieties as reducing conditions were enhanced. Functional metagenomics revealed the potentially important role that the taxonomically diverse microbial community played in this transition. In particular, aerobes dominated in the first day, followed by an increase of facultative anaerobes/denitrifiers at day 4. Toward the mid-end of the sampling period, the functional and taxonomic profiles depicted an anaerobic community distinguished by a higher representation of dissimilatory sulfate reduction and methanogenesis pathways. Our results have important implications to similar near-surface environmental systems in which redox cycling occurs. IMPORTANCEThe role of chemical and microbiological factors in mediating the biogeochemistry of groundwaters from trenches used to dispose of radioactive materials during the 1960s is examined in this study. Specifically, chemical and microbial analyses, including functional and taxonomic information derived from shotgun metagenomics, were collected across a 6-week period immediately after a prolonged rainfall event to assess how changing water levels influence microbial ecology and contaminant mobility. Results demonstrate that oxygen-laden rainwater rapidly altered the redox balance in the trench water, strongly impacting microbial functioning as well as the radiochemistry. Two contaminants of concern, plutonium and americium, were shown to transition from solid-iron-associated species immediately after the initial rainwater pulse to progressively more soluble moieties as reducing conditions were enhanced. Functional metagenomics revealed the important role that the taxonomically diverse microbial community played in this transition. Our results have important implications to similar near-surface environmental systems in which redox cycling occurs.

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Section: Introductionmentioning

confidence: 99%

Response of Microbial Community Function to Fluctuating Geochemical Conditions within a Legacy Radioactive Waste Trench Environment

Vázquez-Campos

Kinsela

Bligh

et al. 2017

Appl Environ Microbiol

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“…Indeed, numerous sediment microcosm studies indicate that microbially-mediated metal and radionuclide reduction do not commence until nitrate and nitrite are completely reduced (e.g. Burke et al 2005;Edwards et al 2007;McBeth et al 2007;Li and Krumholz 2008;Wilkins et al 2010). Further, some biostimulation studies with low pH sediments have demonstrated that the pathways and extent of nitrate removal are strongly pH dependant, with artificial NaHCO 3 or crushed lime amendment necessary to stimulate bioreduction and TEAP progression (North et al 2004;Edwards et al 2007;Michalsen et al 2009).…”

Section: Introductionmentioning

confidence: 99%

The Synergistic Effects of High Nitrate Concentrations on Sediment Bioreduction

Thorpe

Law

Boothman

et al. 2012

Geomicrobiology Journal

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16Groundwaters at nuclear sites are often characterised by low pH and high nitrate 17 concentrations (10-100 mM). These conditions are challenging for bioremediation, often 18 inhibiting microbial Fe(III)-reduction that can limit radionuclide migration. Here, sediment 19 microcosms representative of the UK Sellafield site were used to study the influence of 20 variable pH and nitrate concentrations on microbially-mediated TEAP (terminal electron 21 accepting processes) progression. The rate of bioreduction at low pH (~ 5.5) was slower than 22 that in bicarbonate-amended systems (pH ~ 7.0), but in the low pH systems, denitrification 23 and associated pH buffering resulted in conditioning of the sediments for subsequent Fe(III) 24 and sulfate reduction. Under very high nitrate conditions (100 mM), bicarbonate amendment 25 (pH ~ 7.0) was necessary for TEAP progression beyond denitrification and the reduction of 26 100 mM nitrate created alkaline conditions (pH 9.5). 16S rRNA gene analysis showed that 27 close relatives of known nitrate reducers Bacillus niacini and Ochrobactrum grignonense 28 dominated the microbial communities. In the 100 mM nitrate system, close relatives of the 29

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“…The rapid expansion of an emerging nuclear industry immediately following World War II resulted in substantial volumes of low-level radioactive waste (LLRW) being generated from nuclear fuel cycle, weapons production, medical radioisotope and radiochemical research activities. Although there was no consensus at this time, low-level waste (and in some cases more active material) was commonly disposed of by burial in shallow trenches, as evidenced in the United States at Maxey Flats (1), Oak Ridge (2) and Hanford (3, 4); Canada at Chalk River (5); in the United Kingdom at Harwell (6) and LLRW (7); in Lithuania at Maišiagala (8); and more recently in Ukraine at Chernobyl (9) to name but a few. This was also the case for Australia’s only nuclear (research) reactor at Lucas Heights.…”

Section: Introductionmentioning

confidence: 99%

Response of microbial community function to fluctuating geochemical conditions within a legacy radioactive waste trench environment

Vázquez-Campos

Kinsela

Bligh

et al. 2017

Preprint

View full text Add to dashboard Cite

During the 1960s, small quantities of radioactive materials were co-disposed with chemical waste at the Little Forest Legacy Site (Sydney, Australia) in three-metre-deep, unlined trenches. Chemical and microbial analyses, including functional and taxonomic information derived from shotgun metagenomics, were collected across a six-week period immediately after a prolonged rainfall event to assess how changing water levels impact upon the microbial ecology and contaminant mobility. Collectively, results demonstrated that oxygen-laden rainwater rapidly altered the redox balance in the trench water, strongly impacting microbial functioning as well as the radiochemistry. Two contaminants of concern, plutonium and americium, were shown to transition from solid-iron-associated species immediately after the initial rainwater pulse, to progressively more soluble moieties as reducing conditions were enhanced. Functional metagenomics revealed the potentially important role that the taxonomically-diverse microbial community played in this transition. In particular, aerobes dominated in the first day followed by an increase of facultative anaerobes/denitrifiers at day four. Towards the mid-end of the sampling period, the functional and taxonomic profiles depicted an anaerobic community distinguished by a higher representation of dissimilatory sulfate reduction and methanogenesis pathways. Our results have important implications to similar near-surface environmental systems in which redox cycling occurs.ImportanceThe role of chemical and microbiological factors in mediating the biogeochemistry of groundwaters from trenches used to dispose of radioactive materials during the 1960s is examined in this study. Specifically, chemical and microbial analyses, including functional and taxonomic information derived from shotgun metagenomics, were collected across a six-week period immediately after a prolonged rainfall event to assess how changing water levels influence microbial ecology and contaminant mobility.Results demonstrate that oxygen-laden rainwater rapidly altered the redox balance in the trench water, strongly impacting microbial functioning as well as the radiochemistry. Two contaminants of concern, plutonium and americium, were shown to transition from solidiron-associated species immediately after the initial rainwater pulse, to progressively more soluble moieties as reducing conditions were enhanced. Functional metagenomics revealed the important role that the taxonomically-diverse microbial community played in this transition. Our results have important implications to similar near-surface environmental systems in which redox cycling occurs.

show abstract

Fe(III) Reduction in the Subsurface at a Low-level Radioactive Waste Disposal Site

Cited by 7 publications

References 26 publications

Response of Microbial Community Function to Fluctuating Geochemical Conditions within a Legacy Radioactive Waste Trench Environment

Response of Microbial Community Function to Fluctuating Geochemical Conditions within a Legacy Radioactive Waste Trench Environment

The Synergistic Effects of High Nitrate Concentrations on Sediment Bioreduction

Response of microbial community function to fluctuating geochemical conditions within a legacy radioactive waste trench environment

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