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Payne TE, Harrison JJ, Child DP, Hankin S, Hotchkis MAC, Hughes CE, Johansen MP, Thiruvoth S, Wilsher KL. Accelerator mass spectrometry measurements of 233U in groundwater, soil and vegetation at a legacy radioactive waste site. CHEMOSPHERE 2024; 358:141761. [PMID: 38531499 DOI: 10.1016/j.chemosphere.2024.141761] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2023] [Revised: 02/27/2024] [Accepted: 03/18/2024] [Indexed: 03/28/2024]
Abstract
Low-level radioactive wastes were disposed at the Little Forest Legacy Site (LFLS) near Sydney, Australia between 1960 and 1968. According to the disposal records, 233U contributes a significant portion of the inventory of actinide activity buried in the LFLS trenches. Although the presence of 233U in environmental samples from LFLS has been previously inferred from alpha-spectrometry measurements, it has been difficult to quantify because the 233U and 234U α-peaks are superimposed. Therefore, the amounts of 233U in groundwaters, soils and vegetation from the vicinity of the LFLS were measured using accelerator mass spectrometry (AMS). The AMS results show the presence of 233U in numerous environmental samples, particularly those obtained within, and in the immediate vicinity of, the trenched area. There is evidence for dispersion of 233U in groundwater (possibly mobilised by co-disposed organic liquids), and the data also suggest other sources of 233U contamination in addition to the trench wastes. These may include leakages and spills from waste drums as well as waste burnings, which also occurred at the site. The AMS results confirm the historic information regarding disposal of 233U in the LFLS trenches. The AMS technique has been valuable to ascertain the distribution and environmental behaviour of 233U at the LFLS and the results demonstrate the applicability of AMS for evaluating contamination of 233U at other radioactive waste sites.
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Affiliation(s)
- Timothy E Payne
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia.
| | - Jennifer J Harrison
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - David P Child
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Stuart Hankin
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Michael A C Hotchkis
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Catherine E Hughes
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Mathew P Johansen
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Sangeeth Thiruvoth
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Kerry L Wilsher
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
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Islam MR, Sanderson P, Johansen MP, Payne TE, Naidu R. Environmental chemistry response of beryllium to diverse soil-solution conditions at a waste disposal site. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2023; 25:94-109. [PMID: 36537748 DOI: 10.1039/d2em00313a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
This study evaluated how the variation in different sorption conditions of beryllium (Be) in soil-water systems (electrolytes; ionic strengths; competing, counter, and co-existing ions; concentrations of Be and soil; and temperature) affected Be's environmental behaviour. For this reason, potentially contaminated soil was collected from a legacy waste site near Sydney, Australia. The sorption-desorption plateau for Be was found at >12.5 g L-1 (soil/solution), considering higher sorption and limited desorption. Variable surface charges developed by different added ions (competing ions, counter ions, and co-existence of all ions) were not always correlated with Be sorption. However, effects of added ions in Be sorption (increased by counter ions and decreased by competing ions) primarily occurred at low pH, with no noticeable changes at pH > 6 due to the hydration and precipitation behaviour of Be at higher pH. Both laboratory data and modelling indicated the substantial effect of counter ions on increased sorption of Be. Relatively higher amounts of sorption under the co-existence of all added ions were suggested from synergistic actions. Sorption was favourable (KL > 0, and 0 < RL < 1) across all concentrations and temperatures at pH 5.5, and high retention (84-97%) occurred after four desorption cycles indicated specific sorption. The sorption process was exothermic (ΔH > -43 kJ mole-1), while desorption was endothermic (ΔH > +78.4 kJ mole-1). All sorption-desorption reactions were spontaneous (ΔG = -Ve), and executed without any structural deformation (ΔS = nearly zero) of soil particles. However, the effect of temperature on desorption was influenced by the concentrations of Be. Higher retention and different sorption-desorption parameters (Kd-desorption > Kd-sorption; Kf-desorption > Kf-sorption; ndesorption/nsorption < 1) indicate limited mobility of Be and the presence of desorption hysteresis in the studied soil under the experimental conditions.
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Affiliation(s)
- Md Rashidul Islam
- Global Centre for Environmental Remediation (GCER), College of Engineering, Science and Environment, The University of Newcastle, University Drive, Callaghan Campus, NSW 2308, Australia.
- CRC for Contamination Assessment and Remediation of the Environment (CARE), The University of Newcastle, University Drive, Callaghan Campus, NSW 2308, Australia
| | - Peter Sanderson
- Global Centre for Environmental Remediation (GCER), College of Engineering, Science and Environment, The University of Newcastle, University Drive, Callaghan Campus, NSW 2308, Australia.
- CRC for Contamination Assessment and Remediation of the Environment (CARE), The University of Newcastle, University Drive, Callaghan Campus, NSW 2308, Australia
| | - Mathew P Johansen
- Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia
| | - Timothy E Payne
- Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia
| | - Ravi Naidu
- Global Centre for Environmental Remediation (GCER), College of Engineering, Science and Environment, The University of Newcastle, University Drive, Callaghan Campus, NSW 2308, Australia.
- CRC for Contamination Assessment and Remediation of the Environment (CARE), The University of Newcastle, University Drive, Callaghan Campus, NSW 2308, Australia
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Kinsela AS, Payne TE, Bligh MW, Vázquez-Campos X, Wilkins MR, Comarmond MJ, Rowling B, Waite TD. Contaminant release, mixing and microbial fluctuations initiated by infiltrating water within a replica field-scale legacy radioactive waste trench. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 851:158241. [PMID: 36007652 DOI: 10.1016/j.scitotenv.2022.158241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 08/14/2022] [Accepted: 08/19/2022] [Indexed: 06/15/2023]
Abstract
Numerous legacy near-surface radioactive waste sites dating from the mid 20th century have yet to be remediated and present a global contamination concern. Typically, there is insufficient understanding of contaminant release and redistribution, with invasive investigations often impractical due to the risk of disturbing the often significantly radiotoxic contaminants. Consequently, a replica waste trench (~5.4 m3), constructed adjacent to a legacy radioactive waste site (Little Forest Legacy Site, LFLS), was used to assist our understanding of the release and mixing processes of neodymium (Nd) - a chemical analogue for plutonium(III) and americium(III), two significant radionuclides in many contaminated environments. In order to clarify the behaviour of contaminants released from buried objects such as waste containers, a steel drum, representative of the hundreds of buried drums within the LFLS, was placed within the trench. Dissolved neodymium nitrate was introduced as a point-source contaminant to the base of the trench, outside the steel drum. Hydrologic conditions were manipulated to simulate natural rainfall intensities with dissolved lithium bromide added as a tracer. Neodymium was primarily retained both at its point of release at the bottom of the trench (>97 %) as well as at a steel container corrosion point, simulated through the emplacement of steel wool. However, over the 8-month field experiment, advective mixing initiated by surface water intrusions rapidly redistributed a small proportion of Nd to shallower waters (~1.5-1.7 %), as well as throughout the buried steel drum. Suspended particulate forms of Nd (>0.2 μm) were measured at all depths in the suboxic trench and were persistent across the entire study. Analyses of the microbial communities showed that their relative abundances and metabolic functions were strongly influenced by the prevailing geochemical conditions as a result of fluctuating water depths associated with rainfall events. The site representing steel corrosion exhibited divergent biogeochemical results with anomalous changes (sharp decrease) observed in both dissolved contaminant concentration as well as microbial diversity and functionality. This research demonstrates that experimental trenches provide a safe and unique method for simulating the behaviour of subsurface radioactive contaminants with results demonstrating the initial retention, partial shallow water redistribution, and stability of particulate form(s) of this radioactive analogue. These results have relevance for appropriate management and remediation strategies for the adjacent legacy site as well as for similar sites across the globe.
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Affiliation(s)
- Andrew S Kinsela
- UNSW Water Research Centre and School of Civil and Environmental Engineering, The University of New South Wales, Sydney, Australia
| | - Timothy E Payne
- Environmental Research Theme, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Mark W Bligh
- UNSW Water Research Centre and School of Civil and Environmental Engineering, The University of New South Wales, Sydney, Australia
| | - Xabier Vázquez-Campos
- NSW Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia
| | - Marc R Wilkins
- NSW Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, Australia
| | - M Josick Comarmond
- Environmental Research Theme, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Brett Rowling
- Environmental Research Theme, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - T David Waite
- UNSW Water Research Centre and School of Civil and Environmental Engineering, The University of New South Wales, Sydney, Australia.
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Islam MR, Sanderson P, Payne TE, Deb AK, Naidu R. Role of beryllium in the environment: Insights from specific sorption and precipitation studies under different conditions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 838:155698. [PMID: 35523347 DOI: 10.1016/j.scitotenv.2022.155698] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2022] [Revised: 04/24/2022] [Accepted: 04/30/2022] [Indexed: 06/14/2023]
Abstract
In this study, we examined factors influencing the environmental behaviour of Be, specifically considering soils collected from a legacy radioactive waste disposal site near Sydney (Australia). The precipitation study showed the formation of Be(OH)2 (amorphous) from ICP standard solution, but a mixture of Be(OH)2 (alpha), Be(OH)2 (beta) and ternary Na/S-Be (ΙΙ)-OH(s) solid phase were formed from BeSO4 solutions. The precipitation of Be started at relatively lower pH at higher concentrations than at the lower Be concentration as indicated by both laboratory data and simulation. Across the pH range, the Be sorption curve was divided into three phases, these being pH 3-6, pH 6-10, and pH > 10, within which sorption of Be with soil was 9-97%, 90-97%, and 66-90%, respectively. Beryllium solubility was limited at pH > 7, but a sorption study with soil showed chemisorption under both acidic and alkaline pH (pH 5.5 and 8) conditions, which was confirmed by FTIR and XPS analysis. At pH 5.5 (specifically relevant to the study site), sorption of Be was 72-95%, in which 77% and 46% Be was respectively sorbed by separated fulvic and humic acid fractions. The irreversible chemisorption mechanism was controlled by SOM at higher pH, and by metal oxyhydroxides at lower pH. Both organic and inorganic components synergistically influence the specific chemisorption of Be at the intermediate pH 5.5 of field soil.
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Affiliation(s)
- Md Rashidul Islam
- Global Centre for Environmental Remediation (GCER), College of Engineering, Science and Environment, The University of Newcastle (UoN), University Drive, Callaghan Campus, NSW 2308, Australia; CRC for Contamination Assessment and Remediation of the Environment (CRC CARE), The University of Newcastle (UoN), University Drive, Callaghan Campus, NSW 2308, Australia.
| | - Peter Sanderson
- Global Centre for Environmental Remediation (GCER), College of Engineering, Science and Environment, The University of Newcastle (UoN), University Drive, Callaghan Campus, NSW 2308, Australia; CRC for Contamination Assessment and Remediation of the Environment (CRC CARE), The University of Newcastle (UoN), University Drive, Callaghan Campus, NSW 2308, Australia
| | - Timothy E Payne
- Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW 2234, Australia
| | - Amal Kanti Deb
- Global Centre for Environmental Remediation (GCER), College of Engineering, Science and Environment, The University of Newcastle (UoN), University Drive, Callaghan Campus, NSW 2308, Australia; CRC for Contamination Assessment and Remediation of the Environment (CRC CARE), The University of Newcastle (UoN), University Drive, Callaghan Campus, NSW 2308, Australia; Institute of Leather Engineering and Technology, University of Dhaka, Dhaka 1000, Bangladesh
| | - Ravi Naidu
- Global Centre for Environmental Remediation (GCER), College of Engineering, Science and Environment, The University of Newcastle (UoN), University Drive, Callaghan Campus, NSW 2308, Australia; CRC for Contamination Assessment and Remediation of the Environment (CRC CARE), The University of Newcastle (UoN), University Drive, Callaghan Campus, NSW 2308, Australia.
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Cendón DI, Rowling B, Hughes CE, Payne TE, Hankin SI, Harrison JJ, Peterson MA, Stopic A, Wong H, Gadd P. Rare earth elements and yttrium as tracers of waste/rock-groundwater interactions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 830:154706. [PMID: 35331767 DOI: 10.1016/j.scitotenv.2022.154706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/27/2022] [Revised: 03/03/2022] [Accepted: 03/16/2022] [Indexed: 06/14/2023]
Abstract
Increasing concentrations of Rare Earth Elements (REE) plus yttrium (REY) are entering the environment due to human activities. The similar chemical behaviour across the whole REY, i.e. the lanthanide series (lanthanum to lutetium) and yttrium, allows their use as tracers, fingerprinting rock-forming processes and fluid-rock interactions in earth science systems. However, their use in fingerprinting waste and particularly low-level radioactive waste has not received much attention, despite the direct use of REE in the nuclear industry and the traditional use of REE as proxies to understand the environmental mobility of the actinide series (actinium to lawrencium). The highly instrumented low-level radioactive waste site at Little Forest (Australia) allows a detailed REY study, investigating interactions with local strata, neighbouring waste forms and shallow groundwater flows. Groundwater samples and solids from cored materials were recovered from 2007 to 2012 from the study site and regional baseline sites in the same geological materials. The REY in water samples were analysed by automated chelation pre-concentration (SeaFast, ESI) followed by ICP-MS determination, while solid samples were analysed using Neutron Activation Analysis (NAA) and X-ray fluorescence scanning (ITRAX). Solid rocks showed no REY departed from typical Upper Crust compositions in either Little Forest or regional background sites. Shallow groundwater from ~4-5 m, at or slightly below waste trench levels, showed water-waste interaction as a marked enrichment, relative to shale-normalised patterns, in samarium, europium and gadolinium, with depleted yttrium. Leachate samples from the neighbouring urban landfill show different REY normalised patterns. REY distribution changes with depth through increased interaction with shales and sandstones. Variations in pH and redox conditions lead to widespread precipitation of Fe-hydroxides, which scavenge REY with differential uptake by precipitating solids, resulting in increases in Y and higher Y/Ho ratio in the groundwater along the flow path. Our study revealed that the Little Forest low-level radioactive waste has a REY fingerprint different to that of groundwater in surrounding land uses. REY can be used to fingerprint diverse waste sources, assess the mobility of lanthanides inferring the mobility of selected actinides, and to trace the fate of REY during groundwater recharge. The approach presented can refine source allocation and trace pollutant mobility in current and legacy urban, mixed and radioactive waste sites around the world.
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Affiliation(s)
- Dioni I Cendón
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia; School of Biological, Earth and Environmental Sciences, UNSW Sydney, NSW, 2052, Australia.
| | - Brett Rowling
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Catherine E Hughes
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Timothy E Payne
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Stuart I Hankin
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Jennifer J Harrison
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Mark A Peterson
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Attila Stopic
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Henri Wong
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Patricia Gadd
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
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Vázquez-Campos X, Kinsela AS, Bligh MW, Payne TE, Wilkins MR, Waite TD. Genomic Insights Into the Archaea Inhabiting an Australian Radioactive Legacy Site. Front Microbiol 2021; 12:732575. [PMID: 34737728 PMCID: PMC8561730 DOI: 10.3389/fmicb.2021.732575] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 09/21/2021] [Indexed: 11/29/2022] Open
Abstract
During the 1960s, small quantities of radioactive materials were co-disposed with chemical waste at the Little Forest Legacy Site (LFLS, Sydney, Australia). The microbial function and population dynamics in a waste trench during a rainfall event have been previously investigated revealing a broad abundance of candidate and potentially undescribed taxa in this iron-rich, radionuclide-contaminated environment. Applying genome-based metagenomic methods, we recovered 37 refined archaeal MAGs, mainly from undescribed DPANN Archaea lineages without standing in nomenclature and 'Candidatus Methanoperedenaceae' (ANME-2D). Within the undescribed DPANN, the newly proposed orders 'Ca. Gugararchaeales', 'Ca. Burarchaeales' and 'Ca. Anstonellales', constitute distinct lineages with a more comprehensive central metabolism and anabolic capabilities within the 'Ca. Micrarchaeota' phylum compared to most other DPANN. The analysis of new and extant 'Ca. Methanoperedens spp.' MAGs suggests metal ions as the ancestral electron acceptors during the anaerobic oxidation of methane while the respiration of nitrate/nitrite via molybdopterin oxidoreductases would have been a secondary acquisition. The presence of genes for the biosynthesis of polyhydroxyalkanoates in most 'Ca. Methanoperedens' also appears to be a widespread characteristic of the genus for carbon accumulation. This work expands our knowledge about the roles of the Archaea at the LFLS, especially, DPANN Archaea and 'Ca. Methanoperedens', while exploring their diversity, uniqueness, potential role in elemental cycling, and evolutionary history.
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Affiliation(s)
- Xabier Vázquez-Campos
- NSW Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - Andrew S. Kinsela
- UNSW Water Research Centre, School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW, Australia
| | - Mark W. Bligh
- UNSW Water Research Centre, School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW, Australia
| | - Timothy E. Payne
- Environmental Research Theme, Australian Nuclear Science and Technology Organisation, Kirrawee DC, NSW, Australia
| | - Marc R. Wilkins
- NSW Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney, NSW, Australia
| | - T. David Waite
- UNSW Water Research Centre, School of Civil and Environmental Engineering, The University of New South Wales, Sydney, NSW, Australia
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Bots P, Comarmond MJ, Payne TE, Gückel K, Lunn RJ, Rizzo L, Schellenger AEP, Renshaw JC. Emerging investigator series: a holistic approach to multicomponent EXAFS: Sr and Cs complexation in clayey soils. ENVIRONMENTAL SCIENCE. PROCESSES & IMPACTS 2021; 23:1101-1115. [PMID: 34180934 DOI: 10.1039/d1em00121c] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Strontium and caesium are fission products of concern at many nuclear legacy sites and Cs is additionally a significant consideration at sites in the aftermath of nuclear accidents and incidents. Such sites require long-term management to minimize the risk of such contaminants to the environment and the public. Understanding the geochemical speciation of Sr and Cs in situ in the soils and groundwater is essential to develop engineered management strategies. Here we developed and utilized a comprehensive approach to fitting the EXAFS of Sr and Cs adsorption to single mineral phases and a composite clayey soil. First, a shell-by-shell fitting strategy enabled us to determine that Sr surface complexes involve the formation of bidentate edge sharing complexes with anatase and illite-smectite, and form at the silicon vacancy sites at the kaolinite basal surfaces. Cs surface complexes form at the silicon vacancy sites at the illite-smectite and kaolinite basal surfaces. Second, using a subsequent holistic approach we determined the predominance of these complexes within a composite clayey soil. Sr was dominated by complexation with illite-smectite (72-76%) and to a lesser extent with kaolinite (25-30%) with negligible complexation with anatase, while Cs complexed roughly equally to both illite-smectite and kaolinite. The presented approach to fitting EXAFS spectra will strengthen predictive modelling on the behaviour of elements of interest. For example, the details on Sr and Cs speciation will enable predictive modelling to characterise their long-term behaviour and the design and validation of evidence-based engineering options for long-term management of nuclear legacy sites.
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Affiliation(s)
- Pieter Bots
- Department of Civil and Environmental Engineering, University of Strathclyde, Glasgow, G1 1XJ, UK.
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Kinsela AS, Bligh MW, Vázquez-Campos X, Sun Y, Wilkins MR, Comarmond MJ, Rowling B, Payne TE, Waite TD. Biogeochemical Mobility of Contaminants from a Replica Radioactive Waste Trench in Response to Rainfall-Induced Redox Oscillations. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2021; 55:8793-8805. [PMID: 34110792 DOI: 10.1021/acs.est.1c01604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Results of investigations into factors influencing contaminant mobility in a replica trench located adjacent to a legacy radioactive waste site are presented in this study. The trench was filled with nonhazardous iron- and organic matter (OM)-rich components, as well as three contaminant analogues strontium, cesium, and neodymium to examine contaminant behavior. Imposed redox/water-level oscillations, where oxygen-laden rainwater was added to the anoxic trench, resulted in marked biogeochemical changes including the removal of aqueous Fe(II) and circulation of dissolved carbon, along with shifts to microbial communities involved in cycling iron (Gallionella, Sideroxydans) and methane generation (Methylomonas, Methylococcaceae). Contaminant mobility depended upon element speciation and rainfall event intensity. Strontium remained mobile, being readily translocated under hydrological perturbations. Strong ion-exchange reactions and structural incorporation into double-layer clay minerals were likely responsible for greater retention of Cs, which, along with Sr, was unaffected by redox oscillations. Neodymium was initially immobilized within the anoxic trenches, due to either secondary mineral (phosphate) precipitation or via the chemisorption of organic- and carbonate-Nd complexes onto variably charged solid phases. Oxic rainwater intrusions altered Nd mobility via competing effects. Oxidation of Fe(II) led to partial retention of Nd within highly sorbing Fe(III)/OM phases, whereas pH decreases associated with rainwater influxes resulted in a release of adsorbed Nd to solution with both pH and OM presumed to be the key factors controlling Nd attenuation. Collectively, the behavior of simulated contaminants within this replica trench provided unique insights into trench water biogeochemistry and contaminant cycling in a redox oscillatory environment.
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Affiliation(s)
- Andrew S Kinsela
- UNSW Water Research Centre and School of Civil and Environmental Engineering, The University of New South Wales, Sydney 2052, Australia
| | - Mark W Bligh
- UNSW Water Research Centre and School of Civil and Environmental Engineering, The University of New South Wales, Sydney 2052, Australia
| | - Xabier Vázquez-Campos
- NSW Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney 2052, Australia
| | - Yingying Sun
- UNSW Water Research Centre and School of Civil and Environmental Engineering, The University of New South Wales, Sydney 2052, Australia
| | - Marc R Wilkins
- NSW Systems Biology Initiative, School of Biotechnology and Biomolecular Sciences, The University of New South Wales, Sydney 2052, Australia
| | - M Josick Comarmond
- Environmental Research Theme, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Brett Rowling
- Environmental Research Theme, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Timothy E Payne
- Environmental Research Theme, Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - T David Waite
- UNSW Water Research Centre and School of Civil and Environmental Engineering, The University of New South Wales, Sydney 2052, Australia
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Payne TE, Shatwell J, Comarmond MJ. Priority issues and key findings from evaluation of disposal records for a legacy radioactive waste site. JOURNAL OF RADIOLOGICAL PROTECTION : OFFICIAL JOURNAL OF THE SOCIETY FOR RADIOLOGICAL PROTECTION 2021; 41:S24-S38. [PMID: 33862603 DOI: 10.1088/1361-6498/abf902] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/12/2021] [Accepted: 04/16/2021] [Indexed: 06/12/2023]
Abstract
This paper reports on a detailed investigation into the disposal procedures and records from the operational period (1960-1968) of the Little Forest Legacy Site (LFLS) in eastern Australia. The aims of the paper are firstly, to highlight the priority issues which are relevant to the radiological assessment of the LFLS, and secondly, to present key lessons that may help to guide future investigations of the records at similar sites. Particular effort was put into assessing the various types of relevant documents and the relationships between them. A specific objective of this work was to evaluate an inventory of the wastes which was reported shortly after the time of disposals. A major finding of the study is that the original actinide inventory for LFLS relied solely on estimates from a limited number of specific records known as 'Scrap Disposal Reports' (SDRs). For example, the estimated amount of plutonium disposed at the LFLS was based on only seven SDR records. Given that there are approximately 50000 buried items, it is possible that other Pu-contaminated items could make a significant additional contribution to the amount of Pu present at the site. For some waste components (e.g. beryllium) the documentation shows that rough estimates of disposal quantities were made, based on the number of disposed Be-contaminated items in each trench. The use of such approximations casts some doubt on the accuracy of the previous inventory of wastes at the site. In addition, the early summaries of radionuclide disposals, which categorized radionuclides into groups according to their radiological hazard, contained significant underestimates of the radionuclide inventory in the most hazardous category (referred to at the time as 'Group I' radionuclides). This was mainly due to the omission of the Pu (which had been recorded on the SDRs) from the Group I inventory, but was also in part because the Group I radionuclide content of disposed sludge drums (from a wastewater treatment plant) was not taken into account for most of the disposal period. Establishing the disposal history and radionuclide inventory at legacy sites is an important pre-requisite to evaluating their radiological impact and developing management options. The detailed investigation of the LFLS records shows the importance of understanding the operational practices of the period and the derivation of the original inventories. These insights should help guide future efforts to better understand disposal histories and inventories at LFLS and elsewhere.
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Affiliation(s)
- Timothy E Payne
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - Jonathan Shatwell
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - M Josick Comarmond
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
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Islam MR, Sanderson P, Johansen MP, Payne TE, Naidu R. The influence of soil properties on sorption-desorption of beryllium at a low level radioactive legacy waste site. CHEMOSPHERE 2021; 268:129338. [PMID: 33383279 DOI: 10.1016/j.chemosphere.2020.129338] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2020] [Revised: 12/02/2020] [Accepted: 12/13/2020] [Indexed: 05/14/2023]
Abstract
This study examined the influence of soil physicochemical properties on the sorption, desorption and kinetics of beryllium (Be) uptake and release on soils from a legacy waste site in Australia. This information is needed to help explain the current distribution of Be at the site and evaluate potential future environmental risks. Sorption was determined by a batch study and key soil properties were assessed to explain Be retention. The soil was favourable for sorption of Be (up to 99%) due to organic content, negative surface charge, soil oxyhydroxides (Fe/Al/Mn-O/OH) and the porosity of the soil structure. Lesser sorption was observed in the presence of a background electrolyte (NaNO3). Sorption closely followed pseudo second order kinetics and was best described by the Langmuir model. FTIR analysis suggested that chemisorption was the predominant mechanism of Be sorption. Desorption was very low and best described by the Freundlich model. The low desorption reflected the high Kd (up to 6624 L/kg), and the presence of hysteresis suggested partially irreversible binding of Be with active surfaces of the soil matrix (minerals, SOM, oxyhydroxides of Fe/Al/Mn etc.). Intra-particle diffusion of Be and entrapment in the pores contribute to the irreversible binding. The sorption behaviour of Be helped to explain the relative immobility of Be at the site despite the significant quantities of Be disposed. Soil physicochemical properties were significant for Be sorption, through influencing both the uptake and desorption, and this demonstrates the implications of these measurements for evaluating potential future risks to the environment.
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Affiliation(s)
- Md Rashidul Islam
- Global Centre for Environmental Remediation (GCER), The University of Newcastle (UoN), Callaghan Campus, NSW, 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC-CARE), ATC Building, The University of Newcastle, University Drive, Callaghan, NSW, 2308, Australia
| | - Peter Sanderson
- Global Centre for Environmental Remediation (GCER), The University of Newcastle (UoN), Callaghan Campus, NSW, 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC-CARE), ATC Building, The University of Newcastle, University Drive, Callaghan, NSW, 2308, Australia.
| | - Mathew P Johansen
- Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW, 2234, Australia
| | - Timothy E Payne
- Australian Nuclear Science and Technology Organisation (ANSTO), Lucas Heights, NSW, 2234, Australia
| | - Ravi Naidu
- Global Centre for Environmental Remediation (GCER), The University of Newcastle (UoN), Callaghan Campus, NSW, 2308, Australia; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment (CRC-CARE), ATC Building, The University of Newcastle, University Drive, Callaghan, NSW, 2308, Australia.
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Payne TE, Harrison JJ, Cendon DI, Comarmond MJ, Hankin S, Hughes CE, Johansen MP, Kinsela A, Shahin LM, Silitonga A, Thiruvoth S, Wilsher KL. Radionuclide distributions and migration pathways at a legacy trench disposal site. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2020; 211:106081. [PMID: 31666204 DOI: 10.1016/j.jenvrad.2019.106081] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 10/15/2019] [Accepted: 10/16/2019] [Indexed: 05/14/2023]
Abstract
This paper examines the distributions of several anthropogenic radionuclides (239+240Pu, 241Am, 137Cs, 90Sr, 60Co and 3H) at a legacy trench disposal site in eastern Australia. We compare the results to previously published data for Pu and tritium at the site. Plutonium has previously been shown to reach the surface by a bath-tubbing mechanism, following filling of the former trenches with water during intense rainfall events. This has led to some movement of Pu away from the trenched area, and we also provide evidence of elevated Pu concentrations in shallow subsurface layers above the trenched area. The distribution of 241Am is similar to Pu, and this is attributed to the similar chemistry of these actinides and the likely in-situ generation of 241Am from its parent 241Pu. Concentrations of 137Cs are mostly low in surface soils immediately above the trenches. However, similar to the actinides, there is evidence of elevated 137Cs and 90Sr concentrations in shallow subsurface layers above the trenched area. While the subsurface radionuclide peaks suggest a mechanism of subsurface transport, their interpretation is complicated by the presence of soil layers added following disposals and during the subsequent years. The distribution of 90Sr and 137Cs at the ground surface shows some elevated levels immediately above the trenches which were filled during the final 24 months of disposal operations. This is in agreement with disposal records, which indicate that greater amounts of fission products were disposed in this period. The surface distribution of 239+240Pu is also consistent with the disposal documents. Although there is extensive evidence of a mobile tritium plume in groundwater, migration of the other radionuclides by this pathway is limited. The data highlight the importance of taking into account multiple pathways for the mobilisation of key radioactive contaminants at legacy waste trench sites.
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Affiliation(s)
- Timothy E Payne
- Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia.
| | - Jennifer J Harrison
- Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Dioni I Cendon
- Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - M Josick Comarmond
- Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Stuart Hankin
- Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Catherine E Hughes
- Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Mathew P Johansen
- Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Andrew Kinsela
- Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia; School of Civil and Environmental Engineering, University of New South Wales, Sydney, NSW, 2052, Australia
| | - Lida Mokhber Shahin
- Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Adella Silitonga
- Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Sangeeth Thiruvoth
- Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
| | - Kerry L Wilsher
- Australian Nuclear Science and Technology Organisation (ANSTO), Locked Bag 2001, Kirrawee DC, NSW, 2232, Australia
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Abstract
Neptunium and uranium are important radionuclides in many aspects of the nuclear fuel cycle and are often present in radioactive wastes which require long term management. Understanding the environmental behaviour and mobility of these actinides is essential in underpinning remediation strategies and safety assessments for wastes containing these radionuclides. By combining state-of-the-art X-ray techniques (synchrotron-based Grazing Incidence XAS, and XPS) with wet chemistry techniques (ICP-MS, liquid scintillation counting and UV-Vis spectroscopy), we determined that contrary to uranium(VI), neptunium(V) interaction with magnetite is not significantly affected by the presence of bicarbonate. Uranium interactions with a magnetite surface resulted in XAS and XPS signals dominated by surface complexes of U(VI), while neptunium on the surface of magnetite was dominated by Np(IV) species. UV-Vis spectroscopy on the aqueous Np(V) species before and after interaction with magnetite showed different speciation due to the presence of carbonate. Interestingly, in the presence of bicarbonate after equilibration with magnetite, an unknown aqueous NpO2+ species was detected using UV-Vis spectroscopy, which we postulate is a ternary complex of Np(V) with carbonate and (likely) an iron species. Regardless, the Np speciation in the aqueous phase (Np(V)) and on the magnetite (111) surfaces (Np(IV)) indicate that with and without bicarbonate the interaction of Np(V) with magnetite proceeds via a surface mediated reduction mechanism. Overall, the results presented highlight the differences between uranium and neptunium interaction with magnetite, and reaffirm the potential importance of bicarbonate present in the aqueous phase.
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Rowling B, Kinsela AS, Comarmond MJ, Hughes CE, Harrison JJ, Johansen MP, Payne TE. Measurement of tributyl phosphate (TBP) in groundwater at a legacy radioactive waste site and its possible role in contaminant mobilisation. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2017; 178-179:377-384. [PMID: 28687277 DOI: 10.1016/j.jenvrad.2017.05.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Revised: 03/16/2017] [Accepted: 05/26/2017] [Indexed: 06/07/2023]
Abstract
At many legacy radioactive waste sites, organic compounds have been co-disposed, which may be a factor in mobilisation of radionuclides at these sites. Tri-butyl phosphate (TBP) is a component of waste streams from the nuclear fuel cycle, where it has been used in separating actinides during processing of nuclear fuels. Analyses of ground waters from the Little Forest Legacy Site (LFLS) in eastern Australia were undertaken using solid-phase extraction (SPE) followed by gas chromatographic mass spectrometry (GCMS). The results indicate the presence of TBP several decades after waste disposal, with TBP only being detected in the immediate vicinity of the main disposal area. TBP is generally considered to degrade in the environment relatively rapidly. Therefore, it is likely that its presence is due to relatively recent releases of TBP, possibly stemming from leakage due to container degradation. The ongoing presence and solubility of TBP has the potential to provide a mechanism for nuclide mobilisation, with implications for long term management of LFLS and similar legacy waste sites.
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Affiliation(s)
- Brett Rowling
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia.
| | - Andrew S Kinsela
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia; University of New South Wales, Sydney, NSW 2052, Australia
| | - M Josick Comarmond
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia
| | - Catherine E Hughes
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia
| | - Jennifer J Harrison
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia
| | - Mathew P Johansen
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia
| | - Timothy E Payne
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia
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Response of Microbial Community Function to Fluctuating Geochemical Conditions within a Legacy Radioactive Waste Trench Environment. Appl Environ Microbiol 2017; 83:AEM.00729-17. [PMID: 28667104 PMCID: PMC5561297 DOI: 10.1128/aem.00729-17] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Accepted: 06/20/2017] [Indexed: 02/06/2023] Open
Abstract
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. IMPORTANCE The 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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Kinsela AS, Jones AM, Bligh MW, Pham AN, Collins RN, Harrison JJ, Wilsher KL, Payne TE, Waite TD. Influence of Dissolved Silicate on Rates of Fe(II) Oxidation. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2016; 50:11663-11671. [PMID: 27704793 DOI: 10.1021/acs.est.6b03015] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Increasing concentrations of dissolved silicate progressively retard Fe(II) oxidation kinetics in the circum-neutral pH range 6.0-7.0. As Si:Fe molar ratios increase from 0 to 2, the primary Fe(III) oxidation product transitions from lepidocrocite to a ferrihydrite/silica-ferrihydrite composite. Empirical results, supported by chemical kinetic modeling, indicated that the decreased heterogeneous oxidation rate was not due to differences in absolute Fe(II) sorption between the two solids types or competition for adsorption sites in the presence of silicate. Rather, competitive desorption experiments suggest Fe(II) was associated with more weakly bound, outer-sphere complexes on silica-ferrihydrite compared to lepidocrocite. A reduction in extent of inner-sphere Fe(II) complexation on silica-ferrihydrite confers a decreased ability for Fe(II) to undergo surface-induced hydrolysis via electronic configuration alterations, thereby inhibiting the heterogeneous Fe(II) oxidation mechanism. Water samples from a legacy radioactive waste site (Little Forest, Australia) were shown to exhibit a similar pattern of Fe(II) oxidation retardation derived from elevated silicate concentrations. These findings have important implications for contaminant migration at this site as well as a variety of other groundwater/high silicate containing natural and engineered sites that might undergo iron redox fluctuations.
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Affiliation(s)
- Andrew S Kinsela
- School of Civil and Environmental Engineering, The University of New South Wales , Sydney, New South Wales 2052, Australia
- Institute for Environmental Research, Australian Nuclear Science and Technology Organisation , Locked Bag 2001, Kirrawee DC, New South Wales 2232, Australia
| | - Adele M Jones
- School of Civil and Environmental Engineering, The University of New South Wales , Sydney, New South Wales 2052, Australia
| | - Mark W Bligh
- School of Civil and Environmental Engineering, The University of New South Wales , Sydney, New South Wales 2052, Australia
- Institute for Environmental Research, Australian Nuclear Science and Technology Organisation , Locked Bag 2001, Kirrawee DC, New South Wales 2232, Australia
| | - An Ninh Pham
- School of Civil and Environmental Engineering, The University of New South Wales , Sydney, New South Wales 2052, Australia
| | - Richard N Collins
- School of Civil and Environmental Engineering, The University of New South Wales , Sydney, New South Wales 2052, Australia
| | - Jennifer J Harrison
- Institute for Environmental Research, Australian Nuclear Science and Technology Organisation , Locked Bag 2001, Kirrawee DC, New South Wales 2232, Australia
| | - Kerry L Wilsher
- Institute for Environmental Research, Australian Nuclear Science and Technology Organisation , Locked Bag 2001, Kirrawee DC, New South Wales 2232, Australia
| | - Timothy E Payne
- Institute for Environmental Research, Australian Nuclear Science and Technology Organisation , Locked Bag 2001, Kirrawee DC, New South Wales 2232, Australia
| | - T David Waite
- School of Civil and Environmental Engineering, The University of New South Wales , Sydney, New South Wales 2052, Australia
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Smith BS, Child DP, Fierro D, Harrison JJ, Heijnis H, Hotchkis MAC, Johansen MP, Marx S, Payne TE, Zawadzki A. Measurement of fallout radionuclides, (239)(,240)Pu and (137)Cs, in soil and creek sediment: Sydney Basin, Australia. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2016; 151 Pt 3:579-586. [PMID: 26344369 DOI: 10.1016/j.jenvrad.2015.06.015] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2015] [Revised: 06/12/2015] [Accepted: 06/19/2015] [Indexed: 06/05/2023]
Abstract
Soil and sediment samples from the Sydney basin were measured to ascertain fallout radionuclide activity concentrations and atom ratios. Caesium-137 ((137)Cs) was measured using gamma spectroscopy, and plutonium isotopes ((239)Pu and (240)Pu) were quantified using accelerator mass spectrometry (AMS). Fallout radionuclide activity concentrations were variable ranging from 0.6 to 26.1 Bq/kg for (137)Cs and 0.02-0.52 Bq/kg for (239+240)Pu. Radionuclides in creek sediment samples were an order of magnitude lower than in soils. (137)Cs and (239+240)Pu activity concentration in soils were well correlated (r(2) = 0.80) although some deviation was observed in samples collected at higher elevations. Soil ratios of (137)Cs/(239+240)Pu (decay corrected to 1/1/2014) ranged from 11.5 to 52.1 (average = 37.0 ± 12.4) and showed more variability than previous studies. (240)Pu/(239)Pu atom ratios ranged from 0.117 to 0.165 with an average of 0.146 (±0.013) and an error weighted mean of 0.138 (±0.001). These ratios are lower than a previously reported ratio for Sydney, and lower than the global average. However, these ratios are similar to those reported for other sites within Australia that are located away from former weapons testing sites and indicate that atom ratio measurements from other parts of the world are unlikely to be applicable to the Australian context.
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Affiliation(s)
- B S Smith
- GeoQuEST, School of Earth and Environmental Sciences, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - D P Child
- Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia
| | - D Fierro
- Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia
| | - J J Harrison
- Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia
| | - H Heijnis
- Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia
| | - M A C Hotchkis
- Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia
| | - M P Johansen
- Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia
| | - S Marx
- GeoQuEST, School of Earth and Environmental Sciences, University of Wollongong, Wollongong, NSW, 2522, Australia
| | - T E Payne
- Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia
| | - A Zawadzki
- Institute for Environmental Research, Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW, 2234, Australia
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Harrison JJ, Payne TE, Wilsher KL, Thiruvoth S, Child DP, Johansen MP, Hotchkis MAC. Measurement of (233)U/(234)U ratios in contaminated groundwater using alpha spectrometry. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2016; 151 Pt 3:537-541. [PMID: 26359847 DOI: 10.1016/j.jenvrad.2015.08.013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2015] [Revised: 08/13/2015] [Accepted: 08/18/2015] [Indexed: 06/05/2023]
Abstract
The uranium isotope (233)U is not usually observed in alpha spectra from environmental samples due to its low natural and fallout abundance. It may be present in samples from sites in the vicinity of nuclear operations such as reactors or fuel reprocessing facilities, radioactive waste disposal sites or sites affected by clandestine nuclear operations. On an alpha spectrum, the two most abundant alpha emissions of (233)U (4.784 MeV, 13.2%; and 4.824 MeV, 84.3%) will overlap with the (234)U doublet peak (4.722 MeV, 28.4%; and 4.775 MeV, 71.4%), if present, resulting in a combined (233+234)U multiplet. A technique for quantifying both (233)U and (234)U from alpha spectra was investigated. A series of groundwater samples were measured both by accelerator mass spectrometry (AMS) to determine (233)U/(234)U atom and activity ratios and by alpha spectrometry in order to establish a reliable (233)U estimation technique using alpha spectra. The Genie™ 2000 Alpha Analysis and Interactive Peak Fitting (IPF) software packages were used and it was found that IPF with identification of three peaks ((234)U minor, combined (234)U major and (233)U minor, and (233)U major) followed by interference correction on the combined peak and a weighted average activity calculation gave satisfactory agreement with the AMS data across the (233)U/(234)U activity ratio range (0.1-20) and (233)U activity range (2-300 mBq) investigated. Correlation between the AMS (233)U and alpha spectrometry (233)U was r(2) = 0.996 (n = 10).
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Affiliation(s)
- Jennifer J Harrison
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia.
| | - Timothy E Payne
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Kerry L Wilsher
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Sangeeth Thiruvoth
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - David P Child
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Mathew P Johansen
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
| | - Michael A C Hotchkis
- Australian Nuclear Science and Technology Organisation, Lucas Heights, NSW 2234, Australia
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Ikeda-Ohno A, Harrison JJ, Thiruvoth S, Wilsher K, Wong HKY, Johansen MP, Waite TD, Payne TE. Solution speciation of plutonium and Americium at an Australian legacy radioactive waste disposal site. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2014; 48:10045-53. [PMID: 25126837 DOI: 10.1021/es500539t] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
During the 1960s, radioactive waste containing small amounts of plutonium (Pu) and americium (Am) was disposed in shallow trenches at the Little Forest Burial Ground (LFBG), located near the southern suburbs of Sydney, Australia. Because of periodic saturation and overflowing of the former disposal trenches, Pu and Am have been transferred from the buried wastes into the surrounding surface soils. The presence of readily detected amounts of Pu and Am in the trench waters provides a unique opportunity to study their aqueous speciation under environmentally relevant conditions. This study aims to comprehensively investigate the chemical speciation of Pu and Am in the trench water by combining fluoride coprecipitation, solvent extraction, particle size fractionation, and thermochemical modeling. The predominant oxidation states of dissolved Pu and Am species were found to be Pu(IV) and Am(III), and large proportions of both actinides (Pu, 97.7%; Am, 86.8%) were associated with mobile colloids in the submicron size range. On the basis of this information, possible management options are assessed.
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Affiliation(s)
- Atsushi Ikeda-Ohno
- School of Civil and Environmental Engineering, The University of New South Wales , Sydney, New South Wales 2052, Australia
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