Browsing by Author "Payne, TE"
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- Item12th South Pacific Environmental Radioactivity Association Conference (SPERA 2012)(Australian Nuclear Science and Technology Organisation, 2012-10-16) Heijnis, H; Payne, TE; Lickiss, J; Bruhn, F; Zettinig, M; Zawadzki, A; Hoffmann, EL; Child, DPWelcome to the 12th South Pacific Radioactivity Association Conference, welcome back in Sydney. The conference will be hosted by the Australian Institute for Nuclear Science and Engineering and the Australian Nuclear Science and Technology Organisation. The program for the 12th SPERA conference is very exciting, with key-note speakers setting the scene for a diverse range of sessions. The conference will conclude by offering the participants a tour of ANSTO’s new facilities. We would like to thank Jorden Lickiss for her tireless efforts in conference management. We also like to thank our sponsors AINSE, ANSTO and Nucletron for their financial support. We look forward to your participation and a successful conference.
- ItemAccumulation of plutonium in mammalian wildlife tissues following dispersal by accidental-release tests(Elsevier, 2016-01-01) Johansen, MP; Child, DP; Caffrey, EA; Harrison, JJ; Hotchkis, MAC; Payne, TE; Ikeda-Ohno, A; Thiruvoth, S; Beresford, NA; Twining, JR; Davis, EWe examined the distribution of plutonium (Pu) in the tissues of mammalian wildlife inhabiting the relatively undisturbed, semi-arid former Taranaki weapons test site, Maralinga, Australia. The accumulation of absorbed Pu was highest in the skeleton (83% ± 6%), followed by muscle (10% ± 9%), liver (6% ± 6%), kidneys (0.6% ± 0.4%), and blood (0.2%). Pu activity concentrations in lung tissues were elevated relative to the body average. Foetal transfer was higher in the wildlife data than in previous laboratory studies. The amount of Pu in the gastrointestinal tract was highly elevated relative to that absorbed within the body, potentially increasing transfer of Pu to wildlife and human consumers that may ingest gastrointestinal tract organs. The Pu distribution in the Maralinga mammalian wildlife generally aligns with previous studies related to environmental exposure (e.g. Pu in humans from worldwide fallout), but contrasts with the partitioning models that have traditionally been used for human worker-protection purposes (approximately equal deposition in bone and liver) which appear to under-predict the skeletal accumulation in environmental exposure conditions. © 2015, Elsevier Ltd.
- ItemAccumulation of plutonium in mammalian wildlife tissues: comparison of recent data with the ICRP distribution models(International Conference on Radioecology and Environmental Radioactivity, 2014-07-01) Johansen, MP; Child, DP; Davis, E; Hotchkis, MAC; Payne, TE; Ikeda-Ohno, A; Twining, JRWe examined the distribution of plutonium (Pu) in the tissues of mammalian wildlife to address the paucity of such data under environmental exposure conditions. Pu activity concentrations were measured in Macropus rufus (red kangaroo), Oryctolagus cuniculus (European rabbit), and Pseudomys hermannsburgensis (sandy inland mouse)inhabiting the relatively undisturbed, semi-arid conditions at the former Taranaki weapons test site at Maralinga, Australia. Of the absorbed Pu (distributed via circulatory and lymph systems) accumulation was foremost in bone (83% ±10% SD), followed by muscle (9% ±10%), liver (7% ±7%), kidneys (0.5% ±0.3%), and heart (0.4% ±0.4%). The bone values are higher than those reported in ICRP 19 and 48 (45-50% bone), while the liver values are lower than ICRP values (30-45% liver). The ICRP values were based on data dominated by relatively soluble forms of Pu, including prepared solutions and single-atom ions produced by decay following the volatilisation of uranium during nuclear detonation (fallout Pu, ICRP 1986). In contrast, the Maralinga data relates to low-soluble forms of Pu used in tests designed to simulate accidental release and dispersal. We measured Pu in lung, GI-tract and the skin and fur as distinct from the absorbed Pu in bone, liver, muscle, and kidneys. Compared with the mean absorbed activity concentrations, the results for lung tissues were higher by up to one order of magnitude, and those in the GI tract contents and the washed skin/fur were higher by more than two orders of magnitude. These elevated levels are consistent with the presence of low-soluble Pu, including particulate forms, which pass through, or adhere upon, certain organs, but are not readily absorbed into the bloodstream. This more transitory Pu can provide dose to the lung and GI tract organs, as well as provide potential transfer of contamination when consumed in predator-prey food chains, or during human foodstuff consumption. For example, activity concentrations in O. cuniculus edible samples prepared according to traditional aboriginal methods were more than two orders of magnitude higher than in muscle alone. The increase was due to inclusion of GI tract components and contents in the traditional method. Our results provide new insights into the sequestration of Pu in mammalian tissues under environmental exposure conditions. These results contrast with those related to the specific forms of Pu and exposure conditions upon which the ICRP models were based. However, they provide data relevant to the assessment of key environmental legacy waste sites, and of potential release scenarios for the low-soluble oxide forms in the growing worldwide inventory of Pu associated with power production.
- ItemAdsorption of a jet fuel on a model organic-clay soil: application of small angle neutron scattering(National Research Council Canada, 2009-03-14) Hanley, HJM; Payne, TESmall angle neutron scattering (SANS) data are reported from a system that models the contamination of a clay/organic matter soil from a fuel spillage. The soil was represented as an aqueous dispersion of the synthetic clay mineral Laponite coated with lysine, and the contaminant was a representative jet fuel, quadricyclane, mixed with the detergent cetyltrimethylammonium bromide (CTAB). The adsorbed surface coverage on the clay was estimated. It is shown that the presence of adsorbed lysine considerably enhances the subsequent adsorption of both CTAB and quadricyclane. It is demonstrated that the SANS technique can contribute to the general problem of environmental remediation and retention by probing the interactions of pollutants and clay surfaces. © 2008, National Research Council Canada
- ItemAnalysis of hot particle characteristics affecting environmental fate and interaction with living organisms(SPERA, 2016-09-09) Johansen, MP; Child, DP; Collins, RN; Hotchkis, MAC; Howell, NR; Payne, TE; Ikeda-Ohno, A; Mokhber-Shahin, LThe 2nd International Conference on the Sources, Effects and Risks of Ionizing Radiation (SERIR-2) and the 14th Biennial Conference of the South Pacific Environmental Radioactivity Association (SPERA-2016) and will be held in Bali, Indonesia 5-9 September 2016. The South Pacific Environmental Radioactivity Association (SPERA), in conjunction with the Indonesian National Nuclear Energy Agency (BATAN) and the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) made the decision to jointly hold these conferences in one week at the same venue to avoid topical overlap and to strengthen regional participation at both events. SERIR2 will be a 1-day conference (5 September) and deals with the efforts to enhance data collection and disseminate scientific findings related to the issues of sources, effects and risks of the ionizing radiation, as well as to seek ways of communicating with stakeholders (scientific communities, regulatory authorities and general public) on those issues. The 14th Biennial Conference of the South Pacific Environmental Radioactivity Association (SPERA), to be held 6-9 September, provides a platform for discussion and debate among scientists on the occurrence, behaviour, impact and measurement of radioactive species present in the environment through natural processes, or resulting from human activities. This international conference facilitates knowledge sharing on environmental radioactivity and related topics of local and global significance. The joint conference will be held 5-9 September 2016, with a welcome reception on 4 September, at the Sanur Paradise Plaza Hotel in Bali. The joint conference will include a one-day workshop on the 6 September on topic(s) to be decided.
- ItemApplicability of surface area normalised distribution coefficients (Ka) for uranium sorption(Elsevier, 2011-10-01) Payne, TE; Vinzenz, B; Nebelung, C; Comarmond, MJAdsorption of radionuclides on soils and sediments is commonly quantified by distribution coefficients (Kd values). This paper examines the relationship between Kd values for uranium(VI) adsorption and the specific surface area (SSA) of geologic materials. We then investigate the potential applicability of normalising uranium (U) Kd measurements using the SSA, to produce ‘Ka values’ as a generic expression of the affinity of U for the surface. The data for U provide a reasonably coherent set of Ka values on various solid phases, both with and without ligands. The Ka representation provides a way of harmonising datasets obtained for materials having different specific surface areas, and accounting for the effects of ligands in different systems. In addition, this representation may assist in developing U sorption models for complex materials. However, a significant limitation of the Ka concept is that sorption of radionuclides at trace levels can be dominated by interactions with specific surface sites, whose abundances are not reflected by the SSA. Therefore, calculated Ka values should be interpreted cautiously. © 2011, Elsevier
- ItemApplicability of surface area normalised distribution coefficients (Ka) in interpreting measurements of radionuclide sorption(South Pacific Radioactivity Association, 2008-11-26) Payne, TE; Brendler, V; Comarmond, MJThe mobility of radionuclides in the environment is a key issue in assessing the future performance of nuclear waste repositories and modelling the movement of radionuclides in contaminated sites. There have been numerous experimental studies of the adsorption of radionuclides, however, it remains difficult to model the uptake of radionuclides by soils and other complex multi-component geologic materials. Although it would be desirable to utilise mechanistic sorption models (such as surface complexation models) in environmental radionuclide transport modelling, these require a large amount of experimental data and involve considerable mathematical complexity. Therefore, they are not yet available for predictive modelling of complex systems. As a result, predictions of the mobility of radionuclides in the environment generally rely on descriptive measured parameters, such as the solid-liquid distribution coefficient (Kd value) for which various compilations of data values are available (e.g. Sheppard and Thibault, 1990). In order to better understand the mobility of radionuclides in the environment, it has been proposed to utilise a surface area normalised distribution coefficient (Ka value) in which the Kd values are normalised by the measured sample surface area (Pabalan et al., 1998). The concept is developed in this paper by analysing radionuclide sorption measurements from several data sets, including experimental data for well characterised geological materials that were obtained from candidate low-level nuclear repository sites in Australia. In addition, several data-sets summarised in the extensive RES3T database (Brendler et al., 2003) are also utilised in determining whether the K, would be an applicable tool to constrain the ranges of sorption values expected for natural materials in the environment. Finally, we discuss the conditions under which the K, value provides useful insights into radionuclide mobility and possible limitations in its applicability.
- ItemApplication of FEPs analysis to identify research priorities relevant to the safety case for an Australian radioactive waste facility(The American Society of Mechanical Engineers, 2007-09-02) Payne, TE; McGlinn, PJThe Australian Nuclear Science and Technology Organisation (ANSTO) has established a project to undertake research relevant to the safety case for the proposed Australian radioactive waste facility. This facility will comprise a store for intermediate level radioactive waste, and either a store or a near-surface repository for low-level waste. In order to identify the research priorities for this project, a structured analysis of the features, events and processes (FEPs) relevant to the performance of the facility was undertaken. This analysis was based on the list of 137 FEPs developed by the IAEA project on ‘Safety Assessment Methodologies for Near Surface Disposal Facilities’ (ISAM). A number of key research issues were identified, and some factors which differ in significance for the store, compared to the repository concept, were highlighted. For example, FEPs related to long-term ground-water transport of radionuclides are considered to be of less significance for a store than a repository. On the other hand, structural damage from severe weather, accident or human interference is more likely for a store. The FEPs analysis has enabled the scientific research skills required for the interdisciplinary project team to be specified. The outcomes of the research will eventually be utilised in developing the design, and assessing the performance, of the future facility. It is anticipated that a more detailed application of the FEPs methodology will be undertaken to develop the safety case for the proposed radioactive waste management facility. © 2007 The American Society of Mechanical Engineers
- ItemApplication of neutron activatable tracers (NATs) for cohesive sediment transport studies in contaminated estuaries(International Atomic Energy Agency, 2004-10-29) Hollins, SE; Szymczak, R; Airey, PL; Peirson, WL; Payne, TEANSTO and the University of NSW Water Research Laboratory (WRL) are investigating the migration of contaminants associated with cohesive sediments in Homebush Bay, Sydney. The study area is a highly urbanised and industrialised catchment with a long history of contamination . Until 1890, when an ocean outfall was commissioned, domestic and industrial waste was discharged directly into Sydney Harbour . Heavy metals and other hydrophobic pollutants have a distinct tendency towards solid phase partitioning. This means that the majority of heavy metals in the estuary are linked to particulates rather than occurring in the dissolved phase. Hence, in order to assess the impacts of the pollution and develop a scientific basis for remediation it is necessary to understand processes that resuspend and disperse the contaminated sediments. The study approach involved the evaluation of the numerical model of the processes using activatable tracer techniques . An ideal tracer binds to the material of interest with high integrity and is detected with high sensitivity and selectivity. Tracers can be used to study sediment transport over extended periods and are therefore ideally suited to observing the impact of extreme weather events on sediment mobilisation by monitoring the distribution of the label before and after the event. The tracer must not only adhere to the cohesive sediment with high integrity but must be detectable with high efficiency, high sensitivity and relatively low cost. Identification of the optimum activatable tracer involved an assessment of the nuclear (Table I) and sorption properties. The implementation of the tracer study involved (a) labelling sediment from the study area with indium-115 in the laboratory and equilibrating for 3 weeks; (b) choosing a site where bathymetric surveys indicated significant recent accretion; (c) injection of the labelled sediment into an accurately located site in Homebush Bay (Fig. 1); (d) undertaking three surveys over the subsequent months; (e) analysis of samples via irradiation in the Fast Access Neutron facility in ANSTO’s research reactor, HIFAR and gamma counting on a High Purity Germanium detector3; and (f) data processing, where the tracer concentrations were contoured using the Surfer© routine and interpreted in terms of advective and dispersive transport using a Gaussian approximation (Fig. 2). Information on vertical transport was obtained by coring. These results are being used to evaluate a three-dimensional finite element model of the study area . Estimates have been made of the aerial dispersion coefficients, of the surficial mixing due to bioturbation and of advective transport. This paper will focus on the optimum choice of the tracer for cohesive sediment transport studies and some early results.
- ItemApplications of time-resolved laser fluorescence spectroscopy to the environmental eiogeochemistry of actinides(American Society of Argonomy, 2011-05-01) Collins, RN; Saito, T; Aoyagi, N; Payne, TE; Kimura, T; Waite, TDTime-resolved laser fluorescence spectroscopy ( TRLFS) is a useful means of identifying certain actinide species resulting from various biogeochemical processes. In general, TRLFS diff erentiates chemical species of a fl uorescent metal ion through analysis of diff erent excitation and emission spectra and decay lifetimes. Although this spectroscopic technique has largely been applied to the analysis of actinide and lanthanide ions having fl uorescence decay lifetimes on the order of microseconds, such as UO(2)(2+), Cm(3+), and Eu(3+), continuing development of ultra-fast and cryogenic TRLFS systems off ers the possibility to obtain speciation information on metal ions having room-temperature fl uorescence decay lifetimes on the order of nanoseconds to picoseconds. Th e main advantage of TRLFS over other advanced spectroscopic techniques is the ability to determine in situ metal speciation at environmentally relevant micromolar to picomolar concentrations. In the context of environmental biogeochemistry, TRLFS has principally been applied to studies of ( i) metal speciation in aqueous and solid phases and ( ii) the coordination environment of metal ions sorbed to mineral and bacterial surfaces. In this review, the principles of TRLFS are described, and the literature reporting the application of this methodology to the speciation of actinides in systems of biogeochemical interest is assessed. Signifi cant developments in TRLFS methodology and advanced data analysis are highlighted, and we outline how these developments have the potential to further our mechanistic understanding of actinide biogeochemistry. © American Society of Agronomy
- ItemAppraisal of a cementitious material for waste disposal: neutron imaging studies of pore structure and sorptivity(Laboratoire SUBATECH, 2008-10-14) McGlinn, PJ; de Beer, FC; Aldridge, LP; Radebe, MJ; Nshimirimana, R; Brew, DRM; Payne, TE; Olufson, KPTo characterise and to evaluate the durability, structural properties and sorptivity of a candidate wasteform for ILW and gain an understanding of the factors that control water movement through the matrix and the matrix and the resultant degradation process.
- ItemAppraisal of a cementitious material for waste disposal: neutron imaging studies of pore structure and sorptivity(Elsevier, 2010-08) McGlinn, PJ; de Beer, FC; Aldridge, LP; Radebe, MJ; Nshimirimana, R; Brew, DRM; Payne, TE; Olufson, KPCementitious materials are conventionally used in conditioning intermediate and low level radioactive waste. In this study a candidate cement-based wasteform has been investigated using neutron imaging to characterise the wasteform for disposal in a repository for radioactive materials. Imaging showed both the pore size distribution and the extent of the cracking that had occurred in the samples. The rate of the water penetration measured both by conventional sorptivity measurements and neutron imaging was greater than in pastes made from Ordinary Portland Cement. The ability of the cracks to distribute the water through the sample in a very short time was also evident. The study highlights the significant potential of neutron imaging in the investigation of cementitious materials. The technique has the advantage of visualising and measuring, non-destructively, material distribution within macroscopic samples and is particularly useful in defining movement of water through the cementitious materials. © 2010 Crown Copyright published by Elsevier Ltd.
- ItemAssessment of radionuclide distributions at an Australian legacy radioactive waste site(South Pacific Radioactivity Association, 2010-09-01) Payne, TE; Cendón, DI; Collins, RN; Dore, M; Hankin, SI; Harrison, JJ; Hughes, CE; Johansen, MP; Thiruvoth, S; Twining, JR; Wilsher, KLDuring the 1960s, low level radioactive waste was buried in shallow trenches at a disposal site in south-eastern Australia, known as the Little Forest Burial Ground. This paper discusses preliminary findings of research into the distribution of radionuclides at the site, including soils, groundwater and biota. In particular, we are studying the mobility of radionuclides; and their uptake by plants, insects and small animals. Groundwater monitoring indicates that there has been limited movement of radioactivity, other than a tritium plume that extends at least 100 m. The tritium results are being used to define the groundwater flowpaths, and the effects of seasonal and climatic factors. The pattern of tritium distribution suggests that the source of tritium is predominantly within the waste materials. However, tritium derived from a nearby municipal landfill contributes to tritium concentrations in some groundwaters, with smaller amounts from cosmogenic tritium and atmospheric deposition originating from the nearby HIFAR reactor (shut down in 2007). The tritium data provide a record of water movement against which the relative mobility of other radionuclides can be assessed. There are measurable amounts of 60Co, 90Sr, 137Cs and traces of actinides in some soils, groundwater and vegetation samples taken in close proximity to the disposal area. Isotopic ratios such as δ13C, δ180, δ2H, δ34S and 87Sr/86Sr are being measured in groundwater, in addition to the radioactive isotopes originating from the disposed wastes. Synchrotron EXAFS and XANES studies are being applied to study elemental chemical environments and oxidation states in the soils at the site. We have recently undertaken a major geophysical investigation and drilling program; and installation of an improved array of water sampling boreholes is planned. Therefore, many more samples of groundwater and soils are becoming available for analysis.
- ItemAssessment of radionuclide movement at an Australian legacy radioactive waste site(EMSL, 2009-09-20) Payne, TE; Cendón, DI; Collins, RN; Hankin, SI; Harrison, JJ; Hughes, CE; Johansen, MP; Twining, JR; Waite, TDNot available
- ItemAssessment of surface area normalisation for interpreting distribution coefficients (Kd) for uranium sorption(Elsevier B. V., 2011-10) Payne, TE; Brendler, V; Comarmond, MJ; Nebelung, CAdsorption of radionuclides on soils and sediments is commonly quantified by distribution coefficients (Kd values). This paper examines the relationship between Kd values for uranium(VI) adsorption and the specific surface area (SSA) of geologic materials. We then investigate the potential applicability of normalising uranium (U) Kd measurements using the SSA, to produce ‘Ka values’ as a generic expression of the affinity of U for the surface. The data for U provide a reasonably coherent set of Ka values on various solid phases, both with and without ligands. The Ka representation provides a way of harmonising datasets obtained for materials having different specific surface areas, and accounting for the effects of ligands in different systems. In addition, this representation may assist in developing U sorption models for complex materials. However, a significant limitation of the Ka concept is that sorption of radionuclides at trace levels can be dominated by interactions with specific surface sites, whose abundances are not reflected by the SSA. Therefore, calculated Ka values should be interpreted cautiously. © 2010 Elsevier Ltd.
- ItemBackground report on the Little Forest Burial Ground legacy waste site(Australian Nuclear Science and Technology Organisation, 2012-12-01) Payne, TEThe Australian Atomic Energy Commission (AAEC) buried low-level radioactive waste at the Little Forest Burial Ground (LFBG) near Lucas Heights between 1960 and 1968. The disposal site has since been under a constant care, maintenance and routine monitoring regime by the AAEC and its successor, the Australian Nuclear Science and Technology Organisation (ANSTO). The routine environmental measurements at the site have been reported in ANSTO’s series of monitoring reports. ANSTO has commenced a detailed scientific study of the status of the site, including sampling of vegetation, groundwater and soils. The project has undertaken soil coring, geophysical surveys and installation of groundwater sampling bores. The research applies advanced analytical techniques, such as accelerator mass spectrometry, which have not been employed in the analysis of environmental samples from the LFBG in the past. Project personnel are reviewing documents related to the disposal operations, as well as information and data from over 40 years of monitoring and investigation of the LFBG. In addition to relatively shortlived radionuclides, such as 60Co, 137Cs and 90Sr, the site contains both nonradioactive toxic contaminants (including more than 1000 kg of beryllium) and longlived alpha-emitting radionuclides including plutonium, uranium and thorium. Over the period since operations ceased, a plume of tritium in groundwater has developed and there has been intermittent subsidence of the soil covering the trenches. This subsidence is attributed to voids developing in the buried wastes, due to deterioration of containers and disposed objects. Contamination of the ground surface with radionuclides has been documented in some AAEC reports. The data obtained by the research project at LFBG will enable the assessment of possible management options including continuing the current regime of maintenance and monitoring, in-situ remediation, or exhumation. Unless the site is remediated, it will require some form of institutional control in perpetuity, due to the presence of beryllium and long-lived actinides. The present report provides an overview of the disposal operations at LFBG, briefly reviews previous reports and describes current ANSTO research activities at the site.
- ItemBeryllium sorption to sandy soil at a legacy waste site(CRC CARE Pty Ltd,, 2019-09-08) Islam, MR; Sanderson, P; Naidu, R; Johansen, MP; Payne, TEBeryllium (Be) is utilized in various science and technology applications including aerospace, defence, electronics and nuclear energy (USGS, 2018). Beryllium and its compounds are highly toxic and considered carcinogenic to humans (IARC, 2001). In soil, Be is highly reactive, amphoteric, hydrates readily and reacts with different organic and inorganic elements due to its high charge to size ratio (Alderighi et al., 2000, Boschi and Willenbring, 2016, Rudolph et al., 2009, Edmunds, 2011). The sorption mechanism strongly depends on soil physicochemical properties like pH, cation exchange capacity (CEC), soil texture, soil organic matter (SOM) content, and the presence of sulphur, nitrogen, phosphorous, aluminium etc. (Sutton et al., 2012, Boschi and Willenbring, 2016). Of these, pH is a strong controller of Be sorption, with chemisorption increasing substantially from pH 4 to 6 with precipitation being the predominant mechanism between pH 6-12 (Boschi and Willenbring, 2016). This study examined the sorption of Be in surface soils of a legacy waste site that contains Be and low-level radioactive wastes disposed in shallow trenches to determine how Be may be retained in the surface soil if it is mobilised from the wastes. The sorption of Be with respect to physiochemical properties and the applicability of the Langmuir, Freundlich and Temkin sorption models was examined
- ItemBioaccumulation of 65Zn by the Sydney rock oyster (Saccostrea glomerata) from dissolved and particulate phases(SETAC Australasia, 2014-09) Lee, JH; Birch, GF; Cresswell, T; Payne, TE; Simpson, SLOysters and other similar bivalves are popular ‘biomonitors’ or ‘sentinels’ of the environment and are commonly used to assess the health of marine ecosystems. It has been generally accepted that uptake and bioaccumulation in bivalves is influenced predominantly by dietary ingestion of contaminated particles as well as from dissolved sources. An organism of relevance to Australian ecosystems is the Sydney rock oyster (SRO; Saccostrea glomerata), an intertidal, suspension filter-feeder commonly found on the coasts and estuaries of Victoria, New South Wales, and Queensland, Australia. Farmed SRO organisms were used for a 2 month mesocosm study where specimens were exposed to a gradient of resuspended sediment loads and sediment-bound trace metal concentrations. The results indicated poor correlations between SRO tissue metal concentrations and either sediment metal concentration or resuspended volume, with the greatest bioaccumulation being observed in the control tank containing no sediment. These results suggested that SRO metal bioaccumulation was driven primarily from a dissolved source. To investigate this further, a radiotracer study using the gamma-emitting radioisotope 65Zn was conducted, in which SRO organisms were exposed to the dissolved 65Zn radioisotope at three concentrations (5, 25 and 50 µg/L) for 4 days, followed by 20 days of depuration. Dietary assimilation of Zn was examined through pulse-chase experiments where SRO specimens were fed either 65Zn labelled fine-fraction sediments in suspension, or algae. The outcome of this experiment was to outline the relative importance of dissolved, sedimentary, and algal metal sources, and conclusively determine the primary uptake pathway for metal bioaccumulation. The resulting data were used to establish uptake and efflux rate constants from dissolved sources, and assimilation efficiencies from the dietary sources, which were then incorporated into a biodynamic accumulation model. The results of this study are discussed in the context of the use of bivalves as indicators of sediment quality.
- ItemCan synchrotron micro-x-ray fluorescence spectroscopy be used to map the distribution of cadmium in soil particles?(CSIRO Publishing, 2007-10-30) Milham, PJ; Payne, TE; Lai, B; Trautman, RL; Cai, ZH; Holford, P; Haigh, AM; Conroy, JPPlants take up cadmium (Cd) from the soil, and the concentration of Cd in some plant products is a health concern. Plant uptake of Cd is poorly predicted by its concentration in soils; consequently, there is interest in the binding and distribution of Cd in soil. Synchrotron micro-X-ray fluorescence spectroscopy (micro-XRFS) is the most sensitive method of observing this distribution. We used beam-line 2-ID-D of the Advanced Photon Source (APS), Argonne, to test whether this technique could map the Cd distribution in 5 soils from Greater Sydney that contained 0.3-6.4 mg Cd/kg. A subsample of one soil was spiked to contain similar to 100 mg Cd/kg. Cadmium was readily mapped in the Cd-enriched subsample, whereas in the unamended soils, only one Cd-rich particle was found; that is, sensitivity generally limited Cd mapping. We also examined a sample of Nauru phosphorite, which was a primary source of much of the Cd in farm soils on the peri-urban fringe of Greater Sydney. The phosphorite contained similar to 100 mg Cd/kg and the Cd was relatively uniformly distributed, supporting the findings of an earlier study on an apatite from Africa. The micro-XRFS at beam-line 2-ID-D of the APS can be reconfigured to increase the sensitivity at least 10-fold, which may allow the distribution of Cd and its elemental associations to be mapped in particles of most agricultural soils and facilitate other spectroscopic investigations. © 2007, CSIRO Publishing
- ItemCharacterisation of natural substrates with regard to application of surface complexation models(OECD, 2001) Waite, TD; Fenton, BR; Payne, TE; Lumpkin, GR; Davis, JA; McBeath, MWhile good correspondence between laboratory sorption data and surface complexation modelling results has been obtained for single oxide phase, much poorer correspondence has been obtained for natural substrates. This result arises, at least in part, from the difficulty in ascertaining the identity of sorbing surfaces and in assigning appropriate values for sorbing surface site concentrations. In an attempt to clarify the nature of possible sorbing phases, we have used a variety of techniques to investigate the surfaces of natural solid substrates from the Koongarra weathered zone. Based on insights gained from the surface characterisation studies, we have then proceeded to assess the applicability of various surface complexation modelling approaches as applied to U(VI) uptake. © 2001 OECD