Browsing by Author "Creighton, NM"

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    Analytical method development for tritium in tree transpirate from the Little Forest Burial Ground
    (Australian Nuclear Science and Technology Organisation, 2009-08) Twining, JR; Harrison, JJ; Vine, M; Creighton, NM; Neklapilova, B; Hoffmann, EL
    The Little Forest Burial Ground (LFBG) is a near-surface low-level nuclear waste repository located within the buffer zone surrounding the Lucas Heights Research Laboratories of ANSTO (Figure 1). Tritium (3H, ‘T’), as tritiated water (HTO), was one of the radioactive substances placed into the trenches located within the LFBG (Isaacs and Mears, 1977). This material will behave conservatively in regard to any seepage from the site of deposition. As such, it should be a good indicator of groundwater movement at the site. Water is a vital requirement of plants. Hence, it was proposed that samples from herbs and trees may be useful to assess the biologically available HTO and also provide an indication of a potential exposure for environmental dose assessment, not only for 3H but also for the other radionuclides potentially migrating with the water from the trenches. As part of the initial draft plan for a vegetation survey in the LFBG (Twining and Creighton, 2007) the following two null hypotheses were established: H0a that there is no significantly higher concentration of specific contaminants in foliage of trees growing over, or adjacent to, the pits than there is in the foliage of the same species growing away from the pits; H0b that there is no correlation between contaminant levels in the seepage plume and surface vegetation. These hypotheses are to be tested using the acquired data. However, as part of the process of applying HTO in transpirate as a monitoring tool, some method development has been required. This report covers all aspects of that development and provides a recommended approach to acquiring such data and recording the information.
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    Bioaccumulation from food and water of cadmium, selenium and zinc in an estuarine fish, Ambassis jacksoniensis
    (Elsevier, 2010-10) Creighton, NM; Twining, JR
    The glassfish, Ambassis jacksoniensis, is a key, mid-level species in an estuarine food web on the east coast of Australia. Estuaries are subject to contamination from urban and industrial activities. The biokinetics of Cd, Se and Zn accumulation by glassfish from water and food were assessed using radioisotopes. Metal uptake from water was not regulated over the range of water metal concentrations examined. Metal uptake from food was assessed using brine shrimp (Artemia sp.) fed radio-labelled algae. The assimilation efficiency from food was 9.5 ± 2.5%, 23 ± 2.2% and 4.6 ± 0.6% for Cd, Se and Zn, respectively. The potential for biomagnification was low for all metals. Food is the main metal uptake pathway for glassfish, with 97%, 99% and 98% of the uptake of Cd, Se and Zn, respectively, estimated to be from food. © 2010, Elsevier Ltd.
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    A combined multidisciplinary kinetic modeling approach for determination of coastal ecosystem contaminant fluxes
    (Goldschmidt, 2006-08-26) Szymczak, R; Twining, JR; Hollins, SE; Mazumder, D; Creighton, NM
    The historical operation of manufacturing, chemical and other industries in the Sydney Harbour catchment over many decades has left a legacy of high chemical contamination in the surrounding catchment. These contaminants are now seriously impacting on incident commercial fisheries and public utilisation of estuarine resources. Elucidation of environmental processes is the key to effective ecosystem management, however few tools are available to predict their inter-relationships, rates and directions. This work seeks to combine GIS, contaminant transport, ecological, and bioaccumulation models to improve the accuracy and specificity of a probabilistic ecological risk assessment strategy. This study has four components: (1) determination of chemical linkages between high trophic order species and different habitats resources using stable isotopic analyses of carbon and nitrogen. These studies identify trophic cascades forming the basis for selection of biota for contaminant transfer experiments; (2) short-term (weeks – months) chronology and geochemistry of sediment cores and traps in Homebush Bay to determine rates of sedimentation and resuspension (using environmental/cosmogenic 7-Be). Models derived from these studies provide the contaminants levels against which risk is assessed; (3) biokinetic studies using proxy radiotracer isotopes (eg. 75-Se & 109-Cd for analogous stable metals) of the uptake and trophic transfer of contaminants by specific estaurine biota. Here we identify the rates and extent to which contaminants accumulated and transferred to predators/seafoods; and (4) application of a probabilistic ecological risk assessment model (AQUARISK) set to criteria determined by stakeholder consensus. Here we report initial results of the distribution of natural isotopes and redistribution of artificial isotopes injected into ecological compartments to determine the key trophic linkages, contaminant pathways and their rates in temperate estuarine systems of Sydney Harbour & Botany Bay (Australia).
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    Field and laboratory applications of radionuclides in environmental research
    (Committee on Radiochemistry of the Hungarian Academy of Sciences (HAS), 2008-08-27) Payne, TE; Hughes, CE; Creighton, NM; Twining, JR
    Radionuclides have numerous applications in environmental research. They can be utilised in plant uptake and bioaccumulation studies in both field and laboratory experiments, thereby providing valuable information on elemental and radionuclide pathways and dynamics in ecological systems. In the estuarine environment, radiotracer studies enable experimental evaluation of the numerical models underpinning engineering studies, as well as enabling research into the dynamics of coastal ecosystems. The advantages of radionuclides in laboratory experiments include the wide range of elemental concentrations that can be studied, the capability to study several isotopes simultaneously, and the ability to study the mechanisms, reversibility and kinetics of environmental reactions under controlled conditions. The results of the studies are applicable to the behaviour of both radioactive and non-radioactive environmental contaminants. These attributes are demonstrated using specific examples drawn from case studies in Australia and South East Asia.
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    Method development for tritium measurements and initial evaluation of tritium data for tree transpirate from a legacy waste site in eastern Australia
    (South Pacific Radioactivity Association, 2008-11-25) Twining, JR; Creighton, NM; Harrison, JJ; Hoffmann, EL; Neklapilova, B; Vine, M
    Tritium (3H), as tritiated water, was one of the radioactive substances placed into the trenches located within the former waste disposal site known as the Little Forest Burial Ground (LFBG). This site is located in the 1.6 km exclusion zone surrounding ANSTO the previous research reactor, HIFAR, south of Sydney. Tritium will behave conservatively in regard to any seepage from the site of deposition, and therefore should be a good indicator of groundwater movement at the site. Water is also a vital requirement of plants on the site. Hence, it was proposed that analysis of the tritium content of shrubs and trees may be a useful means to assess and access the biologically available 3H. In addition, it should provide an indication of potential exposure for environmental dose assessment, not only for 3H but also for the other radionuclides potentially migrating with the water from the trenches. To test these ideas, sampling of tree transpirate at LFBG has been initiated. In order to utilise measurements of 3H in transpirate as a monitoring tool, some method development has been required. Relatively small sample volumes have required atypical preparation methods and sample quenching has been an issue. There is also a need to consider background concentrations, given that the HIFAR reactor at the Lucas Heights Research Reactor has emitted 3H to the local environment for several decades. Results of sampling and analysis since July 2007 Will be presented and each of these issues will discussed in this initial report.
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    Probabilistic risk assessment and risk mapping of sediment metals in Sydney Harbour embayments.
    (Taylor & Francis, 2008-11) Twining, JR; Creighton, NM; Hollins, SE; Szymczak, R
    Sediment metal concentrations in embayments of Sydney Harbour, acquired from the literature and from samples collected for this study, were used to generate contaminant probability density distributions using AQUARISK. The sediment metal concentrations often exceeded Australia's interim sediment quality guidelines. Similarly, estuarine spiked sediment toxicity test literature provided adverse biotic effects concentration data to generate species sensitivity distributions using AQUARISK. Although the harbor is subject to other inorganic and organic contamination, we have used sediment metals to demonstrate an approach for ecological risk mapping and environmental management prioritization. Sufficient spiked sediment toxicity test data were found for only three metals Cd, Cu, and Zn and some tests were likely to overestimate toxicity. The estimates of the hazardous concentration to 5% of species (the 50th percentile of the 95% species protection level) were 5, 12, and 40 mg/kg DW of total sediment metal for Cd, Cu, and Zn, respectively. These values were generally low when compared with the interim sediment quality guidelines due to the overestimation of toxic effects in the literature data. The parameters for the species sensitivity distributions have been combined with the measured sediment metal concentrations in Homebush Bay to generate risk maps of the estimated species impact for each metal as well as for all three metals collectively assuming proportional additivity. This has demonstrated the utility of comparing contaminants on a consistent scaleecological risk. © 2008, Taylor & Francis Ltd.