Browsing by Author "Prentice, E"

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    Bioaccumulation kinetics and internal distribution of the fission products radiocaesium and radiostrontium in an estuarine crab
    (Elsevier, 2021-04-15) Cresswell, T; Prentice, E; Howell, NR; Callaghan, PD; Metian, M; Johansen, MP
    Crab has been designated by the ICRP as one of twelve reference/model organisms for understanding the impacts of radionuclide releases on the biosphere. However, radionuclide-crab interaction data are sparse compared with other reference organisms (e.g. deer, earthworm). This study used an estuarine crab (Paragrapsus laevis) to investigate the contribution of water, diet and sediment sources to radionuclide (134Cs and 85Sr) bioaccumulation kinetics using live-animal radiotracing. The distribution of each radionuclide within the crab tissues was determined using dissection, whole-body autoradiography and synchrotron X-ray Fluorescence Microscopy (XFM). When moulting occurred during exposure, it caused significant increases in 85Sr bioaccumulation and efflux of 134Cs under constant aqueous exposure. Dietary assimilation efficiencies were determined as 55 ± 1% for 134Cs and 49 ± 3% for 85Sr. 85Sr concentrated in gonads more than other organs, resulting in proportionally greater radiation dose to the reproductive organs and requires further investigation. 134Cs was found in most soft tissues and was closely associated with S and K. Biodynamic modelling suggested that diet accounted for 90–97% of whole-body 137Cs, while water accounted for 59–81% of 90Sr. Our new data on crab, as a representative invertebrate, improves understanding of the impacts of planned or accidental releases of fission radionuclides on marine ecology. Crown Copyright © 2020 Published by Elsevier B.V.
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    Biofilm-enhanced adsorption of strong and weak cations onto different microplastic sample types: use of spectroscopy, microscopy and radiotracer methods
    (Elsevier, 2019-07-01) Johansen, MP; Cresswell, T; Davis, J; Howard, DL; Howell, NR; Prentice, E
    The adsorption of metals and other elements onto environmental plastics has been previously quantified and is known to be enhanced by surface-weathering and development of biofilms. However, further biofilm-adsorption characterisation is needed with respect to the fate of radionuclides. This study uses spectroscopy, microscopy and radiotracer methods to investigate the adsorption capacity of relatively strong and weak cations onto different microplastic sample types that were conditioned in freshwater, estuarine and marine conditions although marine data were limited. Fourier-transform infrared spectroscopy confirmed that surface oxidation chemistry changes induced by gamma irradiation were similar to those resulting from environmental exposures. Microscopy elemental mapping revealed patchy biofilm development, which contained Si, Al, and O, consistent with microbial-facilitated capture of clays. The plastics+biofilm of all sample types had measurable adsorption for Cs and Sr radiotracers, suggesting environmental plastics act broadly as a sink for the key pervasive environmental radionuclides of 137Cs and 90Sr associated with releases from nuclear activities. Adsorption onto high-density polyethylene plastic types was greater than that on polypropylene. However, in most cases, the adsorption rates of all types of plastic+biofilm were much lower than those of reference sediments and roughly consistent with their relative exchangeable surface areas. Crown Copyright © 2019 Published by Elsevier Ltd.
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    Initial data on adsorption of Cs and Sr to the surfaces of microplastics with biofilm
    (Elsevier, 2018-10) Johansen, MP; Prentice, E; Cresswell, T; Howell, NR
    The adsorption of radiocesium and radiostrontium onto a range of natural materials has been well quantified, but not for the new media of environmental plastics, which may have enhanced adsorption due to surface-weathering and development of biofilms. Microplastic samples were deployed in freshwater, estuarine and marine conditions, then characterised using infrared spectroscopy to document changes to the plastic surface (vs interior). Synchrotron elemental mapping data revealed surfaces that were well-covered by accumulation of reactive water solutes and sulphur, but, in contrast, had highly discrete coverage of elements such as Fe and Ti, indicating adhered mineral/clay-associated agglomerates that may increase overall adsorption capacity. Plastics that had been deployed for nearly five months adsorbed radionuclides in both freshwater and estuarine conditions with the highest Kd for cesium (Cs) in freshwater (80 ml g−1) and lowest for strontium (Sr) in estuarine conditions (5 ml g−1). The degree of Cs and Sr adsorption onto plastics appears to be approximately 2–3 orders of magnitude lower than for sediment reference values. While lower than for sediments, adsorption occurred on all samples and may indicate a significant radionuclide reservoir, given that plastics are relatively buoyant and mobile in water regimes, and are increasing in global aquatic systems. Crown Copyright © 2018 Published by Elsevier Ltd.
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    The use of stable isotope techniques for long-term monitoring of Australian Freshwater Wetlands
    (University of New South Wales and Australian Nuclear Science and Technology Organisation, 2015-07-10) Prentice, E; Mazumder, D; Kobayashi, T; Saintilan, N
    Not provided to ANSTO Library.