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Title: Isotopes in Australian environmental analysis
Authors: Henderson-Sellers, A
Stone, DJM
Hollins, SE
Hotchkis, MAC
Fink, D
Keywords: ANSTO
New South Wales
Non-proliferation treaty
Mass spectroscopy
Trace amounts
Depleted uranium
Issue Date: 24-Oct-2004
Publisher: International Atomic Energy Agency
Citation: Henderson-Sellers, A., Stone, D., Hollins, S., Hotchkis, M., & Fink. D. (2004). Isotopes in Australian environmental analysis. (2004). Paper presented to International Conference on Isotopes in Environmental Studies – Aquatic Forum 2004 Monte-Carlo, Monaco 25–29 October 2004. Book of extended synopses. Retrieved from,-15,800
Abstract: ANSTO Environment is playing a pioneering role in developing new methods for monitoring adherence to the Nuclear Non-proliferation Treaty. Working with the IAEA Department of Safeguards, new analytical procedures have been developed to assist with their environmental monitoring programme. Signatures of nuclear activities, in the form of trace amounts of radioisotopes in environmental samples, can be used to identify undeclared nuclear facilities or undeclared activities at declared facilities. At ANSTO we have developed the use of Accelerator Mass Spectrometry (AMS) for analysis of 236U in environmental samples. 236U is a sensitive indicator of irradiated uranium. AMS is also used to detect the long- lived fission product 129I at extremely low levels. The presence of 129I can be a signature of reprocessing. ANSTO performs analyses of these radioisotopes as an accredited member of the IAEA Safeguards network of analytical laboratories. Australian soldiers on duty in the Gulf risk possible exposure to depleted uranium. Depleted uranium is the uranium that is left after most of the radioactive isotopes are removed for nuclear fuel. Due to its high density, it is the ideal material for use in armour-piercing ammunition and in armour for fighting vehicles. However, like any heavy metal, it is toxic in high doses. Depleted uranium enters the body through inhalation of the dust- like particles, ingestion of contaminated food or through wounds. At ANSTO, a sensitive analytical technique based on isotope dilution and inductively coupled plasma mass spectrometry (ICPMS) was used to detect depleted uranium in urine samples. By addition of known quantities of 236U (isotope dilution) to the urine samples and measuring the relative abundances of different isotopes (236U, 235U and 238U) of uranium by ICP-MS, we are able to quantify (quantification limit of 20 ng/L) and distinguish between natural and depleted uranium. In Australia, there are legislative limits on the amount of surface water that can be utilised in a particular catchment, but that is not the case for groundwater, leading to tension amongst users in connected systems. Isotopes such as the stable and radioactive isotopes of water and carbon are particularly appropriate for the study of our dry landscape in its connected water systems, providing a clear method of determining the source of groundwater, and hence the extent of mixing of nearby surface water and the time frame for the mixing process. In particular, the stable isotopes 2H, 18O, and 13C provide a robust end-member analysis for the hydrographical separation of regional groundwater and any amount of river water which was replenished at a remote location; while the radioactive isotopes 3H and 14C are used to confirm the presence in groundwater of (isotopically modern) surface water, but also accurately determine the apparent rate of mixing at particular distances from the river. Isotope tracer techniques have been applied to study the fate, pathways and risks associated with contaminants and particulates in coastal aquatic systems. Examples include: (i) sand and sediment tracing in coasts and estuaries using radiotracers such as 192Ir labelled sand (MacMasters Beach, NSW) or neutron activatable tracers such as 115In (Homebush Bay, Sydney); (ii) biokinetics of environmental contaminants in aquatic and terrestrial systems have been investigated using radionuclides such as 109Cd, 65Zn and 210Pb; (iii) tracing of sewage effluent from Australian coastal outfalls undertaken using radioisotope tracers such as 198Au and tritiated water; and (iv) groundwater dynamics under tidal forcing using a shortlived radioisotope tracer 82Br to track groundwater movement in three dimensions (Hat Head, NSW). Accelerator Mass Spectrometry is still the only technique able to determine extremely low concentrations (<10-12) of long- lived radioisotopes in small (mg) environmental samples. In Australia, radiocarbon dating is used for the study of paleo environments, climate studies, atmospheric studies and hydrology. Atmospheric studies including the high resolution radiocarbon dating of tropical and Southern Hemisphere tree rings provide data for studying the temporal variations of atmospheric radiocarbon and its inter-hemispheric gradient; and analysis of radio-methane trapped in Antarctic ice cores, a direct method of studying past atmospheric composition. It is also a means of studying palaeo-climate change. Exposure dating has been applied to glacial studies and landscape evolution studies. Using AMS measurement of beryllium-10 and aluminium-26 we have been able to determine Southern Hemisphere glacial chronology in Tasmania and the geomorphic evolution of Australian stony deserts. We apply the in-situ method to evaluate long-term average erosion rates, sand or sediment transport, accumulation and burial stages. 479
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