Browsing by Author "Stone, DJM"

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    Application of environmental isotopes of hydrogen (3H), Carbon (13C & 14C) and oxygen (16O/18O) in studies of groundwater-streamflow interactions
    (International Atomic Energy Agency, 2004-10-25) Stone, DJM; Jacobsen, GE; Hughes, CE; Szymczak, R
    A current major effort in Australian water management is the conjunctive management of hydraulically connected Groundwater and Surface water systems, to provide the maximum benefit to water stakeholders. In particular Australia has a legislative limit 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. Valley and Murray-Darling Basin, NSW. Streamflow was sampled using a plastic bailer while groundwaters were withdrawn with the use of a Grundfos MP1 environmental sampling pump. They were analysed for stable isotopes ({sup 2}H/H, {sup 18}O/{sup 16}O) ratios, tritium ({sup 3}H), radiocarbon ({sup 14}C) and major and minor chemical species. Rainwaters were collected and analysed for stable isotopes only. Previous tritium in precipitation data were also utilised. Ion Chromatography was used for the analysis of the anions while either ICP-MS or ICP-AES was used for cations. The tritium analysis was carried out by standard procedures of electrolytic concentration and liquid scintillation counting. Analysis of the water samples for deuterium was conducted by CSIRO, Isotope Analysis laboratory using the zinc reduction method and a VG Isogas mass spectrometer (error; {+-} 0.8 per mille). Radiocarbon in groundwaters are measured using accelerator mass spectrometry (AMS). The water samples are filtered to 45 {mu}m prior to CO{sub 2} collection. Dissolved inorganic carbon (DIC) is separated by acidifying the water samples with 85% phosphoric acid, the resulting CO{sub 2} is collected by sparging with He for 15 mins and cryogenic trapping. The CO{sub 2} is purified by heating overnight to 600 deg. C in the presence of Ag wire. Graphite targets are then prepared by the reduction of the CO{sub 2} using H{sub 2} with an Fe catalyst at 600 deg. C. The resulting graphite/iron mix is measured in the ANTARES 10MV Tandem Accelerator. The determination of oxygen-18 was conducted at the University of Wollongong using the CO{sub 2} gas equilibration method, purified using a Micromass Multiprep Unit and measured on a Micromass Prism III (error; {+-} 0.1 per mille). A plot of tritium activity versus borehole location and depth, indicates that the Brogo River (Bega Valley, NSW) is not recharging the adjacent alluvium since the tritium is much lower than in the streamwater. The Bega river however is recharging the adjacent alluvium, both above and below its confluence with the Brogo river, since tritium values are similar in stream and alluvium. Isotopes such as the stable and radioactive isotopes of water and carbon are particularly appropriate for the study of these connected water systems, providing a clear method of determining the source of groundwater, and hence the extent of mixing of nearby surface water (such as the local river), and the time frame for the mixing process. In particular the stable isotopes 2-H, 18-O, and 13-C provide a robust end-member analysis for the hydrographic separation of regional groundwater and any amount of river water which was replenished at a remote location; while the radioactive isotopes 3-H and 14-C 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. © The Authors
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    Application of environmental isotopes of hydrogen (3H), Carbon (13C & 14C) and oxygen (16O/18O) in studies of groundwater-streamflow interactions
    (International Atomic Energy Agency, 2006) Stone, DJM; Jacobsen, GE; Hughes, CE; Szymczak, R
    A current major effort in Australian water management is the conjunctive management of hydraulically connected Groundwater and Surface water systems, to provide the maximum benefit to water stakeholders. In particular Australia has a legislative limit 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. Valley and Murray-Darling Basin, NSW. Streamflow was sampled using a plastic bailer while groundwaters were withdrawn with the use of a Grundfos MP1 environmental sampling pump. They were analysed for stable isotopes ({sup 2}H/H, {sup 18}O/{sup 16}O) ratios, tritium ({sup 3}H), radiocarbon ({sup 14}C) and major and minor chemical species. Rainwaters were collected and analysed for stable isotopes only. Previous tritium in precipitation data were also utilised. Ion Chromatography was used for the analysis of the anions while either ICP-MS or ICP-AES was used for cations. The tritium analysis was carried out by standard procedures of electrolytic concentration and liquid scintillation counting. Analysis of the water samples for deuterium was conducted by CSIRO, Isotope Analysis laboratory using the zinc reduction method and a VG Isogas mass spectrometer (error; {+-} 0.8 per mille). Radiocarbon in groundwaters are measured using accelerator mass spectrometry (AMS). The water samples are filtered to 45 {mu}m prior to CO{sub 2} collection. Dissolved inorganic carbon (DIC) is separated by acidifying the water samples with 85% phosphoric acid, the resulting CO{sub 2} is collected by sparging with He for 15 mins and cryogenic trapping. The CO{sub 2} is purified by heating overnight to 600 deg. C in the presence of Ag wire. Graphite targets are then prepared by the reduction of the CO{sub 2} using H{sub 2} with an Fe catalyst at 600 deg. C. The resulting graphite/iron mix is measured in the ANTARES 10MV Tandem Accelerator. The determination of oxygen-18 was conducted at the University of Wollongong using the CO{sub 2} gas equilibration method, purified using a Micromass Multiprep Unit and measured on a Micromass Prism III (error; {+-} 0.1 per mille). A plot of tritium activity versus borehole location and depth, indicates that the Brogo River (Bega Valley, NSW) is not recharging the adjacent alluvium since the tritium is much lower than in the streamwater. The Bega river however is recharging the adjacent alluvium, both above and below its confluence with the Brogo river, since tritium values are similar in stream and alluvium. Isotopes such as the stable and radioactive isotopes of water and carbon are particularly appropriate for the study of these connected water systems, providing a clear method of determining the source of groundwater, and hence the extent of mixing of nearby surface water (such as the local river), and the time frame for the mixing process. In particular the stable isotopes 2-H, 18-O, and 13-C provide a robust end-member analysis for the hydrographic separation of regional groundwater and any amount of river water which was replenished at a remote location; while the radioactive isotopes 3-H and 14-C 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. © The Authors
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    Atmospheric tracer tests and assessment of a potential accident at the National Medical Cyclotron Camperdown, NSW, Australia
    (Australian Nuclear Science and Technology Organisation, 1994-08) Clark, GH; Bartsch, FJK; Muller, HH; Stone, DJM
    In order to assess the impact of a potential atmospheric release of radionuclides from the National Medical Cyclotron facility in Camperdown an atmospheric tracer release sampling and analysis system using SF6 was developed. During eight experiments conducted in a variety of meteorological conditions ten samplers were located in the vicinity of the Cyclotron building and other nearby buildings on the rapid downward movement of the tracer gas plume. The atmospheric dilution factors which lead to the highest observed air concentrations were then applied to the releases of I123and Xe123 from a potential accident scenario in order to assess the impact on nearby receptors. Even given the conservative assumptions about the release of I123 the estimated radiation doses were at least an order of magnitude below the international standards for doses to member of the public.
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    Biosynthesis and characterization of deuterated polyhydroxyoctanoate
    (American Chemical Society, 2006-04) Foster, LJR; Russell, RA; Sanguanchaipaiwong, V; Stone, DJM; Hook, JM; Holden, PJ
    The synthesis of a polyhydroxyalkanoate with medium chain length alkyl substituents by Pseudomonas oleovorans was investigated using protonated and deuterated forms of octanoic acid in a minimal salts medium. Cultivation with deuterated octanoic acid resulted in a reduced rate of polymer accumulation compared to that with its protonated counterpart (107 and 207 mg of polymer L-1 of medium h-1 of cultivation, respectively). Nuclear magnetic resonance and gas chromatography coupled mass spectrometry of the derivatized polymer was used to establish the extent and distribution of deuterium in the biopolymer. A partially deuterated heteropolymer with 3-hydroxyoctanoic acid as the main constituent was produced. Deuteration is an important tool for contrast variation studies using neutron scattering, but predicates that the deuterated polymer is otherwise comparable in its physiochemical and material properties to its protonated counterpart. In studies reported here, the deuterated biopolymer exhibited an additional diffraction maximum at 7.55 Å and slight differences in its melting point (60 and 55 °C) and glass transition temperature (−39 and −36 °C) when compared to its protonated equivalent. While significant differences between the protonated and deuterated biopolymers were determined, our results support the use of this deuterated polyhydroxyalkanoate in its application in investigations using analytical neutron scattering techniques. © 2006, American Chemical Society
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    Data volume of atmospheric tracer studies at Lucas Heights, NSW, Australia -1996 to 1997
    (Australian Nuclear Science and Technology Organisation, 2000-01) Clark, GH; Stone, DJM; Pascoe, JH
    A perfluorocarbon atmospheric tracer system has been used to investigate atmospheric dispersion processes in the region surrounding the Lucas Heights Science and Technology Centre. Tracers have been released from two locations: a laboratory vent near the ridge of the Woronora river valley and from the HIFAR research reactor ventilation system. Most studies have been conducted during the early to late morning periods when valley influences might be expected on dispersion of the tracer plume. This report summarises the meteorological and tracer air concentration data and makes comparisons with estimates from a simple gaussian dispersion model. It is intended that the data will also be used for evaluation of more elaborate wind field and atmospheric models.
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    Deuterium and oxygen-18 ratios in rainfall and streamflow in a major drinking water catchment near Sydney, Australia, during drought
    (International Atomic Energy Agency, 2007-05-21) Hughes, CE; Fischer, MJ; Stone, DJM; Hollins, SE
    The Warragamba catchment near Sydney, Australia, is in the midst of a major drought that is threatening water supplies for Australia's largest city. Over a period of 18 months 227 event based rainfall samples were collected at four locations, 74 streamflow samples were collected from the four major inflowing rivers and their tributaries and and 45 reservoir samples were collected at various depths from Warragamba dam. The samples were analysed for δD and δ18O. These data provide a baseline dataset for establishment of a local meteoric water line for the Sydney region and for use in modelling of flow pathways and weather patterns in the Warragamba catchment.
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    Deuterium and oxygen-18 ratios in rainfall and streamflow in a major drinking water catchment near Sydney, Australia, during drought
    (International Atomic Energy Agency, 2007) Hughes, CE; Fischer, MJ; Stone, DJM; Hollins, SE
    The Warragamba catchment near Sydney, Australia, is in the midst of a major drought that is threatening water supplies for Australia's largest city. Over a period of 18 months 227 event based rainfall samples were collected at four locations, 74 streamflow samples were collected from the four major inflowing rivers and their tributaries and and 45 reservoir samples were collected at various depths from Warragamba dam. The samples were analysed for δD and δ18O. These data provide a baseline dataset for establishment of a local meteoric water line for the Sydney region and for use in modelling of flow pathways and weather patterns in the Warragamba catchment.
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    Evaporative isotope enrichment as a constraint on reach water balance along a dryland river
    (Taylor & Francis, 2008-03) Gibson, JJ; Sadek, MA; Stone, DJM; Hughes, CE; Hankin, SI; Cendón, DI; Hollins, SE
    Deuterium and oxygen-18 enrichment in river water during its transit across dryland region is found to occur systematically along evaporation lines with slopes of close to 4 in H-2-O-18 space, largely consistent with trends predicted by the Craig-Gordon model for an open-water dominated evaporating system. This, in combination with reach balance assessments and derived runoff ratios, strongly suggests that the enrichment signal and its variability in the Barwon-Darling river, Southeastern Australia is acquired during the process of evaporation from the river channel itself, as enhanced by the presence of abundant weirs, dams and other storages, rather than reflecting inherited enrichment signals from soil water evaporation in the watershed. Using a steady-state isotope mass balance analysis based on monthly O-18 and H-2, we use the isotopic evolution of river water to re-construct a perspective of net exchange between the river and its contributing area along eight reaches of the river during a drought period from July 2002 to December 2003, including the duration of a minor flow event. The resulting scenario, which uses a combination of climatological averages and available real-time meteorological data, should be viewed as a preliminary test of the application rather than as a definitive inventory of reach water balance. As expected for a flood-driven dryland system, considerable temporal variability in exchange is predicted. While requiring additional real-time isotopic data for operational use, the method demonstrates potential as a non-invasive tool for detecting and quantifying water diversions, one that can be easily incorporated within existing water quality monitoring activities. © 2008, Taylor & Francis Ltd.
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    Groundwater/surface water exchange and its influence on stable water isotopic signatures along the Darling River, NSW, Australia
    (International Association of Hydrogeologists, 2007-09-17) Meredith, KT; Hollins, SE; Hughes, CE; Cendón, DI; Stone, DJM
    Stable water isotopes (SWIs) have been analysed in surface waters collected from the Darling River over the past five years (2002 to 2007). Run-of-River sampling results were compared with temporal SWI data from three gauging stations located along the river. Darling River surface water samples are generally enriched in heavy isotopes due to evaporation. Partitioning of distinctly labelled isotopic waters such as enriched surface waters and depleted groundwaters allowed for the identification of groundwater/surface water exchange. Preliminary results showed that large flood events recharge the shallow aquifer with fresh-enriched waters and during low flow conditions, saline-depleted groundwaters rebound towards the river. Consequently, during drought periods saline groundwaters discharge into the river system. The flux of saline groundwaters into the surface water system was found to not only increase the salinity of scarce fresh water supplies but also create the desired environmental conditions for cyanobacteria blooms in the Darling River.
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    In vivo deuteration of a native bacterial biopolymer for structural elucidation using SANS
    (Elsevier, 2004-07-15) Holden, PJ; Russell, RA; Stone, DJM; Garvey, CJ; Foster, LJR
    In order to facilitate future structural studies, biodeuteration of bacterial polyhydroxyalkanoates (PHAs) was investigated. We report here the in vivo deuteration of poly 3-hydroxyoctanoate (PHO) produced by its native host, the bacterium Pseudomonas oleovorans. Bacterial biomass was produced in bioreactor studies by growth on hydrogenated substrates and PHO was subsequently produced intracellularly (10–20% w/w) during batch fed growth on deuterated octanoic acid under oxygen limitation. GC-MS analyses of the PHO demonstrated that 13 of the 15 hydrogen atoms had been replaced with deuterium (except in position 3), the remaining two hydrogen presumably being derived from water. A SANS contrast variation study was conducted on whole cells and the results indicate the potential to discriminate inclusion bodies formed from deuterated precursor from an otherwise hydrogenated background. © 2004, Elsevier Ltd.
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    The influence of groundwater/surface water exchange on stable isotopic signatures along the Darling River, NSW, Australia
    (CRC Press, 2013-01-01) Meredith, KT; Hollins, SE; Hughes, CE; Cendón, DI; Stone, DJM
    Stable water isotopes (SWIs) have been analysed in surface waters collected from the Barwon-Darling River over the past five years (2002 to 2007). Run-of-River sampling results were compared with temporal SWI data from three gauging stations located along the river. Darling River surface water samples are generally enriched in heavy isotopes due to evaporation. Partitioning of distinctly labelled isotopic waters such as enriched surface waters and depleted groundwaters allowed for the identification of groundwater/surface water exchange. Preliminary results showed that large flood events recharge the shallow aquifer with fresh-enriched waters and during low flow conditions, saline-deleted groundwaters rebound towards the river. Consequently, during drought periods saline groundwaters discharge into the river system. The flux of saline groundwaters into the surface water system was found to not only increase the salinity of scarce fresh water supplies but also create the desired environmental conditions for cyanobacteria blooms in the Darling River.
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    Isotopes in Australian environmental analysis
    (International Atomic Energy Agency, 2004-10-24) Henderson-Sellers, A; Stone, DJM; Hollins, SE; Hotchkis, MAC; Fink, D
    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.
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    Methods for conduct of atmospheric tracer studies at ANSTO.
    (Australian Nuclear Science and Technology Organisation, 2000-01) Clark, GH; Stone, DJM; Pascoe, JH
    A perfluorocarbon atmospheric tracer system has been developed to investigate atmospheric dispersion processes in the region surrounding the Lucas Heights Science and Technology Centre. This report discusses the tracer release sampling and analysis methods.
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    Moisture isotopes in the biosphere and atmosphere (MIBA) in Australia: a priori estimates and preliminary observations of stable water isotopes in soil, plant and vapour for the Tumbarumba field campaign
    (Elsevier, 2006-05) Twining, JR; Stone, DJM; Tadros, CV; Henderson-Sellers, A; Williams, AG
    An integral part of isotopes in the Program for Intercomparison of Land-surface Parameterisation Schemes (iPILPS) [Henderson-Sellers, A., in press. Improving land-surface parameterization schemes using stable water isotopes; introducing the iPILPS initiative. Global and Planetary Change, in press] is that the models' outputs be evaluated against measured values of δ2H and δ18O in the various simulated environmental compartments. This paper outlines the steps taken in Australia to initiate measurement of these stable water isotopes (SWIs) in the field, at a cool-temperate forest site in S.E. Australia near Tumbarumba, specifically to facilitate the model evaluation process. The selected sampling methodologies are detailed within the context of a conceptual model developed to describe the land-atmosphere exchange systems. This model has also been used to make a priori estimations of the isotopic values to be expected in each measured sub-system. As the data resulting from the Tumbarumba field campaign emerge, they will be compared with these working hypotheses to evaluate and, where necessary, amend the conceptual model. Initial comparisons based on preliminary data are presented here. The new observations derived in March 2005 should allow the land surface schemes used in weather forecast and climate change models to better reflect the environments for which they are attempting to make predictions. © 2006 Elsevier B.V.
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    Nuclear geophysiology: isotopes in Australian environmental analysis
    (International Atomic Energy Agency, 2004-10-28) Henderson-Sellers, A; Stone, DJM; Hollins, SE; Hotchkis, MAC; Fink, D
    Lovelock [1] introduced the term ‘geophysiology’ to describe the holistic study of the Earth systems. By analogy with medicine, and the corresponding field of nuclear medicine, ‘nuclear geophysiology’ describes the application of nuclear techniques to Earth system science. Injections of radioisotopes into the Earth's systems occur naturally and continuously, while artificial radionuclides have been injected at times as a result of human activities. Here, we provide some examples of Australian investigations into the physiology of the Earth derived from the study of these isotopes.
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    A radioisotope tracer study of estuarine goundwater movement of the Eastern Australian coast
    (International Atomic Energy Agency, 2003-05-19) Hughes, CE; Stone, DJM; Acworth, RI
    Groundwater discharge to coastal waters, and the associated transport of nutrients and contaminants, is believed to have a significant impact on coastal ecosystems. However, complex boundary conditions and rapidly changing short-term fluxes make net flows resulting from local or regional groundwater discharge difficult to quantify. Such boundary conditions include beach face wave runup and storm setup, sub-surface tidal forcing, frequent surface inundation and tidally driven surface/groundwater interactions in estuarine and coastal areas. Tracer techniques can complement hydrological and geochemical studies of such systems and help distinguish longer-term net fluxes from the highly variable short-term fluxes. At Hat Head, NSW, on the eastern Australian coast, a comprehensive study of hydrogeology and hydrogeochemistry has being conducted in an estuarine/coastal sand dune aquifer. A scheme currently under construction will dispose of treated sewage effluent from the small coastal community by injection into the sand dune aquifer. Geochemical and isotopic data from the site indicate a high degree of complexity showing evidence of regional groundwater flow occurring at depth and more localised and highly dynamic conditions in the top 10 m of the aquifer. Tritium data indicate that regional groundwater is modern and stable isotope ratios have been used to distinguish between salt flat and sand dune dominated systems where evaporative and seawater mixing processes are observed. Storm wave setup and beach wave runup have been shown to elevate the water table near the coast leading to flow reversal and potential discharge of effluent to the estuarine zone. A radioisotope tracer study of groundwater flow in response to tidal forcing was conducted adjacent to a tidal creek at Hat Head. Using the short-lived radioisotope conservative tracer, bromine-82, groundwater movement was tracked in-situ over a period of ∼5 days on two occasions encompassing both neap and spring tide conditions. The tracer was injected into a screened borehole and gross gamma counts monitored from an adjacent borehole using a variety of collimated NaI detectors as well as down-hole gamma spectrometry. This technique maps the path of the slow moving tracer without sampling and allows the net groundwater movement to be distinguished from short term tidally driven fluxes. Results from the environmental isotope and radiotracer studies will be presented. © The authors.
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    Stable isotope tracing of water exchange along a dryland river
    (Goldschmidt, 2006-08-27) Gibson, JJ; Sadek, MA; Stone, DJM; Hughes, CE; Hankin, SI; Cendón, DI; Hollins, SE
    Deuterium and oxygen-18 enrichment in river water during its transit along the Barwon-Darling River, a dryland region in southeastern Australia, is found to occur systematically along evaporation lines with slopes of close to 4 in 2H–18O space. This is largely consistent with expected trends for an open-water dominated evaporating system. When combined with reach balance assessments and derived runoff ratios, this strongly suggests that the enrichment signal and its variability is acquired during the process of evaporation from the river channel itself, as enhanced by the presence of abundant weirs, dams and other storages, rather than reflecting inherited enrichment signals from soil water evaporation in the watershed. Using a steady-state isotope mass balance analysis based on monthly 18O and 2H, we use the isotopic evolution of river water to re-construct a picture of net exchange between the river and its contributing area along eight reaches of the river from July 2002 to December 2003, including the duration of a minor flood event. As expected for a flood-driven dryland system, considerable temporal variability in exchange is predicted. For 65% of all reach-months evaluated the river was apparently gaining water along its course; about 10% of these times it was also undergoing substantial volumetric drawdown. Overall, a broad systematic decline in the percentage of gaining intervals is noted from the upstream to downstream reaches, with most reaches gaining water substantially more than half of the time. One reach, known to be an intensive cotton-growing area, was found to be fairly balanced between gaining and losing periods. While a more detailed analysis is required to carefully verify the quantities of water exchange, a first assessment of monthly runoff ratios for the reach catchments suggests that the inflow estimates are reasonable. The technique, while requiring additional quantitative ground-truthing, demonstrates potential as a non-invasive tool for detecting and quantifying water diversions, one that can be easily incorporated within existing water quality monitoring activities. © 2006 Published by Elsevier Ltd.
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    Stable isotope tracing of water exchange along a dryland river
    (Goldschmidt, 2006-08-27) Gibson, JJ; Sadek, MA; Stone, DJM; Hughes, CE; Hankin, SI; Cendón, DI; Hollins, SE
    Deuterium and oxygen-18 enrichment in river water during its transit along the Barwon-Darling River, a dryland region in southeastern Australia, is found to occur systematically along evaporation lines with slopes of close to 4 in 2H-18O space. This is largely consistent with expected trends for an open-water dominated evaporating system. When combined with reach balance assessments and derived runoff ratios, this strongly suggests that the enrichment signal and its variability is acquired during the process of evaporation from the river channel itself, as enhanced by the presence of abundant weirs, dams and other storages, rather than reflecting inherited enrichment signals from soil water evaporation in the watershed. Using a steady-state isotope mass balance analysis based on monthly 18O and 2H, we use the isotopic evolution of river water to re-construct a picture of net exchange between the river and its contributing area along eight reaches of the river from July 2002 to December 2003, including the duration of a minor flood event. As expected for a flood-driven dryland system, considerable temporal variability in exchange is predicted. For 65% of all reach-months evaluated the river was apparently gaining water along its course; about 10% of these times it was also undergoing substantial volumetric drawdown. Overall, a broad systematic decline in the percentage of gaining intervals is noted from the upstream to downstream reaches, with most reaches gaining water substantially more than half of the time. One reach, known to be an intensive cotton-growing area, was found to be fairly balanced between gaining and losing periods. While a more detailed analysis is required to carefully verify the quantities of water exchange, a first assessment of monthly runoff ratios for the reach catchments suggests that the inflow estimates are reasonable. The technique, while requiring additional quantitative ground-truthing, demonstrates potential as a non-invasive tool for detecting and quantifying water diversions, one that can be easily incorporated within existing water quality monitoring activities.
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    Stable water isotope investigation of the Barwon–Darling River system, Australia
    (International Atomic Energy Agency, 2012) Hughes, CE; Stone, DJM; Gibson, JJ; Meredith, KT; Sadek, MA; Cendón, DI; Hankin, SI; Hollins, SE; Morrison, TN
    The Murray-Darling Basin is the largest river basin in Australia and is host to agriculture, recreation, water supply reservoirs and significant biodiversity. Through land use practices and climate change there is the potential for significant disruption to the natural hydrological system of the basin. The Barwon-Darling River, in the upper part of the Murray Darling Basin, is primarily in a semi-arid landscape which is subject to significant evaporation, yet evaporative losses from the river remain poorly described. The stable isotope composition of groundwaters has become widely used over the past several decades as an indicator of the circumstances and geographical locations of aquifer recharge, though applications to surface water budgets have been far less extensive. A global isotopic observation initiative, the Global Network for Isotopes in Rivers (GNIR), focussed in Australia on the dryland Barwon-Darling River system. We report on drought driven isotopic signatures in the Barwon-Darling River during 2002-2007 and estimate that the amount of water lost by the Barwon-Darling River system due to evaporation may be up to 80% during severe drought periods. Runoff ratios have been commonly estimated to be between 0.1 and 1% and there is evidence of groundwater exchange with the river. This work highlights the role of stable water isotopes in assessing the amount of water lost from the river by direct evaporation, and in quantifying groundwater inputs and ungauged losses from the river. © The Authors
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    Stable water isotopes as tools for basin-scale water cycle: diagnosis of the Murray–Darling
    (Elsevier Ltd, 2006) Henderson-Sellers, A; Airey, PL; McGuffie, K; Stone, DJM
    We examine the hypothesis that isotopic techniques are applicable to hydrological predictions in difficult-to-simulate semi-arid basins, using the Murray–Darling Basin as an example. Isotopic data from three aquifers in the Murray–Darling characterize precipitation intensity for evaluation of GCMs. Applying these to ‘good’ (water conserving) and ‘poor’ (non-water-conserving) climate model simulations of the Murray–Darling gives rise to large differences in rainfall amount (30–62%). Selecting only ‘good’ models shows a greater than 150 mm annual groundwater recharge loss in El Niño cf. La Niña climates. 2002–2003 El Niño drought data are used to refine isotopic calculation of water lost in evaporation from rivers and irrigation, giving a cumulative loss of 64% of river water during 2002 (cf. 80% using a previous method). This substantiates recent identification of this El Niño drought as evaporatively most extreme and we conclude that stable water isotopes, used synergistically with hydro-climate models, have great potential in future water resource predictions. © 2006 Elsevier B.V.