Browsing by Author "Gibson, JJ"
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- ItemA comparison between direct and pan-derived measurements of the isotopic composition of atmospheric waters(The Modelling and Simulation Society of Australia and New Zealand Inc., 2011-12-12) Azcurra, CS; Hughes, CE; Parkes, SD; Hollins, SE; Gibson, JJ; McCabe, MF; Evans, JPThe stable isotopes of water can be used to examine and quantify the contribution to atmospheric moisture from evaporation, transpiration and surface-waters. However, obtaining extensive and ongoing time series data of the isotopic composition of atmospheric moisture has been difficult. Presented here is an alternate method using an isotope mass balance approach to estimate the isotopic composition of atmospheric moisture using water samples collected from class A evaporation pans. While this evaporation pan method does not provide the high-resolution time series data that can be obtained from an isotope analyser taking in-situ measurements of atmospheric moisture, the method is relatively simple and inexpensive to set-up and maintain. In this preliminary investigation, a comparison between the isotopic composition of atmospheric moisture estimated from the evaporation pan method and in-situ measurements of the isotopic composition of water vapour using a Fourier Transform Infrared (FTIR) spectrometer deployed at the Lucas Heights weather station in New South Wales is undertaken. Through comparison of the two series of hydrogen isotope data, an assessment of the evaporation pan method can be made. Although there was some agreement between the isotopic composition of vapour measured by the FTIR spectrometer and the estimation for the atmospheric moisture (R2 = 0.49), the comparison is sensitive to climatic parameters that vary significantly within a 24-hour period such as the relative humidity of air and the air and pan temperatures. Inverting the model to use the FTIR spectrometer measurements at an hourly resolution improved the performance of the model (R2 =0.57). However, this also revealed that the model produced more depleted values of the evaporation pan water isotopes than those observed. In contrast, there was a variable relationship between the modelled and observed isotope values of atmospheric moisture. These conflicting results will need to be resolved before the evaporation pan method is broadly applied in isotope hydrology. © 2011 The Modelling and Simulation Society of Australia and New Zealand Inc.
- ItemComparison of atmospheric water vapour δ18O and δ2H estimated using evaporation pan, rainfall equilibrium and continuous measurements(Elsevier B. V., 2019-09) Crawford, J; Azcurra, CS; Hughes, CE; Gibson, JJ; Parkes, SDFor a period of 16 months in Sydney, Australia, the variations of 2H/1H and 18O/16O in atmospheric vapour (δ2HA and δ18OA) were estimated using an evaporation pan method as well as using the isotopic precipitation-equilibrium approach. These calculations were then compared with δ2HA values measured at 10 m above ground surface using a Fourier Transform Infrared Spectrometer (FTIR). As pan isotopic composition was available on a weekly time scale, the evaporation rates were measured daily, and the atmospheric variables were available hourly, the weekly time scale was used to calculate the arithmetic averages of the atmospheric variables that were used in the estimation of the pan-derived δ2HA. Good agreement (r = 0.7, P-value = 0.00) was found between the pan-derived and the FTIR measured δ2HA for weekly intervals, although individual differences ranged from −25.0 to 20.4‰, with the absolute difference averaging 8.0‰. A sensitivity analysis showed that the determination of δ2HA is most sensitive to air temperature, relative humidity and the isotopic composition of the pan water. While the precipitation-equilibrium approach only appears to be representative of atmospheric conditions close to times of precipitation events, the pan-derived isotopic composition of atmospheric vapour was found to be closer to the FTIR averages over longer periods including intervals with no precipitation. Overall, this means that the pan method is far more effective for uninterrupted estimation of δ2HA and δ18OA of atmospheric water vapour, as required for water budget studies, than the precipitation-equilibrium method, and it is more cost effective and robust than continuous measurement. Crown Copyright © 2019 Published by Elsevier B.V.
- ItemDaily observations of rainfall, vapour and pan water δ2H for improved quantification of atmospheric and terrestrial water interactions(American Geophysical Union, 2012-12-03) Hughes, CE; Azcurra, CS; Parkes, SD; Hollins, SE; McCabe, MF; Evans, JP; Pickering, D; Gibson, JJ; Edwards, KThe stable isotopes of water (δ2H, δ18O) have been used extensively to track the movement of water through the hydrological cycle. As water moves through the hydrological cycle, its isotopic composition changes (fractionation) as a result of phase changes and interactions with other waters. When combined with other measurements of water fluxes and volumes, the stable isotopes can provide information about sources, processing, and transport of water suitable for determining water and energy balances. While the isotopic composition of atmospheric moisture influences the isotopic composition of terrestrial waters, obtaining ongoing time series data of this has been difficult. One method for estimating the isotopic composition of atmospheric moisture combines the Craig-Gordon isotopic evaporation model with a mass balance approach, using water samples collected from Class A evaporation pans at weekly intervals. The method assumes steady-state conditions and thus does not represent the highly variable meteorological conditions that can strongly influence fractionation. Although water-sampling regimes cannot match the frequency of the observed variability in meteorological conditions, increasing the sampling resolution to a sub-weekly resolution will more closely align isotopic measurements with meteorological conditions and allow the assessment of established water isotope relationships at a greater temporal frequency. An alternate method for estimating the isotopic composition of atmospheric moisture is based on local precipitation being in equilibrium with atmospheric moisture. As per the evaporation pan method, it is assumed that steady-state conditions apply. At the Lucas Heights weather station in south-eastern Australia, atmospheric moisture water isotopes (δA) have been directly measured at sub-hourly intervals using a Fourier Transform Infrared (FTIR) spectrometer. This hydrogen isotope time series was evaluated against daily observations of isotopes in water from a Class A evaporation pan (δL) and in precipitation (δP) collected from the same site. This study assesses the validity of established (steady-state) relationships between liquid and vapor water isotopes for interactions that have been measured at the medium-resolution temporal scale, and provides a basis for improving flux estimates based on an isotope mass balance approach. ©Author(s) 2012
- ItemEvaporative 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, SEDeuterium 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.
- ItemIsotopic and geochemical tracer investigations, southern Athabasca in-situ oil sand region, Northeastern Alberta: 2007 baseline surveys(ConocoPhillips Canada Inc, 2008) Gibson, JJ; Birks, SJ; Tattrie, KR; Lacroix, MP; Cendón, DI; Szabova, M; Richardson, K; Harder, SNot available
- ItemIsotopic tracing of surface/groundwater interactions, groundwater age and salinity in the southern Athabasca in-situ oil sands region: final report on baseline surveys(ConocoPhillips Canada Inc and Nexen Inc, 2010) Gibson, JJ; Birks, SJ; Yi, Y; Moncur, M; Tattrie, KR; Jasechko, S; Richardson, K; Szabova, M; Cendón, DI; Marandi, ANot available
- ItemStable 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, SEDeuterium 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.
- ItemStable 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, SEDeuterium 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.
- ItemStable 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, TNThe 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
- ItemUse of stable isotopes in Sydney catchment process and water quality studies(Australian Water Association and Waste Management Association of Australia, 2006-07-30) Hughes, CE; Mazumder, D; Gibson, JJ; Szymczak, R; Cendón, DI; Hollins, SE; Waring, CLThe use of stable and radioactive isotopes as environmental tracers is becoming more widespread as isotopic analysis techniques become more accessible. ANSTO’s Isotopes for Water Project aims to increase awareness of the potential uses of isotopes in the management of catchments, rivers, reservoirs, aquifers, estuaries and biota. This paper outlines a range of potential applications using a wide range of isotopes (δ18O, δ2H, 14C, δ13C, δ15N, 3H, 7Be, 210Pb, 35S, δ34S, δ18O and Δ17O) in hydrology, hydrogeology, ecology and contaminant geochemistry with examples from the Sydney basin. The studies being undertaken by ANSTO include: • application of stable water isotopes to catchment and reservoir water balance; • age dating of groundwater to underpin sustainability assessment; • tracing the source of contaminants and nutrients such as nitrogen, organic matter and sulfate in catchments and waterways; • quantifying contaminated sediment dynamics and contaminant uptake into biota using shorted-lived radioisotopes; • tracing trophic linkages in aquatic food webs.