Browsing by Author "Lowry, D"

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    Assessing connectivity between an overlying aquifer and a coal seam gas resource using methane isotopes, dissolved organic carbon and tritium
    (National Centre for Groundwater Research And Training, 2015-11-03) Iverach, CP; Cendón, DI; Hankin, SI; Lowry, D; Fisher, RE; France, JL; Nisbet, EG; Baker, AA; Kelly, BFJ
    Coal seam gas (CSG) production can have an impact on groundwater quality and quantity in adjacent or overlying aquifers. To assess this impact we need to determine the background groundwater chemistry and to map geological pathways of hydraulic connectivity between aquifers. In south-east Queensland (Qld), Australia, a globally important CSG exploration and production province, we mapped hydraulic connectivity between the Walloon Coal Measures (WCM, the target formation for gas production) and the overlying Condamine River Alluvial Aquifer (CRAA), using groundwater methane (CH4) concentration and isotopic composition (δ13C-CH4), groundwater tritium (3H) and dissolved organic carbon (DOC) concentration. A continuous mobile CH4 survey adjacent to CSG developments was used to determine the source signature of CH4 derived from the WCM. Trends in groundwater δ13C-CH4 versus CH4 concentration, in association with DOC concentration and 3H analysis, identify locations where CH4 in the groundwater of the CRAA most likely originates from the WCM. The methodology is widely applicable in unconventional gas development regions worldwide for providing an early indicator of geological pathways of hydraulic connectivity. © The Authors.
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    Assessing connectivity between an overlying aquifer and a coal seam gas resource using methane isotopes, dissolved organic carbon and tritium
    (Nature, 2015-11-04) Iverach, CP; Cendón, DI; Hankin, SI; Lowry, D; Fisher, RE; France, JL; Nisbet, EG; Baker, AA; Kelly, BFJ
    Coal seam gas (CSG) production can have an impact on groundwater quality and quantity in adjacent or overlying aquifers. To assess this impact we need to determine the background groundwater chemistry and to map geological pathways of hydraulic connectivity between aquifers. In south-east Queensland (Qld), Australia, a globally important CSG exploration and production province, we mapped hydraulic connectivity between the Walloon Coal Measures (WCM, the target formation for gas production) and the overlying Condamine River Alluvial Aquifer (CRAA), using groundwater methane (CH4) concentration and isotopic composition (δ13C-CH4), groundwater tritium (3H) and dissolved organic carbon (DOC) concentration. A continuous mobile CH4 survey adjacent to CSG developments was used to determine the source signature of CH4 derived from the WCM. Trends in groundwater δ13C-CH4 versus CH4 concentration, in association with DOC concentration and 3H analysis, identify locations where CH4 in the groundwater of the CRAA most likely originates from the WCM. The methodology is widely applicable in unconventional gas development regions worldwide for providing an early indicator of geological pathways of hydraulic connectivity. © The Authors. This work is licensed under a Creative Commons Attribution 4.0 International Licence. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons licence, users will need to obtain permission from the licence holder to reproduce the material.
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    Assessing the hydraulic connection between fresh water aquifers and unconventional gas production using methane and stable isotopes
    (European Geosciences Union, 2015-04-12) Iverach, CP; Cendón, DI; Hankin, SI; Lowry, D; Fisher, RE; France, JL; Nisbet, EG; Baker, AA; Kelly, BFJ
    Unconventional gas developments pose a risk to groundwater quality and quantity in adjacent or overlying aquifers. To manage these risks there is a need to measure the background concentration of indicator groundwater chemicals and to map pathways of hydraulic connectivity between aquifers. This study presents methane (CH4) concentration and isotopic composition, dissolved organic carbon concentration ([DOC]) and tritium (3H) activity data from an area of expanding coal seam gas (CSG) exploration and production (Condamine Catchment, south-east Queensland, Australia). The target formation for gas production within the Condamine Catchment is the Walloon Coal Measures (WCM). This is a 700 m thick, low-rank CSG resource, which consists of numerous thin discontinuous lenses of coal separated by very fine-to medium-grained sandstone, siltstone, and mudstone, with minor calcareous sandstone, impure limestone and ironstone. The thickness of the coal makes up less than 10% of the total thickness of the unit. The WCM are overlain by sandstone formations, which form part of the Great Artesian Basin (GAB). The Condamine Alluvium fills a paleo-valley carved through the above formations. A combination of groundwater and degassing air samples were collected from irrigation bores and government groundwater monitoring boreholes. Degassing air samples were collected using an SKC 222-2301 air pump, which pumped the gas into 3 L Tedlar bags. The groundwater was analysed for 3H and [DOC]. A mobile CH4 survey was undertaken to continuously sample air in and around areas of agricultural and unconventional gas production. The isotopic signature of gas from the WCM was determined by sampling gas that was off-gassing from a co-produced water holding pond as it was the largest emission that could be directly linked to the WCM. This was used to determine the source signature of the CH4 from the WCM. We used Keeling plots to identify the source signature of the gas sampled. For the borehole samples these plots assume that there are only two sources of CH4, each with a unique isotopic signature. When the two sources mix in varying proportions they will plot along a straight line in the Keeling plot. Geometric mean displacement was used to fit a regression line and determine the intercept value. Within the Keeling plot, samples clustered according to their 3H and [DOC] values. One cluster is associated with near surface biological processes, while the other cluster can be attributed to gas sourced from the WCM. This indicates that in places there is hydraulic connectivity between the WCM and the overlying Condamine Alluvium. The results from this case study demonstrate that measuring 3H activity, [DOC] and CH4 concentrations in combination with CH4 isotopic analysis can provide an early indicator of hydraulic connectivity in areas of expanding unconventional gas development. © Author(s) 2015. CC Attribution 3.0 License.
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    A data-model comparison on the glacial thinning history of Byrd Glacier, Antarctica
    (Australian Institute of Nuclear Science and Engineering, 2021-11-17) Stutz, J; Eaves, S; Moore, C; Wilcken, KM; Norton, K; Lowry, D
    Response of marine based sectors of the Antarctic Ice Sheet (AIS) to projected warming remains a significant uncertainty in sea level rise projections. The aim of this project is to provide understanding of past mechanisms and feedbacks of ice sheet change, and to reduce uncertainty in projections of future change. We extend the satellite record of ice sheet change by targeting strategic locations around the margins of the Ross Ice Shelf, which is responsible for buttressing large sectors of the marine-based West AIS. At these locations, glacial sediments deposited on nunataks adjacent to dynamic ice margins record the transient evolution of ice thickness throughout the Holocene period. Here, we focus on the Byrd Glacier, which drains 10% of the East AIS by area and contributes ~20% of the total mass of the Ross Ice Shelf. At Lonewolf Nunataks along the upper Byrd Glacier, our cosmogenic surface exposure ages constrain (i) past rates of ice thinning; (ii) total magnitudes of ice elevation change; and (iii) the absolute timing of ice discharge and thinning events in these sensitive regions. In this presentation, we will review the existing knowledge of Transantarctic Mountain outlet glaciers and present new data from our 2019-20 season along the upper Byrd Glaciers. Comparing our data to recent regional-scale ice sheet model simulations of the last deglaciation, we observe a distinct time lag between modelled thinning and our data-constrained thinning history. Our new data-model comparison will inform high-resolution, sector-scale numerical glacier model experiments, in which we seek to determine drivers of ice sheet thinning and retreat. © The Authors
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    Detecting connectivity between an overlying aquifer and a coal seam gas resource using methane isotopes, dissolved organic carbon and tritium
    (Association of Australian Cotton Scientists, 2015-09-09) Iverach, CP; Cendón, DI; Hankin, SI; Lowry, D; Fisher, RE; France, JL; Nisbet, EG; Baker, AA; Kelly, BFJ
    There is public concern that coal seam gas (CSG) production will affect groundwater quality and quantity in overlying aquifers used to support irrigation, stock and domestic water supplies. To assess this risk there is a need to map pathways of hydraulic connectivity using geochemical and isotopic measurements. We demonstrate that measurements of methane (CH4) concentration and isotopic composition, dissolved organic carbon (DOC) concentration and tritium (3H) activity data highlight potential pathways of hydraulic connectivity between the Walloon Coal Measures (WCM – the target formation for CSG production) and the Condamine Alluvium, south-east Queensland, Australia. At 19 locations, both groundwater and degassing air samples were collected from irrigation bores. Degassing air samples were pumped into 3 L Tedlar bags. This air was analysed for both its methane concentration and isotopic signature. The groundwater was analysed for 3H and [DOC]. To determine the isotopic signature of the WCM, CH4 ambient air samples were collected adjacent to CSG coproduced water holding ponds. We use isotope mixing plots to identify the isotopic source signature of CH4 in the air samples from the degassing irrigation bores and those adjacent to CSG water holding ponds. Within the mixing plots samples graph along clear trend lines, which allows gas sources to be assigned. These trends in the mixing plots indicate potential local hydraulic connectivity between the WCM and the overlying Condamine Alluvium.
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    Detecting hydraulic connection between fresh water aquifers and coal seam gas production using the isotopes of carbon in methane
    (University of New South Wales and Australian Nuclear Science and Technology Organisation, 2015-07-10) Iverach, CP; Cendón, DI; Hankin, SI; Lowry, D; Fisher, RE; France, JL; Nisbet, EG; Baker, AA; Kelly, BFJ
    Not provided to ANSTO Library.
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    Evaluation of the boundary layer dynamics of the TM5 model over Europe
    (Copernicus Publications, 2016-09-14) Koffi, EN; Bergamaschi, P; Karstens, U; Krol, M; Segers, A; Schmidt, M; Levin, I; Vermeulen, AT; Fisher, RE; Kazan, V; Klein Baltink, H; Lowry, D; Manca, G; Meijer, HAJ; Moncrieff, J; Pal, S; Ramonet, M; Scheeren, HA; Williams, AG
    We evaluate the capability of the global atmospheric transport model TM5 to simulate the boundary layer dynamics and associated variability of trace gases close to the surface, using radon (222Rn). Focusing on the European scale, we compare the boundary layer height (BLH) in the TM5 model with observations from the National Oceanic and Atmospheric Admnistration (NOAA) Integrated Global Radiosonde Archive (IGRA) and also with ceilometer and lidar (light detection and ranging) BLH retrievals at two stations. Furthermore, we compare TM5 simulations of 222Rn activity concentrations, using a novel, process-based 222Rn flux map over Europe (Karstens et al., 2015), with harmonised 222Rn measurements at 10 stations. The TM5 model reproduces relatively well the daytime BLH (within 10–20 % for most of the stations), except for coastal sites, for which differences are usually larger due to model representation errors. During night, however, TM5 overestimates the shallow nocturnal BLHs, especially for the very low observed BLHs (< 100 m) during summer. The 222Rn activity concentration simulations based on the new 222Rn flux map show significant improvements especially regarding the average seasonal variability, compared to simulations using constant 222Rn fluxes. Nevertheless, the (relative) differences between simulated and observed daytime minimum 222Rn activity concentrations are larger for several stations (on the order of 50 %) than the (relative) differences between simulated and observed BLH at noon. Although the nocturnal BLH is often higher in the model than observed, simulated 222Rn nighttime maxima are actually larger at several continental stations. This counterintuitive behaviour points to potential deficiencies of TM5 to correctly simulate the vertical gradients within the nocturnal boundary layer, limitations of the 222Rn flux map, or issues related to the definition of the nocturnal BLH. At several stations the simulated decrease of 222Rn activity concentrations in the morning is faster than observed. In addition, simulated vertical 222Rn activity concentration gradients at Cabauw decrease faster than observations during the morning transition period, and are in general lower than observed gradients during daytime. Although these effects may be partially due to the slow response time of the radon detectors, they clearly point to too fast vertical mixing in the TM5 boundary layer during daytime. Furthermore, the capability of the TM5 model to simulate the diurnal BLH cycle is limited by the current coarse temporal resolution (3 h/6 h) of the TM5 input meteorology. © Author(s) 2016.