ORCID Profile
0000-0003-0212-9855
Current Organisations
CSIRO
,
University of Adelaide
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Publisher: Hindawi Limited
Date: 2017
DOI: 10.1155/2017/9839861
Abstract: A study of chloride and 4 He profiles through an aquitard that separates the Great Artesian Basin from the underlying Arckaringa Basin in central Australia is presented. The aquitard separates two aquifers with long water residence times, due to low recharge rates in the arid climate. One-dimensional solute transport models were used to determine the advective flux of groundwater across the aquitard as well as establish any major changes in past hydrological conditions recorded by variations of the pore water composition. This in situ study showed that both diffusion and slow downward advection ( v z = 0.7 mm/yr) control solute transport. Numerical simulations show that an increase in chloride concentration in the upper part of the profile is due to a reduction in recharge in the upper aquifer for at least 3000 years. Groundwater extraction since 2008 has likely increased chloride and 4 He concentrations in the lower aquifer by pulling up water from deeper layers however, there has been insufficient time for upward solute transport into the pore water profile by diffusion against downward advection. The transport model of 4 He and chloride provides insight into how the two aquifers interact through the aquitard and how climate change is being recorded in the aquitard profile.
Publisher: Springer Science and Business Media LLC
Date: 15-02-2022
DOI: 10.1038/S43247-022-00347-3
Abstract: Speleothem oxygen isotopic (δ 18 O) records are used to reconstruct past hydroclimate yet records from the same cave do not always replicate. We use a global database of speleothem δ 18 O to quantify the replicability of records to show that disagreement is common worldwide, occurs across timescales and is unrelated to climate, depth or lithology. Our global analysis demonstrates that within-cave differences in mean speleothem δ 18 O values are consistent with those of dripwater, supporting a ubiquitous influence of flowpaths. We present a case study of four new stalagmite records from Golgotha Cave, southwest Australia, where the isotopic differences between them are informed by cave monitoring. It is demonstrated that karst hydrology is a major driver of within-cave speleothem and dripwater δ 18 O variability, primarily due to the influence of fractures on flowpaths. Applying our understanding of water movement through fractures assists in quantitative reconstruction of past climate variability from speleothem δ 18 O records.
Publisher: Elsevier BV
Date: 10-2016
DOI: 10.1016/J.SCITOTENV.2016.05.147
Abstract: A decrease in flow from the iconic travertine mound springs of the Great Artesian Basin in South Australia has led to the oxidation of hypersulfidic soils and extreme soil acidification, impacting their unique groundwater dependent ecosystems. The build-up of pyrite in these systems occurred over millennia by the discharge of deep artesian sulfate-containing groundwaters through organic-rich subaqueous soils. Rare iron and aluminium hydroxysulfate minerals form thick efflorescences due to high evaporation rates in this arid zone environment, and the oxidised soils pose a significant risk to local aquatic and terrestrial ecosystems. The distribution of extreme acidification hazard is controlled by regional variations in the hydrochemistry of groundwater. Geochemical processes fractionate acidity and alkalinity into separate parts of the discharge zone allowing potentially extreme environments to form locally. Differences in groundwater chemistry in the aquifer along flow pathways towards the spring discharge zone are related to a range of processes including mineral dissolution and redox reactions, which in turn are strongly influenced by degassing of the mantle along deep crustal fractures. There is thus a connection between shallow critical zone ecosystems and deep crustal/mantle processes which ultimately control the formation of hypersulfidic soils and the potential for extreme geochemical environments.
Publisher: Springer Science and Business Media LLC
Date: 09-06-2023
DOI: 10.1038/S43247-023-00858-7
Abstract: Billions of people worldwide rely on groundwater. As rainfall in many regions in the future is projected to decrease, it is critical to understand the impacts of climate change on groundwater recharge. The groundwater recharge response to a sustained decrease in rainfall across southwest Australia that began in the late 1960s was examined in seven modern speleothems and drip waters from four caves. These show a pronounced increase or uptick in regional drip water and speleothem oxygen isotopic composition (δ 18 O) that is not driven by a change in rainfall δ 18 O values, but is in response to the shallow karst aquifers becoming disconnected from rainfall recharge due to regional drying. Our findings imply that rainfall recharge to groundwater may no longer be reliably occurring in this region, which is highly dependent on groundwater resources. Examination of the longer speleothem record shows that this situation is unprecedented over the last 800 years.
Publisher: American Geophysical Union (AGU)
Date: 11-2020
DOI: 10.1029/2020WR027879
Publisher: Frontiers Media SA
Date: 14-02-2022
DOI: 10.3389/FEART.2021.727971
Abstract: The Coorong Lagoon is a unique hydrological and depositional system at the terminus of the Murray–Darling Basin, the largest river system in Australia. It exhibits large salinity, nutrient, and organic matter gradients, providing a modern analogue to study and validate the use of δ 15 N and δ 13 C as tracers of past and contemporary geochemical cycles in estuarine environments. To this end, water and surface sediment s les were analyzed for particulate organic nitrogen (PON) and carbon (POC) concentrations, and the respective δ 15 N and δ 13 C signatures of particulate nitrogen and carbon. PON and POC exhibited positive relationships to chlorophyll-a, indicating the dominance of phytoplankton production upon suspended organic matter. There was also a general trend of increasing δ 15 N of PON (δ 15 N PON ) values and decreasing δ 13 C of particulate carbon (δ 13 C PC ) values with increasing salinity and eutrophication in the restricted South Lagoon. In a multiple linear regression for δ 15 N PON , the best two predictors in combination are PON and C:N molar ratio, highlighting the importance of productivity and the type or source of organic matter. For δ 13 C PC , the best two predictors are total dissolved phosphorus and latitude, suggesting influences from productivity and proximity to the ocean. Sediment δ 15 N values across the Coorong Lagoon overlap with the δ 15 N PON in the water column, suggesting that PON derived from algal material represents the main source of nitrogen to lagoon sediments. We hypothesize that limited N loss via denitrification leads to PON being recycled almost exclusively to ammonium, due to low rates of nitrification and dominance of dissimilatory nitrate reduction to ammonium (DNRA). We propose that preferential volatilization of 14 N in ammonia increases the δ 15 N of ammonium assimilated by phytoplankton, thereby increasing the δ 15 N within suspended organic matter and surface sediment in the South Lagoon. By contrast, the gradient exhibited in δ 13 C PC data was countered by a relatively constant sedimentary organic carbon δ 13 C. Data from the Coorong, therefore, suggest that δ 15 N values in sediments can be used to infer palaeoproductivity in this hypereutrophic and hypersaline depositional environment, however, the measured δ 13 C PC may be influenced by δ 13 C DIC or preferential loss of 13 C during sedimentation that alter the sedimentary δ 13 C record of organic carbon.
Publisher: Hindawi Limited
Date: 10-09-2018
DOI: 10.1155/2018/8325016
Publisher: Elsevier BV
Date: 03-2023
Publisher: Springer Science and Business Media LLC
Date: 06-11-2019
Publisher: Research Square Platform LLC
Date: 02-05-2022
DOI: 10.21203/RS.3.RS-1556439/V1
Abstract: Billions of people worldwide rely on groundwater. As rainfall in many regions in the future is projected to decrease, it is critical to understand the impacts of climate change on groundwater recharge. In this study, five caves record a consistent response to a sustained decrease in rainfall across southwest Australia that began in the late 1960s, characterised by a pronounced increase or ’uptick’ in dripwater and speleothem oxygen isotopic composition (δ18O). It is demonstrated that the uptick is in response to the shallow karst aquifers becoming disconnected from recharge due to regional drying. Our findings imply that rainfall recharge to groundwater across this region is no longer reliably occurring. Examination of the longer speleothem record shows that this is unprecedented over at least the last 800 years. A global network of cave dripwater monitoring would serve as an early warning of reduced groundwater recharge elsewhere, while evidence for upticks in speleothem paleoclimate records would provide a longer-term context to evaluate if current groundwater recharge changes are outside the range of natural variability. This study also validates speleothems as recorders of past hydroclimate via lification of the δ18O signal by karst hydrology highlighting that speleothem δ18O are records of recharge, rather than a direct proxy for rainfall.
Publisher: Elsevier BV
Date: 08-2013
Publisher: Copernicus GmbH
Date: 19-09-2023
Publisher: Elsevier BV
Date: 2018
Publisher: Elsevier BV
Date: 11-2018
Publisher: Springer Science and Business Media LLC
Date: 16-06-2017
Publisher: Elsevier BV
Date: 2020
Publisher: Springer Science and Business Media LLC
Date: 16-12-2019
Publisher: Springer Science and Business Media LLC
Date: 23-12-2019
Publisher: Elsevier BV
Date: 05-2020
DOI: 10.1016/J.SCITOTENV.2019.135105
Abstract: The isotopic composition of groundwater can be a useful indicator of recharge conditions and may be used as an archive to infer past climate variability. Groundwater from two largely confined aquifers in south-west Australia, recharged at the northernmost extent of the westerly wind belt, can help constrain the palaeoclimate record in this region. We demonstrate that radiocarbon age measurements of dissolved inorganic carbon are appropriate for dating groundwater from the Leederville aquifer and Yarragadee aquifer within the Perth Basin. Variations in groundwater δ
Location: Australia
No related grants have been discovered for Stacey Priestley.