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Browsing by Author "Tadros, CV"

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Authenticating genuine Kakadu plum (Terminalia ferdinandiana) powders from fakes using stable isotope analysis and elemental profiling
(Elsevier, 2024-08) Keaney, M; Mazumder, D; Tadros, CV; Crawford, J; Gadd, PS; Saeki, P; Sammut, J; Saintilan, N
Kakadu plum (Terminalia ferdinandiana) is a plant species endemic to northern Australia, attracting increasing consumer interest due to its multiple nutritional qualities. As a consumer product at a premium price point, the Kakadu plum may be susceptible to food fraud. This paper determines the prevalence of food fraud in the e-commerce Kakadu plum market. We applied stable isotope analysis (SIA) and elemental profiling using X-ray fluorescence (XRF) through Itrax to evaluate the authenticity of 13 commercially available Kakadu plum powdered samples purchased from Australian and overseas suppliers against four powdered samples directly provided by First Nations harvesters. Overseas and Australian-sourced powders were found to have distinct isotopic and elemental profiles. All overseas powders showed highly enriched δ13C values indicating they are fakes, not derived from Kakadu plum. Non-metric multi-dimensional scaling (nMDS) of elements also displayed distinct groupings between Australian-sourced and overseas powders, whilst analysis of similarity percentages (SIMPER) differentiated the elemental composition between groups. It was also observed that 89% of overseas products sold as Kakadu plum were deceptively labelled as other products. These results showed food fraud occurred along the supply chain of overseas-sourced product. Given the complexities of multi-national food systems, utilising a combination of stable isotopes and elemental profiling are straightforward applications for detecting fraudulent products. © 2024 Crown Copyright Published by Elsevier Ltd.
Cave drip water solutes in south-eastern Australia: constraining sources, sinks and processes
(Elsevier, 2019-02-15) Tadros, CV; Treble, PC; Baker, AA; Hankin, SI; Roach, R
Constraining sources and site-specific processes of trace elements in speleothem geochemical records is key to an informed interpretation. This paper examines a 10-year data set of drip water solutes from Harrie Wood Cave, south-eastern Australia, and identifies the processes that control their response to El Niño-Southern Oscillation events which varies the site water balance. The contributions of aerosol and bedrock end-members are quantified via hydrochemical mass balance modelling. The parent bedrock is the main source for the drip water solutes: Mg, Sr, K and trace elements (Ba, Al, V, Cr, Mn, Ni, Co, Cu, Pb and U), while atmospheric aerosol inputs also contribute significantly to drip water trace elements and Na, K and Zn. A laboratory investigation evaluating water-soluble fractions of metals in soil samples and soil enrichment factors provided a basis for understanding metal retainment and release to solution and transport from the soil zone. These results identified the role of the soil as a sink for: trace metals, Na and K, and a secondary source for Zn. Further, soil processes including: cation exchange, K-fixation, metal adsorption to colloids and the release of Zn associated with organic matter degradation further modify the chemical composition of the resultant drip waters. This research is significant for the south-eastern Australian region, as well as other sites in a karst setting with clay-rich soil. In particular these results reveal that the response of drip water chemistry to hydroclimatic forcing is non-linear, with the greatest response observed when the long-term gradient in the cumulative water balance reverses. This longer-term drip water monitoring dataset is significant because it provides the pivotal framework required to reliably identify suitable trace element proxies for interpretation in geochemical speleothem records on multi-decadal timescales. © 2018 Crown Copyright © 2018 Published by Elsevier B.V.
Chemical characterisation and source identification of atmospheric aerosols in the Snowy Mountains, south-eastern Australia
(Elsevier, 2018-07-15) Tadros, CV; Crawford, J; Treble, PC; Baker, AA; Cohen, DD; Atanacio, AJ; Hankin, SI; Roach, R
Characterisation of atmospheric aerosols is of major importance for: climate, the hydrological cycle, human health and policymaking, biogeochemical and palaeo-climatological studies. In this study, the chemical composition and source apportionment of PM2.5 (particulate matter with aerodynamic diameters less than 2.5 μm) at Yarrangobilly, in the Snowy Mountains, SE Australia are examined and quantified. A new aerosol monitoring network was deployed in June 2013 and aerosol samples collected during the period July 2013 to July 2017 were analysed for 22 trace elements and black carbon by ion beam analysis techniques. Positive matrix factorisation and back trajectory analysis and trajectory clustering methods were employed for source apportionment and to isolate source areas and air mass travel pathways, respectively. This study identified the mean atmospheric PM2.5 mass concentration for the study period was (3.3 ± 2.5) μg m−3. It is shown that automobile (44.9 ± 0.8)%, secondary sulfate (21.4 ± 0.9)%, smoke (12.3 ± 0.6)%, soil (11.3 ± 0.5)% and aged sea salt (10.1 ± 0.4)% were the five PM2.5 source types, each with its own distinctive trends. The automobile and smoke sources were ascribed to a significant local influence from the road network and bushfire and hazard reduction burns, respectively. Long-range transport are the dominant sources for secondary sulfate from coal-fired power stations, windblown soil from the inland saline regions of the Lake Eyre and Murray-Darling Basins, and aged sea salt from the Southern Ocean to the remote alpine study site. The impact of recent climate change was recognised, as elevated smoke and windblown soil events correlated with drought and El Niño periods. Finally, the overall implications including potential aerosol derived proxies for interpreting palaeo-archives are discussed. To our knowledge, this is the first long-term detailed temporal and spatial characterisation of PM2.5 aerosols for the region and provides a crucial dataset for a range of multidisciplinary research. Crown Copyright © 2018 Published by Elsevier B.V.
A detailed study of Holocene climate variability in south-east Australia based on cellulose inferred lake water isotopes and monitoring and modelling approach at Lake Surprise, western Victoria.
(Australasian Quaternary Association Inc., 2022-12-06) Dharmarathma, A; Tyler, JJ; Tibby, J; Barr, C; Cadd, HR; Ankor, MJ; Jones, MD; Tadros, CV; Hua, Q; Child, DP; Zawadzki, A; Hotchkis, MAC; Gadd, PS; Klaeb, RM; Hall, T
During the Holocene, southeast Australia experienced intense climate conditions including extended droughts. However, knowledge of the frequency and intensity of such episodes is restricted due to the scarcity of quantitative, high-resolution climate records from the region. Where conditions are possible, oxygen isotopes preserved in lake sediments are a useful tool for retracing the past climatic and environment. Here we present a well-dated, highly resolved Holocene record based on δ18O values of aquatic cellulose, alongside organic carbon isotopes and carbon/nitrogen ratios from sediments at Lake Surprise in western Victoria. Our interpretation of the palaeo-data is supported by both monitoring of water and sediment accumulation and lake isotope mass balance modelling to track the modern hydrology of the lake. The lake is highly groundwater dependant alongside its evaporative enrichment of major ions and stable isotopes. The cellulose record indicates a trend of gradually increasing aridity towards the present day, with notable extreme wet periods prevailing from 10900 – 10000, 7600 – 7000 and 5600 – 4500 cal yr BP. the lake represent a significant climate transition to towards aridity at 4500 cal yr BP and remained consistent over the last 4000 years, along with the driest period recorded from 2000 – 1550 cal yr BP. while our record is consistent with other studies from western Victoria, we demonstrate a strong coherence with SWW variability suggesting that the southern Ocean processes were the dominant controls of Holocene climate change at least over the study area. Further, we suggest an increasing influence of ENSO and IOD during the last two millennia. Our record also agrees with the pattern of variation in solar forcing to some extent which may symbolize a connection to proxy data and climate drivers. However, detailed analyses focused on solar activity and climate modes are required to understand teleconnections among these climate drivers and their mechanisms.
Developing a MySQL database for the provenance of black tiger prawns (Penaeus monodon)
(MDPI, 2023-07-11) Gopi, K; Mazumder, D; Crawford, J; Gadd, PS; Tadros, CV; Atanacio, AJ; Saintilan, N; Sammut, J
As the demand for seafood increases, so does the incidence of seafood fraud. Confirming provenance of seafood is important to combat fraudulent labelling but requires a database that contains the isotopic and elemental “fingerprints” of authentic seafood samples. Local isotopic and elemental databases can be scaled up or combined with other databases to increase the spatial and species coverage to create a larger database. This study showcases the use of isotopic and elemental fingerprints of the black tiger prawn (Penaeus monodon) to develop a database that can be used to securely store the data necessary for determining provenance. The utility of this database was tested through querying and building seven different datasets that were used to develop models to determine the provenance of P. monodon. The models built using the data retrieved from the database demonstrated that the provenance of P. monodon could be determined with >80% accuracy. As the database was developed using MySQL, it can be scaled up to include additional regions, species, or methodologies depending on the needs of the users. Combining the database with methods of determining provenance will provide regulatory bodies and the seafood industry with another provenance tool to combat fraudulent seafood labelling. © 2023 The Authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/4.0/)
ENSO–cave drip water hydrochemical relationship: a 7-year dataset from south-eastern Australia
(2020-05-26) Tadros, CV; Treble, PC; Baker, AA; Fairchild, IJ; Hankin, SI; Roach, R; Markowska, M; McDonald, J
Speleothems (cave deposits), used for palaeoenvironmental reconstructions, are deposited from cave drip water. Differentiating climate and karst processes within a drip-water signal is fundamental for the correct identification of palaeoenvironmental proxies and ultimately their interpretation within speleothem records. We investigate the potential use of trace element and stable oxygen-isotope (δ18O) variations in cave drip water as palaeorainfall proxies in an Australian alpine karst site. This paper presents the first extensive hydrochemical and δ18O dataset from Harrie Wood Cave, in the Snowy Mountains, south-eastern (SE) Australia. Using a 7-year long rainfall δ18O and drip-water Ca, Cl, Mg / Ca, Sr / Ca and δ18O datasets from three drip sites, we determined that the processes of mixing, dilution, flow path change, carbonate mineral dissolution and prior calcite precipitation (PCP) accounted for the observed variations in the drip-water geochemical composition. We identify that the three monitored drip sites are fed by fracture flow from a well-mixed epikarst storage reservoir, supplied by variable concentrations of dissolved ions from soil and bedrock dissolution. We constrained the influence of multiple processes and controls on drip-water composition in a region dominated by El Niño–Southern Oscillation (ENSO). During the El Niño and dry periods, enhanced PCP, a flow path change and dissolution due to increased soil CO2 production occurred in response to warmer than average temperatures in contrast to the La Niña phase, where dilution dominated and reduced PCP were observed. We present a conceptual model, illustrating the key processes impacting the drip-water chemistry. We identified a robust relationship between ENSO and drip-water trace element concentrations and propose that variations in speleothem Mg / Ca and Sr / Ca ratios may be interpreted to reflect palaeorainfall conditions. These findings inform palaeorainfall reconstruction from speleothems regionally and provide a basis for palaeoclimate studies globally, in regions where there is intermittent recharge variability. © Author(s) 2016.
Formation and characteristics of ions and charged aerosol particles in a native Australian Eucalypt forest
(Copernicus Publications, 2008-01-14) Suni, T; Kulmala, M; Hirsikko, A; Bergman, T; Laakso, L; Aalto, PP; Leuning, R; Cleugh, H; Zegelin, S; Hughes, D; van Gorsel, E; Kitchen, M; Vana, M; Hõrrak, U; Mirme, S; Mirme, A; Sevanto, S; Twining, JR; Tadros, CV
Abstract. Biogenic aerosol formation is likely to contribute significantly to the global aerosol load. In recent years, new-particle formation has been observed in various ecosystems around the world but hardly any measurements have taken place in the terrestrial Southern Hemisphere. Here, we report the first results of atmospheric ion and charged particle concentrations as well as of new-particle formation in a Eucalypt forest in Tumbarumba, South-East Australia, from July 2005 to October 2006. The measurements were carried out with an Air Ion Spectrometer (AIS) with a size range from 0.34 to 40 nm. The Eucalypt forest was a very strong source of new aerosol particles. Daytime aerosol formation took place on 52% of days with acceptable data, which is 2–3 times as often as in the Nordic boreal zone. Average growth rates for negative/positive 1.5–3 nm particles during these formation events were 2.89/2.68 nmh−1, respectively; for 3-7 nm particles 4.26/4.03, and for 7–20 nm particles 8.90/7.58 nmh−1, respectively. The growth rates for large ions were highest when the air was coming from the native forest which suggests that the Eucalypts were a strong source of condensable vapours. Average concentrations of cluster ions (0.34–1.8 nm) were 2400/1700 cm−3 for negative/positive ions, very high compared to most other measurements around the world. One reason behind these high concentrations could be the strong radon efflux from the soils around the Tumbarumba field site. Furthermore, comparison between night-time and daytime concentrations supported the view that cluster ions are produced close to the surface within the boundary layer also at night but that large ions are mostly produced in daytime. Finally, a previously unreported phenomenon, nocturnal aerosol formation, appeared in 32% of the analysed nights but was clustered almost entirely within six months from summer to autumn in 2006. From January to May, nocturnal formation was 2.5 times as frequent as daytime formation. Therefore, it appears that in summer and autumn, nocturnal production was the major mechanism for aerosol formation in Tumbarumba. © Author(s) 2008. This work is licensed under the Creative Commons Attribution-NonCommercial-Share Alike 2.5 Licence.
The impact of fire on the geochemistry of speleothem-forming drip water in a sub-alpine cave
(Elsevier, 2018-11) Coleborn, K; Baker, AA; Treble, Pauline C; Andersen, MS; Baker, AC; Tadros, CV; Tozer, MG; Fairchild, IJ; Spate, A; Meehan, S
Fire dramatically modifies the surface environment by combusting vegetation and changing soil properties. Despite this well-documented impact on the surface environment, there has been limited research into the impact of fire events on karst, caves and speleothems. Here we report the first experiment designed to investigate the short-term impacts of a prescribed fire on speleothem-forming cave drip water geochemistry. Before and after the fire, water was collected on a bi-monthly basis from 18 drip sites in South Glory Cave, New South Wales, Australia. Two months post-fire, there was an increase in B, Si, Na, Fe and Pb concentrations at all drip sites. We conclude that this response is most likely due to the transport of soluble ash-derived elements from the surface to the cave drip water below. A significant deviation in stable water isotopic composition from the local meteoric water line was also observed at six of the sites. We hypothesise that this was due to partial evaporation of soil water resulting in isotopic enrichment of drip waters. Our results demonstrate that even low-severity prescribed fires can have an impact on speleothem-forming cave drip water geochemistry. These findings are significant because firstly, fires need to be considered when interpreting past climate from speleothem δ18O isotope and trace element records, particularly in fire prone regions such as Australia, North America, south west Europe, Russia and China. Secondly, it supports research that demonstrates speleothems could be potential proxy records for past fires. © 2018 Elsevier B.V.
Insights into recharge processes and speleothem proxy archives from long-term monitoring networks of cave drip water hydrology
(Copernicus GmbH, 2020-05-04) Baker, AA; Treble, PC; Hartmann, A; Cuthbert, MO; Markowska, M; Berthelin, R; Tadros, CV; Leopold, M; Hankin, SI
Since 2010 we have established cave drip water hydrological monitoring networks in four contrasting climate zones (Mediterranean, montane, semi-arid and sub-tropical) across continental Australia. Deploying over one hundred automated drip loggers, we combine these long-term monitoring datasets with climate and water isotope data, lidar mapping, electrical resistivity imaging and karst hydrological modelling to provide insights into recharge processes and the impact of hydrological variability on speleothem proxy archives. We identify increases in drip discharge and compare the timing of those events to antecedent climate conditions (rainfall, evapotranspiration). We find rainfall recharge thresholds vary with climate. At our montane site, recharge occurs after 13 to 31 mm rainfall events, depending on antecedent conditions. At the semi-arid site, recharge occurs after 40 mm rainfall events, and at our sub-tropical sites, recharge occurs following all instances where > 93 mm / week of precipitation occurs, with lower precipitation thresholds (down to 33 mm / week) possible depending on antecedent conditions and at sites with limited vegetation cover. We use these recharge thresholds to constrain simple soil moisture balance models to better understand soil and karst storage volumes. Combined with electrical resistivity imaging, we can relate recharge to the caves to subsurface water flow paths and karst water stores. At our montane and Mediterranean climate sites, relatively consistent drip water isotopic composition confirms the presence of well-mixed water stores. This allows us to quantify the extent of speleothem oxygen isotope variability due to fractionation associated with changes in drip rate. We identify significant differences in long-term mean drip rates between different drip sites within a cave, and significant differences in event-based drip rate responses within a cave. Drip hydrological variability helps explain the within-cave variability of speleothem oxygen isotope composition observed at both sites, and helps identify the primary drip water oxygen isotope signal. At our semi-arid site, drip water isotopic composition is dominated by epikarst evaporation and our drip water monitoring demonstrates that recharge events are infrequent (~1.6 per year). Using both observational and modelling data, we quantify the relative importance of evaporative fractionation in the epikarst and fractionation during calcite precipitation. Using modern speleothem samples, we demonstrate that the oxygen isotope signal in this water limited environment reflects the balance between the oxygen isotope composition of recharge and its subsequent fractionation in the soil, epikarst and cave. © Author(s) 2020. This work is distributed under the Creative Commons Attribution 4.0 Licence.
Measured deuterium in water vapour concentration does not improve the constraint on the partitioning of evapotranspiration in a tall forest canopy, as estimated using a soil vegetation atmosphere transfer model
(Elsevier, 2011-06-15) Haverd, V; Cuntz, M; Griffith, DWT; Keitel, C; Tadros, CV; Twining, JR
Partitioning the evapotanspiration (ET) flux in a forest into its component fluxes is important for understanding the water and carbon budgets of the ecosystem. We use non-linear parameter estimation to determine the vertical profile of the Lagrangian timescale (T(L)) and partitioning of ET that simultaneously optimise agreement between modelled and measured vertical profiles of temperature, water vapour, carbon dioxide concentrations, and deuterated water vapour for a two-week period in November 2006. High precision real-time trace gas measurements were obtained by FTIR spectroscopy. Modelled temperature and concentration profiles are generated using a Lagrangian dispersion theory combined with source/sink distributions of HDO, H(2)O, sensible heat, and CO(2). These distributions are derived from an isotopically enabled multilayer Soil Vegetation Atmospheric Transfer (SVAT) model subject to multiple constraints. The soil component of the model was tested in isolation using measured deuterium content of soil chamber evaporate, while the leaf component was tested using isotopic analyses of leaf and xylem water, combined with leaf-level gas exchange measurements. Optimisation of T(L) and the partition of ET was performed twice: once using only temperature, H(2)O and CO(2) profiles and a second time including HDO as well. The modelled vertical concentration profiles resulting from inclusion of HDO in the cost function demonstrate our ability to make consistent estimates of both the scalar source distributions and the deuterium content of the water vapour sources. However, introducing measurements of deuterium in water vapour does not significantly alter resulting estimates of normalised T(L) (0.4 +/- 0.1 at canopy top) and the partition of ET(85 +/- 2% transpiration), suggesting that the additional data and modelling required to use deuterium are not warranted for the purpose of partitioning ET using the framework presented here. Crown Copyright (C) 2011 Published by Elsevier B.V.
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.
Rainfall isotope (3H, δ2H and δ18O) input to groundwater in Australia
(Geological Society if Australia, 2014-07-07) Hughes, CE; Tadros, CV; Hollins, SE; Crawford, J; Cendón, DI; Meredith, KT
The stable isotopes of water, δ2H and δ18O, are conservative tracers available for studying mixing of water in the hydrosphere. Radioactive tritium (2H, half-life = 12.3 years), derived from both cosmogenic and anthropogenic sources (nuclear testing), is an important tracer for dating of young groundwater. Measurements of stable water isotopes and tritium in Australian rainfall have been made monthly at six coastal sites and Alice Springs since 1962 as part of the Global Network of Isotopes in Precipitation (GNIP). Since 2006 this network has been expanded to include seven inland sites in New South Wales, Queensland, South Australia and Western Australia (δ2H and δ18O analysed only). In addition, event-based studies of stable water isotopes have been conducted at four locations in the Sydney region since 2005. These data have been analysed to determine local meteoric water lines, weighted averages and to investigate the relationships between rainfall isotopic composition, temperature and precipitation amount. Stable water isotopes are not completely conservative as they undergo fractionation as a result of hydrological processes such as evaporation, precipitation, ice and snow formation and melting, and geothermal activity. The fractionation can be used to understand the provenance and history of groundwater and to define end members for mixing studies. For age dating of groundwater using tritium the rainfall tritium composition is required. In addition to the 50-year tritium record available from GNIP for six sites, data for an additional eleven locations throughout eastern Australia were compiled for varying periods mainly between 1970 and 1991, thereby improving the spatial resolution of the tritium time series in Australia. Unlike δ2H and δ18O, the spatial distribution and seasonal variation of tritium in rainfall is largely controlled by the stratosphere to troposphere exchange of anthropogenic tritium from nuclear testing, with the highest concentrations occurring at Adelaide and Melbourne during the early spring. Modern concentrations appear to be stabilising with average annual concentrations in the range 1–3 TU increasing with latitude. These data have also been used to estimate the tritium composition of rainfall resulting in the January 1974 Queensland floods, which are believed to have resulted in significant recharge to aquifers in Queensland and northern NSW. © Geological Society of Australia Inc
Recharge variability in Australia's southeast alpine region derived from cave monitoring and modern stalagmite δ18O records
(Elsevier, 2022-11-01) Tadros, CV; Markowska, M; Treble, PC; Baker, AA; Frisia, S; Adler, L.; Drysdale, RN
Oxygen isotopic (δ18O) variations in stalagmite records have the potential to provide new insights about past climates beyond the instrumental record. This paper presents the first high-resolution oxygen isotope time series of three coeval stalagmite records from the alpine region of south-eastern Australia covering the period 1922–2006 CE. We use extended surface and cave monitoring datasets, petrographic investigation, modelled recharge time series and farmed calcite precipitates to assess the controls on speleothem δ18O and investigate the coherence between three records from Harrie Wood Cave. The drip water response to recent interannual rainfall variability shows that cave drip water Cl−, δ18O and drip rate display a clear response to an increase in rainfall recharge. It is demonstrated that stalagmites from the same drip sites also record variability in interannual recharge, where an increase in δ18O values is observed with lower recharge, while a decrease in δ18O values correspond to higher recharge amounts. The three stalagmite δ18O records are in broad agreement, showing common responses to relatively higher recharge between 1945 and 1995 CE and the low recharge periods between 1937 and 1945 CE (World War II drought) and late 1996 to 2006 CE (beginning of the Millennium Drought). However, differences in the magnitude of the relative response of each stalagmite δ18O record varies. Based on evidence from our cave monitoring study and farmed calcites, we conclude that the differences between the three stalagmite records is attributed to variability in the contribution of preferential flows during recharge events and the store reservoir volume supplying the drip site. When the δ18O decreases in response to enhanced recharge, the speleothem δ13C also decreases, and this is interpreted to reflect a soil respiration response to changes in soil moisture availability due to recharge. Hence, stalagmite δ18O from the Australian alpine region can be applied to reconstruct periods of relatively higher and lower rainfall recharge and thus extend our knowledge of the timing and relative magnitude of droughts as well as past periods of higher recharge in this region. Crown Copyright © 2022 Published by Elsevier Ltd.
Reconstructing past environmental change at Yarrangobilly Caves
(Sydney Speleological Society, 2016-01-01) Treble, PC; Markowska, M; Tadros, CV; Jex, CN; Coleborn, K; Dredge, J; Baker, AA; Roach, R; Spate, A
Not available
Trace elements: from sources to cave drip water, south-eastern Australia
(Australasian Quaternary Association Inc., 2018-12-10) Tadros, CV; Treble, PC; Baker, AA
Speleothem trace element time series are constructed from the infiltrating drip water geochemistry, and hence are examined under contrasting rainfall conditions associated with El Niño and La Niña phases of ENSO. The aim was to identify suitable inorganic element proxies for palaeoclimate interpretation in speleothem records from Harrie Wood Cave, Yarrangobilly. The drip water chemical composition at the stalactite tip reflects a contribution from different endmembers and processes; therefore it is necessary to study the different sources, pathways and processes that occur as water migrates through the atmosphere-soil-karst system. Here we present high resolution aerosol, rainfall and drip water 18O and inorganic drip-water datasets. Analysis of aerosol samples above the caves reveals the atmosphere supplies a suite of elements from automobile emissions, windblown soil, smoke, secondary sulfate and aged sea salt sources. The bedrock and aerosols were identified as contributory sources of solutes to the drip water. The clay-rich soil zone was recognised as a sink for inorganic elements, and a secondary source for Zn. In soil, a number of processes were demonstrated to modify the chemical composition of the resultant drip waters. The drip water chemistry is driven by the long-term gradient in the cumulative water balance. The flow paths feeding the drip sites were shown to be fracture flow, from a ventilated well-mixed pocket within the epikarst storage reservoir. Dilution and reduced prior calcite precipitation (PCP) controlled the drip-water chemistry during the La Niña/wet years whereas enhanced PCP was observed during the El Niño and dry periods. Mg and Sr show particular promise as paleoclimate proxies for drought and flood events, while with further research Na, K and Zn may also be reliably used. These findings will be applied in a modern speleothem record. © Author(s)
Tritium in Australian precipitation: a 50 year record
(Elsevier B. V., 2014-05-26) Tadros, CV; Hughes, CE; Crawford, J; Hollins, SE; Chisari, R
Tritium in precipitation has been measured in Australia over the past 50 years, as an essential research tool in hydro-climate studies, and to contribute to the Global Network for Isotopes in Precipitation (GNIP). Tritium, a component of the water molecule (HTO), is the only true age tracer for waters. The elevated level of tritium in the environment as a result of last century’s atmospheric thermonuclear testing delivers the benefit of tracing groundwater systems over a 100 year timeframe. The concentration of tritium in Australian precipitation reached a maximum of 160 Tritium Units (TU) in 1963, during one of the most intense periods of nuclear weapons testing. From 1963 to present we observe a rapid drop in the concentration of tritium, more than expected from natural decay, and this can be attributed to the wash out of tritium into the oceans and groundwater. Spikes in the tritium level are superimposed over this general trend; the first around 1969, with levels ranging from 39.4 to 84.4 TU was due to French atmospheric weapon testing, and again in 1990, levels peaked between 6.6 and 12.9 TU, which is attributed to tritium leaking from underground tests in the French Pacific. Since 1990 the levels of tritium have declined globally and regionally. Currently the levels of tritium in Australia are stabilising to around 2–3 TU increasing with latitude across the continent, suggesting that today the tritium in precipitation is predominantly natural. The spatial distribution of tritium is presented and found to be dominated by the annual stratosphere–troposphere exchange in combination with latitude and continental effects. A precipitation amount effect is also observed for inland sites. Crown Copyright © 2014 Published by Elsevier B.V.
Unsaturated zone hydrology and cave drip discharge water response: implications for speleothem paleoclimate record variability
(Elsevier, 2015-10-01) Markowska, M; Baker, AA; Treble, PC; Andersen, MS; Hankin, SI; Jex, CN; Tadros, CV; Roach, R
High-frequency, spatially-dense discharge monitoring was conducted over fifteen months to characterise unsaturated zone flow at Harrie Wood Cave (HWC), in the Snowy Mountains, Yarrangobilly (SE Australia). The cave was formed in the Late Silurian Yarrangobilly Limestone, a fractured rock associated with very low primary porosity due to past diagenesis. Over our monitoring period we simultaneously measured rainfall, soil moisture saturation and drip discharge rate at fourteen sites to characterise infiltration–discharge relationships. All drip discharge sites exhibited non-Gaussian distributions, indicating long periods where low discharge predominates, punctuated by short infrequent periods of high discharge. However, there was significant variability in discharge between sites and consequently no spatial correlation in the cave. We investigated the depth–discharge relationship at HWC and found a moderate relationship between depth and drip discharge lag (response) times to soil moisture content, but only weak relationships between depth and mean and maximum discharge. This highlights that the karst architecture plays an important role in controlling drip discharge dynamics. Principal Component Analysis (PCA) and Agglomerative Hierarchal Clustering (AHC) were used to classify similar drip types, revealing five unique drip regimes. Two-phase flow and non-linear response to recharge behaviour were observed, suggesting secondary porosity is controlling unsaturated zone flow in mature limestone environments with low primary porosity. Using the data presented here, the first coupled conceptual and box hydrological flow model was developed. This study highlights the heterogeneous nature of hydrological flow in karst and the need to understand unsaturated zone hydrology at the individual drip discharge level, to inform speleothem studies for high-resolution paleoclimate reconstruction. © 2015, Elsevier B.V.
Unsaturated zone hydrology and implications for paleo-climate speleothem reconstructions
(Australian Government Department of Environment and Bureau of Meterology, 2014-06-26) Markowska, M; Treble, PC; Baker, AA; Andersen, MS; Jex, CN; Tadros, CV; Roach, R; Hankin, SI
Speleothem growth relies on the supply of water which percolates from the surface, through the unsaturated zone and discharges into cavernous voids. The flow path of water feeding individual speleothems varies considerably depending on the karst architecture e.g. micro-fractures, solution pipes, structural voids in the karst, storage reservoirs, etc., all of which may alter the composition of drip waters over the flow route. By monitoring drip waters, we can determine: 1) unsaturated zone flow regimes; 2) connectivity between the surface and cave discharge zone; and 3) thresholds for groundwater recharge. This information can be used to identify suitable speleothems in caves for reconstruction of past climatic and hydrologic variability, at least over the last few thousand years of similar mean climate state. High-frequency, spatially-dense monitoring was conducted in Harrie Wood Cave, Yarrangobilly, Snowy Mountains over a 15 month period to characterise the flow regimes at 14 sites along a depth profile within the cave. Sites were monitored using acoustic drip loggers (stalagmates®). Discharge rates and response to significant rainfall events were highly variable between sites. A moderate relationship was found between decreasing discharge rates and increasing depth (r2 = 0.40). We suggest unsaturated zone storage and mixing, unrelated to depth, also have a significant impact on flow regimes. Using a statistical approach, five different drip types, which often had no spatial commonality, were identified. This information was used to inform the choice of speleothems for paleo-climate reconstruction, using stalagmites with differing hydrological regimes feeding growth, of which the preliminary data 18 will be presented here. The study highlights the need to understand unsaturated zone hydrology at the individual drip discharge level, prior to any speleothem study for paleo-climate, to truly appreciate the drip water signal it is recording. Copyright (C) The Authors.

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