Browsing by Author "Chisari, R"
Now showing 1 - 20 of 22
Results Per Page
Sort Options
- ItemApplication of environmental isotopes to study aquifer interactions and their impact on groundwater salinisation in western Victoria(Australian Institute of Nuclear Science and Engineering (AINSE), 2007-11) Raiber, M; Webb, JA; Jacobsen, GE; Chisari, R; Williams, AA; Neklapilova, B
- ItemBiogeochemical responses to Holocene catchment-lake dynamics in the Tasmanian World Heritage Area, Australia(American Geophysical Union, 2018-04-30) Mariani, M; Beck, KK; Fletcher, MS; Gell, PA; Saunders, KM; Gadd, PS; Chisari, REnvironmental changes such as climate, land use, and fire activity affect terrestrial and aquatic ecosystems at multiple scales of space and time. Due to the nature of the interactions between terrestrial and aquatic dynamics, an integrated study using multiple proxies is critical for a better understanding of climate- and fire-driven impacts on environmental change. Here we present a synthesis of biological and geochemical data (pollen, spores, diatoms, micro X-ray fluorescence scanning, CN content, and stable isotopes) from Dove Lake, Tasmania, allowing us to disentangle long-term terrestrial-aquatic dynamics through the last 12 kyear. We found that aquatic dynamics at Dove Lake are tightly linked to vegetation shifts dictated by regional hydroclimatic variability in western Tasmania. A major shift in the diatom composition was detected at ca. 6 ka, and it was likely mediated by changes in regional terrestrial vegetation, charcoal, and iron accumulation. High rainforest abundance prior ca. 6 ka is linked to increased terrestrially derived organic matter delivery into the lake, higher dystrophy, anoxic bottom conditions, and lower light penetration depths. The shift to a landscape with a higher proportion of sclerophyll species following the intensification of El Niño-Southern Oscillation since ca. 6 ka corresponds to a decline in terrestrial organic matter input into Dove Lake, lower dystrophy levels, higher oxygen availability, and higher light availability for algae and littoral macrophytes. This record provides new insights on terrestrial-aquatic dynamics that could contribute to the conservation management plans in the Tasmanian World Heritage Area and in temperate high-altitude dystrophic systems elsewhere. ©2018. American Geophysical Union
- ItemBiomass uptake and fire as controls on groundwater solute evolution on a southeast Australian granite: Aboriginal land management hypothesis(Copernicus Gesellschaft MBH, 2014-01-01) Dean, JF; Webb, JA; Jacobsen, GE; Chisari, R; Dresel, PEThe chemical composition of groundwater and surface water is often considered to be dominated by water-rock interactions, particularly weathering; however, it has been increasingly realised that plant uptake can deplete groundwater and surface water of nutrient elements. Here we show, using geochemical mass balance techniques, that water-rock interactions do not control the hydrochemistry at our study site within a granite terrain in southwest Victoria, Australia. Instead the chemical species provided by rainfall are depleted by plant biomass uptake and exported, predominantly through fire. Regular landscape burning by Aboriginal land users is hypothesized to have caused the depletion of chemical species in groundwater for at least the past 20 000 yr by accelerating the export of elements that would otherwise have been stored within the local biomass. These findings are likely to be applicable to silicate terrains throughout southeast Australia, as well as similar lithological and climatic regions elsewhere in the globe, and contrast with studies of groundwater and surface water chemistry in higher rainfall areas of the Northern Hemisphere, where water-rock interactions are the dominant hydrochemical control. © 2014, Copernicus Gesellschaft MBH.
- ItemDiscrete interval groundwater samples from uncased boreholes in the Hawkesbury Sandstone, NSW, Australia, reveal mixed results.(International Association of Hydrogeologists, 2013-09-19) Peterson, MA; Cendón, DI; Hankin, SI; Chisari, RThe effects of subsidence and related fracturing from longwall coal mining have raised community concern around the Southern Coalfields of NSW. Shallow fracturing of bedrock streambeds has led to draining of perennial pools and localised diversion within some streams. Consequently, the risk of diverting surface water and shallow groundwaters towards underground mining operations has also been debated in the community. A Zone-of-Interest Groundwater Sampler (ZoIGS) with straddle packers and multiple pressure sensors was used to collect samples from discrete 5 m intervals within uncased 100 mm boreholes. Up to 6 intervals were successfully sampled in each borehole, to a maximum depth of 137 m below ground level. Hydrogeochemical information analysed comprised major ions, water stable isotopes, 3H and 14CDIC . The results were compared to geophysical data and pressure recovery after purges for each of the intervals. Each borehole displayed a unique vertical arrangement of apparent ages, hydraulic conductivities, mixing and pressure gradients. Hydrogeochemical results showed that some of the more evolved groundwater at depth, with corrected 14C ages up to a few thousand years, was also displaying a 3H signature of mixing with much younger waters. In some cases age profiles were overturned with depth, with younger water occurring below older water. Geophysical and pressure recovery data showed that each borehole intersected a number of aquifers, separated by shale aquitards up to five metres thick. The shale beds are sometimes closely associated with high horizontal hydraulic conductivities and outflow zones. 3H indicative of younger water did not always coincide with the higher hydraulic conductivity zones. The results describe a complex heterogeneous system within the Hawkesbury Sandstone, with multiple flow paths contributing to mixing of old and young groundwater at depth. The ability to sample and investigate numerous discrete intervals within uncased boreholes gave an opportunity for better understanding the system, with minimal infrastructure.
- ItemA DNA-based assay for toxic chemicals in wastewater(Wiley-Blackwell, 2011-08-01) Foreman, AL; Philips, L; Kanellis, VG; Hammoudeh, D; Naumann, C; Wong, HKY; Chisari, R; Hibbert, DB; Lee, GSH; Patra, R; Julli, M; Chapman, J; Cooke, AR; dos Remedios, CGChemical toxicants, particularly metal ions, are a major contaminant in global waterways. Live-organism bioassays used to monitor chemical toxicants commonly involve measurements of activity or survival of a freshwater cladoceran (Ceriodaphnia dubia) or light emitted by the marine bacterium Vibrio fischeri, used in the commercial Microtox (R) bioassay. Here we describe a novel molecule-based assay system employing DNA as the chemical biosensor. Metals bind to DNA, causing structural changes that expel a bound (intercalated) fluorescent reporter dye. Analyses of test data using 48 wastewater samples potentially contaminated by metal ions show that the DNA-dye assay results correlate with those from C. dubia and Microtox bioassays. All three assays exhibit additive, antagonistic, and synergistic responses that cannot be predicted by knowing individual metal concentrations. Analyses of metals in these samples imply the presence of chemical toxicants other than metal ions. The DNA-dye assay is robust, has a 12-month shelf life, and is only slightly affected by sample pH in the range 4 to 9. The assay is completed in a matter of minutes, and its portability makes it well suited as a screening assay for use in the field. We conclude that the DNA-dye test is a surrogate bioassay suitable for screening chemical toxicity. Environ. Toxicol. Chem. 2011;30:1810-1818. (C) 2011 SETAC
- ItemEvaporation and concentration gradients created by episodic river recharge in a semi-arid zone aquifer: Insights from Cl−, δ18O, δ2H, and 3H(Elsevier B. V., 2015-10) Meredith, KT; Hollins, SE; Hughes, CE; Cendón, DI; Chisari, R; Griffiths, AD; Crawford, JThis study has significantly advanced our understanding of the origin of groundwater recharge in a semi-arid zone region of the Darling River catchment, Australia. The generally accepted hypothesis in arid zone environments in Australia that river water forms the primary groundwater recharge source has proven difficult to monitor. This is due to the time lags between large floods, the remoteness and expense of studying these hydrologically complex systems in detail. In addition, the highly episodic nature of dryland rivers complicates the interpretation of the groundwater signal. A range of hydrochemical tracers (chloride, oxygen-18, deuterium and tritium) measured in rain, river water, soil water and groundwater were used in this multi-year study to trace the pathways of groundwater recharge under wet and dry climatic conditions. The evaporation and Cl concentrations observed in the unsaturated zone confirmed that small volumetric inputs from periodic rainfall were not the major recharge mechanism. Sampling which included an overbank flooding event in March 2012 provided firm evidence for groundwater originating from high flow episodic river recharge. The use of long-term environmental data to understand how economically important water resources respond to climate change with increasing temperatures is considered essential for future sustainability. Crown Copyright ©2015 Published by Elsevier B.V.
- ItemA groundwater recharge perspective on locating tree plantations within low-rainfall catchments to limit water resource losses(Copernicus Publications, 2015-02-26) Dean, JF; Webb, JA; Jacobsen, GE; Chisari, R; Dresel, PEDespite the many studies that consider the impacts of plantation forestry on groundwater recharge, and others that explore the spatial heterogeneity of recharge in low-rainfall regions, there is little marriage of the two subjects in forestry management guidelines and legislation. Here we carry out an in-depth analysis of the impact of reforestation on groundwater recharge in a low-rainfall (< 700 mm annually), high-evapotranspiration paired catchment characterized by ephemeral streams. Water table fluctuation (WTF) estimates of modern recharge indicate that little groundwater recharge occurs along the topographic highs of the catchments (average 18 mm yr−1); instead the steeper slopes in these areas direct runoff downslope to the lowland areas, where most recharge occurs (average 78 mm yr−1). Recharge estimates using the chloride mass balance (CMB) method were corrected by replacing the rainfall input Cl− value with that for streamflow, because most recharge occurs from infiltration of runoff through the streambed and adjacent low gradient slopes. The calculated CMB recharge values (average 10 mm yr−1) are lower than the WTF recharge values (average 47 mm yr−1), because they are representative of groundwater that was mostly recharged prior to European land clearance (> BP 200 years). The tree plantation has caused a progressive drawdown in groundwater levels due to tree water use; the decline is less in the upland areas. The results of this study show that spatial variations in recharge are important considerations for locating tree plantations. To conserve water resources for downstream users in low-rainfall, high-evapotranspiration regions, tree planting should be avoided in the dominant zone of recharge, i.e. the topographically low areas and along the drainage lines, and should be concentrated on the upper slopes, although this may negatively impact the economic viability of the plantation. © 2015 Author(s)
- ItemGroundwater residence time in a dissected and weathered sandstone plateau: Kulnura–Mangrove Mountain aquifer, NSW, Australia(Taylor Francis Online, 2014-04-14) Cendón, DI; Hankin, SI; Williams, JP; Van der Ley, M; Peterson, MA; Hughes, CE; Meredith, KT; Graham, IT; Hollins, SE; Levchenko, VA; Chisari, RGroundwater residence time in the Kulnura–Mangrove Mountain aquifer was assessed during a multi-year sampling programme using general hydrogeochemistry and isotopic tracers (H2O stable isotopes, δ13CDIC, 3H, 14C and 87Sr/86Sr). The study included whole-rock analysis from samples recovered during well construction at four sites to better characterise water–rock interactions. Based on hydrogeochemistry, isotopic tracers and mineral phase distribution from whole-rock XRD analysis, two main groundwater zones were differentiated (shallow and deep). The shallow zone contains oxidising Na–Cl-type waters, low pH, low SC and containing 3H and 14C activities consistent with modern groundwater and bomb pulse signatures (up to 116.9 pMC). In this shallow zone, the original Hawkesbury Sandstone has been deeply weathered, enhancing its storage capacity down to ∼50 m below ground surface in most areas and ∼90 m in the Peats Ridge area. The deeper groundwater zone was also relatively oxidised with a tendency towards Ca–HCO3-type waters, although with higher pH and SC, and no 3H and low 14C activities consistent with corrected residence times ranging from 11.8 to 0.9 ka BP. The original sandstone was found to be less weathered with depth, favouring the dissolution of dispersed carbonates and the transition from a semi-porous groundwater media flow in the shallow zone to fracture flow at depth, with both chemical and physical processes impacting on groundwater mean residence times. Detailed temporal and spatial sampling of groundwater revealed important inter-annual variations driven by groundwater extraction showing a progressive influx of modern groundwater found at >100 m in the Peats Ridge area. The progressive modernisation has exposed deeper parts of the aquifer to increased NO3− concentrations and evaporated irrigation waters. The change in chemistry of the groundwater, particularly the lowering of groundwater pH, has accelerated the dissolution of mineral phases that would generally be inactive within this sandstone aquifer triggering the mobilisation of elements such as aluminium in the aqueous phase. © 2020 Informa UK Limited
- ItemThe hydrochemical response of cave drip waters to sub-annual and inter-annual climate variability, Wombeyan Caves, SE Australia(Elsevier, 2007-10-15) McDonald, J; Drysdale, RN; Hill, DE; Chisari, R; Wong, HKYA thorough understanding of cave seepage waters is necessary to interpret geochemical variations in speleothem calcite in terms of changing surface climatic conditions at a particular site. Here we present the hydrochemistry of ten cave drip waters from a karst system in SE Australia based on up to 5.5 years of monitoring. Discharge was continuously measured at six sites and manually at the other sites. Dripwater samples were analysed for pH, electrical conductivity, cations and anions at all sites at monthly or more frequent intervals. Each drip possesses a unique chemistry, and not all drip waters responded to antecedent short-term hydrological variations. For example, the hydrochemical behaviour of three adjacent drips at a bedrock depth of 45 m was completely different to that of shallower sites, and was apparently un-related to surface hydrology throughout the investigation. Based on modelled calcite precipitation vectors, prior calcite precipitation was demonstrated at several sites but can only be linked directly to changes in surface recharge at the shallowest sites. At extremely low flow, shallow drip waters accessed a high Mg, Sr and Ba source, thought to be the overlying soil. High-frequency sample collection allows for the calculation of predicted Mg/Ca-calcite and Sr/ Ca-calcite values, highlighting that the sites with the greatest potential to record high-resolution palaeohydrological records are those situated at shallow depth. Longer temporal-resolution palaeohydrological records may be recorded at deeper sites but longer-term monitoring is required to identify probable time scales. Inherent system non-linearities, dissolution of secondary calcite in pore spaces of the aquifer, changes in the source of trace elements, and the presence of multiple reservoirs confirm the need for the use of multiple speleothems and a multi-proxy approach to gain accurate palaeohydrological records from this site. © 2007, Elsevier Ltd.
- ItemThe importance of topographic controls on groundwater recharge for plantation forestry in southeast Australia(International Association of Hydrogeologists, 2013-09-16) Dean, JF; Webb, JA; Jacobsen, GE; Chisari, R; Dresel, PEThe trade off between water use and carbon sequestration by F plantation forestry is the subject of ongoing debate in Australia. Many tree plantations are planted without consideration for their impact on groundwater recharge. The spatial variation of recharge across a landscape can provide useful information on where to best situate a plantation while minimising its impact on groundwater recharge. Recharge is generally assumed to take place at topographic high points across a landscape, especially when rocky outcrops occur. This study analysed recharge rates at several points across a small paired catchment site to determine the most prevalent areas of recharge. Water-table fluctuations, Cl- mass balances, tritium and 14C ages were used to estimate recharge at 23 points across a 0.8 km2 catchment covered predominantly in a blue gum tree plantation, and an adjacent 0.5 km2 pasture catchment, in southwest Victoria, Australia. The CI- mass, balance method and water-table fluctuation methods were modified to better reflect the recharge processes taking place at the study site, including longer term hydrograph fluctuations and input from streams. Hydrographs from data loggers (since 2009) in bores situated close to the drainage line show considerably more recharge taking place compared to bores situated further upslope. Cl-mass balances show a similar trend, as do the hydrographs for the past 20-30 years, indicating that the majority of recharge is occurring along the drainage lines and towards the bottom of the slopes. Hydrograph fluctuations from these areas of the study site also often show significant response to runoff, measured at weirs on both catchments. Fracture heterogeneity contributes to some of the recharge variations, but the general trend is for recharge to occur more consistently in the topographically lower areas. ln order to minimise the interception of groundwater recharge by tree plantations in regions similar to the study area, the bulk of the plantation should be situated on the upper slopes, away from drainage lines and the immediately adjacent slopes. This would have less of an effect on the groundwater levels, as the plantation is not intercepting recharge in the zones where the majority of infiltration is occurring.
- ItemISO 9001 accreditation in an R&D environment - is it possible?(International Atomic Energy Agency, 2006) Szymczak, R; Henderson-Sellers, A; Lowson, RT; Chisari, RThe Australian Nuclear Science and Technology Organisation (ANSTO) is Australia's national nuclear organisation and its centre of Australian nuclear expertise. ANSTO is in the process of replacing its 1950’s, 15 MW, high flux (up to 1015 n cm-2 s-1) reactor with a new reactor which will allow it to continue its cutting edge nuclear science and radiopharmaceutical production well into the 21st century. A ministerial requirement for licensing the facility is ISO 9001 accreditation of its quality management system. The accreditation process has been staggered at ANSTO. Individual divisions are attaining ISO 9001 accreditation separately, leading up to site-wide accreditation of an overarching ANSTO Business Management System. ANSTO Environment is the largest multidisciplinary environmental research group in Australia and the largest R & D unit at ANSTO, comprising around 150 biologists, chemists, engineers, geophysicists, meteorologists, microbiologists, oceanographers, physicists, and technicians (Fig. 1). ANSTO Environment operates and maintains a wide range of advanced nuclear and analytical facilities including three particle accelerators, a 10 MV Tandem accelerator, a 3 MV Van de Graaff accelerator and a newly acquired 2MV HVEE tandetron; a high current 50 kV Metal Vapour Vacuum Arc Ion Implantation (MEVVA) Facility; a Secondary Ion Mass Spectrometer (SIMS); and many other laboratory and field-based facilities. The objective of ANSTO Environment is to carry out a problem-focused, balanced program of strategic and applied research and development, using its nuclear science-based core expertise and closely-related techniques, to: · assist the Commonwealth Government to further its national and international initiatives, and to protect and conserve the natural environment through sustainable development; · assist industry in advancing Australia's competitive position in the world economy; · ensure that environmental monitoring of nuclear facilities is effective in assuring operational adherence to sound environmental protection principles. “Make everything as simple as possible, but not simpler” Albert Einstein In February 2000 ANSTO Environment successfully acquired ISO 9001:2000 accreditation of its quality management system and was amongst the first organisations to adopt the new 2000 revision of the international ISO 9001 standard. The new standard allows a much more flexible and less prescriptive format for quality management systems however, in the absence of examples of accreditation in the R & D area, presented a challenge in concept, definition of process, buy-in by staff and subsequent maintenance of the successful certification. The ANSTO Environment Manual of Good Management Practice [1] outlines our identity, our vision, our core values, our responsibilities, our operational processes and our commitment to continual improvement via internal and external review. This paper is a description and discussion of the elements, concepts and process for achieving staff buy-in in the face of initial opposition. This included identifying those necessary elements of a good management system, rejection of pejorative dogma associated with ‘Quality’ and ownership of the process by all the staff.
- ItemISO 9001 accreditation in an R&D environment - is it possible?(International Atomic Energy Agency, 2004-10-24) Szymczak, R; Henderson-Sellers, A; Lowson, RT; Chisari, RThe Australian Nuclear Science and Technology Organisation (ANSTO) is Australia's national nuclear organisation and its centre of Australian nuclear expertise. ANSTO is in the process of replacing its 1950’s, 15 MW, high flux (up to 1015 n cm-2 s-1) reactor with a new reactor which will allow it to continue its cutting edge nuclear science and radiopharmaceutical production well into the 21st century. A ministerial requirement for licensing the facility is ISO 9001 accreditation of its quality management system. The accreditation process has been staggered at ANSTO. Individual divisions are attaining ISO 9001 accreditation separately, leading up to site-wide accreditation of an overarching ANSTO Business Management System. ANSTO Environment is the largest multidisciplinary environmental research group in Australia and the largest R & D unit at ANSTO, comprising around 150 biologists, chemists, engineers, geophysicists, meteorologists, microbiologists, oceanographers, physicists, and technicians (Fig. 1). ANSTO Environment operates and maintains a wide range of advanced nuclear and analytical facilities including three particle accelerators, a 10 MV Tandem accelerator, a 3 MV Van de Graaff accelerator and a newly acquired 2MV HVEE tandetron; a high current 50 kV Metal Vapour Vacuum Arc Ion Implantation (MEVVA) Facility; a Secondary Ion Mass Spectrometer (SIMS); and many other laboratory and field-based facilities. The objective of ANSTO Environment is to carry out a problem-focused, balanced program of strategic and applied research and development, using its nuclear science-based core expertise and closely-related techniques, to: assist the Commonwealth Government to further its national and international initiatives, and to protect and conserve the natural environment through sustainable development; · assist industry in advancing Australia's competitive position in the world economy; · ensure that environmental monitoring of nuclear facilities is effective in assuring operational adherence to sound environmental protection principles. “Make everything as simple as possible, but not simpler” Albert Einstein In February 2000 ANSTO Environment successfully acquired ISO 9001:2000 accreditation of its quality management system and was amongst the first organisations to adopt the new 2000 revision of the international ISO 9001 standard. The new standard allows a much more flexible and less prescriptive format for quality management systems however, in the absence of examples of accreditation in the R & D area, presented a challenge in concept, definition of process, buy-in by staff and subsequent maintenance of the successful certification. The ANSTO Environment Manual of Good Management Practice [1] outlines our identity, our vision, our core values, our responsibilities, our operational processes and our commitment to continual improvement via internal and external review. This paper is a description and discussion of the elements, concepts and process for achieving staff buy-in in the face of initial opposition. This included identifying those necessary elements of a good management system, rejection of pejorative dogma associated with ‘Quality’ and ownership of the process by all the staff.
- ItemA multi-tracer approach to quantifying groundwater inflows to an upland river; assessing the influence of variable groundwater chemistry(John Wiley & Sons, Inc., 2013-11-27) Atkinson, AP; Cartwright, I; Gilfedder, BS; Hofmann, H; Unland, NP; Cendón, DI; Chisari, RUnderstanding the behaviour and variability of environmental tracers is important for their use in estimating groundwater discharge to rivers. This study utilizes a multi-tracer approach to quantify groundwater discharge into a 27 km upland reach of the Gellibrand River in southwest Victoria, Australia. Ten sampling campaigns were conducted between March 2011 and June 2012, and the distribution of 222Rn activities, Cl and 3H concentrations imply the river receives substantial groundwater inflows. Mass balances based on 222Rn, Cl and 3H yield estimates of groundwater inflows that agree to within ± 12%, with cumulative inflows in individual campaigns ranging from 24 346 to 88 467 m3/day along the studied river section. Groundwater discharge accounts for between 10 and 50% of river flow dependent on the time of year, with a high proportion (>40 %) of groundwater sustaining summer flows. Groundwater inflow is largely governed by regional groundwater flowpaths; between 50 and 90% of total groundwater inflows occur along a narrow 5–10 km section where the river intersects the Eastern View Formation, a major regional aquifer. Groundwater 222Rn activities over the 16 month period were spatially heterogeneous across the catchment, ranging between 2000 Bq/m3 and 16 175 Bq/m3. Although groundwater 222Rn activities display temporal variation, spatial variation in groundwater 222Rn is a key control on 222Rn mass balances in river catchments where groundwater and river 222Rn activities are within an order of magnitude of each other. Calculated groundwater discharges vary from 8.4 to 15 m3/m/day when groundwater 222Rn activities are varied by ± 1 σ. © 2013 John Wiley & Sons, Ltd.
- ItemPhysical hydrogeology and environmental isotopes to constrain the age, origins, and stability of a low-salinity groundwater lens formed by periodic river recharge: Murray Basin, Australia.(Elsevier, 2010-01-15) Cartwright, I; Weaver, TR; Simmons, CT; Fifield, LK; Lawrence, CR; Chisari, R; Varley, SA low-salinity (total dissolved solids, TDS, <5000 mg/L) groundwater lens underlies the Murray River in the Colignan–Nyah region of northern Victoria, Australia. Hydraulic heads, surface water elevations, δ18O values, major ion geochemistry, 14C activities, and 3H concentrations show that the lens is recharged from the Murray River largely through the riverbank with limited recharge through the floodplain. Recharge of the lens occurs mainly at high river levels and the low-salinity groundwater forms baseflow to some river reaches during times of low river levels. Within the lens, flow through the shallow Channel Sands and deeper Parilla Sands aquifers is sub-horizontal. While the Blanchetown Clay locally separates the Channel Sands and the Parilla Sands, the occurrence of recently recharged low-salinity groundwater below the Blanchetown Clay suggests that there is considerable leakage through this unit, implying that it is not an efficient aquitard. The lateral margin of the lens with the regional groundwater (TDS >25,000 mg/L) is marked by a hectometer to kilometer scale transition in TDS concentrations that is not stratigraphically controlled. Rather this boundary represents a mixing zone with the regional groundwater, the position of which is controlled by the rate of recharge from the river. The lens is part of an active and dynamic hydrogeological system that responds over years to decades to changes in river levels. The lens has shrunk during the drought of the late 1990s to the mid 2000s, and it will continue to shrink unless regular high flows in the Murray River are re-established. Over longer timescales, the rise of the regional water table due to land clearing will increase the hydraulic gradient between the regional groundwater and the groundwater in the lens, which will also cause it to degrade. Replacement of low-salinity groundwater in the lens with saline groundwater will ultimately increase the salinity of the Murray River reducing its utility for water supply and impacting riverine ecosystems. © 2010, Elsevier Ltd.
- ItemRapid determination of uranium, thorium, plutonium, americium and strontium activities in water, soil and vegetation(South Pacific Radioactivity Association, 2008-11-25) Harrison, JJ; Zawadzki, A; Chisari, R; Wong, HKYA rapid technique for the isolation of U, Th, Pu, Am and Sr isotopes from environmental matrices has been established using resin cartridges and a vacuum box which are commercially available from Eichrom Technologies (Darien, IL, USA). Separation and isolation of the various elemental fractions from a single sub-sample is possible, thereby eliminating the need for multiple analyses. The time taken for concentration, separation, purification and source preparation is l0 hours for 12 samples, making this technique an excellent option when fast turn-around is required. The technique involves sample dissolution, concentration via calcium phosphate co-precipitation, resin separation and purification using TEVA TM, TRU TM and Sr-Spec TM resin cartridges and alpha spectrometry for U, Th, Pu and Am and Cerenkov counting for Sr. The technique was tested with various standard reference materials. Chemical yields are in the range of 80 — 95 % for all elemental actions, except for Sr which is typically 60%. Sample sizes of up to l0 litres for water, 5 grams for soil and 10 grams for ashed vegetation were able to be processed using this technique. Major matrix interferences that were encountered include potassium and strontium.
- ItemResidence times and mixing of water in river banks: implications for recharge and groundwater–surface water exchange(Copernicus Publications, 2014-12-12) Unland, NP; Cartwright, I; Cendón, DI; Chisari, RBank exchange processes within 50 m of the Tambo River, southeast Australia, have been investigated through the combined use of 3H and 14C. Groundwater residence times increase towards the Tambo River, which suggests the absence of significant bank storage. Major ion concentrations and δ2H and δ18O values of bank water also indicate that bank infiltration does not significantly impact groundwater chemistry under baseflow and post-flood conditions, suggesting that the gaining nature of the river may be driving the return of bank storage water back into the Tambo River within days of peak flood conditions. The covariance between 3H and 14C indicates the leakage and mixing between old (~17 200 years) groundwater from a semi-confined aquifer and younger groundwater (<100 years) near the river, where confining layers are less prevalent. It is likely that the upward infiltration of deeper groundwater from the semi-confined aquifer during flooding limits bank infiltration. Furthermore, the more saline deeper groundwater likely controls the geochemistry of water in the river bank, minimising the chemical impact that bank infiltration has in this setting. These processes, coupled with the strongly gaining nature of the Tambo River are likely to be the factors reducing the chemical impact of bank storage in this setting. This study illustrates the complex nature of river groundwater interactions and the potential downfall in assuming simple or idealised conditions when conducting hydrogeological studies.© Author(s) 2014. CC Attribution 3.0 License.
- ItemSample processing improvements for actinide analysis in low level samples(Australian Nuclear Science and Technology Organisation, 2021-11-17) Child, DP; Chisari, R; Hotchkis, MAC; Amatya Joshi, AA review of the performance statistics of actinides samples measured on the VEGA AMS facility at the Centre for Accelerator Science, ANSTO indicated that inadequate yield was being achieved on a particular subset of samples, namely plutonium isotopic measurements on chemistry blanks, and on low level “clean” low matrix samples (e.g. swipes and filters) when using our routine method [1]. Absolute yields of AMS targets are difficult to ascertain due to the use of isotopic dilution analysis since measurements yield only relative ratios, and variations in ion source output and ionisation efficiency between targets make it hard to compare absolute count rates. The measured count rates of plutonium isotopes in these samples however were routinely <50% of comparable calibration and tuning materials however leading us to conclude that there was a yield issue. Additionally, development was desired on a simplified processing method for multi-actinide extraction and isolation including U, Np, Pu and Am isotopes. An investigation was conducted into the chemical loss of Pu in blanks and low matrix samples during processing as well as to determine the efficacy of a proposed multi-actinide extraction method. This investigation was able to successfully reproduce the systematic loss of Pu during ion exchange extraction chromatography which was correlated to a lack of iron in the sample matrix and its utility as a redox agent for fixing Pu during separation. A revised sample processing method was then developed and tested, confirming an increase in Pu yield >90% for all sample types including blanks and low matrix materials using this revised method. This method employed a streamlined, single pass through utilising paired Eichrom UTEVA/TEVA pre-packed resin cartridges. Additionally >80% yield was achieved on a series of tests samples for U, Np, and Am tracers when employing this revised ion exchange separation method. This revised method will be presented along with data demonstrating the improved performance of this method.
- ItemSeparation and measurement of thorium, plutonium, americium, uranium and strontium in environmental matrices(Elsevier, 2011-10-01) Harrison, JJ; Zawadzki, A; Chisari, R; Wong, HKYA technique for the isolation of thorium (Th), plutonium (Pu), americium (Am), uranium (U) and strontium (Sr) isotopes from various environmental matrices has been adapted from a previously published method specific to water samples (Maxwell, 2006). Separation and isolation of the various elemental fractions from a single sub-sample is possible, thereby eliminating the need for multiple analyses. The technique involves sample dissolution, concentration via calcium phosphate co-precipitation, rapid column extraction using TEVA™, TRU™ and Sr-Spec™ resin cartridges, alpha spectrometry for Th, Pu, U and Am and Cerenkov counting for Sr. Various standard reference materials were analysed and chemical yields are in the range of 70–80% for Th, Am, U and Sr and 50–60% for Pu. Sample sizes of up to 10 L for water, 5 g for dry soil and sediment and 10 g for dry vegetation and seaweed can be processed using this technique. Copyright © 2010 Elsevier Ltd.
- ItemTracing carbon dynamics of groundwater in an evaporative environment(University of New South Wales and Australian Nuclear Science and Technology Organisation, 2015-07-08) Meredith, KT; Hollins, SE; Cendón, DI; Jacobsen, GE; Chisari, R; Levchenko, VANot supplied to the ANSTO Library
- ItemTracing groundwater flow in granite landscapes using δ18O, δ2H, 3H and 14C in the Upper Wimmera catchment, western Victoria(Australasian Environmental Isotope Conference, 2009-12-03) Hagerty, SK; Webb, JA; Dyson, P; Hocking, M; Jacobsen, GE; Chisari, R; Poulson, SPrevious work [1,2] has suggested that low relief, highly weathered granites in the Upper Wimmera in western Victoria are a significant source of salts exported to the catchment via groundwater, whereas high relief, less weathered granites are a source of fresh, good quality groundwater. In order to understand the processes of salt accumulation and movement in the catchment, groundwater recharge and flow has been investigated using the isotope ratios δ18O and δ2H, and the isotopes 3H and 14C. The Upper Wimmera forms part of the Murray Darling Basin [Figure 1], near the township of Ararat in western Victoria. The main geological units in the area are: the highly weathered and fractured basement of Ordovician aged metasediments, the Devonian aged granites that intruded the metasediments (with surrounding Quaternary-aged colluvial aprons), and the overlying Quaternary alluvial sediments of the Shepparton Formation. These three geological units also form the main aquifers of interest in the study area. Stable isotope ratios (δ18O and δ2H) suggest that the groundwater forms two groups; one that plots along the local meteoric water line and is relatively depleted in the heavy isotopes, and another that is more enriched in heavy isotopes, and plots on an evaporation trendline with a slope of 4.1. This latter group of groundwater is also much more saline on average (9.4 mS/cm compared to 2.6 mS/cm). However this is not due to open-water evaporation; the fractionation of isotopes seen in the evaporated water can only account for a loss of <10% of the original water body. However the high salinities observed require a loss of at least 99.5% of the original water body. Hence, the high salinity is likely due to transpiration by vegetation, as this process does not affect stable isotope ratios. Twenty three of these groundwater samples were analysed for 3H and 10 samples contained detectable tritium, suggesting that these samples are ‘modern’ (less than ~50 years old). All of these 10 samples are in the group of groundwater that has undergone evaporation, suggesting that this group is also younger on average. The radiocarbon data agrees with the tritium data; 38 samples were analysed for 14C and the samples in the group of evaporated groundwater are younger on average (78 pMC compared to 60 pMC). The radiocarbon data also shows that vertical flow is an important component of the flow system in weathered granite colluvium, and to a lesser extent in the Ordovician basement. However vertical flow does not appear to be a significant component in the Shepparton Formation.