Browsing by Author "Williams, JP"

Now showing 1 - 6 of 6
  • No Thumbnail Available
    Item
    Can structural or functional changes following traumatic brain injury in the rat predict epileptic outcome?
    (John Wiley and Sons Inc., 2013-07-01) Shultz, SR; Cardamone, L; Liu, YR; Hogan, RE; Maccotta, L; Wright, DK; Zheng, P; Koe, A; Grégoire, MC; Williams, JP; Hicks, RJ; Jones, NC; Myers, DE; O'Brien, TJ; Bouilleret, V
    Posttraumatic epilepsy (PTE) occurs in a proportion of traumatic brain injury (TBI) cases, significantly compounding the disability, and risk of injury and death for sufferers. To date, predictive biomarkers for PTE have not been identified. This study used the lateral fluid percussion injury (LFPI) rat model of TBI to investigate whether structural, functional, and behavioral changes post‐TBI relate to the later development of PTE. © 2013 International League Against Epilepsy
  • Thumbnail Image
    Item
    Deep meteoric leaching and its implications for groundwater residence time in a dissected Hawkesbury sandstone plateau (Kulnura-Mangrove Mountain Aquifier, NSW, Australia)
    (Geological Society of Australia, 2014-07-07) Hankin, SI; Cendón, DI; Williams, JP; Graham, IT
    In the Kulnura-Mangrove region, groundwater extraction for potable water supply and for industrial activities such as farming and mining, can co-exist provided the main recharge areas are protected, pumping does not exceed recharge, and knowledge of the basic parameters within the aquifer are known through appropriate studies. In this study, groundwater residence time in the Kulnura-Mangrove Mountain aquifers was assessed over multiple years using environmental tracers (H2O stable isotopes, δ13CDIC, 3H, 14C and 87Sr/86Sr) and general hydrogeochemistry. The Kulnura-Mangrove Mountain aquifer is mostly hosted in its upper part by the Hawkesbury Sandstone, where intense and deep sandstone weathering profiles have resulted in enhanced groundwater storage. Weathering reactions favoured by the local geological setting has transformed the original Hawkesbury Sandstone quartz arenite into a semisolid or friable sandstone with variable weathering depths where most of the original carbonate cements have been leached, resulting in higher porosity and permeability. XRD analyses show an upper zone down to ~50 m and even 90 m in some areas where all carbonates and probably feldspars have been dissolved and the derived products goethite and kaolinite have formed. With depth, carbonates, mostly siderite, are present representing fresher or less-weathered sandstone. Isotopic analysis of dispersed carbonates shows consistent values with their depositional environment and devoid of 14C. The study incorporated 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 are differentiated in areas not disturbed by groundwater extraction. A shallow zone where oxidising Na–Cl-type waters with low pH and EC contain 3H and 14C activities consistent with very modern groundwater affected by bomb pulse signatures (up to 116.9 pMC). In this shallow zone the original Hawkesbury Sandstone has been deeply weathered, enhancing storage capacity for groundwater down to ~50 m in most areas and up to ~90 m in the Peats Ridge zone. The deeper groundwater zone is also relatively oxidising with a tendency towards Ca–HCO3 type waters, higher pH and EC, no 3H and 14C activities consistent with residence times from 0.9 to 11.8 ka BP, depending on the specific areas. The original sandstone is less weathered with depth, favouring the dissolution of dispersed carbonates and a transition to a fractured-rock flow type aquifer, both impacting on groundwater mean residence times.
  • Thumbnail Image
    Item
    Groundwater modernisation and associated chemical changes in a Hawkesbury sandstone acquifer (Kulnura–Mangrove Mountain, NSW, Australia)
    (Geological Society of Australia, 2014-07-07) Cendón, DI; Hankin, SI; Williams, JP; Graham, IT
    Land and groundwater usage has the potential to influence the groundwater chemistry of an aquifer. Progressive modernisation of groundwater, variation in pH and associated water/rock reactions have been identified in areas of the Kulnura–Mangrove Mountain aquifer (KMMA). Detailed temporal and spatial sampling of groundwater (general hydrogeochemistry, H2O stable isotopes, δ13CDIC 3H, 14C and 87Sr/86Sr) revealed important inter-annual variations driven by groundwater extraction showing a progressive influx of modern groundwater at >100 m depth in some areas. In the Peats Ridge plateau, shallow groundwater samples show high 14C bomb pulse signatures, indicating modern recharged groundwater, while deeper groundwater shows a yearly increase in modern 14C inputs, instead of lower a14C values, as observed in other wells and generally expected. Values evolved from 36.1 pMC (5.2 ka BP) in 2007, to modern values of 103 pMC in 2010 with the latest sample in 2012 failing to graphitise, probably due to the high CO2 generally linked in the study area with modern groundwater. The 3H activities have also evolved from values below the quantification limit in 2007 and 2008 to values of ~1.1 TU in 2012. The minimal buffering capacity of the quartzose sandstone aquifer, at least in its upper zone where dispersed carbonates have long been dissolved, means that shallow groundwater generally has a low pH. Limited historical data (1998) shows higher pH for all samples compared to the same wells analysed for this work. However, it is in the central area where pH changes are most evident. During 2007, groundwater pH was similar to that expected for samples at similar depths with consistent groundwater residence times; however, successive samples show a shift to lower pH similar to those found in much shallower samples, as well as modern groundwater ages. Groundwater extraction is therefore causing an inflow of modern waters at depth with associated acidification. An important consequence of acidification is the capacity to mobilise trace metals. Of particular interest is aluminium as it has been linked to enhanced risks of cognitive decline for subjects with a high daily intake from drinking water (≥ 3.7 μM·day−1). Shallow samples in the Mangrove Mountain area and some of the deeper samples with Al concentrations of ~3.45 μM are a risk for average drinking water intakes. The movement of low pH shallow groundwater is causing an increase in Al concentrations, particularly in the central area of the KMMA, and this may be affecting groundwater for local consumption or that recovered in bottling plants. © Geological Society of Australia Inc
  • No Thumbnail Available
    Item
    Groundwater 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, R
    Groundwater 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
  • Thumbnail Image
    Item
    Groundwater residence time in the Kulnura-Mangrove Mountain Plateau (Gosford, NSW, Australia)
    (Australasian Environmental Isotope Conference, 2009-12-03) Cendón, DI; Hankin, SI; Williams, JP; Dimovski, C; Meredith, KT; Hughes, CE; Hollins, SE
    The Kulnura-Mangrove Mountain plateau consists of the catchments of Mangrove, Narara, Mooney Mooney, and Ourimbah Creeks, and Wyong River. Groundwater plays a key role in sustaining stream flow within these catchments. Estimates indicate up to 50% of annual stream flow is derived from baseflow. The local community water supply relies on the groundwater within the elevated Hawkesbury- Narrabeen sandstone plateau. Furthermore, the Gosford-Wyong Councils’ Water Authority (WSA) is the third largest in NSW and utilises many of the streams flowing from the sandstone plateau for municipal water supply. It is anticipated that the WSA will provide municipal water for 319 000 persons by the year 2010. The increasing volumes of groundwater being extracted and changing land use have the potential to cause damage to the fresh water aquifer through contamination and aquifer depletion. A hydrogeochemical survey (2006-2009) has been conducted in NSW Dept of Water and Energy (DWE) monitoring wells across the plateau in order to determine groundwater residence times. Groundwater was analysed for major ions, minor and trace elements, H2O 18O and 2H, 13CDIC, 87Sr/86Sr, 14CDIC, and 3H, and complemented with mineralogical and isotopic information obtained from soil and drill chips collected during well construction. Water stable isotopes confirm the meteoric origin of the groundwater with most values plotting on the local meteoric water line. Localised evaporative trends suggest recharge with evaporated groundwater stored in ponds. Shallow groundwaters have 3H and 14C activities consistent with modern recharge (Fig 1). Carbon “bomb pulse” signatures of up to 116.8 pmC are found in the central areas of the plateau. The thin soils, lack of carbonates in the intensely weathered near-surface Hawkesbury sandstone, and the shallow depth of the water samples is consistent with the 3H results measured, suggesting minimal dilution of the original 14C. Input of this data into a southern hemisphere bomb pulse model [1] suggest potential recharge during the 1990´s, coinciding with sustained wet conditions and above average rainfalls experienced during this period. Fig. 1. 14C vs 3H plot of groundwater samples in the Kulnura- Mangrove Mountain Plateau Deeper groundwaters have lower 14C and 3H activities in some cases close to background level (Fig. 1). The quantifiable 3H suggests residence times of <70 a. However, non-corrected 14C residence times are submodern (>500 a). This apparent discrepancy can be explained by either mixing with older waters or dissolution of carbonates. The good correlation of total dissolved inorganic carbon (TDIC) and Ca (R2=0.8), 13CTDIC in groundwater and mineralogy results from drill chips suggest that dissolution of dispersed carbonates is taking place. The deepest groundwaters show the most difference in residence time across the study area. The eastern and western plateaus yield old groundwater with 14C corrected residence times of around 9 ka and 4 ka respectively. However, the groundwater at equivalent depths in the central plateau was found to be considerably younger with residence times of <70 a.
  • No Thumbnail Available
    Item
    Progressive metabolic and structural cerebral perturbations following traumatic brain injury: an in vivo imaging study in the rat
    (Society of Nuclear Medicine, 2010-01-01) Liu, YR; Cardamone, L; Hogan, RE; Grégoire, MC; Williams, JP; Hicks, RJ; Binns, D; Koe, A; Jones, NC; Myers, DE; O'Brien, TJ; Bouilleret, DE
    Traumatic brain injury (TBI) has a high incidence of long-term neurologic and neuropsychiatric morbidity. Metabolic and structural changes in rat brains were assessed after TBI using serial 18F-FDG PET and 3-dimensional MRI in vivo. Methods: Rats underwent lateral fluid percussion injury (FPI; n = 16) or a sham procedure (n = 11). PET and MR images were acquired at 1 wk and at 1, 3, and 6 mo after injury. Morphologic changes were assessed using MRI-based regions of interest, and hippocampal shape changes were assessed with large-deformation high-dimensional mapping. Metabolic changes were assessed using region-of-interest analysis and statistical parametric mapping with the flexible factorial analysis. Anxiety-like behavior and learning were assessed at 1, 3, and 6 mo after injury. Results: PET analyses showed widespread hypometabolism in injured rats, in particular involving the ipsilateral cortex, hippocampus, and amygdalae, present at 1 wk after FPI, most prominent at 1 mo, and then decreasing. Compared with the sham group, rats in the FPI group had decreased structural volume which progressively increased over 3–6 mo, occurring in the ipsilateral cortex, hippocampus, and ventricles after FPI (P < 0.05). Large-deformation high-dimensional mapping showed evolving hippocampal shape changes across the 6 mo after FPI. Injured rats displayed increased anxiety-like behavior (P < 0.05), but there were no direct correlations between the severity of the behavior abnormalities and functional or structural imaging changes. Conclusion: In selected brain structures, FPI induces early hypometabolism and delayed progressive atrophic changes that are dynamic and continue to evolve for months. These findings have implications for the understanding of the pathophysiology and evolution of long-term neurologic morbidity following TBI, and indicate an extended window for targeted neuroprotective interventions. © 2010, Society of Nuclear Medicine