Browsing by Author "Grierson, P"

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    Assessing the performance of blended byproduct caps for revegetation and closure of tailings storage facilities
    (Australian Centre for Geomechanics, 2022) Taki, G; Grierson, P; Saini, N; Brand, HEA; Murphy, DV; Santini, T
    Establishment of a vegetative cover during closure of tailings storage facilities is a critical component of the development of an environmentally sustainable landscape after mining. However, establishing vegetation on fresh bauxite residue (alumina refining tailings) is constrained by the high alkalinity, salinity, sodicity, elevated concentration of trace elements, and low plant available nutrients in residues. Currently, design of store and release vegetative covers for closure of tailings storage facilities in southwest Australia requires excavation of local soils and importing nutrients and mulch to apply on top of the tailings storage facility. Where the residues are mostly benign, in situ remediation (application of amendments directly into tailings to remediate the chemical and physical conditions) techniques may be a viable approach to create a plant growth medium for closure and revegetation. Nevertheless, using imported soils and blending products is expensive. Neutralisation of bauxite residue disposal areas (BRDAs) for capping offers a potential alternative and substantial cost savings, especially when coupled with incorporation of materials to develop an improved substrate for plant growth. In this study, a new technique called 'blended byproduct capping' was developed for closure of the South32 Worsley Alumina BRDA in southwest Australia. The blended byproduct cap uses bauxite processing residues that are blended with available byproducts readily and cheaply available onsite at the refinery. Three types of bauxite processing residue (bauxite residue fines, bauxite residue fines plus 10% bauxite residue sand, and bauxite residue sand) were blended with three byproducts (fly ash from power generation, eucalypt mulch from site clearing, and gypsum from other operations nearby) either alone or in combination to create 15 potential capping materials. These capping materials were leached under glasshouse conditions for 18 weeks (three wetting and drying cycles, three weeks each) to assess changes in pH, EC, total elements and nutrients. The three best performing capping materials in terms of chemo-physical properties were then selected for germination and growth experiments. Germination rates of barley (Hordeum vulgare), ryegrass (Lolium multiflorum) and clover (Trifolium spumosum) were assessed and then surviving plants grown for four weeks after the first visible leaf was observed. Root and shoot biomass were harvested at the end of the experiment. More than 90% of barley and ryegrass seeds germinated. Clover germination was less than 60% both blended byproduct caps and potting mix. However, biomass and growth rates were significantly lower in blended byproduct caps compared to potting mix for all three species. Overall, we conclude that blended byproducts caps show significant promise as a cost-effective alternative for BRDA closure and revegetation but require further optimisation. © Copyright 2025, Australian Centre for Geomechanics (ACG), The University of Western Australia. Open access courtesy of Mine Earth.
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    Nuclear science and the story of a preserved leaf from a copy of the great bible
    (Elsevier, 2013-04-01) Dodson, JR; Grierson, P; Bennett, JW; de Howard, SM; Wong, HKY
    Three pressed leaves of Ulmus glabra (Wych Elm) were found within the pages of a copy of the Great Bible in the Library of the University of Western Australia. The Bible dates from AD 1540 and was originally housed at Ely Cathedral in Cambridgeshire. A radiocarbon age on one of the leaves found it was about as old as the Great Bible itself, and stable C and N isotope and neutron activation analyses were carried out on the same leaf. The δ15N values were elevated and the content of iron, arsenic, bromine, silver, gold and mercury were relatively high. These analyses are consistent with an environment where water logging is present, as at Ely at the time, and the silver and gold content are probably consistent with the cathedral setting. The mercury was found to be associated with the red ink in the Bible. It is intriguing to ponder why Wych elm leaves were placed in the Bible, especially in the light that a copy of an original edition of the King James version of the Bible from Ely, also in the library in Perth has many dozens of U. glabra leaves also preserved within in its pages.© 2012, Elsevier Ltd.
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    Towards the development of fire proxies in speleothems using geochemical signatures in ashes from bushfires
    (Australasian Quaternary Association Inc., 2022-12-06) Campbell, M; McDonough, LK; Naeher, S; Treble, PC; Grierson, P; Sinclair, D; Howard, DL; Baker, AA
    Our knowledge of past fire regimes is limited by short observational records. Proxy archives (such as sediment cores, ice cores, speleothems, and tree scars) are used to extend these records and develop a better understanding of past fire regimes. Recently, stalagmites (i.e., cave deposits), have been shown to record past fire events, and it is possible that they include other attributes of the fire regime (e.g. burn severity). Stalagmite fire proxies are both chemical (e.g. oxygen isotope composition of calcite, and nutrient and trace metal concentrations), and physical (e.g. growth rate, fabric). Trace metals and nutrients are leached from ash and subsequently transported to the stalagmite via hydrological pathways. We collected ash from four Australian karst sites which experienced fires in recent years (2019 and 2022). Ash chemical composition was determined by analysis of leachates (inorganic chemistry) and by analysis of the ash itself (organic biomarker concentrations of a subset of the ash dataset). The concentrations of inorganic components (e.g. of trace metals strontium and magnesium) show a clear difference between more- and less-combusted materials, as inferred by ash colour. Common fire biomarker concentrations (e.g. polycyclic aromatic hydrocarbons and levoglucosan) showed no clear relationship with inferred burn severity. Together, this has implications for the use of both organic and inorganic fire proxies in stalagmites and other sedimentary proxy archives. Inorganic ash geochemistry results will be used to contextualise changes in stalagmite geochemistry from Western Australian stalagmites (as measured by LA-ICP-MS and Synchrotron micro-XFM) which experienced bushfires during the satellite era. We aim to determine whether stalagmite chemistry can be used as a proxy for burn severity.
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    Towards the development of fire proxies in speleothems using geochemical signatures in ashes from bushfires
    (Australasian Quaternary Association Inc., 2022-12-06) Campbell, M; McDonough, LK; Naeher, S; Treble, PC; Grierson, P; Sinclair, D; Howard, DL; Baker, AA
    Our knowledge of past fire regimes is limited by short observational records. Proxy archives (such as sediment cores, ice cores, speleothems, and tree scars) are used to extend these records and develop a better understanding of past fire regimes. Recently, stalagmites (i.e., cave deposits), have been shown to record past fire events, and it is possible that they include other attributes of the fire regime (e.g. burn severity). Stalagmite fire proxies are both chemical (e.g. oxygen isotope composition of calcite, and nutrient and trace metal concentrations), and physical (e.g. growth rate, fabric). Trace metals and nutrients are leached from ash and subsequently transported to the stalagmite via hydrological pathways. We collected ash from four Australian karst sites which experienced fires in recent years (2019 and 2022). Ash chemical composition was determined by analysis of leachates (inorganic chemistry) and by analysis of the ash itself (organic biomarker concentrations of a subset of the ash dataset). The concentrations of inorganic components (e.g. of trace metals strontium and magnesium) show a clear difference between more- and less-combusted materials, as inferred by ash colour. Common fire biomarker concentrations (e.g. polycyclic aromatic hydrocarbons and levoglucosan) showed no clear relationship with inferred burn severity. Together, this has implications for the use of both organic and inorganic fire proxies in stalagmites and other sedimentary proxy archives. Inorganic ash geochemistry results will be used to contextualise changes in stalagmite geochemistry from Western Australian stalagmites (as measured by LA-ICP-MS and Synchrotron micro-XFM) which experienced bushfires during the satellite era. We aim to determine whether stalagmite chemistry can be used as a proxy for burn severity.
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    Tracking down carbon inputs underground from an arid zone Australian calcrete
    (Public Library of Science (PLOS), 2020-08-28) Saccò, M; Blyth, AJ; Humphreys, WF; Middleton, JA; White, NE; Campbell, M; Mousavi-Derazmahalleh, M; Laini, A; Hua, Q; Meredith, KT; Cooper, SJB; Griebler, C; Allard, S; Grierson, P; Grice, K
    Freshwater ecosystems play a key role in shaping the global carbon cycle and maintaining the ecological balance that sustains biodiversity worldwide. Surficial water bodies are often interconnected with groundwater, forming a physical continuum, and their interaction has been reported as a crucial driver for organic matter (OM) inputs in groundwater systems. However, despite the growing concerns related to increasing anthropogenic pressure and effects of global change to groundwater environments, our understanding of the dynamics regulating subterranean carbon flows is still sparse. We traced carbon composition and transformations in an arid zone calcrete aquifer using a novel multidisciplinary approach that combined isotopic analyses of dissolved organic carbon (DOC) and inorganic carbon (DIC) (δ13CDOC, δ13CDIC, 14CDOC and 14CDIC) with fluorescence spectroscopy (Chromophoric Dissolved OM (CDOM) characterisation) and metabarcoding analyses (taxonomic and functional genomics on bacterial 16S rRNA). To compare dynamics linked to potential aquifer recharge processes, water samples were collected from two boreholes under contrasting rainfall: low rainfall ((LR), dry season) and high rainfall ((HR), wet season). Our isotopic results indicate limited changes and dominance of modern terrestrial carbon in the upper part (northeast) of the bore field, but correlation between HR and increased old and 13C-enriched DOC in the lower area (southwest). CDOM results show a shift from terrestrially to microbially derived compounds after rainfall in the same lower field bore, which was also sampled for microbial genetics. Functional genomic results showed increased genes coding for degradative pathways—dominated by those related to aromatic compound metabolisms—during HR. Our results indicate that rainfall leads to different responses in different parts of the bore field, with an increase in old carbon sources and microbial processing in the lower part of the field. We hypothesise that this may be due to increasing salinity, either due to mobilisation of Cl- from the soil, or infiltration from the downstream salt lake during HR. This study is the first to use a multi-technique assessment using stable and radioactive isotopes together with functional genomics to probe the principal organic biogeochemical pathways regulating an arid zone calcrete system. Further investigations involving extensive sampling from diverse groundwater ecosystems will allow better understanding of the microbiological pathways sustaining the ecological functioning of subterranean biota. © 2020 Saccò et al