Browsing by Author "Goralewski, J"

Now showing 1 - 4 of 4
  • Thumbnail Image
    Item
    Another piece of the Southern Hemispheric puzzle: developing a high-resolution climate record for multiple glacial cycles in eastern Australia
    (International Union For Quaternary Research (INQUA), 2015-08-01) Kermode, SJ; Shulmeister, J; Mueller, D; Goralewski, J; Gadd, PS; Chang, J; Heijnis, H; Cohen, TJ
    Understanding likely climate change and subsequent environmental responses is critical to our long term ability to manage and mitigate such changes. Investigations of previous responses to notable (either abrupt or large scale) climate change provides boundary conditions and targets that can be used to both validate and parameterize the climate models used to predict future change. High-resolution records from the Southern Hemisphere lag considerably behind available data from the Northern hemisphere, and are particularly sparse in Australia. Given that most (>80%) of Australia’s population, industry and agriculture lie in the mid-latitudes between Southern Queensland and Tasmania, one might expect that past climate changes from this region are well understood, but this is not the case. Long, high resolution records are needed to address this gap. An 11 m core has been collected from a permanent swamp/lagoon (Mountain Lagoon), in the Blue Mountains west of Sydney, which appears to span at least one complete glacial cycle. This is potentially the most continuous record recovered from this part of SE Australia. Much of the record is at least moderately organic and preliminary sedimentary and Itrax data indicate that significant environmental changes are recorded. Multi-proxy investigations including pollen, diatoms, charcoal and phytoliths are planned and the chronology will be underpinned using OSL and radiocarbon dating. The focus of the investigation will be to develop climatologies for the Sydney region during the last glacial cycle. The Mountain Lagoon project will consequently contribute to understanding how climate systems in SE Australia respond to large scale global change on Milankovitch time scales. By determining the climate response in Australia to these changes we will help predict future response in rainfall and temperature to human-induced and natural climate change.
  • No Thumbnail Available
    Item
    ITRAX core scanner capabilities combined with other geochemical and radiochemical techniques to evaluate environmental changes in a local catchment, South Sydney, NSW, Australia
    (Springer, 2015-07-22) Gadd, PS; Heijnis, H; Chagué-Goff, C; Zawadzki, A; Fierro, D; Atahan, P; Croudace, IW; Goralewski, J
    In this study, geochemical and radioanalytical techniques are used together with the ITRAX core scanner to reconstruct the environmental history of Mill Creek catchment, located on the south-western fringes of Sydney. This ITRAX capability study was undertaken to investigate environmental changes in a local catchment which incorporates a nuclear research reactor, a small legacy nuclear waste burial ground, extensive new housing developments, a large rubbish tip, as well as quarries. This catchment changed from being near pristine in the 1950’s to an extensively developed catchment with wide ranging land uses. This rapid development has led to silting up near the mouth of the creek, and there is also evidence of periodic siltation triggered by catchment disturbance from local bushfires, associated with peaks in magnetic susceptibility. The sedimentary environment changed from a creek system to a mangrove swamp and saltmarsh. Changes in Cu, Zn and Pb distributions over the last 60 years suggest an anthropogenically-driven input, although concentrations measured by WD-XRF indicate that the level of urbanisation is lower in the study area than in many of the more industrialised and urbanised neighbouring catchments of Sydney estuary and Botany Bay. The activities of 239 + 240Pu and 241Am in the sediment are below detection limit, which strongly suggests that the legacy nuclear waste has not entered the creek system. © 2015, Springer.
  • No Thumbnail Available
    Item
    Late Holocene environmental changes and anthropogenic impact in Dee Why Lagoon, New South Wales
    (Taylor & Francis, 2019-02-02) Chagué, C; Edwards, D; Ruszczyk, J; Gadd, PS; Zawadzki, A; Jacobsen, GE; Fierro, D; Goralewski, J; Clement, L; Albani, A
    Late Holocene environmental changes were examined in Dee Why Lagoon, New South Wales, based on the sedimentological, geochemical and geochronological analysis of six cores collected from the fluvial delta and lagoon basin. The lagoon formed about 7300–7200 cal yr BP, following the post-glacial marine transgression and establishment of a sand barrier. Infilling of the lagoon occurred at a rate of 0.09–0.15 mm/yr until about 3300–3200 cal yr BP, when the barrier closed, resulting in mostly freshwater conditions, as evidenced by a change from pyrite-rich units to sediment containing little sulfur and a lack of foraminifera. Sedimentation rates increased to 0.23 then 0.43 mm/yr until about 100 years ago. Post-European land clearance led to an increase in sedimentation rates to 1.0–1.3 mm/yr on the fluvial delta, which are lower than those from other wave-dominated estuaries in New South Wales as well as those estimated by previous studies in Dee Why Lagoon. Our study shows that the fluvial delta started forming much earlier than originally thought, based on results of radiometric dating, and confirmed using sedimentological and geochemical data, as well as a critical examination of historic aerial photographs. Human impact has resulted in an increase in heavy metal (Cu, Pb, Zn) and metalloid (As) concentrations in the recent sediment, most likely attributed to stormwater discharge. Pb and As concentrations are above the ANZECC high sediment quality guideline values at the site closest to the stormwater outlet, with As-based pesticides one of the possible sources. Using the mean enrichment quotient, which is based on normalised Cu, Pb and Zn concentrations over their normalised background concentrations, we show that the surface sediments in Dee Why Lagoon are severely enriched, reflecting the recent anthropogenic impact that has also led to an increase in sedimentation rates. Copyright © 2019 Informa UK Limited
  • Thumbnail Image
    Item
    Radioanalytical method developments to determine polonium-210 and radium-226 activities in bone samples to be used in forensic studies
    (Australian Nuclear Science and Technology Organisation, 2012-10-16) Zawadzki, A; Goralewski, J; Heijnis, H; Fierro, D; Lee, G; Watling, J; May, C
    210Pb dating on human skeletal remains has been proposed in forensic studies for the determination of time since death (TSD) or post-mortem intervals. 210Pb and its granddaughter 210Po enter the human body from two main sources, direct ingestion in foodstuffs and the decay of ingested 226Ra which is retained in the bone and bony tissue [1]. One of the methods in dating human bones is based on the decay unsupported 210Pb (total 210Pb minus supported 210Pb) since the time of death. Total 210Pb can be determined from 210Pb granddaughter, 210Po, and supported 210Pb from 210Pb grandparent, 226Ra. A reliable and sensitive method of determining 210Po and 226Ra activities in bone samples is required in order to produce reliable postmortem intervals. A method was developed, using pig bone samples, to analyse these radionuclides by alpha spectrometry. In this presentation, the methodology employed is discussed, along with some of the difficulties encountered and how these were overcome.