Browsing by Author "Harle, KJ"
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- ItemBuilding a future on knowledge from the past: what paleo-science can reveal about climate change and its potential impacts in Australia(Commonwealth Scientific and Industrial Research Organisation, 2005-06) Harle, KJ; Etheridge, DM; Whetton, P; Jones, R; Hennessy, K; Goodwin, ID; Brooke, BP; van Ommen, TD; Barbetti, M; Barrows, TT; Chappell, J; De Deckker, P; Fink, D; Gagan, MK; Haberle, SG; Heijnis, H; Henderson-Sellers, A; Hesse, PP; Hope, GS; Kershaw, P; Nicholls, NIn Australia, high quality instrumental climate records only extend back to the late 19th century and therefore only provide us with a brief snapshot of our climate, its mean state and its short-term variability. Palaeo-records extend our knowledge of climate back beyond the instrumental record, providing us with the means of testing and improving our understanding of the nature and impacts of climate change and variability in Australia. There is a vast body of palaeo-records available for the Australian region (including Antarctica), ranging from continuous records of sub-decadal up to millennial scale (such as those derived from tree rings, speleothems, corals, ice cores, and lake and marine sediments) through to discontinuous records representing key periods in time (such as coastal deposits, palaeo-channels, glacial deposits and dunes). These records provide a large array of evidence of past atmospheric, terrestrial and marine environments and their varying interactions through time. There are a number of key ways in which this evidence can, in turn, be used to constrain uncertainties about climate change and its potential impacts in Australia.
- ItemHuman activity and climate variability project: annual report 2001.(Australian Nuclear Science and Technology Organisation, 2002-01) Harle, KJ; Heijnis, H; Henderson-Sellers, A; Sharmeen, S; Zahorowski, WKnowledge of the state of the Australian environment including natural climate variability prior to colonial settlement is vital if we are to define and understand the impact of over two hundred years of post-industrial human activity on our landscape. ANSTO in conjunction with university partners is leading a major research effort to provide natural archives of human activity and climate variability over the last 500 years in Australia utilising a variety of techniques including lead-210 and radiocarbon dating and analyses of proxy indicators (such as microfossils) as well as direct evidence (such as trace elements) of human activity and climate variability. The other major project objectives were to contribute to the understanding of the impact of human induced and natural aerosols in the East Asian region on climate through analysis and sourcing of fine particles and characterisation of air samples using radon concentrations and to contribute to the improvement of land surface parameterisation schemes and investigate the potential to use stable isotopes to improve global climate models and thus improve our understanding of future climate.
- ItemHuman activity and climate variability project: annual report 2002.(Australian Nuclear Science and Technology Organisation, 2002-11) Chambers, SD; Harle, KJ; Sharmeen, S; Zahorowski, W; Cohen, DD; Heijnis, H; Henderson-Sellers, AThis project aims to utilise nuclear techniques to investigate evidence of human activity and climate variability in the Asia Australasian regions. It was originally designed to run over three years, commencing July 1999, with three parallel research tasks: Task 1: Past -- Natural archives of human activity and climate variability; Task 2: Present -- Characterisation of the global atmosphere using radon and fine particles; Task 3: Future -- Climate modelling: evaluation and improvement; Main project objectives -- To determine what proportions of changes in natural archives are due to human activity and climate variability; -- To contribute to the understanding of the impact of human induced and natural aerosols in the East Asian region on climate through analysis and sourcing of fine particles and characterisation of air samples using radon concentrations; -- To contribute to the improvement of land surface parameterisation schemes and investigate the potential to use isotopes to improve global climate models and thus improve our understanding of future climate. Significant project outcomes -- An improved understanding of natural and anthropogenic factors influencing change in our environment; -- A better understanding of the role of aerosols in climate forcing in the Asian region, leading to improved ability to predict climate change; -- An improved understanding of long term changes in the concentrations of trace species in the atmosphere on a regional and a global basis and their use in model evaluation; -- Improved understanding of the impact of different land-surface schemes on simulations by atmospheric models. The next two years of the project Our new and extended projects efforts include: 1) Aligning ourselves with the recently developed mission of the IGBP/PAGES research program 'Human Interactions on Terrestrial Ecosystems' and co-ordinating the Australasian research effort. Further research will focus on: (1) How widespread and reliable are evidence of major climatic events, such as storms and El Nino/La Nina cycles, in natural archives? This would require more natural archives to be examined from northern Australia and also records to be obtained from southern Australia. (2) The spatial extent of mining related pollutants, in the form of aerosol particles, which is of importance to managing the waste in the future. A combination of aerosol and archival studies will address this issue. In Summary: To achieve these extended goals we successfully gained another two years of further support for our project.
- ItemLithological and geochemical record of mining-induced changes in sediments from Macquarie Harbour, southwest Tasmania, Australia.(Springer, 2010-08) Augustinus, PC; Barton, CE; Zawadzki, A; Harle, KJMacquarie Harbour in southwest Tasmania, Australia, has been affected severely by the establishment of mines in nearby Queenstown in the 1890s. As well as heavy metal-laden acid rock drainage from the Mount Lyell mine area, over 100 Mt of mine tailings and slag were discharged into the Queen and Ring Rivers, with an estimated 10 Mt of mine tailings building a delta of ca. 2.5 km2 and ca. 10 Mt of fine tailings in the harbour beyond the delta. Coring of sediments throughout Macquarie Harbour indicated that mine tailings accreted most rapidly close to the King River delta source with a significant reduction in thickness of tailings and heavy metal contamination with increasing distance from the King River source. Close to the King River delta the mine tailings are readily discriminated from the background estuarine sediments on the basis of visual logging of the core (laminations, colour), sediment grain size, sediment magnetic susceptibility and elemental geochemistry, especially concentrations of the heavy metals Cu, Zn and Pb. The high heavy metal concentrations are demonstrated by the very high contamination factors (CF > 6) for Cu and Zn, with CF values mostly >50 for Cu for the mine-impacted sediments. Although the addition of mine waste into the King River catchment has ceased, the catchment continues to be a source of these heavy metals due to acid rock drainage and remobilisation of mine waste in storage in the river banks, river bed and delta. The addition of heavy metals to the harbour sourced from the Mount Lyell mines preceded the advent of direct tailings disposal into the Queen River in 1915 with the metals probably provided by acid rock drainage from the Mount Lyell mining area. © 2010, Springer.
- ItemMyall Lakes – isotope dating of short term environmental changes in a coastal lake system - anthropogenic pressures causing blue- green algae outbreaks in a national park(International Atomic Energy Agency, 2004-10-25) Flett, I; Heijnis, H; Harle, KJ; Skillbeck, GThe Myall Lakes system, 50 km North of Newcastle, Australia, is a barrier lake system covering 10000ha, and is brackish (ranging from Oligohaline to Mesohaline under the Venice System classification). The Myall Lakes system is far less disturbed than similar coastal lakes, and as an important migratory bird habitat, they are protected under the RAMSAR agreement. They are also fully encompassed by the Myall Lakes National Park, declared in 1972, and are important to the local tourism and fisheries industries. Only two small streams provide freshwater input therefore water-retention time is of concern, because any changes to nutrient regimes, or pollution in the catchment affecting the Lakes, may take a long time to be corrected. In recent summers a series of cyanobacteria blooms have occurred which may indicate that human activities such as agriculture and recreational boating and fishing are affecting the Myall Lakes. Four sediment cores, up to 95cm long, were collected and sub-sampled for trace elements, palynological assemblages, sediment grain size and organic/carbonate content. Lead-210 (210Pb) was used to determine sedimentation rates and construct a chronology. Fossilised algal remains, specifically the akinetes of cyanobacteria, were used to estimate previous algal populations in the lake system. This technique has the potential to be an important tool in not only historical environmental reconstruction but also in catchment management. Results indicate that there have been cyclical fluctuations in the populations of aquatic plants and algae throughout recent history
- ItemWestern Tasmania - a reconstructed history of wide-spread aerial pollution in a formerly "pristine" area - the use of 210Pb & 226Ra in retrospective monitoring of the environment(International Atomic Energy Agency, 2006) Heijnis, H; Harle, KJ; Harrison, JJThe study of global climate change recorded and archived in corals, tree-rings, glacial deposits, ocean sediments and ice cores reveals a complex scale of variations ranging from major glacial cycles (100,000 years), millennial (1,000 years) timescales and even decadal changes (i.e. ENSO). ‘Global patterns’ of climate cycles are inferred principally from Northern Hemisphere records and modelling approaches. For the major glacial- interglacial cycles this seems to be reliable – however data is now emerging that on the millennial scale of climate change particularly over the Last Glacial-Interglacial Transition (20,000 to 10,000 years ago) and through the Holocene, things are not so simple, let alone ‘global’. Critical questions are now being asked as to the synchronicity, intensity and mode of abrupt climate patterns across Earth’s hemispheres. However, with a paucity of Southern Hemisphere studies, answers are not readily available. Long-lived cosmogenic radioisotopes, such as 10Be, 14C, 26Al and 36Cl, are produced by cosmic ray bombardment of Earth’s atmosphere and lithosphere. The measurement by Accelerator Mass Spectrometry of concentration profiles of these radioactive ‘clocks’ and ‘tracers‘ in climate archives is emerging as key parameters to provide the essential chronological frameworks and rates of climate processes to address these vexing questions. This talk will present 2 examples of cosmogenic isotopes in the study of Southern Hemisphere climate change records. The first relates to application of in-situ produced 10Be and 26Al in glacially transported surface rocks to determine the chronology of glacial cycles in Tasmania and New Zealand during the last deglaciation. The Younger Dryas (YD) is a major short term and intense climatic reversal towards colder temperatures occurring between 11,500-12,800 cal year BP superimposed on the last deglaciation. Its presence has now been identified in most, if not all, of the northern hemisphere archives of late Quaternary climate change. Recently, investigations have centered on searching for a cooling reversal coeval with the YD chronozone in Southern Hemisphere archives. The implications of such an appraisal are significant as a positive outcome directly supports the presence of a global triggering mechanism coupled with climate change synchronicity across the equator. The second deals with a detailed comparison in the variations of atmospheric radiocarbon recorded in tropical tree rings from Thailand to that in mid- latitude Huon Pine tree-rings from Tasmania during the Little Ice Age (LIA) from ~1600-1800 AD. Such a study allows a better understanding of the mechanisms that control regional 14C atmospheric concentration offsets in terms of atmospheric mixing and the role of the Asian monsoon during periods of known Northern Hemisphere climate cooling such as occurred in the LIA.
- ItemWestern Tasmania - a reconstructed history of wide-spread aerial pollution in a formerly "pristine" area - the use of 210Pb & 226Ra in retrospective monitoring of the environment(International Atomic Energy Agency, 2004-10-24) Heijnis, H; Harle, KJ; Harrison, JJUsing nuclear dating techniques and trace metal analysis of sediment cores an environmental history of Western Tasmania was reconstructed. Seven sites were selected to encompass a range of environments from highly human impacted to relatively pristine. They include subalpine tarns and coastal lowland lakes. Disturbed areas have been impacted by activities associated with logging, mining and colonial settlement while the near-pristine sites were located in areas with little disturbance, such as the Tasmanian Wilderness World Heritage Area. Lead-210 (210Pb) and radium-226 (226Ra), both naturally occurring radioisotopes, were used to determine sediment accumulation rates and establish chronologies. Sediment cores collected from near pristine lakes were expected to reveal low and relatively constant trace metal concentrations consistent with areas subject to little to no human impact. However, evidence from these sediment cores revealed trace metal concentrations peaked in the 1960s and then began to decrease in the 1980s. This trend was also discovered, to a greater extent, in sediment cores collected from human impacted sites particularly those surrounding the Central Western mining area. Of all the metals investigated, lead (Pb), arsenic (As), tin (Sn) and copper (Cu) were found to show the most marked increases. Temporal increases in metal concentrations were found to be a result of mining activities in Central Western Tasmania. Evidence for the most significant increase as shown by the trace metal profile coincided with the escalation of open cut mining while decreases in metal concentrations around 1980 coincided with the cessation of mining. Spatially, the dispersal was predominantly due to aerial pollution as concentrations of Pb, As, Sn and Cu were highest close to the mining areas although sites as far as 150 kilometres away showed marked metal concentration increases above background levels around 1960.