Browsing by Author "Markich, SJ"

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    Accumulation of radionuclide and metal contaminants in flesh and osteoderms of estuarine crocodiles (crocodylus porosus): pathways and histories of catchment-specific exposure
    (EDP Sciences, 2002-02) Jeffree, RA; Markich, SJ; Hammerton, KM; Russell, RA
    Flesh and osteoderms of estuarine crocodiles (C. porosus) from Kakadu National Park, Northern Australia, were analysed for a range of metals, including uranium, to assess their capability for accumulation, in relation to their catchment-specific exposure to i) uranium mine effluents and mineralisation and ii) lead shot ammunition through their consumption of fauna shot by the traditional owners of the Park. Uranium in osteoderms was significantly (P<0.05) elevated in the East Alligator River catchment, that contains the Ranger and Jabiluka uranium mine sites, relative to two other adjacent catchments. The mean concentrations of other elements in flesh and osteoderms were also significantly (P<0.05) different between catchments. Linear discriminant analysis was used to demonstrate that multi-element signatures in both flesh and osteoderms could be used to classify individual crocodiles to their respective catchments. This approach may be useful for the identification of source catchments of itinerant 'nuisance crocodiles' that find their way into Darwin Harbour, close to dense human habitation. Lead concentrations were significantly (P<0.05) enhanced in flesh and osteoderms of crocodiles sampled within two areas hunted with guns using Pb ammunition. Enhanced ratios of Pb:Ca in the annual laminations of their osteoderms are consistent with their history of continual exposure to elevated anthropogenic Pb sources. Subsequent experimental studies have demonstrated the ability of the crocodilian stomach to retain ingested Pb shot, that is readily solubilised and absorbed into the blood and then archived in the contemporary osteodermal lamination. © EDP Sciences, 2002
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    The Akoya pearl oyster shell as an archival monitor of lead exposure
    (Elsevier, 2006-09) MacFarlane, GR; Markich, SJ; Linz, K; Gifford, S; Dunstan, RH; O'Connor, W; Russell, RA
    The Akoya pearl oyster (Pinctada imbricata) was experimentally exposed to (a) constant levels of lead (Pb) at 180 μg L−1 for nine weeks, or (b) two short term (pulse) exposures of Pb at 180 μg L−1 (three weeks each) with an intervening depuration period (three weeks), to assess its utility as an (i) accumulative monitor of Pb contamination and an (ii) archival monitor for discriminating constant versus pulsed Pb exposure events. P. imbricata showed similar reductions in growth (based on shell morphology and wet weight) and Pb accumulation patterns for whole tissue and shell in response to both Pb exposure regimes. Thus the whole oyster was deemed an inappropriate accumulative monitor for assessing short-term temporal variation of Pb exposure and effect. However, using secondary ion mass spectrometry, Pb was shown to accumulate in the successively deposited nacreous layers of the shell of P. imbricata, documenting the exposure history of constant versus pulsed Pb events. Patterns of Pb deposition not only reflected the frequency of Pb exposure events but also their relative durations. Thus, the shell of P. imbricata may be employed as a suitable biological archive of Pb exposure. © 2005 Elsevier Ltd.
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    Comparative accumulation of Cd-109 and Se-75 from water and food by an estuarine fish (Tetractenos glaber)
    (Elsevier, 2008-01) Alquezar, R; Markich, SJ; Twining, JR
    Few data are available on the comparative accumulation of metal(loid)s from water and food in estuarine/marine fish. Smooth toadfish (Tetractenos glaber), commonly found in estuaries in south-eastern Australia, were separately exposed to radio-labelled seawater (14 kBq L-1 of Cd-109 and 24 kBq L-1 of Se-75) and food (ghost shrimps; Trypaea australiensis: 875 Bq g(-1) Cd-109 and 1130 Bq g(-1) Se-75) for 25 days (uptake phase), followed by exposure to radionuclide-free water or food for 30 days (loss phase). Toadfish accumulated Cd-109 predominantly from water (85%) and Se-75 predominantly from food (62%), although the latter was lower than expected. For both the water and food exposures, Cd-109 was predominantly located in the gut lining (60-75%) at the end of the uptake phase, suggesting that the gut may be the primary pathway of Cd-109 uptake. This may be attributed to toadfish drinking large volumes of water to maintain osmoregulation. By the end of the loss phase, Cd-109 had predominantly shifted to the excretory organs - the liver (81%) in toadfish exposed to radio-labelled food, and in the liver, gills and kidney (82%) of toadfish exposed to radio-labelled water. In contrast, Se-75 was predominantly located in the excretory organs (gills, kidneys and liver; 66-76%) at the end of the uptake phase, irrespective of the exposure pathway, with minimal change in percentage distribution (76-83%) after the loss phase. This study emphasises the importance of differentiating accumulation pathways to better understand metal(loid) transfer dynamics and subsequent toxicity, in aquatic biota. © 2007, Elsevier Ltd.
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    Crocodile bones as archives of pollution exposure: lead contamination in Kakadu National Park, and what's in Sweetheart's Osteoderms?
    (Australian Nuclear Science and Technology Organisation, 2001-08-23) Jeffree, RA; Markich, SJ; Hammerton, KM; Russell, RA
    Experimental findings made it then possible to evaluate the hypothesis that the estuarine crocodile osteodermal laminations would record enhanced blood lead concentrations resulting from the ingestion of lead shot. At about 140 days following lead shot ingestion, two osteoderms were removed from each exposed and control animal. SIMS analysis of Pb-208 and Ca-42 signal intensities was then performed on sections that were prepared and analysed using similar methods previously used on field-collected specimens (Twining et al., 1999). These initial findings are consistent with the hypothesis that incremental laminations of the osteoderm will archive a lead signal that responds to enhanced levels of lead in the animal's blood during its life. SEM analysis identified the laminated structure of the osteoderm, however microprobe analysis did not detect appreciable amounts of even Ca and P, although the organic matrix was obviously present. It is proposed that this anomalous result is due to the preparatory tanning of the skin, in acid solution, that could be expected to leach elements from the organic matrix. An analogy is drawn with the decalcified skeletons in the bodies of the Druid sacrifices due their deposition in acid swamp waters in the UK. The challenge is now to sample osteoderms from large crocodiles in the Finniss River, preferably in close proximity to the Rum Jungle mine site, where any archived pollution signal would be more intense, and then repeat this analytical investigation of the osteodermal history of contaminant loadings. © 2002 Commonwealth of Australia
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    The effect of the pH on the toxicity and accumulation of Cu and Zn in a tropical freshwater alga (Chlorella sp)
    (Royal Australian Chemical Institute & Australasian Society of Ecotoxicology, 2002-07-21) Wilde, KL; Markich, SJ; Stauber, JL; Franklin, NM
    As part of a larger study to test the biotic ligand model (BLM) with unicellular algae, the effect of pH (5.5, 6.5 and 7.5) on the toxicity and accumulation of Cu and Zn in the freshwater alga Chorella sp was investigated.
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    Environmental and effluent monitoring at ANSTO sites, 2002-2003
    (Australian Nuclear Science and Technology Organisation, 2003-06) Hoffmann, EL; Ferris, JM; Markich, SJ
    This report presents the results of environmental and effluent monitoring at the Lucas Heights Science and Technology Centre (LHSTC) and the National Medical Cyclotron (NMC) from January 2002 to June 2003. Potential effective dose rates to the general public from airborne discharges from the LHSTC site were less than 0.01 mSv/year, well below the 1 mSv/year dose rate limit for long term exposure that is recommended by the Australian National Occupational Health and Safety Commission. The effective dose rates to hypothetical individuals potentially exposed to radiation in routine liquid effluent discharges from the LHSTC were recently calculated to be less than 0.001 mSv/year. This is much less than dose rates estimated for members of public potentially exposed to airborne emissions. The levels of tritium detected in groundwater and stormwater at the LHSTC were less than the Australian drinking water guidelines. The airborne and liquid effluent emissions from the NMC were below the ARPANSA-approved notification levels and NSW EPA limits, respectively. ANSTO's routine operations at the LHSTC and the NMC make only a very small addition to the natural background radiation dose experienced by members of the Australian public.
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    The Finniss River: a natural laboratory of mining impact- past present and future
    (Australian Nuclear Science and Technology Organisation, 2002-08) Markich, SJ; Jeffree, RA
    The Rum Jungle uranium-copper mine in tropical northern Australia has been a source of acid rock drainage contaminants since the 1950s which have had adverse impacts on the receiving waters of the Finniss River. Mine site remediation began in 1982 followed by long-term monitoring of water quality and flow based on daily measurements within the Finniss River system. A decade or more after the initiation of these remedial activities a set of investigations have been completed that have measured the post-remedial ecological status of the Finniss River system relative to this environmental benchmark. These studies have also been complemented by studies on various other ecological endpoints. Moreover the Finniss River system has provided unique opportunities for broader scientific goals to be pursued. Because it has been so well-monitored it can be viewed as a natural laboratory to investigate the impacts of acid rock drainage on tropical freshwater biodiversity. The scientific papers presented at this symposium address a broad spectrum of issues that are directly related to environmental sustainability and mining. The topics range across future contaminant scenarios and their predicted ecological impacts the various metrics used to assess ecological detriment to biodiversity the abilities of laminated biological structures to act as archives of pollution history and also spin-off applications in environmental and wildlife management. Furthermore the participation of many stakeholders in open discussion during the symposium provided an important set of views and opinions on the needs for future studies in the Finniss River system.
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    Thermochemical data (log K) for environmentally-relevant elements : 1. H, Na, K, Ca, Mg, Fe, Mn, U, A1, Pb, Zn, Cu and Cd with model fulvic acid (Aspartate, citrate, malonate, salicylate and tricarballyate)
    (Australian Nuclear Science and Technology Organisation, 1999-12) Markich, SJ; Brown, PL
    This study provides an extensive stability constant (log K) database suitable for calculating the speciation of selected environmentally-relevant elements (H Na K Ca Mg Fe Mn U Al Pb Zn Cu and Cd) in an aqueous system where a model fulvic acid (comprising aspartic citric malonic salicylic and tricarballylic acids) is used to simulate metal binding by dissolved organic material Stability constants for inorganic metal complexes and minerals were selected primarily from critical literature complications and/or reviews. In contrast few critically evaluated data were available for metal complexes with aspartic citric, malonic, salicylic and tricarballylic acids. Consequently, data from original research articles were carefully evaluated and compiled as part of the study, following defined selection criteria. To meet the objective of compiling a comprehensive and reliable database of stability constants, all relevant equilibria and species, ranging from simple binary metal complexes to more complex ternary, and even quaternary, metal complexes were included where possible. In addition to the selection of stability constants from empirical sources, estimates of stability constants were performed when this could be done reliably, based on the unified theory of metal ion complexation and/or linear free energy relationships. The stability constants are given as common logarithms (log10) in the form required by the HARPHRQ geochemical code and refer to the standard state, i.e. 298.15 k (25—C), 106 Pa (1 atm) and, for all species, infinite dilution (ionic strength = 0 moI L-1). In addition to the compilation of stability constant data, an overview is given of geochemical speciation modeling in aqueous systems and available conceptual models of metal binding by humic substances.
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    Tolerance of fish to contaminated habitats: underlying mechanisms probed with isotopic tracers
    (International Atomic Energy Agency, 2006) Jeffree, RA; Markich, SJ; Twining, JR; Gale, S
    Future scenarios indicate agricultural and industrial expansions in major river basins and enhanced world populations focusing in coastal watersheds [1], particularly in SE Asia. Such scenarios are consistent with increasing concentrations of various contaminants, including metals and radionuclides. It is important to assess the likely impacts on fisheries, their response and possible adaptability to enhanced contaminant levels and the implications for resulting transfer factors and contaminant levels in fisheries, that can be the major sources of subsistence and livelihood for coastal communities. The likely future responses of fisheries to projected increases in contaminant loadings over broad geographical scales can be probed through the employment of currently highly contaminated aquatic environments. Such a system with these attributes, that we have investigated periodically since the early 1970s, is the Finniss River in tropical northern Australia, that has continued to receive acid mine drainage from the Rum Jungle U/Cu mine since the 1950s. Prior to mine-site remediation in the early 1980’s measured loadings of Cu, Zn, Mn and sulfate caused severe impact to fish diversity and abundanc e, including fish kills observed in the main Finniss River and its East Branch. Following mine-site remediation and measured reductions in contaminant loadings, there has been recovery of fish communities in the main Finniss River and considerable recolonisation of the still highly contaminated region of the East Branch, that was virtually devoid of fish populations prior to remediation [2]. Following mine site remediation reductions in annual-cycle contaminant loads of sulfate, Cu, Zn, and Mn by factors of 3-7 were accompanied by an unexpected degree recovery in fish community structure in the contaminated region of the Finniss River, to the extent that they were not statistically (P > 0.05) distinguishable from unexposed environments [2]. However, these fish communities continue to be exposed to considerable annual tonnages of these contaminants, as well as the naturally-occurring radionuclides associated with uranium mine wastes. Hence their capacity to accumulate contaminants under these conditions of long-term exposure and their adaptive response can be critically investigated, and is of concern to local stakeholders, both Aboriginal and European, who consume some of these fish species [ 3]. A more unexpected field observation was made in 1993 when five small fish species were found living in the East Branch of the Finniss River, where individual species penetrated the pollution gradient to varying degrees, but with one species (Melanotaenia nigrans) occurring at extremely high concentrations of Cu [4]. A laboratory-based study investigated the mechanisms of copper tolerance in M. nigrans from the polluted East Branch, compared to unexposed or reference populations. The bioconcentration of cyclotron-generated 64/67Cu in fish was used to investigate the mechanism of copper tolerance in exposed fish. In this shortterm experiment Cu concentrations in all tissue sections were significantly (P<0.05) less (up to 50%) in exposed fish compared with the respective tissue sections of reference fish, when exposed to both low and elevated Cu water concentrations. The mechanism of copper tolerance was concluded to be reduced copper uptake in the gills, rather than increased binding or elimination. Initial and subsequent allozyme electrophoresis showed that heterozygosity was reduced in exposed fish compared with that of reference fish. Collectively, these results suggest that genetic selection may have occurred in the exposed fish population. This was the first study on the mechanisms of copper tolerance in a wild fish population that has been exposed to elevated copper concentrations [5]. A pilot study of Cu, U, Zn, Co, Ni, Pb, Mn, Ra and Po-210 in several edible species of fish that now occur in abundance in the region of the main Finniss exposed to mine effluents has shown the following. Each contaminant water concentration was enhanced in the contaminated zone at the time of sampling. Compared to unexposed control sites, flesh samples from two species [Bony bream (Nematalosa erebi) and Eel- tailed catfish (Neosilurus ater)] were not significantly (P>0.05) enhanced in mean concentrations of any of these contaminants, with some being actually reduced (P<0.05) in the most contaminated region. This pattern of reduced accumulation in the exposed populations under field conditions is comparable to that obtained experimentally for Cu uptake in M. nigrans.
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    Tolerance of fish to contaminated habitats: underlying mechanisms probed with isotopic tracers
    (International Atomic Energy Agency, 2004-10-24) Jeffree, RA; Markich, SJ; Twining, JR; Gale, S
    Future scenarios indicate agricultural and industrial expansions in major river basins and enhanced world populations focusing in coastal watersheds [1], particularly in SE Asia. Such scenarios are consistent with increasing concentrations of various contaminants, including metals and radionuclides. It is important to assess the likely impacts on fisheries, their response and possible adaptability to enhanced contaminant levels and the implications for resulting transfer factors and contaminant levels in fisheries, that can be the major sources of subsistence and livelihood for coastal communities. The likely future responses of fisheries to projected increases in contaminant loadings over broad geographical scales can be probed through the employment of currently highly contaminated aquatic environments. Such a system with these attributes, that we have investigated periodically since the early 1970s, is the Finniss River in tropical northern Australia, that has continued to receive acid mine drainage from the Rum Jungle U/Cu mine since the 1950s. Prior to mine-site remediation in the early 1980’s measured loadings of Cu, Zn, Mn and sulfate caused severe impact to fish diversity and abundanc e, including fish kills observed in the main Finniss River and its East Branch. Following mine-site remediation and measured reductions in contaminant loadings, there has been recovery of fish communities in the main Finniss River and considerable recolonisation of the still highly contaminated region of the East Branch, that was virtually devoid of fish populations prior to remediation [2]. Following mine site remediation reductions in annual-cycle contaminant loads of sulfate, Cu, Zn, and Mn by factors of 3-7 were accompanied by an unexpected degree recovery in fish community structure in the contaminated region of the Finniss River, to the extent that they were not statistically (P > 0.05) distinguishable from unexposed environments [2]. However, these fish communities continue to be exposed to considerable annual tonnages of these contaminants, as well as the naturally-occurring radionuclides associated with uranium mine wastes. Hence their capacity to accumulate contaminants under these conditions of long-term exposure and their adaptive response can be critically investigated, and is of concern to local stakeholders, both Aboriginal and European, who consume some of these fish species [ 3]. A more unexpected field observation was made in 1993 when five small fish species were found living in the East Branch of the Finniss River, where individual species penetrated the pollution gradient to varying degrees, but with one species (Melanotaenia nigrans) occurring at extremely high concentrations of Cu [4]. A laboratory-based study investigated the mechanisms of copper tolerance in M. nigrans from the polluted East Branch, compared to unexposed or reference populations. The bioconcentration of cyclotron-generated 64/67Cu in fish was used to investigate the mechanism of copper tolerance in exposed fish. In this shortterm experiment Cu concentrations in all tissue sections were significantly (P<0.05) less (up to 50%) in exposed fish compared with the respective tissue sections of reference fish, when exposed to both low and elevated Cu water concentrations. The mechanism of copper tolerance was concluded to be reduced copper uptake in the gills, rather than increased binding or elimination. Initial and subsequent allozyme electrophoresis showed that heterozygosity was reduced in exposed fish compared with that of reference fish. Collectively, these results suggest that genetic selection may have occurred in the exposed fish population. This was the first study on the mechanisms of copper tolerance in a wild fish population that has been exposed to elevated copper concentrations [5]. A pilot study of Cu, U, Zn, Co, Ni, Pb, Mn, Ra and Po-210 in several edible species of fish that now occur in abundance in the region of the main Finniss exposed to mine effluents has shown the following. Each contaminant water concentration was enhanced in the contaminated zone at the time of sampling. Compared to unexposed control sites, flesh samples from two species [Bony bream (Nematalosa erebi) and Eel- tailed catfish (Neosilurus ater)] were not significantly (P>0.05) enhanced in mean concentrations of any of these contaminants, with some being actually reduced (P<0.05) in the most contaminated region. This pattern of reduced accumulation in the exposed populations under field conditions is comparable to that obtained experimentally for Cu uptake in M. nigrans.