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Groundwater seeps facilitate exposure to Burkholderia pseudomallei

- Baker, Anthony, Tahani, Donald, Gardiner, Christopher, Bristow, Keith, Greenhill, Andrew, Warner, Jeffrey

  • Authors: Baker, Anthony , Tahani, Donald , Gardiner, Christopher , Bristow, Keith , Greenhill, Andrew , Warner, Jeffrey
  • Date: 2011
  • Type: Text , Journal article
  • Relation: Applied and Environmental Microbiology Vol. 77, no. 20 (2011), p. 7243-7246
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  • Description: Burkholderia pseudomallei is a saprophytic bacterium which is the causative agent of melioidosis, a common cause of fatal bacterial pneumonia and sepsis in the tropics. The incidence of melioidosis is clustered spatially and temporally and is heavily linked to rainfall and extreme weather events. Clinical case clustering has recently been reported in Townsville, Australia, and has implicated Castle Hill, a granite monolith in the city center, as a potential reservoir of infection. Topsoil and water from seasonal groundwater seeps were collected around the base of Castle Hill and analyzed by quantitative real-time PCR targeting the type III secretion system genes for the presence of B. pseudomallei. The organism was identified in 65% (95% confidence interval [CI], 49.5 to 80.4) of soil samples (n =40) and 92.5% (95% CI, 83.9 to 100) of seasonal groundwater samples (n =40). Further sampling of water collected from roads and gutters in nearby residential areas after an intense rainfall event found that 88.2% (95% CI, 72.9 to 100) of samples (n =16) contained viable B. pseudomallei at concentrations up to 113 CFU/ml. Comparison of isolates using multilocus sequence typing demonstrated clinical matches and close associations between environmental isolates and isolates derived from clinical samples from patients in Townsville. This study demonstrated that waterborne B. pseudomallei from groundwater seeps around Castle Hill may facilitate exposure to B. pseudomallei and contribute to the clinical clustering at this site. Access to this type of information will advise the development and implementation of public health measures to reduce the incidence of melioidosis. © 2011, American Society for Microbiology.

Decade-long response of arid-land mallee vegetation to fire, flooding and grazing in south-eastern Australia

- Florentine, Singarayer, Milberg, Per, Di Stefano, Julian, Westbrooke, Martin, Graz, Patrick

  • Authors: Florentine, Singarayer , Milberg, Per , Di Stefano, Julian , Westbrooke, Martin , Graz, Patrick
  • Date: 2015
  • Type: Text , Journal article
  • Relation: Journal of Arid Environments Vol. 121, no. October (2015), p. 7-14
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  • Description: Australian arid vegetation has evolved within highly variable environments characterised by low rainfall and sporadic fire events. Episodic high rainfall events are a significant factor in plant species recruitment, but their unpredictability makes them difficult to study. We report on the response of vascular plants to a major rainfall event and flood in an arid region of south-eastern Australia. Fire that occurred two months before the flood was incorporated into the study. Paired fenced and unfenced plots were established at control locations and also in areas that had been either flooded, burnt, or flooded and burnt. Objectives were to quantify the long-term effects of fire, flood and vertebrate herbivory, and their interactions, on vegetation composition, plant life forms and species diversity. We found that relative to controls (i) there was a significant effect of flooding on vegetation composition, (ii) changes in life form abundance were driven by flooding and grazing, (iii) there was a strong positive relationship between grazer exclusion and species diversity that was maintained over time and (iv) there was little effect of fire. Understanding the long-term effects of both natural disturbances and vertebrate herbivory will benefit plant conservation in the arid zone. © 2015 Elsevier Ltd.

Assessment of spatiotemporal varying relationships between rainfall, land cover and surface water area using geographically weighted regression

- Brown, Stuart, Versace, Vincent, Laurenson, Laurie, Ierodiaconou, Daniel, Fawcett, Jonathon, Salzman, Scott

  • Authors: Brown, Stuart , Versace, Vincent , Laurenson, Laurie , Ierodiaconou, Daniel , Fawcett, Jonathon , Salzman, Scott
  • Date: 2012
  • Type: Text , Journal article
  • Relation: Environmental Modeling and Assessment Vol. 17, no. 3 (2012), p. 241-254
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  • Description: Traditional regression techniques such as ordinary least squares (OLS) are often unable to accurately model spatially varying data and may ignore or hide local variations in model coefficients. A relatively new technique, geographically weighted regression (GWR) has been shown to greatly improve model performance compared to OLS in terms of higher R 2 and lower corrected Akaike information criterion (AIC C). GWR models have the potential to improve reliabilities of the identified relationships by reducing spatial autocorrelations and by accounting for local variations and spatial non-stationarity between dependent and independent variables. In this study, GWR was used to examine the relationship between land cover, rainfall and surface water habitat in 149 sub-catchments in a predominately agricultural region covering 2.6 million ha in southeast Australia. The application of the GWR models revealed that the relationships between land cover, rainfall and surface water habitat display significant spatial non-stationarity. GWR showed improvements over analogous OLS models in terms of higher R 2 and lower AIC C. The increased explanatory power of GWR was confirmed by the results of an approximate likelihood ratio test, which showed statistically significant improvements over analogous OLS models. The models suggest that the amount of surface water area in the landscape is related to anthropogenic drainage practices enhancing runoff to facilitate intensive agriculture and increased plantation forestry. However, with some key variables not present in our analysis, the strength of this relationship could not be qualified. GWR techniques have the potential to serve as a useful tool for environmental research and management across a broad range of scales for the investigation of spatially varying relationships. © 2011 Springer Science+Business Media B.V.

Stability study on the northern batter of MBC Open Pit using Plaxis 3D

- Zhao, Lei, You, Greg

  • Authors: Zhao, Lei , You, Greg
  • Date: 2018
  • Type: Text , Journal article
  • Relation: Arabian Journal of Geosciences Vol. 11, no. 6 (2018), p. 1-11
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  • Description: Cracks appeared on the northern batter at Maddingley Brown Coal Open Pit Mine, Victoria, Australia, on 8 November 2013 and a 2-day rainfall event happened 5 days later. This study models the stability of the northern batter considering the effect of the rainfall event and an emergency buttress using finite element method (FEM) encoded in Plaxis 3D. It is found that the batter tended to lead to block sliding after overburden removal. The observed vertical crack would be a combined action of the overburden removal and groundwater flow. The simulated location of cracks agrees well with the actual location, and the simulated heave of the coal seam is in good agreement with the experience in Victoria brown coal open pit mining. The rainfall accelerated the development of the cracks. With the construction of the emergency buttress, the batter became stable that is in good agreement with the monitored data.

Stability of schwertmannite and jarosite in an acidic landscape : Prolonged field incubation

- Vithana, Chamindra, Sullivan, Leigh, Burton, Edward, Bush, Richard

  • Authors: Vithana, Chamindra , Sullivan, Leigh , Burton, Edward , Bush, Richard
  • Date: 2015
  • Type: Text , Journal article
  • Relation: Geoderma Vol. 239, no. (2015), p. 47-57
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  • Description: Schwertmannite and jarosite are two of the main secondary iron(III) minerals commonly found in acidic, iron and sulfate-rich environments such as acid mine drainage and coastal acid sulfate soils (CASS). Both minerals exert major influence on the water and soil quality in these environments. While there are many studies conducted on the stability of these two minerals under controlled laboratory conditions, the behaviour of schwertmannite and jarosite under field conditions and the factors influencing their behaviour have not been investigated directly. In the present study, we examined the net transformation of introduced schwertmannite and jarosite samples incubated in a typical acidic CASS environment. Pure (synthetic) schwertmannite and jarosite samples were exposed to two main chemical regimes: 1) aerobic-acidic water column and 2) anaerobic-neutral sediment in a CASS environment. Changes in mineralogy, micromorphology, and composition of schwertmannite and jarosite samples were monitored over a period of 12months. Schwertmannite suspended in the water column and buried in sediments transformed to goethite by the end of 12months but more quickly in anoxic, reducing sediments. However, schwertmannite incubated in the acidic water column transformed at a much faster rate than those reported for acidic and aerobic conditions in the laboratory. Jarosite incubated in both the water column and sediments was also transformed to goethite but at a much slower rate than schwertmannite. Dissimilatory microbial reduction and Fe2+-catalysed transformation likely played a major role in accelerating the transformation of both minerals to goethite in sediments. The transformation of both minerals in the water column was sensitive to the hydrological conditions and fluctuations in the water column in relation to antecedent rainfall. In comparison, the sediment's geochemistry was relatively stable and consequently the rate of transformation and dissolution of both schwertmannite and jarosite in this environment was not appreciably affected by variable hydrology. © 2014 Elsevier B.V.

Climate change and the future of Australia's country towns

- Beer, Andrew, Tually, Selina, Kroehn, Michael, Martin, John, Gerritsen, Rolf, Taylor, Mike, Graymore, Michelle, Law, Julia

  • Authors: Beer, Andrew , Tually, Selina , Kroehn, Michael , Martin, John , Gerritsen, Rolf , Taylor, Mike , Graymore, Michelle , Law, Julia
  • Date: 2014
  • Type: Text , Book chapter
  • Relation: Applied Studies in Climate Adaptation p. 332-341
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  • Description: This chapter presents the future of Australia's country towns in the context of anticipated climate change, where it is assumed Australia faces moderate climate change as predicted by the CSIRO's MK3.5 model. It argues that the future of Australia's country towns is not simply a product of climate change and its manifestation in terms of altered rainfall patterns, increased average temperatures and more frequent extreme events. The chapter discusses Australia's country towns within the context of contemporary and anticipated social, economic and climatic trends, before moving on to discuss the estimation of vulnerability within these communities. It describes both the implications for rural communities and the paths potentially available to governments across Australia. The adaptation and future of Australia's country towns is not simply a story of a changing climate and its impacts. © 2015 by John Wiley & Sons, Ltd. All rights reserved.

Paleoclimate studies and natural-resource management in the Murray-Darling Basin I: past, present and future climates

- Mills, Keely, Gell, Peter, Hesse, Paul, Jones, R., Kershaw, Peter, Drysdale, Russell, McDonald, Janece

  • Authors: Mills, Keely , Gell, Peter , Hesse, Paul , Jones, R. , Kershaw, Peter , Drysdale, Russell , McDonald, Janece
  • Date: 2013
  • Type: Text , Journal article
  • Relation: Australian Journal of Earth Sciences Vol. 60, no. 5 (2013), p. 547-560
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  • Description: This paper provides an incisive review of paleoclimate science and its relevance to natural-resource management within the Murray-Darling Basin (MDB). The drought of 1997-2010 focussed scientific, public and media attention on intrinsic climate variability and the confounding effect of human activity, especially in terms of water-resource management. Many policy and research reviews make statements about future planning with little consideration of climate change and without useful actionable knowledge. In order to understand future climate changes, modellers need, and demand, better paleoclimate data to constrain their model projections. Here, we present an insight into a number of existing long-term paleoclimate studies relevant to the MDB. Past records of climate, in response to orbital forcing (glacial-interglacial cycles) are found within, and immediately outside, the MDB. High-resolution temperature records, spanning the last 105 years, exist from floodplains and cave speleothems, as well as evidence from lakes and their associated lunettes. More recently, historical climate records show major changes in relation to El Niño-Southern Oscillation cycles and decadal shifts in rainfall regimes. A considerable body of research currently exists on the past climates of southeastern Australia but, this has not been collated and validated over large spatial scales. It is clear that a number of knowledge gaps still exist, and there is a pressing need for the establishment of new paleoclimatic research within the MDB catchment and within adjacent, sensitive catchments if past climate science is to fulfil its potential to provide policy-relevant information to natural-resource management into the future. © 2013 Copyright Taylor and Francis Group, LLC.
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Effects of grazing exclusion on plant species richness and phytomass accumulation vary across a regional productivity gradient

- Schultz, Nick, Morgan, John, Lunt, Ian

  • Authors: Schultz, Nick , Morgan, John , Lunt, Ian
  • Date: 2011
  • Type: Text , Journal article
  • Relation: Journal of Vegetation Science Vol. 22, no. 1 (2011), p. 130-142
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  • Description: Question: Does long-term grazing exclusion affect plant species diversity? And does this effect vary with long-term phytomass accumulation across a regional productivity gradient? Location: Lowland grassy ecosystems across the state of Victoria, southeast Australia. Methods: Floristic surveys and phytomass sampling were conducted across a broad-scale productivity gradient in grazing exclusion plots and adjacent grazed areas. Differences in species richness, evenness and life-form evenness between grazed and ungrazed areas were analysed. The environmental drivers of long-term phytomass accumulation were assessed using multiple linear regression analysis. Results: Species richness declined in the absence of grazing only at the high productivity sites (i.e. when phytomass accumulation was >500 gm-2). Species evenness and life-form evenness also showed a negative relationship with increasing phytomass accumulation. Phytomass accumulation was positively associated with both soil nitrogen and rainfall, and negatively associated with tree cover. Conclusions: Competitive dominance is a key factor regulating plant diversity in productive grassy ecosystems, but canopy disturbance is not likely to be necessary to maintain diversity in less productive systems. The results support the predictions of models of the effects of grazing on plant diversity, such as the dynamic equilibrium model, whereby the effects of herbivory are context-dependent and vary according to gradients of rainfall, soil fertility and tree cover. © 2010 International Association for Vegetation Science.
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