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Tidally driven water column hydro-geochemistry in a remediating acidic wetland

- Johnston, Scott, Keene, Annabelle, Bush, Richard, Sullivan, Leigh, Wong, Vanessa

  • Authors: Johnston, Scott , Keene, Annabelle , Bush, Richard , Sullivan, Leigh , Wong, Vanessa
  • Date: 2011
  • Type: Text , Journal article
  • Relation: Journal of Hydrology Vol. 409, no. 1-2 (2011), p. 128-139
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  • Description: Managed tidal inundation is a newly evolved technique for remediating coastal acid sulphate soil (CASS) wetlands. However, there remains considerable uncertainty regarding the hydro-geochemical pathways and spatiotemporal dynamics of residual H+ and metal(loid) mobilisation into the tidal fringe surface waters of these uniquely iron-rich landscapes. Here, we examine the hydrology and water column chemistry across the intertidal slope of a remediating CASS wetland during several tide cycles. There was extreme spatial and temporal dynamism in water column chemistry, with pH fluctuating by ∼3 units (∼3.5-6.5) during a single tide cycle. Acute acidity was spatially confined to the upper intertidal slope, reflecting surface sediment properties, and tidal overtopping is an important pathway for mobilisation of residual H+ and Al3+ to the water column. Marine derived HCO3- was depleted from surface waters migrating across the intertidal slope and a strong gradient in HCO3- was observed from the tidal fringe to the adjacent tributary channel and nearby estuary. Tidal forcing generated oscillating hydraulic gradients in the shallow fringing aquifer, favouring ebb-tide seepage and driving rapid, heterogeneous advection of groundwater on the lower intertidal slope via surface connected macropores. A combination of diffusive and advective flux across the sediment-water interface led to persistent, elevated surface water Fe2+ (∼10-1000μM). The geochemical processes associated with Fe2+ mobilisation displayed distinct spatial zonation, with low pH, proton-promoted desorption occurring on the upper intertidal slope, whilst circum-neutral pH, Fe(III)-reducing processes dominated the lower intertidal slope. Arsenic was also mobilised into surface waters on the lower intertidal slope under moderate pH (∼6.0) conditions and was strongly positively correlated with Fe2+. Saturation index values for aragonite were substantially depressed (-1 to -5) and significantly negatively correlated with elevation, thereby presenting a barrier to re-colonisation of the upper intertidal slope by calcifying benthic organisms. These findings highlight the spatially complex hydrological and geochemical controls on surface water quality that can occur in tidally inundated acid sulphate soil environments. © 2011 Elsevier B.V.

Unbearable pressures on paradise? Tourism and heritage management in Luang Prabang, a World Heritage Site

- Reeves, Keir, Long, Colin

  • Authors: Reeves, Keir , Long, Colin
  • Date: 2011
  • Type: Text , Journal article
  • Relation: Critical Asian Studies Vol. 43, no. 1 (2011), p. 3-22
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  • Description: This article critically appraises and evaluates tourism strategies and heritage management in Luang Prabang, Lao People’s Democratic Republic, a Unesco-designated ‘world heritage’ city. Luang Prabang is widely regarded as one of the most significant heritage cities in Southeast Asia. The city is renowned for its Buddhist and royal culture and also its historic vernacular Lao, French, and Lao-French architecture. The city earned world heritage status in 1995, but since that time the boom in in-bound Asian tourism has put pressures on Luang Prabang’s authenticity and, for some, called into question the validity of its world heritage status. This article examines these substantial and wide-ranging pressures and argues that the growth in tourism and the treatment of Luang Prabang’s heritage are symptoms of broader regional processes of political and economic change, including the expansion of Chinese and Korean investments and the growth of intra-regional tourism. The authors argue that it is unreasonable to expect traditional heritage management mechanisims, including the world heritage listing, to be able to cope with the pressures on sites like Luang Prabang. The very least that is required, the authors contend, is an expanded understanding of the context in which heritage places sit, and the authors make a case that the cultural landscapes approach, combined with explicit concerns for intangible heritage and poverty alleviation, must be at the core of any strategy for long-term protection of the city’s cultural values.

Arsenic effects and behavior in association with the fe(II)-catalyzed transformation of schwertmannite

- Burton, Edward, Johnston, Scott, Watling, Kym, Bush, Richard, Keene, Annabelle, Sullivan, Leigh

  • Authors: Burton, Edward , Johnston, Scott , Watling, Kym , Bush, Richard , Keene, Annabelle , Sullivan, Leigh
  • Date: 2010
  • Type: Text , Journal article
  • Relation: Environmental Science and Technology Vol. 44, no. 6 (2010), p. 2016-2021
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  • Description: In acid-mine drainage and acid-sulfate soil environments, the cycling of Fe and As are often linked to the formation and fate of schwertmannite(Fe 8O8(OH)8-2x(SO4)x).When schwertmanniterich material is subjected to near-neutral Fe(III)-reducing conditions (e.g., in reflooded acid-sulfate soils or mining-lake sediments), the resulting Fe(II) can catalyze transformation of schwertmannite to goethite. This work examines the effects of arsenic(V) and arsenic(III) on the Fe(II)-catalyzed transformation of schwertmannite and investigates the associated consequences of this mineral transformation for arsenic mobilization. A series of 9-day anoxic transformation experiments were conducted with synthetic schwertmannite and various additions of Fe(II), As(III), and As(V). X-ray diffraction (XRD) and Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy demonstrated that, in the absence of Fe(II), schwertmannite persisted as the dominant mineral phase. Under arsenic-free conditions, 10 mM Fe(II) catalyzed rapid and complete transformation of schwertmannite to goethite. However, the magnitude of Fe(II)-catalyzed transformation decreased to 72% in the presence of 1 mM As(III) and to only 6% in the presence of 1mM As(V). This partial Fe(II)-catalyzed transformation of As(III)-sorbed schwertmannite did not cause considerable As(III) desorption. In contrast, the formation of goethite via partial transformation of As(III)- and As(V)-sorbed schwertmannite significantly decreased arsenic mobilization under Fe(III)-reducing conditions. This implies that the Fe(II)-catalyzed transformation of schwertmannite to goethite may help to stabilize solid-phase arsenic and retard its subsequent release to groundwater. © 2010 American Chemical Society.

Arsenic microdistribution and speciation in toenail clippings of children living in a historic gold mining area

- Pearce, Dora, Dowling, Kim, Gerson, Andrea, Sim, Malcolm, Sutton, Stephen, Newville, Matthew, Russell, Robert, McOrist, Gordon

  • Authors: Pearce, Dora , Dowling, Kim , Gerson, Andrea , Sim, Malcolm , Sutton, Stephen , Newville, Matthew , Russell, Robert , McOrist, Gordon
  • Date: 2010
  • Type: Text , Journal article
  • Relation: Science of the Total Environment Vol. 408, no. 12 (2010), p. 2590-2599
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  • Description: Arsenic is naturally associated with gold mineralisation and elevated in some soils and mine waste around historical gold mining activity in Victoria, Australia. To explore uptake, arsenic concentrations in children's toenail clippings and household soils were measured, and the microdistribution and speciation of arsenic in situ in toenail clipping thin sections investigated using synchrotron-based X-ray microprobe techniques. The ability to differentiate exogenous arsenic was explored by investigating surface contamination on cleaned clippings using depth profiling, and direct diffusion of arsenic into incubated clippings. Total arsenic concentrations ranged from 0.15 to 2.1

Arsenic mobilization in a seawater inundated acid sulfate soil

- Johnston, Scott, Keene, Annabelle, Burton, Edward, Bush, Richard, Sullivan, Leigh, McElnea, Angus, Ahern, Col, Smith, C. Douglas, Powell, Bernard, Hocking, Rosalie

  • Authors: Johnston, Scott , Keene, Annabelle , Burton, Edward , Bush, Richard , Sullivan, Leigh , McElnea, Angus , Ahern, Col , Smith, C. Douglas , Powell, Bernard , Hocking, Rosalie
  • Date: 2010
  • Type: Text , Journal article
  • Relation: Environmental Science and Technology Vol. 44, no. 6 (2010), p. 1968-1973
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  • Description: Tidal seawater inundation of coastal acid sulfate soils can generate Fe- and SO4-reducing conditions in previously oxicacidic sediments, This creates potential for mobilization of As during the redox transition. We explore the consequences for As by investigating the hydrology, porewater geochemistry, solid-phase speciation, and mineralogical partitioning of As across two tidal fringe toposequences. Seawater inundation induced a tidally controlled redox gradient. Maximum porewater As (∼400μg/L) occurred in the shallow (<1 m), intertidal, redox transition zone between Fe-oxidizing and SO 4-reducing conditions. Primary mechanisms of As mobilization include the reduction of solid-phase As(V) to As(III), reductive dissolution of As(V)-bearing secondary Fe(III) minerals and competitive anion desorption. Porewater As concentrations decreased in the zone of contemporary pyrite reformation, Oscillating hydraulic gradients caused by tidal pumping promote upward advection of As and Fe2+-enriched porewater in the intertidal zone, leading to accumulation of As(V)-enriched Fe(III) (hydr)oxides at the oxic sediment-water interface. While this provides a natural reactive-Fe barrier, it does not completely retard the flux of porewater As to overtopping surface waters. Furthermore, the accumulated Fe minerals may be prone to future reductive dissolution, A conceptual model describing As hydro-geochemical coupling across an intertidal fringe is presented. © 2010 American Chemical Society.

Biological toxicity of lanthanide elements on algae

- Tai, Pei Dong, Zhao, Qing, Su, Dan, Li, Peijun, Stagnitti, Frank

  • Authors: Tai, Pei Dong , Zhao, Qing , Su, Dan , Li, Peijun , Stagnitti, Frank
  • Date: 2010
  • Type: Text , Journal article
  • Relation: Chemosphere Vol. 80, no. 9 (2010), p. 1031-1035
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  • Description: The biological toxicity of lanthanides on marine monocellular algae was investigated. The specific objective of this research was to establish the relationship between the abundance in the seawater of lanthanides and their biological toxicities on marine monocellular algae. The results showed that all single lanthanides had similar toxic effects on Skeletonema costatum. High concentrations of lanthanides (29.04 ± 0.61

Efficient prediction of deterministic size effects using the scaled boundary finite element method

- Ooi, Ean Tat, Yang, Zhenjun

  • Authors: Ooi, Ean Tat , Yang, Zhenjun
  • Date: 2010
  • Type: Text , Journal article
  • Relation: Engineering Fracture Mechanics Vol. 77, no. 6 (2010), p. 985-1000
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  • Description: This paper develops an efficient numerical approach to predict deterministic size effects in structures made of quasi-brittle materials using the scaled boundary finite element method (SBFEM). Depending on the structure's size, two different SBFEM-based crack propagation modelling methodologies are used for fracture analyses. When the length of the fracture process zone (FPZ) in a structure is of the order of its characteristic dimension, nonlinear fracture analyses are carried out using the finite element-SBFEM coupled method. In large-sized structures, a linear elastic fracture mechanics (LEFM)-based SBFEM is used to reduce computing time due to small crack propagation length required to represent the FPZ in an equivalent nonlinear analysis. Remeshing is used in both methods to model crack propagation with crack paths unknown a priori. The resulting peak loads are used to establish the size effect laws. Three concrete structures were modelled to validate the approach. The predicted size effect is in good agreement with experimental data. The developed approach was found more efficient than the finite element method, at least in modelling LEFM problems and is thus an attractive tool for predicting size effect. © 2010 Elsevier Ltd.

How would global trade liberalization affect rural and regional incomes in Australia?

- Anderson, Kym, Giesecke, James, Valenzuela, Ernesto

  • Authors: Anderson, Kym , Giesecke, James , Valenzuela, Ernesto
  • Date: 2010
  • Type: Text , Journal article
  • Relation: Australian Journal Of Agricultural And Resource Economics Vol. 54, no. 4 (2010), p. 389-406
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  • Description: For decades rural Australia has been discriminated against by industrial policies at home and agricultural protectionism abroad. While agricultural export taxation in poor countries had the opposite impact, recent reforms there mean that that offsetting effect on Australia has diminished. There has also been some re-instrumentation of rich-country farm policies away from trade measures. This paper draws on new evidence to examine whether Australian farmers and rural regions are still adversely affected by farm price-distortive policies abroad, using a global and a national economy-wide model. The results vindicate the continuing push by Australia's rural communities for multilateral agricultural trade liberalization.

Loose cannons : White masculinity and the vulgar teen comedy film

- Speed, Lesley

  • Authors: Speed, Lesley
  • Date: 2010
  • Type: Journal article
  • Relation: The Journal of Popular Culture Vol. 43, no. 4 (2010), p. 820-841
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  • Description: Although infamous for its focus on adolescent sexual strivings, the vulgar teen comedy film has been the subject of little sustained analysis. Yet there are numerous reasons to examine more closely this teen subgenre, of which the most prominent examples are Porky's and American Pie. The vulgar teen films of the early 1980s and late 1990s exemplify contemporary Hollywood production strategies and reflect changes in youth's social and economic status. In particular, the pivotal early 1980s cycle reflects a crisis in young, middle-class men's presumed right to behave hedonistically on other people's territory. Such films as Porky's, Losin It and Spring Break revolve around characters whose belief in their hedonistic freedom is oblivious to the social implications of their actions. A waning male, middle-class privilege is evident in the failure of the male sexual quest in Porky's and prefigures the subsequent suburbanization of teenage sexuality in American Pie. Vulgar teen comedy films thus reflect the changing social status of male youth.

Monosulfidic black ooze accumulations in sediments of the Geographe Bay area, Western Australia

- Ward, Nicholas, Bush, Richard, Burton, Edward, Appleyard, Steve, Wong, Stephen, Sullivan, Leigh, Cheeseman, Paul

  • Authors: Ward, Nicholas , Bush, Richard , Burton, Edward , Appleyard, Steve , Wong, Stephen , Sullivan, Leigh , Cheeseman, Paul
  • Date: 2010
  • Type: Text , Journal article
  • Relation: Marine Pollution Bulletin Vol. 60, no. 11 (2010), p. 2130-2136
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  • Description: Mobilisation of sedimentary monosulfidic black ooze (MBO) may result in rapid deoxygenation and acidification of surface waters, and release of potentially toxic metals. This study examines the extent and nature of MBO accumulation in the Geographe Bay area, Western Australia. MBO accumulations were found to be widespread in benthic sediments of the Geographe Bay area with acid-volatile sulfide (AVS) contents as high as 320μmolg-1. The MBO materials often had unusually high dissolved sulfide (S-II) concentrations in their pore-waters (up to 610mgL-1) and elevated elemental sulfur (S0) contents (up to 51μmolg-1). Dissolved S-II is able to accumulate due to limited iron availability and S0 is largely its partial oxidation product. The availability of organic carbon and Fe limited MBO accumulation at many sites. A comparison of AVS and simultaneously extracted metal (SEM) concentrations has shown that metals are likely to be bound in sulfide complexes. © 2010 Elsevier Ltd.

Reactive trace element enrichment in a highly modified, tidally inundated acid sulfate soil wetland : East Trinity, Australia

- Keene, Annabelle, Johnston, Scott, Bush, Richard, Burton, Edward, Sullivan, Leigh

  • Authors: Keene, Annabelle , Johnston, Scott , Bush, Richard , Burton, Edward , Sullivan, Leigh
  • Date: 2010
  • Type: Text , Journal article
  • Relation: Marine Pollution Bulletin Vol. 60, no. 4 (2010), p. 620-626
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  • Description: This study examines the abundance of trace elements in surface sediments of a former acid sulfate soil (ASS) wetland subjected to marine tidal inundation. Sediment properties of this highly modified study site are compared with those of an adjacent unmodified, intertidal mangrove forest. Whilst some trace elements (Al, Cd, Mn, Ni and Zn) were clearly depleted due to mobilisation and leaching in the previous oxic-acidic phase, other trace elements (As and Cr) displayed significant enrichment in the tidally inundated ASS. Many trace elements were strongly associated with the reactive Fe and acid volatile sulfide (AVS) fractions, suggesting that trace elements may be adsorbed to abundant reactive Fe phases or sequestered as sulfide minerals. These findings provide an important understanding of the fate and mobility of reactive iron, AVS and trace elements during tidal remediation of a formerly acidified Great Barrier Reef (GBR) catchment. © 2010 Elsevier Ltd.

Rockfalls : Predicting high-risk behaviour from beliefs

- Aucote, Helen, Miner, Anthony, Dahlhaus, Peter

  • Authors: Aucote, Helen , Miner, Anthony , Dahlhaus, Peter
  • Date: 2010
  • Type: Journal article
  • Relation: Disaster Prevention and Management Vol. 19, no. 1 (2010), p. 20-31
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  • Description: Purpose – The purpose of this paper is to gain an understanding of the public's beliefs, attitudes and knowledge regarding rockfalls, and to see whether these variables could predict whether a person is likely to enter high-risk rockfall areas. Design/methodology/approach – A questionnaire was developed to measure beliefs (informed by the health belief model), knowledge, and previous behaviour in relation to rockfalls. Questions were also included to measure attitudes regarding rockfall caution signs. In total, 138 members of the general public completed the questionnaire. Findings – High-risk behaviour was more likely if the person was male and if the person had the belief that sign-posted high-risk areas were not dangerous. Further, believing that the sign-posted areas were not dangerous was more likely among people who held negative attitudes towards cautionary signs; specifically, these participants were more likely to doubt the validity of the warning signs. Research limitations/implications – The research was exploratory in nature. Further research should be conducted with a larger sample size and a more random selection of the general population. Ways of improving measurement of the variables are discussed. Practical implications – Efforts should be made to increase the public's perception of the validity of rockfall cautionary signs. Doing so may decrease injury and death as a result of rockfalls. Suggestions on ways to increase the validity of signage are made. Originality/value – It is presumed that this study is the first to attempt to gain an understanding of the beliefs and attitudes that may lead a person into engaging in high-risk behaviour in relation to rockfalls.

Spatial differentiation of landscape values in the Murray River region of Victoria, Australia

- Zhu, Xuan, Pfueller, Sharron, Whitelaw, Paul, Winter, Caroline

  • Authors: Zhu, Xuan , Pfueller, Sharron , Whitelaw, Paul , Winter, Caroline
  • Date: 2010
  • Type: Text , Journal article
  • Relation: Environmental Management Vol. 45, no. 5 (2010), p. 896-911
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  • Description: This research advances the understanding of the location of perceived landscape values through a statistically based approach to spatial analysis of value densities. Survey data were obtained from a sample of people living in and using the Murray River region, Australia, where declining environmental quality prompted a reevaluation of its conservation status. When densities of 12 perceived landscape values were mapped using geographic information systems (GIS), valued places clustered along the entire river bank and in associated National/State Parks and reserves. While simple density mapping revealed high value densities in various locations, it did not indicate what density of a landscape value could be regarded as a statistically significant hotspot or distinguish whether overlapping areas of high density for different values indicate identical or adjacent locations. A spatial statistic Getis-Ord Gi* was used to indicate statistically significant spatial clusters of high ! value densities or "hotspots". Of 251 hotspots, 40% were for single non-use values, primarily spiritual, therapeutic or intrinsic. Four hotspots had 11 landscape values. Two, lacking economic value, were located in ecologically important river red gum forests and two, lacking wilderness value, were near the major towns of Echuca-Moama and Albury-Wodonga. Hotspots for eight values showed statistically significant associations with another value. There were high associations between learning and heritage values while economic and biological diversity values showed moderate associations with several other direct and indirect use values. This approach may improve confidence in the interpretation of spatial analysis of landscape values by enhancing understanding of value relationships.

Household water use behavior: An integrated model

- Jorgensen, Bradley, Graymore, Michelle, O'Toole, Kevin

  • Authors: Jorgensen, Bradley , Graymore, Michelle , O'Toole, Kevin
  • Date: 2009
  • Type: Text , Journal article
  • Relation: Journal of Environmental Management Vol. 91, no. 1 (2009), p. 227-236
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  • Description: Water authorities are dealing with the challenge of ensuring that there is enough water to meet demand in the face of drought, population growth and predictions of reduced supply due to climate change. In order to develop effective household demand management programs, water managers need to understand the factors that influence household water use. Following an examination and re-analysis of current water consumption behavioral models we propose a new model for understanding household water consumption. We argue that trust plays a role in household water consumption, since people will not save water if they feel others are not minimizing their water use (inter-personal trust). Furthermore, people are less likely to save water if they do not trust the water authority (institutional trust). This paper proposes that to fully understand the factors involved in determining household water use the impact of trust on water consumption needs investigation.

How do consumers define retail centre convenience?

- Clulow, Val, Reimers, Vaughan

  • Authors: Clulow, Val , Reimers, Vaughan
  • Date: 2009
  • Type: Text , Journal article
  • Relation: Australasian Marketing Journal Vol. 17, no. 3 (2009), p. 125-132
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  • Description: The 1980s and 1990s have been labelled the ‘decades of convenience’. In spite of this, retail research has often indicated that when compared with other shopping motives, consumers assign relatively less importance to the convenience of a retail centre when deciding where to shop. Such counter-intuitive findings could be due to the way in which academics have defined retail centre convenience. This study develops and tests an alternative definition. Comprising 16 attributes, it represents a fourfold increase over any existing definition. Subsequent empirical analysis provides strong support for the alternative definition, with respondents indicating that 14 of the test attributes serve as convenience attributes. The failure of existing definitions to incorporate so many of these attributes is a likely explanation behind the counter-intuitive proposition that convenience often serves as a less-than-salient determinant of retail centre patronage.

Iron-monosulfide oxidation in natural sediments : Resolving microbially mediated S transformations using XANES, electron microscopy, and selective extractions

- Burton, Edward, Bush, Richard, Sullivan, Leigh, Hocking, Rosalie, Mitchell, David, Johnston, Scott, Fitzpatrick, Rob W., Raven, Mark, McClure, Stuart, Jang, Lingyun

  • Authors: Burton, Edward , Bush, Richard , Sullivan, Leigh , Hocking, Rosalie , Mitchell, David , Johnston, Scott , Fitzpatrick, Rob W. , Raven, Mark , McClure, Stuart , Jang, Lingyun
  • Date: 2009
  • Type: Text , Journal article
  • Relation: Environmental Science and Technology Vol. 43, no. 9 (2009), p. 3128-3134
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  • Description: Iron-monosulfide oxidation and associated S transformations in a natural sediment were examined by combining selective extractions, electron microscopy and S K-edge X-ray absorption near-edge structure (XANES) spectroscopy. The sediment examined in this study was collected from a waterway receiving acid-sulfate soil drainage. It contained a high acid-volatile sulfide content (1031 μ mol g-1), reflecting an abundance of iron-monosulfide. The iron-monosulfide speciation in the initial sediment sample was dominated by nanocrystalline mackinawite (tetragonal FeS). At near-neutral pH and an O 2 partial pressure of ∼0.2 atm, the mackinawite was found to oxidize rapidly, with a half-time of 29 ± 2 min. This oxidation rate did not differ significantly (P < 0.05) between abiotic versus biotic conditions, demonstrating that oxidation of nanocrystalline mackinawite was not microbially mediated. The extraction results suggested that elemental S (S0 8) was a key intermediate S oxidation product. Transmission electron microscopy showed the S0 8 to be amorphous nanoglobules, 100-200 nm in diameter. The quantitative importance of S0 8 was confirmed by linear combination XANES spectroscopy, after accounting for the inherent effect of the nanoscale S0 8 particle-size on the corresponding XANES spectrum. Both the selective extraction and XANES data showed that oxidation of S0 8 SO4 2- was madiated by microbial activity. In addition to directly revealing important S transformations, the XANES results support the accuracy of the selective extraction scheme employed here. © 2009 American Chemical Society.

Nights at the airport

- Mills, Alice

  • Authors: Mills, Alice
  • Date: 2009
  • Type: Text , Journal article
  • Relation: Nebula Vol. 6, no. 2 p. 174-176
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  • Description: A personal narrative is presented in which the author explains her experiences while waiting for a plane at the airport at night.
  • Description: 2003008013

Sorption of Arsenic(V) and Arsenic(III) to schwertmannite

- Burton, Edward, Bush, Richard, Johnston, Scott, Watling, Kym, Hocking, Rosalie, Sullivan, Leigh, Parker, Gretel

  • Authors: Burton, Edward , Bush, Richard , Johnston, Scott , Watling, Kym , Hocking, Rosalie , Sullivan, Leigh , Parker, Gretel
  • Date: 2009
  • Type: Text , Journal article
  • Relation: Environmental Science and Technology Vol. 43, no. 24 (2009), p. 9202-9207
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  • Description: This study describes the sorption of As(V) and As(III) to schwertmannite as a function of pH and arsenic loading. In general, sorption of As(V) was greatest at low pH, whereas high pH favored the sorption of As(III). The actual pH of equivalent As(V) and As(III) sorption was strongly loading dependent, decreasing from pH ∼ 8.0 at loadings <120 mmolAs mol Fe -1 to pH ∼ 4.6 at a loading of 380 mmolAs molFe -1. Sorption isotherms for As(V) were characterized by strong partitioning to the schwertmannite solid-phase at low loadings and sorption capacities of 225-330 mmolAs(V) molFe -1 at high loadings. In contrast, the As(III) isotherms revealed a weak affinity for sorption of As(III) versus As(V) at low loadings yet a greater affinity for As(III) sorption compared with As(V) at high loadings (when pH > 4.6). Sorption of As(V) and As(III) caused significant release of SO 4 2- from within the schwertmannite solid-phase, without major degradation of the schwertmannite structure (as evident by X-ray diffraction and Raman spectroscopy). This can be interpreted as arsenic sorption via incorporation into the schwertmannite structure, rather than merely surface complexation at the mineral-water interface. The results of this study have important implications for arsenic mobility in the presence of schwertmannite, such as in areas affected by acidmine drainage and acid-sulfate soils. In particular, arsenic speciation, arsenic loading, and pH should be considered when predicting and managing arsenic mobility in schwertmanniterich systems. © 2009 American Chemical Society.

Verification of a numerical model for the prediction of low slope vertical slot fishway hydraulics.

- Barton, Andrew, Keller, Robert, Katopodis, Christos

  • Authors: Barton, Andrew , Keller, Robert , Katopodis, Christos
  • Date: 2009
  • Type: Text , Journal article
  • Relation: Australian Journal of Water Resources Vol. 13, no. 1 (2009), p. 53-60
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  • Description: A numerical model has been developed to predict the three-dimensional flow character within low scope vertical slot fishways (VSFs). The modek solves the three dimensional Reynolds averaged Navier-Stokes equations, closed with the renormalised k-e turbulence formulations. The model employs the volume of fluid method to deal with the free surface. Results are presented for velocities and surface elevations utilising two fishway designs from prototype and laboratory studies. The respective data from the studies are direct compared to the numerical model predictions forming the basis of verification. The model is shown to predict critical design velocities, slot flow characteristics, flow recirculation and water surface elevations well enough to be useful in low slope VSF design.

Diverse cytokine production by NKT cell subsets and identification of an IL-17-producing CD4-NK1.1- NKT cell population

- Coquet, Jonathan, Chakravarti, Sumone, Kyparissoudis, Konstantinos, McNab, Finlay, Pitt, Lauren, McKenzie, Brent, Berzins, Stuart, Smyth, Mark, Godfrey, Dale