List of Titles

Effect of pyrolysis conditions on bone char characterization and its ability for arsenic and fluoride removal

- Alkurdi, Susan, Al-Juboori, Raed, Bundschuh, Jochen, Bowtell, Les, McKnight, Stafford

Authors: Alkurdi, Susan , Al-Juboori, Raed , Bundschuh, Jochen , Bowtell, Les , McKnight, Stafford
Date: 2020
Type: Text , Journal article
Relation: Environmental Pollution Vol. 262, no. (2020), p.
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Description: This study examined arsenite [As(III)], arsenate [As(V)] and fluoride (F−) removal potential of bone char produced from sheep (Ovis aries) bone waste. Pyrolysis conditions tested were in the 500 °C–900 °C range, for a holding time of 1 or 2 h, with or without N2 gas purging. Previous bone char studies mainly focused on either low or high temperature range with limited information provided on As(III) removal. This study aims to address these gaps and provide insights into the effect of pyrolysis conditions on bone char sorption capacity. A range of advanced chemical analyses were employed to track the change in bone char properties. As pyrolysis temperature and holding time increased, the resulting pH, surface charge, surface roughness, crystallinity, pore size and CEC all increased, accompanied by a decrease in the acidic functional groups and surface area. Pyrolysis temperature was a key parameter, showing improvement in the removal of both As(III) and As(V) as pyrolysis temperature was increased, while As(V) removal was higher than As(III) removal overall. F− removal displayed an inverse relationship with increasing pyrolysis temperature. Bone char prepared at 500 °C released significantly more dissolved organic carbon (DOC) then those prepared at a higher temperature. The bone protein is believed to be a major factor. The predominant removal mechanisms for As were surface complexation, precipitation and interaction with nitrogenous functional groups. Whereas F− removal was mainly influenced by interaction with oxygen functional groups and electrostatic interaction. This study recommends that the bone char pyrolysis temperature used for As and F− removal are 900 °C and 650 °C, respectively. © 2020 Elsevier Ltd
Description: This research was performed as a part of PhD research which was supported in part by the Iraqi Government and the Australian Research Training Program.

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

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 âˆ¼3 units (âˆ¼3.5-6.5) 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+ (âˆ¼10-1000Î¼M). 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 (âˆ¼6.0) 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.

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