Browsing by Author "Islam, MR"

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    Beryllium in contaminated soils: implication of beryllium bioaccessibility by different exposure pathways
    (Elsevier, 2022-01-05) Islam, MR; Sanderson, P; Naidu, R; Payne, TE; Johansen, MP; Bari, ASMF; Rahman, MM
    Inhalation exposure and beryllium (Be) toxicity are well-known, but research on bioaccessibility from soils via different exposure pathways is limited. This study examined soils from a legacy radioactive waste disposal site using in vitro ingestion (Solubility Bioaccessibility Research Consortium [SBRC], physiologically based extraction test [PBET], in vitro gastrointestinal [IVG]), inhalation (simulated epithelial lung fluid [SELF]) and dynamic two-stage bioaccessibility (TBAc) methods, as well as 0.43 M HNO3 extraction. The results showed, 70 ± 4.8%, 56 ± 16.8% and 58 ± 5.7% of total Be were extracted (gastric phase [GP] + intestinal phase [IP]) in the SBRC, PBET, and IVG methods, respectively. Similar bioaccessibility of Be (~18%) in PBET-IP and SELF was due to chelating agents in the extractant. Moreover, TBAc–IP showed higher extraction (20.8 ± 2.0%) in comparison with the single-phase (SBRC–IP) result (4.8 ± 0.23%), suggesting increased Be bioaccessibility and toxicity in the gastrointestinal tract when the contamination derives from the inhalation route. The results suggested Be bioaccessibility depends on solution pH; time of extraction; soil reactive fractions (organic–inorganic); particle size, and the presence of chelating agents in the fluid. This study has significance for understanding Be bioaccessibility via different exposure routes and the application of risk-based management of Be-contaminated sites. © 2021 Elsevier B.V.
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    Beryllium sorption to sandy soil at a legacy waste site
    (CRC CARE Pty Ltd,, 2019-09-08) Islam, MR; Sanderson, P; Naidu, R; Johansen, MP; Payne, TE
    Beryllium (Be) is utilized in various science and technology applications including aerospace, defence, electronics and nuclear energy (USGS, 2018). Beryllium and its compounds are highly toxic and considered carcinogenic to humans (IARC, 2001). In soil, Be is highly reactive, amphoteric, hydrates readily and reacts with different organic and inorganic elements due to its high charge to size ratio (Alderighi et al., 2000, Boschi and Willenbring, 2016, Rudolph et al., 2009, Edmunds, 2011). The sorption mechanism strongly depends on soil physicochemical properties like pH, cation exchange capacity (CEC), soil texture, soil organic matter (SOM) content, and the presence of sulphur, nitrogen, phosphorous, aluminium etc. (Sutton et al., 2012, Boschi and Willenbring, 2016). Of these, pH is a strong controller of Be sorption, with chemisorption increasing substantially from pH 4 to 6 with precipitation being the predominant mechanism between pH 6-12 (Boschi and Willenbring, 2016). This study examined the sorption of Be in surface soils of a legacy waste site that contains Be and low-level radioactive wastes disposed in shallow trenches to determine how Be may be retained in the surface soil if it is mobilised from the wastes. The sorption of Be with respect to physiochemical properties and the applicability of the Langmuir, Freundlich and Temkin sorption models was examined
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    Environmental chemistry response of beryllium to diverse soil-solution conditions at a waste disposal site
    (Royal Society of Chemistry, 2022-11-29) Islam, MR; Sanderson, P; Johansen, MP; Payne, TE; Naidu, R
    This study evaluated how the variation in different sorption conditions of beryllium (Be) in soil–water systems (electrolytes; ionic strengths; competing, counter, and co-existing ions; concentrations of Be and soil; and temperature) affected Be's environmental behaviour. For this reason, potentially contaminated soil was collected from a legacy waste site near Sydney, Australia. The sorption–desorption plateau for Be was found at >12.5 g L−1 (soil/solution), considering higher sorption and limited desorption. Variable surface charges developed by different added ions (competing ions, counter ions, and co-existence of all ions) were not always correlated with Be sorption. However, effects of added ions in Be sorption (increased by counter ions and decreased by competing ions) primarily occurred at low pH, with no noticeable changes at pH > 6 due to the hydration and precipitation behaviour of Be at higher pH. Both laboratory data and modelling indicated the substantial effect of counter ions on increased sorption of Be. Relatively higher amounts of sorption under the co-existence of all added ions were suggested from synergistic actions. Sorption was favourable (KL > 0, and 0 < RL < 1) across all concentrations and temperatures at pH 5.5, and high retention (84–97%) occurred after four desorption cycles indicated specific sorption. The sorption process was exothermic (ΔH > −43 kJ mole−1), while desorption was endothermic (ΔH > +78.4 kJ mole−1). All sorption–desorption reactions were spontaneous (ΔG = −Ve), and executed without any structural deformation (ΔS = nearly zero) of soil particles. However, the effect of temperature on desorption was influenced by the concentrations of Be. Higher retention and different sorption–desorption parameters (Kd-desorption > Kd-sorption; Kf-desorption > Kf-sorption; ndesorption/nsorption < 1) indicate limited mobility of Be and the presence of desorption hysteresis in the studied soil under the experimental conditions. © Royal Society of Chemistry