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Rahman MS, Clark MW, Yee LH, Comarmond MJ, Payne TE, Kappen P, Mokhber-Shahin L. Arsenic solid-phase speciation and reversible binding in long-term contaminated soils. CHEMOSPHERE 2017; 168:1324-1336. [PMID: 27916260 DOI: 10.1016/j.chemosphere.2016.11.130] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 11/19/2016] [Accepted: 11/26/2016] [Indexed: 06/06/2023]
Abstract
Historic arsenic contamination of soils occurs throughout the world from mining, industrial and agricultural activities. In Australia, the control of cattle ticks using arsenicals from the late 19th to mid 20th century has led to some 1600 contaminated sites in northern New South Wales. The effect of aging in As-mobility in two dip-site soil types, ferralitic and sandy soils, are investigated utilizing isotopic exchange techniques, and synchrotron X-ray adsorption spectroscopy (XAS). Findings show that historic soil arsenic is highly bound to the soils with >90% irreversibly bound. However, freshly added As (either added to historically loaded soils or pristine soils) has a significantly higher degree of As-accessibility. XAS data indicates that historic soil arsenic is dominated as Ca- (svenekite, & weilite), Al-(mansfieldite), and Fe- (scorodite) like mineral precipitates, whereas freshly added As is dominated by mineral adsorption surfaces, particularly the iron oxy-hydroxides (goethite and hematite), but also gibbsite and kaolin surfaces. SEM data further confirmed the presence of scorodite and mansfieldite formation in the historic contaminated soils. These data suggest that aging of historic soil-As has allowed neoformational mineral recrystallisation from surface sorption processes, which greatly reduces As-mobility and accessibility.
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Affiliation(s)
- M S Rahman
- School of Environment Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia; Marine Ecology Research Centre, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia.
| | - M W Clark
- School of Environment Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia; Marine Ecology Research Centre, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia
| | - L H Yee
- School of Environment Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia; Marine Ecology Research Centre, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia
| | - M J Comarmond
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - T E Payne
- School of Environment Science and Engineering, Southern Cross University, PO Box 157, Lismore, NSW 2480, Australia; Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
| | - P Kappen
- Australian Synchrotron, 800 Blackburn Road, Clayton, VIC 3168, Australia
| | - L Mokhber-Shahin
- Australian Nuclear Science and Technology Organisation, Locked Bag 2001, Kirrawee DC, NSW 2232, Australia
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The pH-dependence and reversibility of uranium and thorium binding on a modified bauxite refinery residue using isotopic exchange techniques. J Colloid Interface Sci 2011; 356:699-705. [DOI: 10.1016/j.jcis.2011.01.068] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Revised: 01/16/2011] [Accepted: 01/19/2011] [Indexed: 11/18/2022]
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Benkdad A, Laissaoui A, El Bari H, Benmansour M, Ibnmajah M. Partitioning of radiostrontium in marine aqueous suspensions: laboratory experiments and modeling studies. JOURNAL OF ENVIRONMENTAL RADIOACTIVITY 2008; 99:748-756. [PMID: 18061319 DOI: 10.1016/j.jenvrad.2007.10.005] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2007] [Revised: 10/12/2007] [Accepted: 10/12/2007] [Indexed: 05/25/2023]
Abstract
Quantitative information on the adsorption/desorption of radionuclides by suspended loads is important in the study of their environmental behavior. In this paper, controlled laboratory experiments were directed at studying the kinetic transfer and final distribution of radiostrontium in aqueous suspensions using 85Sr as tracer. The results showed that the uptake of 85Sr in seawater can be properly described by one reversible-reaction model. However, in the absence of competitive cations, it has been shown that two reactions of different characteristic times are unambiguously involved in the kinetic evolution of adsorption. Thus, a modeling approach consisting of three-box model has been applied. The model predicts in a satisfactory way the time evolution of activities in the dissolved phase and two sites in the particles. Experimental evidence showed, through comparison among kinetic and distribution coefficients corresponding to different conditions, that Ca2+ affects strongly the rate and extent of Sr uptake by suspended particles. On the other hand, distribution coefficients were found to be sensitive to changes in suspended particulate matter (SPM) concentration, exhibiting a reverse effect with this parameter on the adsorption. In addition, desorption from particles is important showing that Sr can be easily released due to cation-exchange processes.
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Affiliation(s)
- A Benkdad
- Centre National de l'Energie, des Sciences et des Techniques Nucléaires, Division of Applications to Earth Sciences and Environment, B.P. 1382 R.P. 10001 Rabat, Morocco
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