Synchrotron X-ray absorption spectroscopy reveals antimony sequestration by reduced sulfur in a freshwater wetland sediment

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Author(s)
Bennett, William W
Hockmann, Kerstin
Johnston, Scott G
Burton, Edward D
Griffith University Author(s)
Year published
2017
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The biogeochemistry of antimony (Sb) in wetland sediments is poorly characterised, despite their importance as contaminant sinks. The organic-rich, reducing nature of wetland sediments may facilitate sequestration mechanisms that are not typically present in oxic soils, where the majority of research to date has taken place. Using X-ray absorption spectroscopy (XAS), we present evidence of antimony speciation being dominated by secondary antimony–sulfur phases in a wetland sediment. Our results demonstrate that, by incorporating a newly developed SbIII–organic sulfur reference standard, linear combination fitting analysis ...
View more >The biogeochemistry of antimony (Sb) in wetland sediments is poorly characterised, despite their importance as contaminant sinks. The organic-rich, reducing nature of wetland sediments may facilitate sequestration mechanisms that are not typically present in oxic soils, where the majority of research to date has taken place. Using X-ray absorption spectroscopy (XAS), we present evidence of antimony speciation being dominated by secondary antimony–sulfur phases in a wetland sediment. Our results demonstrate that, by incorporating a newly developed SbIII–organic sulfur reference standard, linear combination fitting analysis of antimony K-edge XAS spectra and robust statistical assessment of fit quality allows the reliable discrimination of SbIII coordination environments. We found that a contaminated wetland sediment in New South Wales, Australia, contained 57 % of the total antimony as SbIII–phases, with 44 % present as a highly-disordered antimony phase, likely consisting of SbIII complexed by organic sulfur (e.g. thiols) or an amorphous SbIII sulfide (e.g. SbS3). The methodological approach outlined in this study and our identification of the importance of reduced sulfur in sequestering antimony has implications for future research in the area of antimony biogeochemistry, and for the management of both natural and artificial wetlands contaminated with antimony.
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View more >The biogeochemistry of antimony (Sb) in wetland sediments is poorly characterised, despite their importance as contaminant sinks. The organic-rich, reducing nature of wetland sediments may facilitate sequestration mechanisms that are not typically present in oxic soils, where the majority of research to date has taken place. Using X-ray absorption spectroscopy (XAS), we present evidence of antimony speciation being dominated by secondary antimony–sulfur phases in a wetland sediment. Our results demonstrate that, by incorporating a newly developed SbIII–organic sulfur reference standard, linear combination fitting analysis of antimony K-edge XAS spectra and robust statistical assessment of fit quality allows the reliable discrimination of SbIII coordination environments. We found that a contaminated wetland sediment in New South Wales, Australia, contained 57 % of the total antimony as SbIII–phases, with 44 % present as a highly-disordered antimony phase, likely consisting of SbIII complexed by organic sulfur (e.g. thiols) or an amorphous SbIII sulfide (e.g. SbS3). The methodological approach outlined in this study and our identification of the importance of reduced sulfur in sequestering antimony has implications for future research in the area of antimony biogeochemistry, and for the management of both natural and artificial wetlands contaminated with antimony.
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Journal Title
Environmental Chemistry
Volume
14
Issue
6
Grant identifier(s)
DE140100056
Copyright Statement
© CSIRO 2017. This is an Open Access article distributed under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International (CC BY-NC-ND 4.0) License (http://creativecommons.org/licenses/by-nc-nd/4.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, providing that the work is properly cited.
Subject
Chemical sciences
Other chemical sciences not elsewhere classified
Earth sciences
Environmental sciences