Investigating Arsenic Speciation and Mobilization in Sediments with DGT and DET: A Mesocosm Evaluation of Oxic-Anoxic Transitions

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Title Investigating Arsenic Speciation and Mobilization in Sediments with DGT and DET: A Mesocosm Evaluation of Oxic-Anoxic Transitions
Author Bennett, William; Teasdale, Peter; Panther, Jared; Welsh, David Thomas; Zhao, Huijun; Jolley, Dianne F.
Journal Name Environmental Science & Technology
Year Published 2012
Place of publication United States
Publisher American Chemical Society
Abstract Mobilization of arsenic from freshwater and estuarine sediments during the transition from oxic to anoxic conditions was investigated using recently developed diffusive sampling techniques. Arsenic speciation and Fe(II) concentrations were measured at high resolution (1−3 mm) with in situ diffusive gradients in thin films (DGT) and diffusive equilibration in thin films (DET) techniques. Water column anoxia induced Fe(II) and As(III) fluxes from the sediment. A correlation between water column Fe(II) and As(III) concentrations was observed in both freshwater (rs = 0.896, p < 0.001) and estuarine (rs = 0.557, p < 0.001) mesocosms. Porewater sampling by DGT and DET techniques confirmed that arsenic mobilization was associated with the reductive dissolution of Fe(III) (hydr)oxides in the suboxic zone of the sediment; a relationship that was visible because of the ability to measure the coincident profiles of these species using combined DGT and DET samplers. The selective measurement of As(III) and total inorganic arsenic by separate DGT samplers indicated that As(III) was the primary species mobilized from the solid phase to the porewater. This measurement approach effectively ruled out substantial As(V) mobilization from the freshwater and estuarine sediments in this experiment. This study demonstrates the capabilities of the DGT and DET techniques for investigating arsenic speciation and mobilization over a range of sediment conditions.
Peer Reviewed Yes
Published Yes
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Copyright Statement Self-archiving of the author-manuscript version is not yet supported by this journal. Please refer to the journal link for access to the definitive, published version or contact the authors for more information.
Volume 46
Issue Number 7
Page from 3981
Page to 3989
ISSN 0013-936X
Date Accessioned 2012-10-09
Language en_US
Research Centre Environmental Futures Research Institute
Faculty Faculty of Science, Environment, Engineering and Technology
Subject Environmental Chemistry (incl Atmospheric Chemistry); Environmental Monitoring; Soil Chemistry (excl Carbon Sequestration Science)
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1

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