- Title
- Arsenic effects and behavior in association with the fe(II)-catalyzed transformation of schwertmannite
- Creator
- Burton, Edward; Johnston, Scott; Watling, Kym; Bush, Richard; Keene, Annabelle; Sullivan, Leigh
- Date
- 2010
- Type
- Text; Journal article
- Identifier
- http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/99574
- Identifier
- vital:10377
- Identifier
-
https://doi.org/10.1021/es903424h
- Identifier
- ISSN:0013-936X
- Abstract
- In acid-mine drainage and acid-sulfate soil environments, the cycling of Fe and As are often linked to the formation and fate of schwertmannite(Fe 8O8(OH)8-2x(SO4)x).When schwertmanniterich material is subjected to near-neutral Fe(III)-reducing conditions (e.g., in reflooded acid-sulfate soils or mining-lake sediments), the resulting Fe(II) can catalyze transformation of schwertmannite to goethite. This work examines the effects of arsenic(V) and arsenic(III) on the Fe(II)-catalyzed transformation of schwertmannite and investigates the associated consequences of this mineral transformation for arsenic mobilization. A series of 9-day anoxic transformation experiments were conducted with synthetic schwertmannite and various additions of Fe(II), As(III), and As(V). X-ray diffraction (XRD) and Fe K-edge extended X-ray absorption fine structure (EXAFS) spectroscopy demonstrated that, in the absence of Fe(II), schwertmannite persisted as the dominant mineral phase. Under arsenic-free conditions, 10 mM Fe(II) catalyzed rapid and complete transformation of schwertmannite to goethite. However, the magnitude of Fe(II)-catalyzed transformation decreased to 72% in the presence of 1 mM As(III) and to only 6% in the presence of 1mM As(V). This partial Fe(II)-catalyzed transformation of As(III)-sorbed schwertmannite did not cause considerable As(III) desorption. In contrast, the formation of goethite via partial transformation of As(III)- and As(V)-sorbed schwertmannite significantly decreased arsenic mobilization under Fe(III)-reducing conditions. This implies that the Fe(II)-catalyzed transformation of schwertmannite to goethite may help to stabilize solid-phase arsenic and retard its subsequent release to groundwater. © 2010 American Chemical Society.
- Publisher
- ACS Publications
- Relation
- Environmental Science and Technology Vol. 44, no. 6 (2010), p. 2016-2021
- Rights
- Copyright © 2010 American Chemical Society.
- Rights
- This metadata is freely available under a CCO license
- Subject
- MD Multidisciplinary; Acid mine drainage; Anoxic transformation; Arsenic mobilization; Fe K-edge; Lake sediments; Mineral phase; Mineral transformations; Partial transformation; Reducing conditions; Schwertmannite; Solid-phase; Sulfate soils
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