Arsenic effects and behavior in association with the fe(II)-catalyzed transformation of schwertmannite

Edward D. Burton, Scott G. Johnston, Kym Watling, Richard T. Bush, Annabelle F. Keene, Leigh A. Sullivan

Research output: Contribution to journalArticle

50 Citations (Scopus)

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.

Original languageEnglish
Pages (from-to)2016-2021
Number of pages6
JournalEnvironmental Science and Technology
Volume44
Issue number6
DOIs
Publication statusPublished - 15 Mar 2010
Externally publishedYes

Fingerprint

schwertmannite
Arsenic
arsenic
goethite
acid sulfate soil
Sulfates
Acids
Minerals
mobilization
Extended X ray absorption fine structure spectroscopy
Soils
effect
acid mine drainage
mineral
Drainage
Lakes
lacustrine deposit
Groundwater
Desorption
desorption

Cite this

Burton, Edward D. ; Johnston, Scott G. ; Watling, Kym ; Bush, Richard T. ; Keene, Annabelle F. ; Sullivan, Leigh A. / Arsenic effects and behavior in association with the fe(II)-catalyzed transformation of schwertmannite. In: Environmental Science and Technology. 2010 ; Vol. 44, No. 6. pp. 2016-2021.
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title = "Arsenic effects and behavior in association with the fe(II)-catalyzed transformation of schwertmannite",
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.",
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Arsenic effects and behavior in association with the fe(II)-catalyzed transformation of schwertmannite. / Burton, Edward D.; Johnston, Scott G.; Watling, Kym; Bush, Richard T.; Keene, Annabelle F.; Sullivan, Leigh A.

In: Environmental Science and Technology, Vol. 44, No. 6, 15.03.2010, p. 2016-2021.

Research output: Contribution to journalArticle

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T1 - Arsenic effects and behavior in association with the fe(II)-catalyzed transformation of schwertmannite

AU - Burton, Edward D.

AU - Johnston, Scott G.

AU - Watling, Kym

AU - Bush, Richard T.

AU - Keene, Annabelle F.

AU - Sullivan, Leigh A.

PY - 2010/3/15

Y1 - 2010/3/15

N2 - 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.

AB - 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.

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U2 - 10.1021/es903424h

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