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Per Persson. Photo.

Per Persson

Director

Per Persson. Photo.

Reactivity of Fe from a natural stream water towards As(V)

Author

  • Anneli Sundman
  • Torbjorn Karlsson
  • Per Persson

Summary, in English

Interactions between iron (Fe) and arsenic (As) play a vital role in aquatic and terrestrial ecosystems influencing the reactivity and transport of arsenic. A key aspect is the effect of natural organic matter (NOM) on these interactions, and previous investigations have reported the existence of ternary As-Fe-NOM species. In this study, the reactivity of Fe, from a boreal stream water, towards As(V) was investigated using Fe and As K-edge X-ray absorption spectroscopy (XAS). The native stream water was shown to contain mononuclear Fe-NOM complexes together with Fe(III) (hydr) oxides associated with the NOM. Addition of As(V) to this water at Fe to As ratios of 2.0-15.6 resulted in substantial changes in the Fe speciation; the Fe(III) (hydr) oxides were partly converted into FeAsO4(s) or a solid solution where As(V) was incorporated into Fe(III) (hydr) oxide structures. Under the same conditions no or only small effects of As(V) on the Fe-NOM complexes initially present were observed, and the concurrent existence of these complexes and free As(V) showed that a large fraction of the Fe-NOM complexes were non-reactive towards As(V). This study suggests that complexation of Fe by NOM in organic rich environments may lead to elevated free, aqueous arsenic levels as these complexes do not interact with As(V). Moreover, the formation of Fe-NOM complexes also reduce the tendency of Fe to form reactive Fe(III) (hydr) oxides particles and Fe(III)-arsenate precipitates. (C) 2015 Elsevier Ltd. All rights reserved.

Department/s

  • Centre for Environmental and Climate Science (CEC)
  • MEMEG
  • Microbial Ecology

Publishing year

2015

Language

English

Pages

185-191

Publication/Series

Applied Geochemistry

Volume

61

Document type

Journal article

Publisher

Elsevier

Topic

  • Geochemistry

Status

Published

Project

  • MICCS - Molecular Interactions Controlling soil Carbon Sequestration

Research group

  • Microbial Ecology

ISBN/ISSN/Other

  • ISSN: 0883-2927