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

Author:
  • Anneli Sundman
  • Torbjorn Karlsson
  • Per Persson
Publishing year: 2015
Language: English
Pages: 185-191
Publication/Series: Applied Geochemistry
Volume: 61
Document type: Journal article
Publisher: Elsevier

Abstract 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.

Keywords

  • Geochemistry

Other

Published
  • MICCS - Molecular Interactions Controlling soil Carbon Sequestration
  • ISSN: 0883-2927
Per Persson
E-mail: per [dot] persson [at] biol [dot] lu [dot] se

Professor

MEMEG

+46 46 222 17 96

+46 70 266 38 79

E-C350

50

Professor

Centre for Environmental and Climate Research (CEC)

+46 46 222 17 96

+46 70 266 38 79

D350

Ekologihuset, Sölvegatan 37, Lund

50