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XAS study of iron speciation in soils and waters from a boreal catchment

Sundman, Anneli; Karlsson, Torbjorn; Laudon, Hjalmar and Persson, Per LU (2014) In Chemical Geology 364. p.93-102
Abstract
Iron (Fe) is a key element, strongly influencing the biogeochemistry of soils, sediments and waters, but the knowledge about the variety of Fe species present in these systems is still limited. In this work we have used X-ray absorption spectroscopy (XAS) to study the speciation of Fe in soils and waters from a boreal catchment in northern Sweden. The aim was to better understand the controls of Fe speciation across different, but adjacent landscape elements including soil, soil solution, groundwater and stream water draining catchments with contrasting land characteristics. Our results showed that all samples contained mixtures of Fe(II) and Fe(III). The soils consisted of Fe phyllosilicates, Fe (hydr) oxides and Fe complexed by natural... (More)
Iron (Fe) is a key element, strongly influencing the biogeochemistry of soils, sediments and waters, but the knowledge about the variety of Fe species present in these systems is still limited. In this work we have used X-ray absorption spectroscopy (XAS) to study the speciation of Fe in soils and waters from a boreal catchment in northern Sweden. The aim was to better understand the controls of Fe speciation across different, but adjacent landscape elements including soil, soil solution, groundwater and stream water draining catchments with contrasting land characteristics. Our results showed that all samples contained mixtures of Fe(II) and Fe(III). The soils consisted of Fe phyllosilicates, Fe (hydr) oxides and Fe complexed by natural organic matter (NOM). All aqueous samples contained Fe(II)- and Fe(III)-NOM complexes, often in combination with Fe(III) (hydr) oxides that were associated with NOM. The variation in contribution from Fe-NOM and Fe (hydr) oxides was controlled by pH and total concentrations of NOM. The XAS spectra suggested formation of mononuclear Fe-NOM complexes consisting of chelate ring structures, but it could not be determined whether they originated solely from Fe(III)- or from a mixture of Fe(II)/Fe(III)-NOM complexes. Our collective results showed that the Fe speciation was highly variable across the different landscape elements and streams. This variation was manifested both in the distribution between mononuclear Fe-NOM complexes and Fe (hydr) oxides associated with NOM and between Fe(II) and Fe(III). These results highlight the complexity of Fe speciation in natural environmental systems and thus the challenges in interpreting Fe reactivity. (C) 2013 Elsevier B.V. All rights reserved. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Fe speciation, XAS, Stream water, Soil solutions, Ground water, Krycklan, catchment
in
Chemical Geology
volume
364
pages
93 - 102
publisher
Elsevier
external identifiers
  • wos:000329409600009
  • scopus:84891357618
ISSN
0009-2541
DOI
10.1016/j.chemgeo.2013.11.023
project
MICCS - Molecular Interactions Controlling soil Carbon Sequestration
BECC
language
English
LU publication?
yes
id
0ca44fbe-d2e5-4d0a-b96a-2264234d911e (old id 4327003)
date added to LUP
2014-02-28 09:59:02
date last changed
2017-10-22 03:05:44
@article{0ca44fbe-d2e5-4d0a-b96a-2264234d911e,
  abstract     = {Iron (Fe) is a key element, strongly influencing the biogeochemistry of soils, sediments and waters, but the knowledge about the variety of Fe species present in these systems is still limited. In this work we have used X-ray absorption spectroscopy (XAS) to study the speciation of Fe in soils and waters from a boreal catchment in northern Sweden. The aim was to better understand the controls of Fe speciation across different, but adjacent landscape elements including soil, soil solution, groundwater and stream water draining catchments with contrasting land characteristics. Our results showed that all samples contained mixtures of Fe(II) and Fe(III). The soils consisted of Fe phyllosilicates, Fe (hydr) oxides and Fe complexed by natural organic matter (NOM). All aqueous samples contained Fe(II)- and Fe(III)-NOM complexes, often in combination with Fe(III) (hydr) oxides that were associated with NOM. The variation in contribution from Fe-NOM and Fe (hydr) oxides was controlled by pH and total concentrations of NOM. The XAS spectra suggested formation of mononuclear Fe-NOM complexes consisting of chelate ring structures, but it could not be determined whether they originated solely from Fe(III)- or from a mixture of Fe(II)/Fe(III)-NOM complexes. Our collective results showed that the Fe speciation was highly variable across the different landscape elements and streams. This variation was manifested both in the distribution between mononuclear Fe-NOM complexes and Fe (hydr) oxides associated with NOM and between Fe(II) and Fe(III). These results highlight the complexity of Fe speciation in natural environmental systems and thus the challenges in interpreting Fe reactivity. (C) 2013 Elsevier B.V. All rights reserved.},
  author       = {Sundman, Anneli and Karlsson, Torbjorn and Laudon, Hjalmar and Persson, Per},
  issn         = {0009-2541},
  keyword      = {Fe speciation,XAS,Stream water,Soil solutions,Ground water,Krycklan,catchment},
  language     = {eng},
  pages        = {93--102},
  publisher    = {Elsevier},
  series       = {Chemical Geology},
  title        = {XAS study of iron speciation in soils and waters from a boreal catchment},
  url          = {http://dx.doi.org/10.1016/j.chemgeo.2013.11.023},
  volume       = {364},
  year         = {2014},
}