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

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XAS study of iron speciation in soils and waters from a boreal catchment. / Sundman, Anneli; Karlsson, Torbjorn; Laudon, Hjalmar; Persson, Per.

In: Chemical Geology, Vol. 364, 2014, p. 93-102.

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Sundman, Anneli ; Karlsson, Torbjorn ; Laudon, Hjalmar ; Persson, Per. / XAS study of iron speciation in soils and waters from a boreal catchment. In: Chemical Geology. 2014 ; Vol. 364. pp. 93-102.

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TY - JOUR

T1 - XAS study of iron speciation in soils and waters from a boreal catchment

AU - Sundman, Anneli

AU - Karlsson, Torbjorn

AU - Laudon, Hjalmar

AU - Persson, Per

PY - 2014

Y1 - 2014

N2 - 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.

AB - 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.

KW - Fe speciation

KW - XAS

KW - Stream water

KW - Soil solutions

KW - Ground water

KW - Krycklan

KW - catchment

U2 - 10.1016/j.chemgeo.2013.11.023

DO - 10.1016/j.chemgeo.2013.11.023

M3 - Article

VL - 364

SP - 93

EP - 102

JO - Chemical Geology (Isotopic Geoscience) Section

JF - Chemical Geology (Isotopic Geoscience) Section

SN - 0009-2541

ER -