A microanalytical study of iron, aluminium and organic matter relationships in soils with contrasting hydrological regimes

CA Wilson, JM Cloy, MC Graham, LE Hamlet

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

It is recognised that interactions between mineral oxides and soil organic matter (SOM) are an important factor in the stabilisation of soil organic carbon (SOC). The nature of these interactions is particularly complex in gleyed soils that experience periodic waterlogging and changeable redox conditions. This study explores the complex patterns of iron (Fe) (hydr)oxides and SOM in three soils with contrasting hydrological regimes (Gleysol, Stagnosol and Cambisol). Micromorphological examination of undisturbed soil thin sections was teamed with SEM–EDS analysis and sequential dissolution of Fe pedofeatures to gain a better understanding of the mechanisms involved in SOM stabilisation by mineral oxides. All soils contained a diverse range of particulate SOM forms and Fe pedofeatures; the degree of impregnation of the Fe pedofeatures was found to increase with depth and a strong correlation between the presence of SOM and Fe pedofeatures was found to exist through all soils. Weakly crystalline Fe (hydr)oxides were found in association with partially degraded tissue residues and amorphous fine organic matter (OM). Strongly crystalline Fe (hydr)oxides were found in all impregnative Fe pedofeatures and high Fe/C ratios suggested precipitative processes rather than sorption dominate SOC sequestration in these features. In addition, at the core of some strongly impregnated Fe nodules, occluded well preserved organic tissues were identified. The study highlights the range of processes and complexity involved in SOC sequestration over mm to cm scales and untangling this complexity is vital to understanding and modelling terrestrial C fluxes. Whilst the methods used here are not without their complications, the value of micro-scale studies of undisturbed soil thin sections is clearly demonstrated. © 2013 Elsevier B.V. All rights reserved.
Original languageEnglish
Pages (from-to)71 - 81
Number of pages11
JournalGeoderma
Volume202-203
Early online date11 Apr 2013
DOIs
Publication statusPrint publication - Jul 2013
Externally publishedYes

Fingerprint

hydrological regime
aluminum
organic matter
iron
oxide
soil organic matter
soil
thin section
stabilization
organic carbon
Gleysol
Cambisol
waterlogging
redox conditions
mineral
carbon sequestration
sorption
dissolution
modeling

Keywords

  • Gley soil
  • Iron (hydr)oxides
  • Micromorphology
  • SEM–EDS
  • Sequential dissolution
  • Soil organic matter

Cite this

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abstract = "It is recognised that interactions between mineral oxides and soil organic matter (SOM) are an important factor in the stabilisation of soil organic carbon (SOC). The nature of these interactions is particularly complex in gleyed soils that experience periodic waterlogging and changeable redox conditions. This study explores the complex patterns of iron (Fe) (hydr)oxides and SOM in three soils with contrasting hydrological regimes (Gleysol, Stagnosol and Cambisol). Micromorphological examination of undisturbed soil thin sections was teamed with SEM–EDS analysis and sequential dissolution of Fe pedofeatures to gain a better understanding of the mechanisms involved in SOM stabilisation by mineral oxides. All soils contained a diverse range of particulate SOM forms and Fe pedofeatures; the degree of impregnation of the Fe pedofeatures was found to increase with depth and a strong correlation between the presence of SOM and Fe pedofeatures was found to exist through all soils. Weakly crystalline Fe (hydr)oxides were found in association with partially degraded tissue residues and amorphous fine organic matter (OM). Strongly crystalline Fe (hydr)oxides were found in all impregnative Fe pedofeatures and high Fe/C ratios suggested precipitative processes rather than sorption dominate SOC sequestration in these features. In addition, at the core of some strongly impregnated Fe nodules, occluded well preserved organic tissues were identified. The study highlights the range of processes and complexity involved in SOC sequestration over mm to cm scales and untangling this complexity is vital to understanding and modelling terrestrial C fluxes. Whilst the methods used here are not without their complications, the value of micro-scale studies of undisturbed soil thin sections is clearly demonstrated. {\circledC} 2013 Elsevier B.V. All rights reserved.",
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A microanalytical study of iron, aluminium and organic matter relationships in soils with contrasting hydrological regimes. / Wilson, CA; Cloy, JM; Graham, MC; Hamlet, LE.

In: Geoderma, Vol. 202-203, 07.2013, p. 71 - 81.

Research output: Contribution to journalArticle

TY - JOUR

T1 - A microanalytical study of iron, aluminium and organic matter relationships in soils with contrasting hydrological regimes

AU - Wilson, CA

AU - Cloy, JM

AU - Graham, MC

AU - Hamlet, LE

PY - 2013/7

Y1 - 2013/7

N2 - It is recognised that interactions between mineral oxides and soil organic matter (SOM) are an important factor in the stabilisation of soil organic carbon (SOC). The nature of these interactions is particularly complex in gleyed soils that experience periodic waterlogging and changeable redox conditions. This study explores the complex patterns of iron (Fe) (hydr)oxides and SOM in three soils with contrasting hydrological regimes (Gleysol, Stagnosol and Cambisol). Micromorphological examination of undisturbed soil thin sections was teamed with SEM–EDS analysis and sequential dissolution of Fe pedofeatures to gain a better understanding of the mechanisms involved in SOM stabilisation by mineral oxides. All soils contained a diverse range of particulate SOM forms and Fe pedofeatures; the degree of impregnation of the Fe pedofeatures was found to increase with depth and a strong correlation between the presence of SOM and Fe pedofeatures was found to exist through all soils. Weakly crystalline Fe (hydr)oxides were found in association with partially degraded tissue residues and amorphous fine organic matter (OM). Strongly crystalline Fe (hydr)oxides were found in all impregnative Fe pedofeatures and high Fe/C ratios suggested precipitative processes rather than sorption dominate SOC sequestration in these features. In addition, at the core of some strongly impregnated Fe nodules, occluded well preserved organic tissues were identified. The study highlights the range of processes and complexity involved in SOC sequestration over mm to cm scales and untangling this complexity is vital to understanding and modelling terrestrial C fluxes. Whilst the methods used here are not without their complications, the value of micro-scale studies of undisturbed soil thin sections is clearly demonstrated. © 2013 Elsevier B.V. All rights reserved.

AB - It is recognised that interactions between mineral oxides and soil organic matter (SOM) are an important factor in the stabilisation of soil organic carbon (SOC). The nature of these interactions is particularly complex in gleyed soils that experience periodic waterlogging and changeable redox conditions. This study explores the complex patterns of iron (Fe) (hydr)oxides and SOM in three soils with contrasting hydrological regimes (Gleysol, Stagnosol and Cambisol). Micromorphological examination of undisturbed soil thin sections was teamed with SEM–EDS analysis and sequential dissolution of Fe pedofeatures to gain a better understanding of the mechanisms involved in SOM stabilisation by mineral oxides. All soils contained a diverse range of particulate SOM forms and Fe pedofeatures; the degree of impregnation of the Fe pedofeatures was found to increase with depth and a strong correlation between the presence of SOM and Fe pedofeatures was found to exist through all soils. Weakly crystalline Fe (hydr)oxides were found in association with partially degraded tissue residues and amorphous fine organic matter (OM). Strongly crystalline Fe (hydr)oxides were found in all impregnative Fe pedofeatures and high Fe/C ratios suggested precipitative processes rather than sorption dominate SOC sequestration in these features. In addition, at the core of some strongly impregnated Fe nodules, occluded well preserved organic tissues were identified. The study highlights the range of processes and complexity involved in SOC sequestration over mm to cm scales and untangling this complexity is vital to understanding and modelling terrestrial C fluxes. Whilst the methods used here are not without their complications, the value of micro-scale studies of undisturbed soil thin sections is clearly demonstrated. © 2013 Elsevier B.V. All rights reserved.

KW - Gley soil

KW - Iron (hydr)oxides

KW - Micromorphology

KW - SEM–EDS

KW - Sequential dissolution

KW - Soil organic matter

U2 - 10.1016/j.geoderma.2013.03.020

DO - 10.1016/j.geoderma.2013.03.020

M3 - Article

VL - 202-203

SP - 71

EP - 81

JO - Geoderma

JF - Geoderma

SN - 0016-7061

ER -