Abundance and fractionation of Al, Fe and trace metals following tidal inundation of a tropical acid sulfate soil

Scott G. Johnston, Edward D. Burton, Richard T. Bush, Annabelle F. Keene, Leigh A. Sullivan, Douglas Smith, Angus E. McElnea, Col R. Ahern, Bernard Powell

Research output: Contribution to journalArticle

35 Citations (Scopus)

Abstract

Tidal inundation was restored to a severely degraded tropical acid sulfate soil landscape and subsequent changes in the abundance and fractionation of Al, Fe and selected trace metals were investigated. After 5 a of regular tidal inundation there were large decreases in water-soluble and exchangeable Al fractions within former sulfuric horizons. This was strongly associated with decreased soil acidity and increases in pH, suggesting pH-dependent immobilisation of Al via precipitation as poorly soluble phases. The water-soluble fractions of Fe, Zn, Ni and Mn also decreased. However, there was substantial enrichment (2-5×) of the reactive Fe fraction (FeR; 1 M HCl extractable) near the soil surface, plus a closely corresponding enrichment of 1 M HCl extractable Cr, Zn, Ni and Mn. Surficial accumulations of Fe(III) minerals in the inter-tidal zone were poorly crystalline (up to 38% FeR) and comprised mainly of schwertmannite (Fe8O8(OH)6SO4) with minor quantities of goethite (α-FeOOH) and lepidocrocite (γ-FeOOH). These Fe (III) mineral accumulations provide an effective substrate for the adsorption/co-precipitation and accumulation of trace metals. Arsenic displayed contrary behaviour to trace metals with peak concentrations (∼60 μg g-1) near the redox minima. Changes in the abundance and fractionation of the various metals can be primarily explained by the shift in the geochemical regime from oxic-acidic to reducing-circumneutral conditions, combined with the enrichment of reactive Fe near the soil surface. Whilst increasing sequestration of trace metals via sulfidisation is likely to occur over the long-term, the current abundance of reactive Fe near the sediment-water interface favours a dynamic environment with respect to metals in the tidally inundated areas.

Original languageEnglish
Pages (from-to)323-335
Number of pages13
JournalApplied Geochemistry
Volume25
Issue number3
DOIs
Publication statusPublished - 2010
Externally publishedYes

Fingerprint

acid sulfate soil
Fractionation
Sulfates
trace metal
fractionation
Soils
Acids
Minerals
Water
soil surface
Metals
schwertmannite
lepidocrocite
metal
Arsenic
sediment-water interface
mineral
Coprecipitation
goethite
intertidal environment

Cite this

Johnston, Scott G. ; Burton, Edward D. ; Bush, Richard T. ; Keene, Annabelle F. ; Sullivan, Leigh A. ; Smith, Douglas ; McElnea, Angus E. ; Ahern, Col R. ; Powell, Bernard. / Abundance and fractionation of Al, Fe and trace metals following tidal inundation of a tropical acid sulfate soil. In: Applied Geochemistry. 2010 ; Vol. 25, No. 3. pp. 323-335.
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title = "Abundance and fractionation of Al, Fe and trace metals following tidal inundation of a tropical acid sulfate soil",
abstract = "Tidal inundation was restored to a severely degraded tropical acid sulfate soil landscape and subsequent changes in the abundance and fractionation of Al, Fe and selected trace metals were investigated. After 5 a of regular tidal inundation there were large decreases in water-soluble and exchangeable Al fractions within former sulfuric horizons. This was strongly associated with decreased soil acidity and increases in pH, suggesting pH-dependent immobilisation of Al via precipitation as poorly soluble phases. The water-soluble fractions of Fe, Zn, Ni and Mn also decreased. However, there was substantial enrichment (2-5×) of the reactive Fe fraction (FeR; 1 M HCl extractable) near the soil surface, plus a closely corresponding enrichment of 1 M HCl extractable Cr, Zn, Ni and Mn. Surficial accumulations of Fe(III) minerals in the inter-tidal zone were poorly crystalline (up to 38{\%} FeR) and comprised mainly of schwertmannite (Fe8O8(OH)6SO4) with minor quantities of goethite (α-FeOOH) and lepidocrocite (γ-FeOOH). These Fe (III) mineral accumulations provide an effective substrate for the adsorption/co-precipitation and accumulation of trace metals. Arsenic displayed contrary behaviour to trace metals with peak concentrations (∼60 μg g-1) near the redox minima. Changes in the abundance and fractionation of the various metals can be primarily explained by the shift in the geochemical regime from oxic-acidic to reducing-circumneutral conditions, combined with the enrichment of reactive Fe near the soil surface. Whilst increasing sequestration of trace metals via sulfidisation is likely to occur over the long-term, the current abundance of reactive Fe near the sediment-water interface favours a dynamic environment with respect to metals in the tidally inundated areas.",
author = "Johnston, {Scott G.} and Burton, {Edward D.} and Bush, {Richard T.} and Keene, {Annabelle F.} and Sullivan, {Leigh A.} and Douglas Smith and McElnea, {Angus E.} and Ahern, {Col R.} and Bernard Powell",
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Johnston, SG, Burton, ED, Bush, RT, Keene, AF, Sullivan, LA, Smith, D, McElnea, AE, Ahern, CR & Powell, B 2010, 'Abundance and fractionation of Al, Fe and trace metals following tidal inundation of a tropical acid sulfate soil', Applied Geochemistry, vol. 25, no. 3, pp. 323-335. https://doi.org/10.1016/j.apgeochem.2009.11.015

Abundance and fractionation of Al, Fe and trace metals following tidal inundation of a tropical acid sulfate soil. / Johnston, Scott G.; Burton, Edward D.; Bush, Richard T.; Keene, Annabelle F.; Sullivan, Leigh A.; Smith, Douglas; McElnea, Angus E.; Ahern, Col R.; Powell, Bernard.

In: Applied Geochemistry, Vol. 25, No. 3, 2010, p. 323-335.

Research output: Contribution to journalArticle

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T1 - Abundance and fractionation of Al, Fe and trace metals following tidal inundation of a tropical acid sulfate soil

AU - Johnston, Scott G.

AU - Burton, Edward D.

AU - Bush, Richard T.

AU - Keene, Annabelle F.

AU - Sullivan, Leigh A.

AU - Smith, Douglas

AU - McElnea, Angus E.

AU - Ahern, Col R.

AU - Powell, Bernard

PY - 2010

Y1 - 2010

N2 - Tidal inundation was restored to a severely degraded tropical acid sulfate soil landscape and subsequent changes in the abundance and fractionation of Al, Fe and selected trace metals were investigated. After 5 a of regular tidal inundation there were large decreases in water-soluble and exchangeable Al fractions within former sulfuric horizons. This was strongly associated with decreased soil acidity and increases in pH, suggesting pH-dependent immobilisation of Al via precipitation as poorly soluble phases. The water-soluble fractions of Fe, Zn, Ni and Mn also decreased. However, there was substantial enrichment (2-5×) of the reactive Fe fraction (FeR; 1 M HCl extractable) near the soil surface, plus a closely corresponding enrichment of 1 M HCl extractable Cr, Zn, Ni and Mn. Surficial accumulations of Fe(III) minerals in the inter-tidal zone were poorly crystalline (up to 38% FeR) and comprised mainly of schwertmannite (Fe8O8(OH)6SO4) with minor quantities of goethite (α-FeOOH) and lepidocrocite (γ-FeOOH). These Fe (III) mineral accumulations provide an effective substrate for the adsorption/co-precipitation and accumulation of trace metals. Arsenic displayed contrary behaviour to trace metals with peak concentrations (∼60 μg g-1) near the redox minima. Changes in the abundance and fractionation of the various metals can be primarily explained by the shift in the geochemical regime from oxic-acidic to reducing-circumneutral conditions, combined with the enrichment of reactive Fe near the soil surface. Whilst increasing sequestration of trace metals via sulfidisation is likely to occur over the long-term, the current abundance of reactive Fe near the sediment-water interface favours a dynamic environment with respect to metals in the tidally inundated areas.

AB - Tidal inundation was restored to a severely degraded tropical acid sulfate soil landscape and subsequent changes in the abundance and fractionation of Al, Fe and selected trace metals were investigated. After 5 a of regular tidal inundation there were large decreases in water-soluble and exchangeable Al fractions within former sulfuric horizons. This was strongly associated with decreased soil acidity and increases in pH, suggesting pH-dependent immobilisation of Al via precipitation as poorly soluble phases. The water-soluble fractions of Fe, Zn, Ni and Mn also decreased. However, there was substantial enrichment (2-5×) of the reactive Fe fraction (FeR; 1 M HCl extractable) near the soil surface, plus a closely corresponding enrichment of 1 M HCl extractable Cr, Zn, Ni and Mn. Surficial accumulations of Fe(III) minerals in the inter-tidal zone were poorly crystalline (up to 38% FeR) and comprised mainly of schwertmannite (Fe8O8(OH)6SO4) with minor quantities of goethite (α-FeOOH) and lepidocrocite (γ-FeOOH). These Fe (III) mineral accumulations provide an effective substrate for the adsorption/co-precipitation and accumulation of trace metals. Arsenic displayed contrary behaviour to trace metals with peak concentrations (∼60 μg g-1) near the redox minima. Changes in the abundance and fractionation of the various metals can be primarily explained by the shift in the geochemical regime from oxic-acidic to reducing-circumneutral conditions, combined with the enrichment of reactive Fe near the soil surface. Whilst increasing sequestration of trace metals via sulfidisation is likely to occur over the long-term, the current abundance of reactive Fe near the sediment-water interface favours a dynamic environment with respect to metals in the tidally inundated areas.

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U2 - 10.1016/j.apgeochem.2009.11.015

DO - 10.1016/j.apgeochem.2009.11.015

M3 - Article

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EP - 335

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JF - Applied Geochemistry

SN - 0883-2927

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