- Title
- Abundance and fractionation of Al, Fe and trace metals following tidal inundation of a tropical acid sulfate soil
- Creator
- Johnston, Scott; Burton, Edward; Bush, Richard; Keene, Annabelle; Sullivan, Leigh; Smith, Douglas; McElnea, Angus; Ahern, Col; Powell, Bernard
- Date
- 2010
- Type
- Text; Journal article
- Identifier
- http://researchonline.federation.edu.au/vital/access/HandleResolver/1959.17/99588
- Identifier
- vital:10388
- Identifier
-
https://doi.org/10.1016/j.apgeochem.2009.11.015
- Identifier
- ISSN:0883-2927
- 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. © 2009 Elsevier Ltd. All rights reserved.
- Publisher
- Elsevier Ltd
- Relation
- Applied Geochemistry Vol. 25, no. 3 (2010), p. 323-335
- Rights
- Copyright © 2009 Elsevier Ltd. All rights reserved.
- Rights
- This metadata is freely available under a CCO license
- Subject
- 0402 Geochemistry; 0502 Environmental Science and Management; Acid sulfate soils; Dynamic environments; Immobilisation; Intertidal zones; Lepidocrocite; Peak concentrations; PH-dependent; Schwertmannite; Sediment water interface; Soil acidity; Soil surfaces; Trace metal; Water soluble fraction
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