Enrichment and heterogeneity of trace elements at the redox-interface of Fe-rich intertidal sediments

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

Research output: Contribution to journalArticle

7 Citations (Scopus)

Abstract

Redox-interfacial sediments can undergo radical geochemical changes with oscillating tides. In this study, we examine trace element enrichment and availability, at both landscape and pedon-scales, in the surface sediments of a remediating acidic tidal wetland. Fe-rich sediments at the surface-water interface (0-10. mm in depth) were collected across an elevation gradient spanning the supratidal to subtidal range. These sediments were analysed for solid phase Fe fractions and trace elements (As, Pb, Cr, Cu, Mn, Ni, Zn, V, B, Co, Mo, Ba and U) via dilute HCl-extractions and total digests. Their concentrations were compared with those of underlying (0.05-0.65. m in depth) former sulfuric horizon sediments of a coastal acid sulfate soil (CASS). Reactive Fe was enriched at the redox interface by up to 16 times (197. g. Fe/kg) that of the former sulfuric horizon. The proportion of total trace elements associated with reactive phases was high in interfacial sediments, representing over 90% of B and U and 50% of Pb, Cu, Zn, V and Ba extractable by dilute HCl. The interfacial sediments were particularly enriched in reactive Cr, Cu, Ni, Zn, B, Mo and U, with reactive B, Mo and U concentrations between 5 and 10 times greater than in the former sulfuric horizon. Surface enrichment of trace elements is strongly co-associated with Fe(III) mineralisation, likely via sorption and co-precipitation processes. Enrichment is highly spatially heterogeneous and is strongly influenced by elevation and tidal zonation at a landscape-scale and by sediment micro-topography and preferential advective transport via surface connected macropores at the pedon-scale. The results from this study provide new insights to the processes influencing trace element enrichment in Fe-rich redox-interfacial sediments across a remediating acidic tidal wetland.

Original languageEnglish
Pages (from-to)1-12
Number of pages12
JournalChemical Geology
Volume383
DOIs
Publication statusPublished - 2014
Externally publishedYes

Fingerprint

Trace Elements
Sediments
trace element
sediment
pedon
Wetlands
wetland
Oxidation-Reduction
acid sulfate soil
microtopography
macropore
Tides
Coprecipitation
Surface waters
Topography
zonation
Sulfates
Sorption
advection
tide

Cite this

Keene, Annabelle F. ; Johnston, Scott G. ; Bush, Richard T. ; Burton, Edward D. ; Sullivan, Leigh A. ; Dundon, Matthew ; McElnea, Angus E. ; Smith, C. Doug ; Ahern, Col R. ; Powell, Bernard. / Enrichment and heterogeneity of trace elements at the redox-interface of Fe-rich intertidal sediments. In: Chemical Geology. 2014 ; Vol. 383. pp. 1-12.
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abstract = "Redox-interfacial sediments can undergo radical geochemical changes with oscillating tides. In this study, we examine trace element enrichment and availability, at both landscape and pedon-scales, in the surface sediments of a remediating acidic tidal wetland. Fe-rich sediments at the surface-water interface (0-10. mm in depth) were collected across an elevation gradient spanning the supratidal to subtidal range. These sediments were analysed for solid phase Fe fractions and trace elements (As, Pb, Cr, Cu, Mn, Ni, Zn, V, B, Co, Mo, Ba and U) via dilute HCl-extractions and total digests. Their concentrations were compared with those of underlying (0.05-0.65. m in depth) former sulfuric horizon sediments of a coastal acid sulfate soil (CASS). Reactive Fe was enriched at the redox interface by up to 16 times (197. g. Fe/kg) that of the former sulfuric horizon. The proportion of total trace elements associated with reactive phases was high in interfacial sediments, representing over 90{\%} of B and U and 50{\%} of Pb, Cu, Zn, V and Ba extractable by dilute HCl. The interfacial sediments were particularly enriched in reactive Cr, Cu, Ni, Zn, B, Mo and U, with reactive B, Mo and U concentrations between 5 and 10 times greater than in the former sulfuric horizon. Surface enrichment of trace elements is strongly co-associated with Fe(III) mineralisation, likely via sorption and co-precipitation processes. Enrichment is highly spatially heterogeneous and is strongly influenced by elevation and tidal zonation at a landscape-scale and by sediment micro-topography and preferential advective transport via surface connected macropores at the pedon-scale. The results from this study provide new insights to the processes influencing trace element enrichment in Fe-rich redox-interfacial sediments across a remediating acidic tidal wetland.",
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Keene, AF, Johnston, SG, Bush, RT, Burton, ED, Sullivan, LA, Dundon, M, McElnea, AE, Smith, CD, Ahern, CR & Powell, B 2014, 'Enrichment and heterogeneity of trace elements at the redox-interface of Fe-rich intertidal sediments', Chemical Geology, vol. 383, pp. 1-12. https://doi.org/10.1016/j.chemgeo.2014.06.003

Enrichment and heterogeneity of trace elements at the redox-interface of Fe-rich intertidal sediments. / Keene, Annabelle F.; Johnston, Scott G.; Bush, Richard T.; Burton, Edward D.; Sullivan, Leigh A.; Dundon, Matthew; McElnea, Angus E.; Smith, C. Doug; Ahern, Col R.; Powell, Bernard.

In: Chemical Geology, Vol. 383, 2014, p. 1-12.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Enrichment and heterogeneity of trace elements at the redox-interface of Fe-rich intertidal sediments

AU - Keene, Annabelle F.

AU - Johnston, Scott G.

AU - Bush, Richard T.

AU - Burton, Edward D.

AU - Sullivan, Leigh A.

AU - Dundon, Matthew

AU - McElnea, Angus E.

AU - Smith, C. Doug

AU - Ahern, Col R.

AU - Powell, Bernard

PY - 2014

Y1 - 2014

N2 - Redox-interfacial sediments can undergo radical geochemical changes with oscillating tides. In this study, we examine trace element enrichment and availability, at both landscape and pedon-scales, in the surface sediments of a remediating acidic tidal wetland. Fe-rich sediments at the surface-water interface (0-10. mm in depth) were collected across an elevation gradient spanning the supratidal to subtidal range. These sediments were analysed for solid phase Fe fractions and trace elements (As, Pb, Cr, Cu, Mn, Ni, Zn, V, B, Co, Mo, Ba and U) via dilute HCl-extractions and total digests. Their concentrations were compared with those of underlying (0.05-0.65. m in depth) former sulfuric horizon sediments of a coastal acid sulfate soil (CASS). Reactive Fe was enriched at the redox interface by up to 16 times (197. g. Fe/kg) that of the former sulfuric horizon. The proportion of total trace elements associated with reactive phases was high in interfacial sediments, representing over 90% of B and U and 50% of Pb, Cu, Zn, V and Ba extractable by dilute HCl. The interfacial sediments were particularly enriched in reactive Cr, Cu, Ni, Zn, B, Mo and U, with reactive B, Mo and U concentrations between 5 and 10 times greater than in the former sulfuric horizon. Surface enrichment of trace elements is strongly co-associated with Fe(III) mineralisation, likely via sorption and co-precipitation processes. Enrichment is highly spatially heterogeneous and is strongly influenced by elevation and tidal zonation at a landscape-scale and by sediment micro-topography and preferential advective transport via surface connected macropores at the pedon-scale. The results from this study provide new insights to the processes influencing trace element enrichment in Fe-rich redox-interfacial sediments across a remediating acidic tidal wetland.

AB - Redox-interfacial sediments can undergo radical geochemical changes with oscillating tides. In this study, we examine trace element enrichment and availability, at both landscape and pedon-scales, in the surface sediments of a remediating acidic tidal wetland. Fe-rich sediments at the surface-water interface (0-10. mm in depth) were collected across an elevation gradient spanning the supratidal to subtidal range. These sediments were analysed for solid phase Fe fractions and trace elements (As, Pb, Cr, Cu, Mn, Ni, Zn, V, B, Co, Mo, Ba and U) via dilute HCl-extractions and total digests. Their concentrations were compared with those of underlying (0.05-0.65. m in depth) former sulfuric horizon sediments of a coastal acid sulfate soil (CASS). Reactive Fe was enriched at the redox interface by up to 16 times (197. g. Fe/kg) that of the former sulfuric horizon. The proportion of total trace elements associated with reactive phases was high in interfacial sediments, representing over 90% of B and U and 50% of Pb, Cu, Zn, V and Ba extractable by dilute HCl. The interfacial sediments were particularly enriched in reactive Cr, Cu, Ni, Zn, B, Mo and U, with reactive B, Mo and U concentrations between 5 and 10 times greater than in the former sulfuric horizon. Surface enrichment of trace elements is strongly co-associated with Fe(III) mineralisation, likely via sorption and co-precipitation processes. Enrichment is highly spatially heterogeneous and is strongly influenced by elevation and tidal zonation at a landscape-scale and by sediment micro-topography and preferential advective transport via surface connected macropores at the pedon-scale. The results from this study provide new insights to the processes influencing trace element enrichment in Fe-rich redox-interfacial sediments across a remediating acidic tidal wetland.

KW - Acid sulfate soils

KW - Iron

KW - Remediation

KW - Tidal wetland

KW - Trace elements

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U2 - 10.1016/j.chemgeo.2014.06.003

DO - 10.1016/j.chemgeo.2014.06.003

M3 - Article

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JO - Chemical Geology (Isotopic Geoscience) Section

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