Oxidative transformation of iron monosulfides and pyrite in estuarine sediments

Implications for trace metals mobilisation

Girish Choppala, Richard Bush, Ellen Moon, Nicholas Ward, Zhaohui Wang, Nanthi Bolan, Leigh Sullivan

Research output: Contribution to journalArticle

5 Citations (Scopus)

Abstract

Iron monosulfides are the initial iron sulfide minerals that form under reducing conditions in organic-rich sediments. Frequently referred as monosulfidic black ooze (MBO), these sediments exists in a range of anoxic systems including estuaries, coastal wetlands and permeable reactive barriers. The objective of this study was to investigate the transformation of solid phase sulfur, iron fractions and trace metals mobilisation in organic-rich hypersulfidic sediments during dredging. Two sediments from geographically contrasting sites in the Peel-Harvey Estuary were collected and subjected to oxidation through resuspension over 14 days. During oxidation, redox potential rapidly and continuously increased, although minimal change in pH was observed in both sediments. The majority of FeS was oxidised within 48 h. Although not as dynamic as FeS, unusually high rates of FeS 2 oxidation were measured in both sediments at circumneutral pH, with between 39 and 58% of FeS 2 oxidised over 14 days. The rapid oxidation of FeS 2 may be attributed to the presence of nano-size FeS 2 crystals (≈550–860 nm) with a high surface area. Before resuspension, solid bound Fe(total) was most abundant as measured by HCl-extractable Fe(II), followed by organic bound Fe(total) and oxide bound Fe(total). There was a marked decrease in these three fractions in both sediments during resuspension, with an increase in Fe(III) fraction. No significant release of trace metals was observed during resuspension of sulfidic sediments. However, disturbance to these estuarine sediments increases Fe(III) formation and further deteriorates the environment through smothering biological surfaces, deteriorating food sources and the quality of benthic habitats.

Original languageEnglish
Pages (from-to)158-166
Number of pages9
JournalJournal of Environmental Management
Volume186
Issue number2
DOIs
Publication statusPublished - 2017
Externally publishedYes

Fingerprint

estuarine sediment
Pyrites
trace metal
mobilization
Estuaries
pyrite
Sediments
Iron
Metals
iron
resuspension
sediment
Food Quality
Wetlands
Sulfides
Sulfur
oxidation
Oxides
Oxidation-Reduction
Minerals

Cite this

Choppala, Girish ; Bush, Richard ; Moon, Ellen ; Ward, Nicholas ; Wang, Zhaohui ; Bolan, Nanthi ; Sullivan, Leigh. / Oxidative transformation of iron monosulfides and pyrite in estuarine sediments : Implications for trace metals mobilisation. In: Journal of Environmental Management. 2017 ; Vol. 186, No. 2. pp. 158-166.
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abstract = "Iron monosulfides are the initial iron sulfide minerals that form under reducing conditions in organic-rich sediments. Frequently referred as monosulfidic black ooze (MBO), these sediments exists in a range of anoxic systems including estuaries, coastal wetlands and permeable reactive barriers. The objective of this study was to investigate the transformation of solid phase sulfur, iron fractions and trace metals mobilisation in organic-rich hypersulfidic sediments during dredging. Two sediments from geographically contrasting sites in the Peel-Harvey Estuary were collected and subjected to oxidation through resuspension over 14 days. During oxidation, redox potential rapidly and continuously increased, although minimal change in pH was observed in both sediments. The majority of FeS was oxidised within 48 h. Although not as dynamic as FeS, unusually high rates of FeS 2 oxidation were measured in both sediments at circumneutral pH, with between 39 and 58{\%} of FeS 2 oxidised over 14 days. The rapid oxidation of FeS 2 may be attributed to the presence of nano-size FeS 2 crystals (≈550–860 nm) with a high surface area. Before resuspension, solid bound Fe(total) was most abundant as measured by HCl-extractable Fe(II), followed by organic bound Fe(total) and oxide bound Fe(total). There was a marked decrease in these three fractions in both sediments during resuspension, with an increase in Fe(III) fraction. No significant release of trace metals was observed during resuspension of sulfidic sediments. However, disturbance to these estuarine sediments increases Fe(III) formation and further deteriorates the environment through smothering biological surfaces, deteriorating food sources and the quality of benthic habitats.",
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Oxidative transformation of iron monosulfides and pyrite in estuarine sediments : Implications for trace metals mobilisation. / Choppala, Girish; Bush, Richard; Moon, Ellen; Ward, Nicholas; Wang, Zhaohui; Bolan, Nanthi; Sullivan, Leigh.

In: Journal of Environmental Management, Vol. 186, No. 2, 2017, p. 158-166.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Oxidative transformation of iron monosulfides and pyrite in estuarine sediments

T2 - Implications for trace metals mobilisation

AU - Choppala, Girish

AU - Bush, Richard

AU - Moon, Ellen

AU - Ward, Nicholas

AU - Wang, Zhaohui

AU - Bolan, Nanthi

AU - Sullivan, Leigh

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N2 - Iron monosulfides are the initial iron sulfide minerals that form under reducing conditions in organic-rich sediments. Frequently referred as monosulfidic black ooze (MBO), these sediments exists in a range of anoxic systems including estuaries, coastal wetlands and permeable reactive barriers. The objective of this study was to investigate the transformation of solid phase sulfur, iron fractions and trace metals mobilisation in organic-rich hypersulfidic sediments during dredging. Two sediments from geographically contrasting sites in the Peel-Harvey Estuary were collected and subjected to oxidation through resuspension over 14 days. During oxidation, redox potential rapidly and continuously increased, although minimal change in pH was observed in both sediments. The majority of FeS was oxidised within 48 h. Although not as dynamic as FeS, unusually high rates of FeS 2 oxidation were measured in both sediments at circumneutral pH, with between 39 and 58% of FeS 2 oxidised over 14 days. The rapid oxidation of FeS 2 may be attributed to the presence of nano-size FeS 2 crystals (≈550–860 nm) with a high surface area. Before resuspension, solid bound Fe(total) was most abundant as measured by HCl-extractable Fe(II), followed by organic bound Fe(total) and oxide bound Fe(total). There was a marked decrease in these three fractions in both sediments during resuspension, with an increase in Fe(III) fraction. No significant release of trace metals was observed during resuspension of sulfidic sediments. However, disturbance to these estuarine sediments increases Fe(III) formation and further deteriorates the environment through smothering biological surfaces, deteriorating food sources and the quality of benthic habitats.

AB - Iron monosulfides are the initial iron sulfide minerals that form under reducing conditions in organic-rich sediments. Frequently referred as monosulfidic black ooze (MBO), these sediments exists in a range of anoxic systems including estuaries, coastal wetlands and permeable reactive barriers. The objective of this study was to investigate the transformation of solid phase sulfur, iron fractions and trace metals mobilisation in organic-rich hypersulfidic sediments during dredging. Two sediments from geographically contrasting sites in the Peel-Harvey Estuary were collected and subjected to oxidation through resuspension over 14 days. During oxidation, redox potential rapidly and continuously increased, although minimal change in pH was observed in both sediments. The majority of FeS was oxidised within 48 h. Although not as dynamic as FeS, unusually high rates of FeS 2 oxidation were measured in both sediments at circumneutral pH, with between 39 and 58% of FeS 2 oxidised over 14 days. The rapid oxidation of FeS 2 may be attributed to the presence of nano-size FeS 2 crystals (≈550–860 nm) with a high surface area. Before resuspension, solid bound Fe(total) was most abundant as measured by HCl-extractable Fe(II), followed by organic bound Fe(total) and oxide bound Fe(total). There was a marked decrease in these three fractions in both sediments during resuspension, with an increase in Fe(III) fraction. No significant release of trace metals was observed during resuspension of sulfidic sediments. However, disturbance to these estuarine sediments increases Fe(III) formation and further deteriorates the environment through smothering biological surfaces, deteriorating food sources and the quality of benthic habitats.

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KW - Western Australia

KW - Oxidation-Reduction

KW - Sulfides/chemistry

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KW - Minerals

KW - Sulfur/chemistry

KW - Water Quality

KW - Iron/chemistry

KW - Ferric Compounds/chemistry

KW - Hydrogen-Ion Concentration

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