The association of Cobalt with Iron and Manganese (Oxyhydr)oxides in marine sediment

Anthony Stockdale, William Davison, Hao Zhang, John Hamilton-Taylor

Research output: Contribution to journalArticlepeer-review

Abstract

Formation and dissolution of authigenic Fe and Mn (oxyhydr)oxides influence cycling of trace metals in oxic/suboxic surface sediments. We used the diffusive gradients in thin films technique (DGT) to estimate the association of cobalt with iron and manganese oxides. We compared Co, Fe and Mn maxima measured by DGT in the pore waters of fresh and aged marine sediment cores and estimated the Co/Fe and Co/Mn ratios in the metal oxides. A Mn maximum was not visible in DGT concentration profiles of freshly collected sediment cores, but after ageing the sediment, we observed a distinct Mn peak, presumably due to broadening of the depth range over which the various electron acceptors occur. Estimated Co/Mn ratios from both experiments are within the range of literature values for marine sediments, but the value from the aged experiment is at the lower end of the range. This is attributed to stimulation of sulphate reduction and precipitation of cobalt sulphides. The good correlation between Co and Fe maxima in the fresh sediments is attributed to the similarity of their reactions with sulphide rather than Co being released during authigenic Fe oxide reduction.

Original languageEnglish
Pages (from-to)575-585
Number of pages11
JournalAquatic Geochemistry
Volume16
Issue number4
DOIs
Publication statusPublished - 10 Feb 2010
Externally publishedYes

Keywords

  • Biogeochemical cycling
  • DGT
  • Porewater
  • Trace metal

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