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Thread: Ocean chemistry in the Precambrian [Fe ions] [FREE]

  1. #1
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    Thumbs up Ocean chemistry in the Precambrian [Fe ions] [FREE]

    Swanner, E. D., et al. (2018). "Oxic Fe(III) reduction could have generated Fe(II) in the photic zone of Precambrian seawater." Scientific Reports 8(1): 4238.
    Many marine Precambrian iron formations (IF) record deep anoxic seawater enriched in Fe(II) (i.e. ferruginous) overlain by mildly oxygenated surface water. This is reflected by iron-rich sediments forming in deep basins, and relatively iron-poor sediments forming in shallow, sunlit waters. Such an iron gradient is often interpreted as a redox interface where dissolved Fe(II) was oxidized and precipitated as Fe(III)-bearing minerals. As such, sedimentary iron enrichments are proxy to the progressive oxidation of the oceans through geological time. However, this interpretation is founded on the assumption that Fe(II) could not persist within an oxygenated water column. Here, we cultivated cyanobacteria in an illuminated column supplied with Fe(II)-rich seawater medium in a laboratory-scale analog of a continental margin supporting IF deposition. We first observed Fe(II) oxidation with oxygen, then biologically-mediated reduction of Fe(III) (oxyhydr)oxides, which maintained a pool of Fe(II) in the presence of oxygen. Such steady-state iron redox cycling may have maintained dissolved, and hence mobile Fe(II) in oxygenated seawater above ferruginous deep basins such as those inferred for many Precambrian IF. were deposited
    https://doi.org/10.1038/s41598-018-22694-y

    https://www.nature.com/articles/s41598-018-22694-y.pdf

    https://www.sciencedaily.com/release...0309125246.htm
    Just stick to the idea that science tests falsifiable hypotheses to destruction.

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  3. #2
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    Default Re: Ocean chemistry in the Precambrian [Fe ions] [FREE]

    When I need reminders of how actually ignorant I am, papers such as this are handy.
    EJB

    Iím not one of the dead ones yet. - Ms Fishie.


  4. #3
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    Default Re: Ocean chemistry in the Precambrian [Fe ions] [FREE]

    moi aussi!
    Just stick to the idea that science tests falsifiable hypotheses to destruction.

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