Research ArticleGEOLOGY

Biomass recycling and Earth’s early phosphorus cycle

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Science Advances  22 Nov 2017:
Vol. 3, no. 11, eaao4795
DOI: 10.1126/sciadv.aao4795
  • Fig. 1 Redox evolution of the Earth.

    Compilations of (A) electron acceptor availability in seawater and (B) sedimentary organic carbon isotope record. The prevalence of extremely negative δ13C values from ~2.8 to 2.5 Ga has been interpreted by some as a signal of widespread methanogenesis [(90) and references therein].

  • Fig. 2 Total possible P recycling through geologic time.

    Black line indicates preferred values. Gray shaded area is uncertainty envelope for C/P ratios of 106:1. Blue shaded region is uncertainty envelope for C/P ratios of 400:1; red shaded region corresponds to C/P of 1000:1. Dotted line shows modern concentration of P in the deep ocean and upwelling water (~2 μM).

  • Fig. 3 Total possible Archean P recycling as a function of ferric iron and sulfate availability.

    Calculations are presented for C/P ratios of (A) 106, (B) 400, and (C) 1000. Diamond shows preferred values; pink shaded region shows published range of estimates for Archean seawater. Ferric iron reduction could have played a large role in P recycling if bioavailable Fe3+ levels were ~1 mM, but this scenario is very unlikely (discussed in the text). Elevated C/P ratios in primary producers would have severely impeded P recycling in all scenarios.

  • Fig. 4 Total possible Proterozoic P recycling as a function of sulfate availability.

    Blue shaded region shows range of published estimates for Proterozoic sulfate concentrations. An increase in seawater sulfate levels after the GOE would have considerably increased the capacity for P recycling, although high C/P ratios could still have kept P levels low at the lower end of published estimates.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/3/11/eaao4795/DC1

    Supplementary Text

    fig. S1. Estimated annual fluxes of C, N, P, and O2 consumption as a function of depth.

    fig. S2. Box model schematic.

    fig. S3. P concentrations and organic C/P ratios in marginal marine siliciclastic sedimentary rocks.

    References (3789)

  • Supplementary Materials

    This PDF file includes:

    • Supplementary Text
    • fig. S1. Estimated annual fluxes of C, N, P, and O2 consumption as a function of depth.
    • fig. S2. Box model schematic.
    • fig. S3. P concentrations and organic C/P ratios in marginal marine siliciclastic sedimentary rocks.
    • References (37–89)

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