Research ArticleGEOCHEMISTRY

Photoferrotrophy, deposition of banded iron formations, and methane production in Archean oceans

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Science Advances  27 Nov 2019:
Vol. 5, no. 11, eaav2869
DOI: 10.1126/sciadv.aav2869
  • Fig. 1 The organic matter concentrations in BIFs, other Precambrian sedimentary rocks, typical modern marine sediments, and oxygen minimum zone (OMZ) sediments.

    The solid lines represent the group means, while the dotted lines delineate one SD above and below the mean. The black dashed line that spans the figure represents the theoretical organic carbon concentration that would be expected in BIFs deposited by photoferrotrophs (2.04 wt % C), assuming quantitative co-sedimentation of biomass with ferric Fe. References for this figure can be found in table S5.

  • Fig. 2 Cell surface characteristics for strain KB01 and the relationship between ferric iron surface charge and medium anions.

    Fractions of planktonic (blue) versus sedimented (red) cells (A) for photoferrotrophic strain KB01 under varying geochemical conditions: 400 μM Fe(II) with low P (3 μM) [unmarked]; 400 μM Fe(II), low P (3 μM), with 0.6 mM Si [A]; 400 μM Fe(II), low P (3 μM), with 1.0 mM Si [B]; 400 μM Fe(II), low P (3 μM), with 1.5 mM Si [C]; and 10 mM Fe(II) with 4.4 mM P [D]. C. ferrooxidans and Synechococcus are also shown under the [C] conditions. Rhodobacter strain SW2 is shown under the [D] conditions. The zeta potential (B), in millivolts, of the ferric iron precipitates is depicted with an increasing ratio of Si or P to Fe, where the error bars are all within the data points. Last, for the extended DVLO modeling for strain KB01 (C), the main graph depicts the interaction energies of the three forces (AB, Lewis acid base; LW, Lifshitz–van der Waals; EL, electrostatic) and the total (TOT) for those forces from 3 to 5 nm, while the inset depicts the forces from 0 to 5 nm.

  • Fig. 3 Scanning electron microscopy and transmission electron microscopy image of strain KB01.

    Scanning electron photomicrograph (A) and transmission electron photomicrograph (B) of C. phaeoferrooxidans strain KB01 revealing various internal and external cell structures as well as a lack of encrustation (A and B) and a rare association with Fe(III) precipitates (A).

  • Fig. 4 Model of an Archean coastal upwelling zone.

    A schematic (A) depicting the cycling of iron and carbon in the model and the boxes (B) that were used to create the model structure, accompanied by arrows demonstrating the fluxes of various biochemical parameters between the boxes.

  • Fig. 5 Iron and carbon box model sensitivity results.

    (A) Model sensitivity results for varying continent size. (B) Percentage of cells associated with Fe(III) (oxyhydr)oxides. (C) Deep ocean Fe(II). (D) Varying upwelling rates in the upwelling provinces. Iron deposition rates in the upwelling provinces are depicted on the y axis, while global rates of primary production and methane production are both shown on the x axis in Tmol/year.

  • Table 1 Model results for both the carbon cycle (primary production, carbon burial, carbon remineralization, and methane production) and the iron cycle (iron recycling and iron deposition) at 2.5 Ga.

    Low, Middle, and High represent the model outputs from the low, middle, and high parts of the ranges depicted by the gray boxes in Fig. 5 and fig. S8. For reference, modern rates of primary production (PP) range from 2760 to 3510 Tmol C year−1 (60).

    C
    PP
    C burialC remineralizationC to Fe reductionC to CH4
    production
    Fe
    recycling
    Fe
    deposition
    (upwelling
    province)
    Global Fe
    deposition
    Global CH4
    Tmol
    C/year
    % of PP% of PP% of
    remineralization
    % of
    remineralization
    Tmol
    Fe/year
    Tmol
    Fe/year
    Tmol
    Fe/year
    Tmol
    CH4/year
    2.5 Ga Low4.514.885.272.627.411.11.017.90.5
    2.5 Ga Middle14.814.785.349.150.924.89.959.13.2
    2.5 Ga High22.514.685.441.059.031.417.589.95.7

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/11/eaav2869/DC1

    Supplementary Materials and Methods

    Section S1. Cell surface features and acid-base chemistry

    Section S2. Cell-iron surface interaction and extended DVLO modeling

    Section S3. Iron concentration and supply

    Section S4. Physical separation of ferric iron oxyhydroxides and cellular biomass in an ocean setting

    Section S5. Box model of Archean marine carbon and iron cycles

    Section S6. Organic carbon burial and diagenesis

    Table S1. Range of concentrations in the growth media used throughout experiments.

    Table S2. Cell surface characteristics and cell-mineral interaction modeling.

    Table S3. Modern and Archean Fe fluxes.

    Table S4. Different scenarios of the physical separation model, with each case using a different water velocity.

    Table S5. Data compilations for Fig. 1 and fig. S1.

    Fig. S1. The redox state of iron in BIF through time where the red bars indicate the siderite-rich BIFs.

    Fig. S2. Growth curve for C. phaeoferrooxidans strain KB01.

    Fig. S3. Additional SEM and TEM images of strains KB01 and KoFox under two conditions.

    Fig. S4. Surface charge of strains KB01 and KoFox.

    Fig. S5. Additional cell surface characteristics for strain KoFox.

    Fig. S6. Modeling the settling velocity of carbon and iron using a range of horizontal current velocities.

    Fig. S7. Modeled weight % organic carbon in the coastal and open ocean sediments.

    Fig. S8. Iron and carbon box model sensitivity results.

    References (61103)

  • Supplementary Materials

    This PDF file includes:

    • Supplementary Materials and Methods
    • Section S1. Cell surface features and acid-base chemistry
    • Section S2. Cell-iron surface interaction and extended DVLO modeling
    • Section S3. Iron concentration and supply
    • Section S4. Physical separation of ferric iron oxyhydroxides and cellular biomass in an ocean setting
    • Section S5. Box model of Archean marine carbon and iron cycles
    • Section S6. Organic carbon burial and diagenesis
    • Table S1. Range of concentrations in the growth media used throughout experiments.
    • Table S2. Cell surface characteristics and cell-mineral interaction modeling.
    • Table S3. Modern and Archean Fe fluxes.
    • Table S4. Different scenarios of the physical separation model, with each case using a different water velocity.
    • Table S5. Data compilations for Fig. 1 and fig. S1.
    • Fig. S1. The redox state of iron in BIF through time where the red bars indicate the siderite-rich BIFs.
    • Fig. S2. Growth curve for C. phaeoferrooxidans strain KB01.
    • Fig. S3. Additional SEM and TEM images of strains KB01 and KoFox under two conditions.
    • Fig. S4. Surface charge of strains KB01 and KoFox.
    • Fig. S5. Additional cell surface characteristics for strain KoFox.
    • Fig. S6. Modeling the settling velocity of carbon and iron using a range of horizontal current velocities.
    • Fig. S7. Modeled weight % organic carbon in the coastal and open ocean sediments.
    • Fig. S8. Iron and carbon box model sensitivity results.
    • References (61103)

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