Research ArticleENVIRONMENTAL STUDIES

Pyrogenic iron: The missing link to high iron solubility in aerosols

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Science Advances  01 May 2019:
Vol. 5, no. 5, eaau7671
DOI: 10.1126/sciadv.aau7671
  • Fig. 1 Atmospheric concentration of total aerosol Fe (ng m−3) versus Fe solubility (%) for simulated estimates (colored circles) and field data (black circles).

    (A to E) The color represents the (combustion)/(combustion + dust) ratio for labile Fe concentration in aerosols.

  • Fig. 2 Comparison of simulated atmospheric Fe solubility with field data (black circles) over the Bay of Bengal and Arabian Sea.

    (A to D) The color represents the simulated (combustion)/(combustion + dust) ratio (percent) for labile Fe concentration in aerosols.

  • Fig. 3 Fe solubility versus Fe concentration (ng m−3) for field data and models over the North Atlantic.

    The colors for field data (A) represent percentage contributions of labile Fe to the sum of less labile and labile Fe concentrations in aerosols. The colors for the models (B to D) represent the simulated contribution of combustion aerosols to the sum of combustion and dust aerosols to labile Fe. The field data in light gray color represent no data for the 25% acetic acid leach. The aerosol samples are classified as sourced by two different air masses from North Africa (triangles) or other air mass regimes (circles) including North America, Europe, marine (no interaction with major land masses within 5 days before sample collection), or high latitudes (air masses originating north of 50°N) (23).

  • Fig. 4 Comparison of simulated atmospheric Fe solubility (colored points) with field data (black points) over the equatorial Atlantic.

    (A to D) The color represents the simulated (combustion)/(combustion + dust) ratio (percent) for labile Fe concentration in aerosols.

  • Fig. 5 Fe solubility versus Fe concentration (ng m−3) for field data (black squares), IMPACT (red squares), TM4-ECPL (orange squares), CAM4 (purple squares), and GEOS-Chem (blue squares) over the Southern Ocean (>45°S).

    The vertical lines in symbols correspond to ±1 SD for Fe solubility in aerosols.

  • Fig. 6 Proportion of pyrogenic Fe in total aerosol Fe and labile Fe.

    Percentage of total aerosol Fe from combustion aerosols (A, D, and G) and the percentage of labile Fe from combustion aerosols to the total atmospheric Fe deposition flux (combustion and dust) calculated from three models with atmospheric processing (B, E, and H) and without atmospheric processing (C, F, and I).

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/5/eaau7671/DC1

    Fig. S1. Fe solubility (%) of aerosols collected during multiple field campaigns for the field data and the simulated estimates from models used in this study.

    Fig. S2. Comparison of simulated estimates and observed values for total Fe concentration (ng m−3).

    Fig. S3. Comparison of simulated estimates with combustion aerosols plus mineral dust and observed values for labile Fe concentration (ng m−3).

    Fig. S4. Comparison of simulated estimates with mineral dust only and observed values for labile Fe concentration (ng m−3).

    Fig. S5. Model estimates of Fe solubility in aerosols versus field data collected during multiple field campaigns (triangles for Arabian Sea and circles for others).

    Fig. S6. Deposition fluxes of total Fe (ng Fe m−2 s−1) from dust and combustion sources to present-day oceans.

    Fig. S7. Deposition fluxes of labile Fe (ng Fe m−2 s−1) from dust and combustion sources to present-day oceans.

    Table S1. Summary of averaged Fe solubility in atmospheric models used in this study.

    Table S2. Latitude, longitude, month, and Fe solubility (%) in aerosols for the intercomparison study.

    Table S3. Comparison of Fe solubility (%) between the simulated estimates from models and field data.

  • Supplementary Materials

    This PDF file includes:

    • Fig. S1. Fe solubility (%) of aerosols collected during multiple field campaigns for the field data and the simulated estimates from models used in this study.
    • Fig. S2. Comparison of simulated estimates and observed values for total Fe concentration (ng m−3).
    • Fig. S3. Comparison of simulated estimates with combustion aerosols plus mineral dust and observed values for labile Fe concentration (ng m−3).
    • Fig. S4. Comparison of simulated estimates with mineral dust only and observed values for labile Fe concentration (ng m−3).
    • Fig. S5. Model estimates of Fe solubility in aerosols versus field data collected during multiple field campaigns (triangles for Arabian Sea and circles for others).
    • Fig. S6. Deposition fluxes of total Fe (ng Fe m−2 s−1) from dust and combustion sources to present-day oceans.
    • Fig. S7. Deposition fluxes of labile Fe (ng Fe m−2 s−1) from dust and combustion sources to present-day oceans.
    • Table S1. Summary of averaged Fe solubility in atmospheric models used in this study.
    • Table S2. Latitude, longitude, month, and Fe solubility (%) in aerosols for the intercomparison study.
    • Table S3. Comparison of Fe solubility (%) between the simulated estimates from models and field data.

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