0000-0003-0663-8323 (Sedwick)

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Publication Title

Global Biogeochemical Cycles






e2023GB007837 (1-23)


Particulate phases transport trace metals (TM) and thereby exert a major control on TM distribution in the ocean. Particulate TMs can be classified by their origin as lithogenic (crustal material), biogenic (cellular), or authigenic (formed in situ), but distinguishing these fractions analytically in field samples is a challenge often addressed using operational definitions and assumptions. These different phases require accurate characterization because they have distinct roles in the biogeochemical iron cycle. Particles collected from the upper 2,000 m of the northwest subtropical Atlantic Ocean over four seasonal cruises throughout 2019 were digested with a chemical leach to operationally distinguish labile particulate material from refractory lithogenics. Direct measurements of cellular iron (Fe) were used to calculate the biogenic contribution to the labile Fe fraction, and any remaining labile material was defined as authigenic. Total particulate Fe (PFe) inventories varied <15% between seasons despite strong seasonality in dust inputs. Across seasons, the total PFe inventory (±1SD) was composed of 73 ± 13% lithogenic, 18 ± 7% authigenic, and 10 ± 8% biogenic Fe above the deep chlorophyll maximum (DCM), and 69 ± 8% lithogenic, 30 ± 8% authigenic, and 1.1 ± 0.5% biogenic Fe below the DCM. Data from three other ocean regions further reveal the importance of the authigenic fraction across broad productivity and Fe gradients, comprising ca. 20%-27% of total PFe.


© 2023 The Authors.

This is an open access article under the terms of the Creative Commons Attribution 4.0 International (CC BY 4.0) License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Data Availability

Article states: "Phytoplankton stoichiometries from the Bermuda Atlantic Iron Time-series (BAIT) study are available from Zenodo at https://doi.org/10.5281/ZENODO.8305791 (Twining & Sofen, 2023). Particle elemental concentrations from the BAIT study are available from BCO-DMO at https://doi.org/10.26008/1912/bco-dmo.888772.1 (Twining et al., 2023). Supporting data provided by the BATS program are available at http://bats.bios.edu/bats-data/. Dissolved trace element data from the BAIT study are available from BCO-DMO at https://doi.org/10.26008/1912/BCO-DMO.869081.1 (Buck & Caprara, 2023). Aerosol and dissolved trace element data from the BAIT study were previously published by Sedwick et al. (2023). Elemental contents of phytoplankton and particles at the Southern Ocean Time Series site are available from the Zenodo data repository at https://doi.org/10.5281/zenodo.5191479 (Sofen & Twining, 2021) and https://doi.org/10.5281/zenodo.7703343 (Twining, 2023a), respectively. Elemental contents of phytoplankton and particles from the IrnBru project are available from BCO-DMO at https://doi.org/10.26008/1912/bco-dmo.841583.1 (Twining, 2021) and https://doi.org/10.26008/1912/bco-dmo.6631983.1 (Twining, 2016), respectively. Particulate elemental concentrations from the Arctic GT cruise GN01 are available from GEOTRACES IDP2021 at https://www.geotraces.org/geotraces-intermediate-data-product-2021/ (GEOTRACES Intermediate Data Product Group, 2023). Arctic phytoplankton stoichiometries are available from BCO-DMO at https://doi.org/10.26008/1912/bco-dmo.904895.1 (Twining, 2023b)."

Original Publication Citation

Sofen, L. E., Antipova, O. A., Buck, K. N., Caprara, S., Chacho, L., Johnson, R. J., Kim, G., Morton, P., Ohnemus, D. C., Rauschenberg, S., Sedwick, P. N., Tagliabue, A., & Twining, B. S. (2023). Authigenic iron is a significant component of oceanic labile particulate iron inventories. Global Biogeochemical Cycles, 37(12), 1-23, Article e2023GB007837. https://doi.org/10.1029/2023GB007837


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