Skip to main content

Thank you for visiting You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

The impact of ocean deoxygenation on iron release from continental margin sediments


In the oceans’ high-nitrate–low-chlorophyll regions, such as the Peru/Humboldt Current system and the adjacent eastern equatorial Pacific1, primary productivity is limited by the micronutrient iron. Within the Peruvian upwelling area, bioavailable iron is released from the reducing continental margin sediments2. The magnitude of this seafloor source could change with fluctuations in the extension or intensity of the oxygen minimum zones3,4. Here we show that measurements of molybdenum, uranium and iron concentrations can be used as a proxy for sedimentary iron release, and use this proxy to assess iron release from the sea floor beneath the Peru upwelling system during the past 140,000 years. We observe a coupling between levels of denitrification, as indicated by nitrogen isotopes, trace metal proxies for oxygenation, and sedimentary iron concentrations. Specifically, periods with poor upper ocean oxygenation are characterized by more efficient iron retention in the sediment and a diminished iron supply to the water column. We attribute efficient iron retention under more reducing conditions to widespread sulphidic conditions in the surface sediment and concomitant precipitation of iron sulphides. We argue that iron release from continental margin sediments is most effective in a narrow redox window where neither oxygen nor sulphide is present. We therefore suggest that future deoxygenation in the Peru upwelling area would be unlikely to result in increased iron availability, whereas in weaker oxygen minimum zones partial deoxygenation may enhance the iron supply.

This is a preview of subscription content, access via your institution

Relevant articles

Open Access articles citing this article.

Access options

Rent or buy this article

Prices vary by article type



Prices may be subject to local taxes which are calculated during checkout

Figure 1: Relationship between water column oxygenation and iron release from continental margin sediments.
Figure 2: Study area and biogeochemical context.
Figure 3: Age model.
Figure 4: Redox proxies.


  1. Moore, C. M. et al. Processes and patterns of oceanic nutrient limitation. Nature Geosci. 6, 701–710 (2013).

    Article  Google Scholar 

  2. Bruland, K. W., Rue, E. L., Smith, G. J. & DiTullio, G. R. Iron, macronutrients and diatom blooms in the Peru upwelling regime: Brown and blue waters of Peru. Mar. Chem. 93, 81–103 (2005).

    Article  Google Scholar 

  3. Capone, D. G. & Hutchins, D. A. Microbial biogeochemistry of coastal upwelling regimes in a changing ocean. Nature Geosci. 6, 711–717 (2013).

    Article  Google Scholar 

  4. Keeling, R. F., Körtzinger, A. & Gruber, N. Ocean deoxygenation in a warming world. Ann. Rev. Mar. Sci. 2, 199–229 (2011).

    Article  Google Scholar 

  5. Mix, A. C. et al. Rapid climate oscillations in the Northeast Pacific during the last deglaciation reflect northern and southern hemisphere sources. Geoph. Monogr. Ser. 112, 127–148 (1999).

    Google Scholar 

  6. Johnson, K. S., Chavez, F. P. & Friederich, G. E. Continental-shelf sediment as a primary source of iron for coastal phytoplankton. Nature 398, 697–700 (1999).

    Article  Google Scholar 

  7. Lam, P. J. et al. Wintertime phytoplankton bloom in the subarctic Pacific supported by continental margin iron. Glob. Biogeochem. Cycle 20, GB1006 (2006).

    Article  Google Scholar 

  8. Raiswell, R. & Canfield, D. E. The iron biogeochemical cycle past and present. Geochem. Perspect. 1, 1–220 (2012).

    Article  Google Scholar 

  9. Scholz, F., Severmann, S., McManus, J. & Hensen, C. Beyond the Black Sea paradigm: The isotopic fingerprint of an open-marine iron shuttle. Geochim. Cosmochim. Acta 127, 368–380 (2014).

    Article  Google Scholar 

  10. Tribovillard, N., Algeo, T. J., Lyons, T. & Riboulleau, A. Trace metals as paleoredox and paleoproductivity proxies: An update. Chem. Geol. 232, 12–32 (2006).

    Article  Google Scholar 

  11. Helz, G. R. et al. Mechanism of molybdenum removal from the sea and its concentration in black shales: EXAFS evidence. Geochim. Cosmochim. Acta 60, 3631–3642 (1996).

    Article  Google Scholar 

  12. Scholz, F. et al. Early diagenesis of redox-sensitive trace metals in the Peru upwelling area: Response to ENSO-related oxygen fluctuations in the water column. Geochim. Cosmochim. Acta 75, 7257–7276 (2011).

    Article  Google Scholar 

  13. Böning, P. et al. Geochemistry of Peruvian near-surface sediments. Geochim. Cosmochim. Acta 68, 4429–4451 (2004).

    Article  Google Scholar 

  14. Brink, K. H., Halpern, D., Huyer, A. & Smith, R. L. The physical environment of the Peruvian upwelling system. Prog. Oceanogr. 12, 285–305 (1983).

    Article  Google Scholar 

  15. Heinze, P-M. & Wefer, G. The history of coastal upwelling off Peru (11° S, ODP leg 112, Site 680B) over the past 650,000 years. Geol. Soc. Spec. 64, 451–462 (1992).

    Article  Google Scholar 

  16. Lisiecki, L. E. & Raymo, M. E. A Pliocene–Pleistocene stack of 57 globally distributed benthic δ18O records. Paleoceanography 20, PA1003 (2005).

    Google Scholar 

  17. Ziegler, M., Jilbert, T., de Lange, G. J., Lourens, L. J. & Reichart, G. J. Bromine counts from XRF scanning as an estimate of the marine organic carbon content of sediment cores. Geochem. Geophys. Geosyst. 9, Q05009 (2008).

    Article  Google Scholar 

  18. Ganeshram, R. S., Pedersen, T. F., Calvert, S. E., McNeill, G. W. & Fontugne, M. R. Glacial–interglacial variability in denitrification in the world’s oceans: Causes and consequences. Paleoceanography 15, 361–376 (2000).

    Article  Google Scholar 

  19. Galbraith, E. D., Kienast, M., Pedersen, T. F. & Calvert, S. E. Glacial–interglacial modulation of the marine nitrogen cycle by high-latitude O2 supply to the global thermocline. Paleoceanography 19, PA4007 (2004).

    Article  Google Scholar 

  20. Jaccard, S. L. & Galbraith, E. D. Large climate-driven changes of oceanic oxygen concentrations during the last deglaciation. Nature Geosci. 5, 151–156 (2012).

    Article  Google Scholar 

  21. Nameroff, T. J., Calvert, S. E. & Murray, J. W. Glacial–interglacial variability in the eastern tropical North Pacific oxygen minimum zone recorded by redox-sensitive trace metals. Paleoceanography 24, PA1010 (2004).

    Google Scholar 

  22. Muratli, J. M., Chase, Z., Mix, A. C. & McManus, J. Increased glacial-age ventilation of the Chilean margin by antarctic intermediate water. Nature Geosci. 3, 23–26 (2010).

    Article  Google Scholar 

  23. Sarmiento, J. L., Gruber, N., Brzezinski, M. A. & Dunne, J. P. High-latitude controls of thermocline nutrients and low latitude biological productivity. Nature 427, 56–60 (2004).

    Google Scholar 

  24. Meissner, K. J., Galbraith, E. D. & Völker, C. Denitrification under glacial and interglacial conditions: A physical approach. Paleoceanography 20, PA3001 (2005).

    Article  Google Scholar 

  25. Schrader, H. Peruvian coastal primary palaeo-productivity during the last 200,000 years. Geol. Soc. Spec. 64, 391–410 (1992).

    Article  Google Scholar 

  26. Murray, R. W., Leinen, M. & Knowlton, C. W. Links between iron input and opal deposition in the Pleistocene equatorial Pacific Ocean. Nature Geosci. 5, 270–274 (2012).

    Article  Google Scholar 

  27. Elrod, V. A., Berelson, W. M., Coale, K. H. & Johnson, K. S. The flux of iron from continental margin sediments: A missing source for global budgets. Geophys. Res. Lett. 31, L12307 (2004).

    Article  Google Scholar 

  28. Moore, J. K. & Braucher, O. Sedimentary and mineral dust sources of dissolved iron to the world ocean. Biogeosciences 5, 631–656 (2008).

    Article  Google Scholar 

  29. Schunck, H. et al. Giant hydrogen sulfide plume in the oxygen minimum zone off Peru supports chemolithoautotrophy. PLoS ONE 8, e68661 (2013).

    Article  Google Scholar 

  30. McLennan, S. M. Relationships between the trace element composition of sedimentary rocks and upper continental crust. Geochem. Geophys. Geosyst. 2, 1021 (2001).

    Article  Google Scholar 

Download references


Financial support for this study was provided by the 7th Framework Program of the European Union (Marie Curie IOF to F.S., BICYCLE, Project No. 300648) and the German Research Foundation through Collaborative Research Centre 754 ‘Climate-Biogeochemistry Interactions in the Tropical Ocean’ ( The US National Science Foundation supported J.M. (Grant No. 1029889) and A.C.M. (Grant No. 1131834). We thank A. Bleyer, B. Domeyer, J. McKay and A. Ungerer for assistance in the laboratory and A. Schmittner for insightful comments on the manuscript.

Author information

Authors and Affiliations



F.S., J.M., A.C.M. and C.H. designed the study; F.S. carried out the laboratory work; R.R.S. guided the coring campaign and contributed radiocarbon dates; F.S. wrote the manuscript with contributions from all co-authors.

Corresponding author

Correspondence to Florian Scholz.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Supplementary Information

Supplementary Information (PDF 1465 kb)

Rights and permissions

Reprints and Permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Scholz, F., McManus, J., Mix, A. et al. The impact of ocean deoxygenation on iron release from continental margin sediments. Nature Geosci 7, 433–437 (2014).

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI:

This article is cited by


Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing