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Gulf Stream rings as a source of iron to the North Atlantic subtropical gyre

Nature Geoscience volume 11, pages 594–598 (2018)Cite this article

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Abstract

Substantial amounts of nitrogen fixation occur in the North Atlantic subtropical gyre, due to the activity of cyanobacteria with high iron requirements. Iron is delivered to this region by dust from the Sahara Desert. However, this dust deposition is typically localized and episodic. Therefore, other sources of iron may also be important. Here, we report observations of dissolved iron concentrations in a Gulf Stream cold-core ring, which transported iron-rich water from near the continental slope into the subtropical gyre. We find that iron concentrations were elevated in the ring compared with subtropical waters, reflecting its source waters. Using iron data from these source waters and the identification of ring activity in satellite data, we estimate that cold-core rings provide a net flux of 0.3 ± 0.17 × 108 mol Fe yr−1 across the northwestern gyre edge, on the order of 15% of our median estimates of gyre-wide supply of iron by dust deposition. We suggest that iron supply from cold-core rings is an important source of iron to the northwestern gyre edge. We conclude that mesoscale ocean circulation features may play an important role in subtropical nutrient and carbon cycling.

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Fig. 1: GA03 Fe station sampling locations20, Gulf Stream and cold-core ring in satellite altimetry.
Fig. 2: A cold-core ring observed in the GA03 section.
Fig. 3: GA03 temperature–salinity diagram, with Fe concentrations10 in colour.
Fig. 4: Ring-driven dissolved Fe supply compared with atmospheric dissolved Fe deposition.

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References

  1. Boyd, P. W. et al. Mesoscale iron enrichment experiments 1993-2005: synthesis and future directions. Science 315, 612–617 (2007).

    Article  Google Scholar 

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

    Article  Google Scholar 

  3. Tagliabue, A. et al. The integral role of iron in ocean biogeochemistry. Nature 543, 51–59 (2017).

    Article  Google Scholar 

  4. Mahowald, N. M. et al. Atmospheric global dust cycle and iron inputs to the ocean. Glob. Biogeochem. Cycles 19, GB4024 (2005).

    Google Scholar 

  5. Sedwick, P. N. et al. Iron in the Sargasso Sea (Bermuda Atlantic Time-Series Study region) during summer: eolian imprint, spatiotemporal variability, and ecological implications. Global Biogeochem. Cycles 19, GB4006 (2005).

    Article  Google Scholar 

  6. Gruber, N. & Sarmiento, J. L. Global patterns of marine nitrogen fixation and denitrification. Global Biogeochem. Cycles 11, 235–266 (1997).

    Article  Google Scholar 

  7. Geider, R. J. & La Roche, J. The role of iron in phytoplankton photosynthesis, and the potential for iron-limitation of primary productivity in the sea. Photosynth. Res. 39, 275–301 (1994).

    Article  Google Scholar 

  8. Jickells, T. D., Baker, A. R. & Chance, R. Atmospheric transport of trace elements and nutrients to the oceans. Phil. Trans. R. Soc. Lond. A 374, 20150286 (2016).

    Article  Google Scholar 

  9. Moxim, W. J., Fan, S.-M. & Levy, H. The meteorological nature of variable soluble iron transport and deposition within the North Atlantic Ocean basin. J. Geophys. Res. 116, D03203 (2011).

    Article  Google Scholar 

  10. Conway, T. M. & John, S. G. Quantification of dissolved iron sources to the North Atlantic Ocean. Nature 511, 212–215 (2014).

    Article  Google Scholar 

  11. Moore, C. M. et al. Iron limits primary productivity during spring bloom development in the central North Atlantic. Global Change Biol. 12, 626–634 (2006).

    Article  Google Scholar 

  12. Browning, T. J. et al. Iron limitation of microbial phosphorus acquisition in the tropical North Atlantic. Nat. Commun. 8, 15465 (2017).

    Article  Google Scholar 

  13. Olson, D. B. Rings in the ocean. Ann. Rev. Earth. Planet. Sci. 19, 283–311 (1991).

    Article  Google Scholar 

  14. Palter, J. B., Lozier, M. S., Sarmiento, J. L. & Williams, R. G. The supply of excess phosphate across the Gulf Stream and the maintenance of subtropical nitrogen fixation. Global Biogeochem. Cycles 25, GB4007 (2011).

    Article  Google Scholar 

  15. Williams, R. G. & Follows, M. J. The Ekman transfer of nutrients and maintenance of new production over the North Atlantic. Deep-Sea Res. Part I 45, 461–489 (1998).

    Article  Google Scholar 

  16. Williams, R. G. et al. Nutrient streams in the North Atlantic: advective pathways of inorganic and dissolved organic nutrients. Global Biogeochem. Cycles 25, GB4008 (2011).

    Article  Google Scholar 

  17. Williams, R. G., Roussenov, V. & Follows, M. J. Nutrient streams and their induction into the mixed layer. Global Biogeochem. Cycles 20, GB1016 (2006).

    Article  Google Scholar 

  18. Letscher, R. T., Primeau, F. F. & Moore, J. K. Nutrient budgets in the subtropical ocean gyres dominated by lateral transport. Nat. Geosci. 9, 815–819 (2016).

    Article  Google Scholar 

  19. Faghmous, J. H. et al. A daily global mesoscale ocean eddy dataset from satellite altimetry. Sci. Data 2, 150028 (2015).

    Article  Google Scholar 

  20. Mawji, E. et al. The GEOTRACES Intermediate Data Product 2014. Mar. Chem. 177, 1–8 (2015).

    Article  Google Scholar 

  21. Jenkins, W. J., Smethie, W. M., Boyle, E. A. & Cutter, G. A. Water mass analysis for the US GEOTRACES (GA03) North Atlantic sections. Deep-Sea Res. Part II 116, 6–20 (2015).

    Article  Google Scholar 

  22. Townsend, D. W. & Ellis, W. G. in Carbon and Nutrient Fluxes in Continental Margins: A Global Synthesis (eds Liu, K.-K. et al.) 7234–7248 (Springer, Berlin, Heidelberg 2010).

  23. Palter, J. B., Lozier, M. S. & Barber, R. T. The effect of advection on the nutrient reservoir in the North Atlantic subtropical gyre. Nature 437, 687–692 (2005).

    Article  Google Scholar 

  24. Rijkenberg, M. J. A. et al. The distribution of dissolved iron in the West Atlantic Ocean. PLoS ONE 9, e101323 (2014).

    Article  Google Scholar 

  25. Middag, R. et al. Intercomparison of dissolved trace elements at the Bermuda Atlantic Time Series station. Mar. Chem. 177, 476–489 (2015).

    Article  Google Scholar 

  26. Conway, T. M., John, S. G. & Lacan, F. Intercomparison of dissolved iron isotope profiles from reoccupation of three GEOTRACES stations in the Atlantic Ocean. Mar. Chem. 183, 50–61 (2016).

    Article  Google Scholar 

  27. Wu, J. & Luther, G. W. Spatial and temporal distribution of iron in the surface water of the northwestern Atlantic Ocean. Geochim. Cosmochim. Acta 60, 2729–2741 (1996).

    Article  Google Scholar 

  28. Conway, T. M. & John, S. G. The cycling of iron, zinc and cadmium in the North East Pacific Ocean—insights from stable isotopes. Geochim. Cosmochim. Acta 164, 262–283 (2015).

    Article  Google Scholar 

  29. Bower, A. S., Rossby, H. T. & Lillibridge, J. L. The Gulf Stream: barrier or blender? J. Phys. Ocean. 15, 24–32 (1985).

    Article  Google Scholar 

  30. Qiu, B., Chen, S. & Hacker, P. Effect of mesoscale eddies on subtropical mode water variability from the Kuroshio Extension System Study (KESS). J. Phys. Oceanogr. 37, 982–1000 (2007).

    Article  Google Scholar 

  31. Lai, D. Y., Richardson, P. L., Lai, D. Y. & Richardson, P. L. Distribution and movement of Gulf Stream rings. J. Phys. Oceanogr. 7, 670–683 (1977).

    Article  Google Scholar 

  32. Buck, K., Sohst, B. M. & Sedwick, P. N. The organic complexation of dissolved iron along the US GEOTRACES (GA03) North Atlantic Section. Deep-Sea Res. Part II 116, 152–165 (2015).

    Article  Google Scholar 

  33. Fishwick, M. P. et al. The impact of changing surface ocean conditions on the dissolution of aerosol iron. Global Biogeochem. Cycles 28, 1235–1250 (2014).

    Article  Google Scholar 

  34. Moreno, A. R. & Martiny, A. C. Ecological stoichiometry of ocean plankton. Ann. Rev. Mar. Sci. 10, 43–69 (2018).

    Article  Google Scholar 

  35. Deutsch, C., Sarmiento, J. L., Sigman, D. M., Gruber, N. & Dunne, J. P. Spatial coupling of nitrogen inputs and losses in the ocean. Nature 445, 163–167 (2007).

    Article  Google Scholar 

  36. Ward, B. A., Dutkiewicz, S., Moore, C. M. & Follows, M. J. Iron, phosphorus, and nitrogen supply ratios define the biogeography of nitrogen fixation. Limnol. Oceanogr. 58, 2059–2075 (2013).

    Article  Google Scholar 

  37. Tilman, D. Resource competition between plankton algae: an experimental and theoretical approach. Ecology 58, 338–348 (1977).

    Article  Google Scholar 

  38. Twining, B. S. & Baines, S. B. The trace metal composition of marine phytoplankton. Ann. Rev. Mar. Sci. 5, 191–215 (2013).

    Article  Google Scholar 

  39. Conway, T. M. & John, S. G. The biogeochemical cycling of zinc and zinc isotopes in the North Atlantic Ocean. Global Biogeochem. Cycles 28, 1111–1128 (2014).

    Article  Google Scholar 

  40. Shaked, Y., Xu, Y., Leblanc, K. & Morel, F. M. M. Zinc availability and alkaline phosphatase activity in Emiliania huxleyi: implications for Zn–P co-limitation in the ocean. Limnol. Oceanogr. 51, 299–309 (2006).

    Article  Google Scholar 

  41. Mahaffey, C., Reynolds, S., Davis, C. E. & Lohan, M. C. Alkaline phosphatase activity in the subtropical ocean: insights from nutrient, dust and trace metal addition experiments. Front. Mar. Sci. 1, 73 (2014).

    Article  Google Scholar 

  42. Orcutt, K., Gundersen, K. & Ammerman, J. Intense ectoenzyme activities associated with Trichodesmium colonies in the Sargasso Sea. Mar. Ecol. Prog. Ser. 478, 101–113 (2013).

    Article  Google Scholar 

  43. Sohm, J. A., Mahaffey, C. & Capone, D. G. Assessment of relative phosphorus limitation of Trichodesmium spp. in the North Pacific, North Atlantic, and the north coast of Australia. Limnol. Oceanogr. 53, 2495–2502 (2008).

    Article  Google Scholar 

  44. Xiu, P., Palacz, A. P., Chai, F., Roy, E. G. & Wells, M. L. Iron flux induced by Haida eddies in the Gulf of Alaska. Geophys. Res. Lett. 38, L13607 (2011).

    Article  Google Scholar 

  45. Richardson, P. L., Cheney, R. E. & Worthington, L. V. A census of Gulf Stream rings, spring 1975. J. Geophys. Res. 83, 6136–6144 (1978).

    Article  Google Scholar 

  46. de Boyer Montégut, C., Madec, G., Fischer, A. S., Lazar, A. & Iudicone, D. Mixed layer depth over the global ocean: an examination of profile data and a profile-based climatology. J. Geophys. Res. 109, C12003 (2004).

    Article  Google Scholar 

  47. LaCasce, J. H. Statistics from Lagrangian observations. Prog. Oceanogr. 77, 1–29 (2008).

    Article  Google Scholar 

  48. The Climode Group. The Climode field campaign: observing the cycle of convection and restratification over the Gulf Stream. Bull. Am. Meteorol. Soc. 90, 1337–1350 (2009).

  49. Trapp, J. M., Millero, F. J. & Prospero, J. M. Trends in the solubility of iron in dust-dominated aerosols in the equatorial Atlantic trade winds: importance of iron speciation and sources. Geochem. Geophys. Geosyst. 11, Q03014 (2010).

    Article  Google Scholar 

  50. Shelley, R. U., Morton, P. & Landing, W. M. Elemental ratios and enrichment factors in aerosols from the US-GEOTRACES North Atlantic transects. Deep-Sea Res. Part II 116, 262–272 (2015).

    Article  Google Scholar 

  51. Patey, M. D., Achterberg, E. P., Rijkenberg, M. J. & Pearce, R. Aerosol time-series measurements over the tropical Northeast Atlantic Ocean: dust sources, elemental composition and mineralogy. Mar. Chem. 174, 103–119 (2015).

    Article  Google Scholar 

  52. Taylor, S. R. & McLennan, S. M. The Continental Crust: Its Composition and Evolution (Blackwell Scientific Publishing, Oxford, 1985).

  53. Anderson, R. F. et al. How well can we quantify dust deposition to the ocean? Phil. Trans. R. Soc. Lond. A 374, 20150285 (2016).

    Article  Google Scholar 

  54. Measures, C. I., Hatta, M., Fitzsimmons, J. N. & Morton, P. Dissolved Al in the zonal N Atlantic section of the US GEOTRACES 2010/2011 cruises and the importance of hydrothermal inputs. Deep-Sea Res. Part II 116, 176–186 (2015).

    Article  Google Scholar 

  55. Baker, A. R., Adams, C., Bell, T. G., Jickells, T. D. & Ganzeveld, L. Estimation of atmospheric nutrient inputs to the Atlantic Ocean from 50°N to 50°S based on large-scale field sampling: iron and other dust-associated elements. Global Biogeochem. Cycles 27, 755–767 (2013).

    Article  Google Scholar 

  56. Powell, C. F. et al. Estimation of the atmospheric flux of nutrients and trace metals to the eastern tropical North Atlantic Ocean. J. Atmos. Sci. 72, 4029–4045 (2015).

    Article  Google Scholar 

  57. Sholkovitz, E. R., Sedwick, P. N., Church, T. M., Baker, A. R. & Powell, C. F. Fractional solubility of aerosol iron: synthesis of a global-scale data set. Geochim. Cosmochim. Acta 89, 173–189 (2012).

    Article  Google Scholar 

  58. Luo, C. et al. Combustion iron distribution and deposition. Global Biogeochem. Cycles 22, GB1012 (2008).

    Article  Google Scholar 

  59. Albani, S. et al. Paleodust variability since the Last Glacial Maximum and implications for iron inputs to the ocean. Geophys. Res. Lett. 43, 3944–3954 (2016).

    Article  Google Scholar 

  60. Albani, S. et al. Improved dust representation in the Community Atmosphere Model. J. Adv. Model. Earth Syst. 6, 541–570 (2014).

    Article  Google Scholar 

  61. Zhang, Y. et al. Modeling the global emission, transport and deposition of trace elements associated with mineral dust. Biogeosci. Discuss. 11, 17491–17541 (2015).

    Article  Google Scholar 

  62. Wang, R. et al. Sources, transport and deposition of iron in the global atmosphere. Atmos. Chem. Phys. 15, 6247–6270 (2015).

    Article  Google Scholar 

  63. Ito, A. & Shi, Z. Delivery of anthropogenic bioavailable iron from mineral dust and combustion aerosols to the ocean. Atmos. Chem. Phys. 16, 85–99 (2016).

    Article  Google Scholar 

  64. Conway, T. M., Wolff, E. W., Röthlisberger, R., Mulvaney, R. & Elderfield, H. E. Constraints on soluble aerosol iron flux to the Southern Ocean at the Last Glacial Maximum. Nat. Commun. 6, 7850 (2015).

    Article  Google Scholar 

  65. Longo, A. F. et al. Influence of atmospheric processes on the solubility and composition of iron in Saharan dust. Environ. Sci. Technol. 50, 6912–6920 (2016).

    Article  Google Scholar 

  66. Schlitzer, R. et al. The GEOTRACES Intermediate Data Product 2017. Chem. Geol. https://doi.org/10.1016/j.chemgeo.2018.05.040 (2018).

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Acknowledgements

We thank all those who contributed to the US GEOTRACES GA03 cruises; scientists from the US GEOTRACES Program and the Ocean Data Facility who measured the trace metals, nutrients and physical parameters for the USGT11 cruise used in this study; N. Mahowald, S. Albani, A. Ito and R. Wang for making model output available; and P. Sedwick, W. Landing, N. Mahowald, C. Measures and D. Vance for useful discussions. T.M.C. acknowledges support from the University of South Florida; J.B.P. acknowledges support from the University of Rhode Island; G.F.d.S. is supported by the European Union’s Horizon 2020 research and innovation programme under Marie Skłodowska-Curie grant agreement #708407.

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  1. These authors contributed equally: Tim M. Conway, Jaime B. Palter, Gregory F. de Souza.

Authors and Affiliations

  1. College of Marine Science and School of Geosciences, University of South Florida, St Petersburg, FL, USA

    Tim M. Conway

  2. Institute of Geochemistry and Petrology, ETH Zürich, Department of Earth Sciences, Zürich, Switzerland

    Tim M. Conway & Gregory F. de Souza

  3. School of Oceanography, University of Rhode Island, Narragansett, RI, USA

    Jaime B. Palter

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All authors contributed equally to this work. T.M.C. and G.F.d.S. conceived the idea, J.B.P. carried out the ring-driven Fe transport calculations and G.F.d.S. carried out the atmospheric deposition calculations.

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Correspondence to Tim M. Conway.

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Conway, T.M., Palter, J.B. & de Souza, G.F. Gulf Stream rings as a source of iron to the North Atlantic subtropical gyre. Nature Geosci 11, 594–598 (2018). https://doi.org/10.1038/s41561-018-0162-0

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