Nutrient release to oceans from buoyancy-driven upwelling at Greenland tidewater glaciers

Abstract

The discharge of nutrient-rich meltwater from the Greenland Ice Sheet has emerged as a potentially important contributor to regional marine primary production and nutrient cycling. While significant, this direct nutrient input by the ice sheet may be secondary to the upwelling of deep-ocean-sourced nutrients driven by the release of meltwater at depth in glacial fjords. Here, we present a comprehensive suite of micro- and macronutrient observations collected in Sermilik Fjord at the margin of Helheim, one of Greenland’s largest glaciers, and quantitatively decompose glacial and ocean contributions to fjord dissolved nutrient inventories. We show that the substantial enrichment in nitrate, phosphate and silicate observed in the upper 250 m of the glacial fjord is the result of upwelling of warm subtropical waters present at depth throughout the fjord. These nutrient-enriched fjord waters are subsequently exported subsurface to the continental shelf. The upwelled nutrient transport within Sermilik rivals exports by the largest Arctic rivers and the ice sheet as a whole, suggesting that glacier-induced pumping of deep nutrients may constitute a major source of macronutrients to the surrounding coastal ocean. The importance of this mechanism is likely to grow given projected increases in surface melt of the ice sheet.

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Fig. 1: Sermilik Fjord study region and hydrography in August 2015.
Fig. 2: Shifts in upper water column physical and chemical properties resulting from glacially driven circulation.
Fig. 3: Evidence of subglacial discharge and submarine melt impacts on fjord waters.

Data availability

Continuous hydrographic (CTD) profiles are available from the National Oceanographic Data Center (http://accession.nodc.noaa.gov/0171277), while discrete nutrient measurements and CTD bottle data (https://doi.org/10.1594/PANGAEA.887304), as well as discrete iron data (https://doi.org/10.1594/PANGAEA.887324), are available from the PANGEA information system77,78. Ocean current data for Sermilik Fjord are publicly available from Data.gov(NODC accession number 0126772 and NCEI accession number 0127325). Downscaled RACMO2.3.2 data were provided by M. van den Broeke and B. Noël and are available from them upon request. Hydrographic data for the West Greenland continental shelf (Supplementary Table 2 and Supplementary Fig. 12) are available from K. Azetsu-Scott upon request. Other data supporting the findings of this study are available as described in the Methods, and otherwise from the corresponding author upon request.

References

  1. 1.

    Wadham, J. L. et al. The potential role of the Antarctic Ice Sheet in global biogeochemical cycles. Earth Environ. Sci. Trans. R. Soc. Edinb. 104, 55–67 (2013).

    Google Scholar 

  2. 2.

    O’Neel, S. et al. Icefield-to-ocean linkages across the northern Pacific coastal temperate rainforest ecosystem. BioScience 65, 499–512 (2015).

    Article  Google Scholar 

  3. 3.

    Böning, C. W., Behrens, E., Biastoch, A., Getzlaff, K. & Bamber, J. L. Emerging impact of Greenland meltwater on deepwater formation in the North Atlantic Ocean. Nat. Geosci. 9, 523–527 (2016).

    Article  Google Scholar 

  4. 4.

    Hodson, A. et al. Glacial ecosystems. Ecol. Monogr. 78, 41–67 (2008).

    Article  Google Scholar 

  5. 5.

    Wadham, J. L. et al. Biogeochemical weathering under ice: size matters. Global Biogeochem. Cycles 24, GB3025 (2010).

    Article  Google Scholar 

  6. 6.

    Hawkings, J. R. et al. The effect of warming climate on nutrient and solute export from the Greenland Ice Sheet. Geochem. Perspect. Lett. 1, 94–104 (2015).

    Article  Google Scholar 

  7. 7.

    Hawkings, J. et al. The Greenland Ice Sheet as a hot spot of phosphorus weathering and export in the Arctic. Global Biogeochem. Cycles 30, 191–210 (2016).

    Article  Google Scholar 

  8. 8.

    Bhatia, M. P. et al. Greenland meltwater as a significant and potentially bioavailable source of iron to the ocean. Nat. Geosci. 6, 274–278 (2013).

    Article  Google Scholar 

  9. 9.

    Hawkings, J. R. et al. Ice sheets as a significant source of highly reactive nanoparticulate iron to the oceans. Nat. Commun. 5, 3929 (2014).

    Article  Google Scholar 

  10. 10.

    Hopwood, M. J. et al. Seasonal changes in Fe along a glaciated Greenlandic fjord. Front. Earth Sci. 4, 15 (2016).

    Article  Google Scholar 

  11. 11.

    Luo, H. et al. Oceanic transport of surface meltwater from the southern Greenland ice sheet. Nat. Geosci. 9, 528–532 (2016).

    Article  Google Scholar 

  12. 12.

    Arrigo, K. R. et al. Melting glaciers stimulate large summer phytoplankton blooms in southwest Greenland waters. Geophys. Res. Lett. 44, 6278–6285 (2017).

    Article  Google Scholar 

  13. 13.

    Oliver, H. et al. Exploring the potential impact of Greenland meltwater on stratification, photosynthetically active radiation, and primary production in the Labrador Sea. J. Geophys. Res. Oceans 123, 2570–2591 (2018).

    Article  Google Scholar 

  14. 14.

    Meire, L. et al. Marine-terminating glaciers sustain high productivity in Greenland fjords. Global Change Biol. 23, 5344–5357 (2017).

    Article  Google Scholar 

  15. 15.

    Kanna, N. et al. Upwelling of macronutrients and dissolved inorganic carbon by a subglacial freshwater driven plume in Bowdoin Fjord, Northwestern Greenland. J. Geophys. Res. Biogeosci. 123, 1666–1682 (2018).

    Article  Google Scholar 

  16. 16.

    Enderlin, E. M. et al. An improved mass budget for the Greenland Ice Sheet. Geophys. Res. Lett. 41, 866–872 (2014).

    Article  Google Scholar 

  17. 17.

    Straneo, F. & Cenedese, C. The dynamics of Greenland’s glacial fjords and their role in climate. Annu. Rev. Mar. Sci. 7, 89–112 (2015).

    Article  Google Scholar 

  18. 18.

    van den Broeke, M. et al. Partitioning recent Greenland mass loss. Science 326, 984–986 (2009).

    Article  Google Scholar 

  19. 19.

    Rignot, E. & Mouginot, J. Ice flow in Greenland for the International Polar Year 2008–2009. Geophys. Res. Lett. 39, L11501 (2012).

    Article  Google Scholar 

  20. 20.

    Chu, V. W. Greenland ice sheet hydrology: a review. Prog. Phys. Geogr. 38, 19–54 (2014).

    Article  Google Scholar 

  21. 21.

    Moon, T. et al. Subsurface iceberg melt key to Greenland fjord freshwater budget. Nat. Geosci. 11, 49–54 (2018).

    Article  Google Scholar 

  22. 22.

    Jenkins, A. Convection-driven melting near the grounding lines of ice shelves and tidewater glaciers. J. Phys. Oceanogr. 41, 2279–2294 (2011).

    Article  Google Scholar 

  23. 23.

    Sciascia, R., Straneo, F., Cenedese, C. & Heimbach, P. Seasonal variability of submarine melt rate and circulation in an East Greenland fjord. J. Geophys. Res. Oceans 118, 2492–2506 (2013).

    Article  Google Scholar 

  24. 24.

    Bendtsen, J., Mortensen, J., Lennert, K. & Rysgaard, S. Heat sources for glacial ice melt in a west Greenland tidewater outlet glacier fjord: the role of subglacial freshwater discharge. Geophys. Res. Lett. 42, 4089–4095 (2015).

    Article  Google Scholar 

  25. 25.

    Beaird, N., Straneo, F. & Jenkins, W. Spreading of Greenland meltwaters in the ocean revealed by noble gases. Geophys. Res. Lett. 42, 7705–7713 (2015).

    Article  Google Scholar 

  26. 26.

    Straneo, F. et al. Impact of fjord dynamics and glacial runoff on the circulation near Helheim Glacier. Nat. Geosci. 4, 322–327 (2011).

    Article  Google Scholar 

  27. 27.

    Mortensen, J. et al. On the seasonal freshwater stratification in the proximity of fast-flowing tidewater outlet glaciers in a sub-Arctic sill fjord. J. Geophys. Res. Oceans 118, 1382–1395 (2013).

    Article  Google Scholar 

  28. 28.

    Beaird, N., Straneo, F. & Jenkins, W. Characteristics of meltwater export from Jakobshavn Isbræ and Ilulissat Icefjord. Ann. Glaciol. 58, 107–117 (2017).

    Article  Google Scholar 

  29. 29.

    Bamber, J., van den Broeke, M., Ettema, J., Lenaerts, J. & Rignot, E. Recent large increases in freshwater fluxes from Greenland into the North Atlantic. Geophys. Res. Lett. 39, L19501 (2012).

    Article  Google Scholar 

  30. 30.

    Harden, B. E., Straneo, F. & Sutherland, D. A. Moored observations of synoptic and seasonal variability in the East Greenland Coastal Current. J. Geophys. Res. Oceans 119, 8838–8857 (2014).

    Article  Google Scholar 

  31. 31.

    Sutherland, D. A., Straneo, F. & Pickart, R. S. Characteristics and dynamics of two major Greenland glacial fjords. J. Geophys. Res. Oceans 119, 3767–3791 (2014).

    Article  Google Scholar 

  32. 32.

    Beaird, N. L., Straneo, F. & Jenkins, W. Export of strongly diluted Greenland meltwater from a major glacial fjord. Geophys. Res. Lett. 45, 4163–4170 (2018).

    Article  Google Scholar 

  33. 33.

    Straneo, F. et al. Rapid circulation of warm subtropical waters in a major glacial fjord in East Greenland. Nat. Geosci. 3, 182–186 (2010).

    Article  Google Scholar 

  34. 34.

    Straneo, F. et al. Characteristics of ocean waters reaching Greenland’s glaciers. Ann. Glaciol. 53, 202–210 (2012).

    Article  Google Scholar 

  35. 35.

    Jackson, R. H. & Straneo, F. Heat, salt, and freshwater budgets for a glacial fjord in Greenland. J. Phys. Oceanogr. 46, 2735–2768 (2016).

    Article  Google Scholar 

  36. 36.

    Lydersen, C. et al. The importance of tidewater glaciers for marine mammals and seabirds in Svalbard, Norway. J. Mar. Syst. 129, 452–471 (2014).

    Article  Google Scholar 

  37. 37.

    Azetsu-Scott, K. & Syvitski, J. P. M. Influence of melting icebergs on distribution, characteristics and transport of marine particles in an East Greenland fjord. J. Geophys. Res. Solid Earth 104, 5321–5328 (1999).

    Article  Google Scholar 

  38. 38.

    Hawkings, J. R. et al. Ice sheets as a missing source of silica to the polar oceans. Nat. Commun. 8, 14198 (2017).

    Article  Google Scholar 

  39. 39.

    Gade, H. G. Melting of ice in sea water: a primitive model with application to the Antarctic Ice Shelf and icebergs. J. Phys. Oceanogr. 9, 189–198 (1979).

    Article  Google Scholar 

  40. 40.

    Jenkins, A. The impact of melting ice on ocean waters. J. Phys. Oceanogr. 29, 2370–2381 (1999).

    Article  Google Scholar 

  41. 41.

    Bhatia, M. P. Hydrological and Biogeochemical Cycling along the Greenland Ice Sheet Margin. PhD thesis, Massachusetts Institute of Technology (2012).

  42. 42.

    Wadham, J. L. et al. Sources, cycling and export of nitrogen on the Greenland Ice Sheet. Biogeosciences 13, 6339–6352 (2016).

    Article  Google Scholar 

  43. 43.

    Tomczak, M. & Large, D. G. B. Optimum multiparameter analysis of mixing in the thermocline of the eastern Indian Ocean. J. Geophys. Res. Oceans 94, 16141–16149 (1989).

    Article  Google Scholar 

  44. 44.

    Hartley, C. H. & Dunbar, M. J. On the hydrographic mechanism of the so-called brown zones associated with tidal glaciers. J. Mar. Res. 1, 305–311 (1938).

    Google Scholar 

  45. 45.

    Dunbar, M. J. Glaciers and nutrients in Arctic fiords. Science 182, 398–398 (1973).

    Article  Google Scholar 

  46. 46.

    Horne, E. P. W. Ice-induced vertical circulation in an Arctic fiord. J. Geophys. Res. 90, 1078–1086 (1985).

    Article  Google Scholar 

  47. 47.

    Jackson, R. H., Straneo, F. & Sutherland, D. A. Externally forced fluctuations in ocean temperature at Greenland glaciers in non-summer months. Nat. Geosci. 7, 503–508 (2014).

    Article  Google Scholar 

  48. 48.

    Millan, R. et al. Vulnerability of Southeast Greenland glaciers to warm Atlantic water from Operation IceBridge and Ocean Melting Greenland data. Geophys. Res. Lett. 45, 2688–2696 (2018).

    Article  Google Scholar 

  49. 49.

    Holmes, R. M. et al. Seasonal and annual fluxes of nutrients and organic matter from large rivers to the Arctic Ocean and surrounding seas. Estuaries Coast. 35, 369–382 (2011).

    Article  Google Scholar 

  50. 50.

    Emmerton, C. A., Lesack, L. F. W. & Vincent, W. F. Nutrient and organic matter patterns across the Mackenzie River, estuary and shelf during the seasonal recession of sea-ice. J. Mar. Syst. 74, 741–755 (2008).

    Article  Google Scholar 

  51. 51.

    Meire, L. et al. High export of dissolved silica from the Greenland Ice Sheet. Geophys. Res. Lett. 43, 9173–9182 (2016).

    Article  Google Scholar 

  52. 52.

    Hopwood, M. J., Bacon, S., Arendt, K., Connelly, D. P. & Statham, P. J. Glacial meltwater from Greenland is not likely to be an important source of Fe to the North Atlantic. Biogeochemistry 124, 1–11 (2015).

    Article  Google Scholar 

  53. 53.

    Boyle, E. A., Edmond, J. M. & Sholkovitz, E. R. The mechanism of iron removal in estuaries. Geochim. Cosmochim. Acta 41, 1313–1324 (1977).

    Article  Google Scholar 

  54. 54.

    Schroth, A. W., Crusius, J., Hoyer, I. & Campbell, R. Estuarine removal of glacial iron and implications for iron fluxes to the ocean. Geophys. Res. Lett. 41, 3951–3958 (2014).

    Article  Google Scholar 

  55. 55.

    Achterberg, E. P. et al. Iron biogeochemistry in the high latitude North Atlantic Ocean. Sci. Rep. 8, 1283 (2018).

    Article  Google Scholar 

  56. 56.

    Straneo, F. & Heimbach, P. North Atlantic warming and the retreat of Greenland’s outlet glaciers. Nature 504, 36–43 (2013).

    Article  Google Scholar 

  57. 57.

    Fouest, V. L., Babin, M. & Tremblay, J. É. The fate of riverine nutrients on Arctic shelves. Biogeosciences 10, 3661–3677 (2013).

    Article  Google Scholar 

  58. 58.

    Guo, L., Zhang, J.-Z. & Guéguen, C. Speciation and fluxes of nutrients (N, P, Si) from the upper Yukon River. Global Biogeochem. Cycles 18, GB1038 (2004).

    Google Scholar 

  59. 59.

    Macdonald, R. W., McLaughlin, F. A. & Wong, C. S. The storage of reactive silicate samples by freezing. Limnol. Oceanogr. 31, 1139–1142 (2003).

    Article  Google Scholar 

  60. 60.

    Rice, E. W., Baird, R. B., Eaton, A. D. & Clesceri, L. S. (eds) Standard Methods for the Examination of Water and Wastewater 22nd edn (American Public Health Association, American Water Works Association (AWWA), Water Environment Federation, Washington DC, 2012).

  61. 61.

    Grasshoff, K., Kremling, K. & Ehrhardt, M. (eds) Methods of Seawater Analysis 3rd edn (Wiley-VCH Verlag, Weinheim, 2007).

  62. 62.

    Cutter, G. A. Intercalibration in chemical oceanography—getting the right number. Limnol. Oceanogr. Methods 11, 418–424 (2013).

    Article  Google Scholar 

  63. 63.

    Martin, J. H. et al. Testing the iron hypothesis in ecosystems of the equatorial Pacific Ocean. Nature 371, 123–129 (1994).

    Article  Google Scholar 

  64. 64.

    Abualhaija, M. M. & van den Berg, C. M. G. Chemical speciation of iron in seawater using catalytic cathodic stripping voltammetry with ligand competition against salicylaldoxime. Mar. Chem. 164, 60–74 (2014).

    Article  Google Scholar 

  65. 65.

    Hinrichsen, H. H. & Tomczak, M. Optimum multiparameter analysis of the water mass structure in the western North Atlantic Ocean. J. Geophys. Res. Oceans 98, 10155–10169 (1993).

    Article  Google Scholar 

  66. 66.

    Karstensen, J. & Tomczak, M. Age determination of mixed water masses using CFC and oxygen data. J. Geophys. Res. Oceans 103, 18599–18609 (1998).

    Article  Google Scholar 

  67. 67.

    Saito, M. A. et al. Slow-spreading submarine ridges in the South Atlantic as a significant oceanic iron source. Nat. Geosci. 6, 775–779 (2013).

    Article  Google Scholar 

  68. 68.

    Carroll, D. et al. Modeling turbulent subglacial meltwater plumes: implications for fjord-scale buoyancy-driven circulation. J. Phys. Oceanogr. 45, 2169–2185 (2015).

    Article  Google Scholar 

  69. 69.

    Noël, B. et al. A daily, 1 km resolution data set of downscaled greenland ice sheet surface mass balance (1958–2015). Cryosphere 10, 2361–2377 (2016).

    Article  Google Scholar 

  70. 70.

    Mernild, S. H. et al. Freshwater flux to Sermilik Fjord, SE Greenland. Cryosphere 4, 453–465 (2010).

    Article  Google Scholar 

  71. 71.

    Lewis, S. Hydrologic Sub-basins of Greenland Version 1 (National Snow and Ice Data Center, Boulder, 2009).

  72. 72.

    Lewis, S. M. & Smith, L. C. Hydrologic drainage of the Greenland Ice Sheet. Hydrol. Process. 23, 2004–2011 (2009).

    Article  Google Scholar 

  73. 73.

    Azetsu-Scott, K., Petrie, B., Yeats, P. & Lee, C. Composition and fluxes of freshwater through Davis Strait using multiple chemical tracers. J. Geophys. Res. Oceans 117, C12011 (2012).

    Article  Google Scholar 

  74. 74.

    Vernon, C. L. et al. Surface mass balance model intercomparison for the Greenland Ice Sheet. Cryosphere 7, 599–614 (2013).

    Article  Google Scholar 

  75. 75.

    Sutterley, T. C. et al. Evaluation of reconstructions of snow/ice melt in Greenland by regional atmospheric climate models using laser altimetry data. Geophys. Res. Lett. 45, 8324–8333 (2018).

    Google Scholar 

  76. 76.

    Mernild, S. H. et al. Freshwater flux and spatiotemporal simulated runoff variability into Ilulissat Icefjord, West Greenland, linked to salinity and temperature observations near tidewater glacier margins obtained using instrumented ringed seals. J. Phys. Oceanogr. 45, 1426–1445 (2015).

    Article  Google Scholar 

  77. 77.

    Cape, M. R., Straneo, F. & Charette, M. A. Hydrographic sensor and bottle data collected during an August 2015 cruise to Sermilik Fjord, East Greenland. PANGAEA https://doi.org/10.1594/PANGAEA.887304(2018).

  78. 78.

    Cape, M. R., Bundy, R. M. & Straneo, F. Surface total dissolvable iron data collected during an August 2015 cruise to Sermilik Fjord, East Greenland. PANGAEA https://doi.org/10.1594/PANGAEA.887324(2018).

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Acknowledgements

This work was supported by: an internal grant from the Woods Hole Oceanographic Institution (WHOI) Ocean and Climate Change Institute (to M.R.C., F.S. and M.A.C.), grants from the National Science Foundation to M.A.C. (OCE-1458305), N.B. (OCE-1536856) and F.S. (OCE-1657601), and Woods Hole Oceanographic Institution Postdoctoral Fellowships to M.R.C. and R.M.B. We are grateful to J. Hawkings for sharing Leverett Glacier nutrient data, to K. Azetsu-Scott and B. Curry for sharing the Davis Strait and West Greenland continental shelf hydrographic data, to P. Henderson and the WHOI Nutrient Analytical Facility for assistance with macronutrient sample collection and analysis, to R. Jackson for helpful conversations concerning data analysis, to A. Ramsey for logistical support, to S. Laney for loan of and technical assistance with oceanographic instrumentation, to M. Swartz for CTD assembly and testing, and to the captain and crew of the RV Adolf Jensen for support in the field.

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M.R.C. and F.S. conceived the study with input from M.A.C. M.R.C., F.S. and N.B. collected data and samples in the field. M.A.C. and R.M.B analysed water samples. M.R.C., N.B. and R.M.B. analysed the resulting data. M.R.C. wrote the paper, with assistance from all co-authors.

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Correspondence to Mattias R. Cape.

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Supplementary Data Table 1 and 2 and Supplementary Figures 1–13.

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Cape, M.R., Straneo, F., Beaird, N. et al. Nutrient release to oceans from buoyancy-driven upwelling at Greenland tidewater glaciers. Nature Geosci 12, 34–39 (2019). https://doi.org/10.1038/s41561-018-0268-4

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