The polar regions are biologically productive and play a critical role in regional and global biogeochemical cycling. A key nutrient is dissolved silicon, required for the growth of siliceous phytoplankton, diatoms, which form an important component of polar ecosystems. Glacial weathering is thought to be an important dissolved silicon source to coastal waters, especially critical in regions experiencing seasonal silicon limitation of diatom growth. However, complex physical and biogeochemical interactions in fjords and coastal regions modulate the downstream supply of dissolved and particulate nutrients, including silicon. Here, we review the biogeochemical complexities of glaciated margins and the insights into this system that silicon isotope geochemistry offer. We show that stable and radioisotopic measurements and biogeochemical numerical modelling provide a quantitative mechanistic understanding of subglacial silica mobilisation and its cycling across the land-ocean continuum. Subglacial weathering produces isotopically light amorphous silica, which dissolves in seawater to release dissolved silicon. Our findings show that isotopically light, detrital silica, likely containing glacial material, reaches the ocean and there could support a substantial proportion of diatom productivity, especially in the Arctic. Outstanding questions about silicon cycling in these crucial environments will be addressed through novel and cross-discipline approaches that overcome traditionally viewed ecosystem boundaries.

BGeosys Department of Geosciences Université libre de Bruxelles Brussels Belgium

British Antarctic Survey High Cross Cambridge UK

Dauphin Island Sea Lab Dauphin Island AL USA

Department of Biology University of Antwerp Wilrijk Belgium

Department of Earth and Environmental Science University of Pennsylvania Philadelphia PA USA

Department of Earth Sciences University of Cambridge Cambridge UK

Department of Ecology Faculty of Science Charles University Prague 2 Czechia

Department of Estuarine and Delta Systems Royal Netherlands Institute for Sea Research Yerseke The Netherlands

Department of Marine Science University of Otago Dunedin New Zealand

Greenland Climate Research Centre Greenland Institute of Natural Resources Nuuk Greenland

iC3 Centre for ice Cryosphere Carbon and Climate Department of Geosciences UiT The Arctic University of Norway Tromsø Norway

National Institute of Water and Atmospheric Research Wellington New Zealand

National Oceanography Centre Southampton Southampton UK

Plymouth Marine Laboratory Prospect Place The Hoe Plymouth UK

School of Earth Sciences University of Bristol Bristol UK

Stokes School of Marine and Environmental Sciences University of South Alabama Mobile AL USA

UK Centre for Ecology and Hydrology Environment Centre Wales Bangor UK

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Tréguer, P. J. et al. Reviews and syntheses: the biogeochemical cycle of silicon in the modern ocean. Biogeosciences18, 1269–1289 (2021).

Krause, J. W. & Lomas, M. W. Understanding diatoms’ past and future biogeochemical role in high-latitude seas. Geophys. Res. Lett.47, e2019GL085602 (2020).

Tréguer, P. et al. Influence of diatom diversity on the ocean biological carbon pump. Nat. Geosci.11, 27–37 (2018).

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

Hopwood, M. J. et al. How does glacier discharge affect marine biogeochemistry and primary production in the Arctic?. Cryosphere14, 1347–1383 (2020).

Cape, M. R., Straneo, F., Beaird, N., Bundy, R. M. & Charette, M. A. Nutrient release to oceans from buoyancy-driven upwelling at Greenland tidewater glaciers. Nat. Geosci.12, 34–39 (2019).

Hawkings, J. R. et al. The silicon cycle impacted by past ice sheets. Nat. Commun.9, 3210 (2018). PubMed PMC

Hatton, J. E. et al. Silicon isotopes in Arctic and sub-Arctic glacial meltwaters: the role of subglacial weathering in the silicon cycle. Proc. R. Soc. A475, 20190098 (2019). PubMed PMC

Hatton, J. E. et al. Silicon isotopic composition of dry and wet-based glaciers in Antarctica. Front. Earth Sci.8, 286 (2020).

Hatton, J. et al. Investigation of subglacial weathering under the Greenland Ice Sheet using silicon isotopes. Geochim. Cosmochim. Acta247, 191–206 (2019).

Hatton, J. et al. Physical weathering by glaciers enhances silicon mobilisation and isotopic fractionation. Geochem. Perspect. Lett.19, 7–12 (2021).

Hendry, K. R. et al. The biogeochemical impact of glacial meltwater from Southwest Greenland. Prog. Oceanogr.176, 102126 (2019).

Hatton, J. et al. Silicon isotopes highlight the role of glaciated fjords in modifying coastal waters. J. Geophys. Res.: Biogeosci.128, e2022JG007242 (2023).

Ward, J. P. et al. Benthic silicon cycling in the Arctic Barents Sea: a reaction–transport model study. Biogeosciences19, 3445–3467 (2022).

Ng, H. C., et al. Benthic dissolved silicon and iron cycling at glaciated Patagonian fjord heads. Glob. Biogeochem. Cycles36, e2022GB007493 (2022). PubMed PMC

Cassarino, L., Coath, C. D., Xavier, J. R. & Hendry, K. R. Silicon isotopes of deep sea sponges: new insights into biomineralisation and skeletal structure. Biogeosciences15, 6959–6977 (2018).

Wadham, J. et al. Hydro-biogeochemical coupling beneath a large polythermal Arctic glacier: Implications for subice sheet biogeochemistry. J. Geophys. Res.: Earth Surf.115, F04017 (2010).

Wadham, J. L. et al. Ice sheets matter for the global carbon cycle. Nat. Commun.10, 3567 (2019). PubMed PMC

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

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

Hopwood, M. J. et al. A close look at dissolved silica dynamics in Disko Bay, west Greenland. Glob. Biogeochem. Cycles39, e2023GB008080 (2025). PubMed PMC

Zhu, X., Hopwood, M. J., Laufer-Meiser, K. & Achterberg, E. P. Incubation experiments characterize turbid glacier plumes as a major source of Mn and Co, and a minor source of Fe and Si, to seawater. Glob. Biogeochem. Cycles38, e2024GB008144 (2024).

Georg, R., Reynolds, B. C., West, A., Burton, K. & Halliday, A. N. Silicon isotope variations accompanying basalt weathering in Iceland. Earth Planet. Sci. Lett.261, 476–490 (2007).

Opfergelt, S., Burton, K., Von Strandmann, P. P., Gislason, S. & Halliday, A. Riverine silicon isotope variations in glaciated basaltic terrains: Implications for the Si delivery to the ocean over glacial–interglacial intervals. Earth Planet. Sci. Lett.369, 211–219 (2013).

Blackburn, T. et al. Composition and formation age of amorphous silica coating glacially polished surfaces. Geology47, 347–350 (2019).

Casey, W. H., Westrich, H. R., Banfield, J. F., Ferruzzi, G. & Arnold, G. W. Leaching and reconstruction at the surfaces of dissolving chain-silicate minerals. Nature366, 253–256 (1993).

Hellmann, R. et al. Unifying natural and laboratory chemical weathering with interfacial dissolution–reprecipitation: a study based on the nanometer-scale chemistry of fluid–silicate interfaces. Chem. Geol.294, 203–216 (2012).

Pryer, H. V. et al. The effects of glacial cover on riverine silicon isotope compositions in Chilean Patagonia. Front. Earth Sci.8, 368 (2020).

Pryer, H. V., et al. The influence of glacial cover on riverine silicon and iron exports in Chilean Patagonia. Glob. Biogeochem. Cycles34, e2020GB006611 (2020). PubMed PMC

Torres, M. A., Moosdorf, N., Hartmann, J., Adkins, J. F. & West, A. J. Glacial weathering, sulfide oxidation, and global carbon cycle feedbacks. Proc. Natl. Acad. Sci.114, 8716–8721 (2017). PubMed PMC

Martin, J. B., Pain, A. J., Martin, E. E., Rahman, S. & Ackerman, P. Comparisons of nutrients exported from Greenlandic glacial and deglaciated watersheds. Glob. Biogeochem. Cycles34, e2020GB006661 (2020).

Krause, J. W. et al. Silicic acid limitation drives bloom termination and potential carbon sequestration in an Arctic bloom. Sci. Rep.9, 8149 (2019). PubMed PMC

Krause, J. W. et al. Biogenic silica production and diatom dynamics in the Svalbard region during spring. Biogeosciences15, 6503–6517 (2018).

Rey, F. Declining silicate concentrations in the Norwegian and Barents Seas. ICES J. Mar. Sci.69, 208–212 (2012).

Hátún, H. et al. The subpolar gyre regulates silicate concentrations in the North Atlantic. Sci. Rep.7, 14576 (2017). PubMed PMC

Bhatia, M. P., et al. Glaciers and nutrients in the Canadian Arctic Archipelago marine system. Glob. Biogeochem. Cycles35, e2021GB006976 (2021).

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).

Brown, M. T., Lippiatt, S. M. & Bruland, K. W. Dissolved aluminum, particulate aluminum, and silicic acid in northern Gulf of Alaska coastal waters: glacial/riverine inputs and extreme reactivity. Mar. Chem.122, 160–175 (2010).

Meire, L. et al. Glacier retreat alters downstream fjord ecosystem structure and function in Greenland. Nat. Geosci.16, 671–674 (2023). PubMed PMC

Ehlert, C. et al. Stable silicon isotope signatures of marine pore waters–Biogenic opal dissolution versus authigenic clay mineral formation. Geochim. Cosmochim. Acta191, 102–117 (2016).

Michalopoulos, P. & Aller, R. C. Early diagenesis of biogenic silica in the Amazon delta: alteration, authigenic clay formation, and storage. Geochim. Cosmochim. Acta68, 1061–1085 (2004).

Rahman, S., Aller, R. & Cochran, J. Cosmogenic 32Si as a tracer of biogenic silica burial and diagenesis: major deltaic sinks in the silica cycle. Geophys. Res. Lett.43, 7124–7132 (2016).

Pickering, R. A., et al. Using stable isotopes to disentangle marine sedimentary signals in reactive silicon pools. Geophys. Res. Lett.47, e2020GL087877 (2020).

Huang, T.-H. et al. Separating Si phases from diagenetically-modified sediments through sequential leaching. Chem. Geol.637, 121681 (2023).

Wallington, H., Hendry, K., Perkins, R., Yallop, M. & Arndt, S. Benthic diatoms modify riverine silicon export to a marine zone in a hypertidal estuarine environment. Biogeochemistry162, 177–200 (2023).

Cassarino, L. et al. Sedimentary nutrient supply in productive hot spots off the West Antarctic Peninsula revealed by silicon isotopes. Glob. Biogeochem. Cycles34, e2019GB006486 (2020).

Ward, J. P. et al. Stable silicon isotopes uncover a mineralogical control on the benthic silicon cycle in the Arctic Barents Sea. Geochim. Cosmochim. Acta329, 206–230 (2022).

Ng, H. C. et al. Sediment efflux of silicon on the Greenland margin and implications for the marine silicon cycle. Earth Planet. Sci. Lett.529, 115877 (2020).

Wang, T. et al. Silicon isotopes reveal the impact of fjordic processes on the transport of reactive silicon from glaciers to coastal regions. Chem. Geol.670, 122403 (2024).

Shoenfelt, E. M., Winckler, G., Annett, A. L., Hendry, K. R. & Bostick, B. C. Physical weathering intensity controls bioavailable primary iron (II) silicate content in major global dust sources. Geophys. Res. Lett.46, 10854–10864 (2019).

Raiswell, R. & Canfield, D. E. Section 6. iron export by icebergs and subglacial runoff. Geochem. Perspect.1, 72–80 (2012).

Wehrmann, L. M. et al. Iron and manganese speciation and cycling in glacially influenced high-latitude fjord sediments (West Spitsbergen, Svalbard): evidence for a benthic recycling-transport mechanism. Geochim. Cosmochim. Acta141, 628–655 (2014).

Ng, H. C., et al. Detrital input sustains diatom production off a glaciated Arctic coast. Geophys. Res. Lett.51, e2024GL108324 (2024).

Krause, J. W. et al. Picoplankton contribution to biogenic silica stocks and production rates in the Sargasso Sea. Glob. Biogeochem. Cycles31, 762–774 (2017).

Rysgaard, S. et al. An updated view on water masses on the pan-west Greenland continental shelf and their link to proglacial fjords. J. Geophys. Res.: Oceans125, e2019JC015564 (2020).

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

Hendry, K. R., et al. Tracing glacial meltwater from the Greenland Ice Sheet to the ocean using gliders. J. Geophys. Res.: Oceans126, e2021JC017274 (2021).

Agustí, S. et al. Arctic (Svalbard islands) active and exported diatom stocks and cell health status. Biogeosciences17, 35–45 (2020).

Geilert, S. et al. Impact of ambient conditions on the Si isotope fractionation in marine pore fluids during early diagenesis. Biogeosciences17, 1745–1763 (2020).

Geilert, S., Grasse, P., Wallmann, K., Liebetrau, V. & Menzies, C. D. Serpentine alteration as source of high dissolved silicon and elevated δ30Si values to the marine Si cycle. Nat. Commun.11, 5123 (2020). PubMed PMC

Freitas, F. et al. Benthic organic matter transformation drives pH and carbonate chemistry in Arctic marine sediments. Glob. Biogeochem. Cycles36, e2021GB007187 (2022).

Regnier, P., O’kane, J., Steefel, C. & Vanderborght, J.-P. Modeling complex multi-component reactive-transport systems: towards a simulation environment based on the concept of a Knowledge Base. Appl. Math. Model.26, 913–927 (2002).

Aguilera, D., Jourabchi, P., Spiteri, C. & Regnier, P. A knowledge-based reactive transport approach for the simulation of biogeochemical dynamics in Earth systems. Geochem. Geophys. Geosyst.6, Q07012 (2005).

Berner, R. A. Early Diagenesis: A Theoretical Approach. (Princeton University Press, 1980).

Boudreau, B. P. Diagenetic Models and their Implementation. 505 (Springer Berlin, 1997).

Arndt, S. et al. Quantifying the degradation of organic matter in marine sediments: a review and synthesis. Earth-Sci. Rev.123, 53–86 (2013).

Nelson, D. M., Brzezinski, M. A., Sigmon, D. E. & Franck, V. M. A seasonal progression of Si limitation in the Pacific sector of the Southern Ocean. Deep Sea Res. Part II: Topical Stud. Oceanogr.48, 3973–3995 (2001).

Whitehouse, M. J., Hendry, K. R., Tarling, G. A., Thorpe, S. E. & ten Hoopen, P. A database of marine macronutrient, temperature and salinity measurements made around the highly productive island of South Georgia, the Scotia Sea and the Antarctic Peninsula between 1980 and 2009. Earth Syst. Sci. Data15, 211–224 (2023).

Meredith, M. et al. Polar Regions. in IPCC Special Report on the Ocean and Cryosphere in a Changing Climate (eds Pörtner, H.-O. et al.) 203–320 (Cambridge University Press, 2019).

Polyakov, I. V. et al. Borealization of the Arctic Ocean in response to anomalous advection from sub-Arctic seas. Front. Mar. Sci.7, 491 (2020).

Beaton, A. D. et al. High-resolution sensors reveal nitrate and dissolved silica dynamics in an Arctic fjord. J. Geophys. Res.: Biogeosci.130, e2024JG008523 (2025).

Jones, R. L. et al. Continued glacial retreat linked to changing macronutrient supply along the West Antarctic Peninsula. Mar. Chem.251, 104230 (2023).

RGI-Consortium. Randolf Glacier Inventory - A Dataset of Global Glacier Outlines, Version 7.0. 10.5067/f6jmovy5navz (NSIDC: National Snow and Ice Data Centre, 2023).

Debyser, M. C. et al. Tracing the role of Arctic shelf processes in Si and N cycling and export through the Fram Strait: insights from combined silicon and nitrate isotopes. Biogeosciences19, 5499–5520 (2022).

Link, H., Chaillou, G., Forest, A., Piepenburg, D. & Archambault, P. Multivariate benthic ecosystem functioning in the Arctic–benthic fluxes explained by environmental parameters in the southeastern Beaufort Sea. Biogeosciences10, 5911–5929 (2013).

März, C., Meinhardt, A.-K., Schnetger, B. & Brumsack, H.-J. Silica diagenesis and benthic fluxes in the Arctic Ocean. Mar. Chem.171, 1–9 (2015).

Sutton, J. N. et al. A review of the stable isotope bio-geochemistry of the global silicon cycle and its associated trace elements. Front. Earth Sci.5, 112 (2018).

Hendry, K. R. et al. Silicon isotopic systematics of deep-sea sponge grounds in the North Atlantic. Quat. Sci. Rev.210, 1–14 (2019).

Krause, J. W., Brzezinski, M. A. & Jones, J. L. Application of low-level beta counting of 32Si for the measurement of silica production rates in aquatic environments. Mar. Chem.127, 40–47 (2011).