Stable silicon isotopes as tracers of Arctic sea ice–ocean macronutrient cycling

Stable silicon isotopes have emerged as powerful tracers of marine biogeochemical processes, yet their application in high-latitude environments remains comparatively underexplored. Here we synthesize silicon isotope observations from the Eurasian Arctic Ocean to show how isotope patterns help disentangle physical transport, including open-ocean circulation, shelf–basin exchange, and river influence, from biological utilization across ice-covered and seasonally ice-free regimes. Using published case studies from the Siberian shelves and the Transpolar Drift, we illustrate how Si isotope signatures resolve coupled physical and biogeochemical controls on nutrient pathways. We then outline key methodological challenges for extending Si isotope work into sea ice, including defining open versus closed brine habitats, linking isotope signals to brine-network connectivity, and avoiding sampling artifacts that integrate unknown source volumes. Finally, we discuss how ongoing Arctic observing efforts, including large international campaigns, open new avenues for applying Si isotope techniques to questions of nutrient availability, ecosystem change, and ice–ocean coupling in a rapidly transforming Arctic system.