The 79°N Glacier cavity modulates subglacial iron export to the NE Greenland Shelf

• Published in: Nature Communications
• Main Authors: Krisch, Stephan, Hopwood, Mark James, Schaffer, Janin, Al-Hashem, Ali, Höfer, Juan, Rutgers van der Loeff, Michiel M., Conway, Tim M., Summers, Brent A., Lodeiro, Pablo, Ardiningsih, Indah, Steffens, Tim, Achterberg, Eric Pieter
• Format: Article in Journal/Newspaper
• Language: English
• Published: Springer Science and Business Media LLC 2021
• Subjects: General Physics and Astronomy; General Biochemistry, Genetics and Molecular Biology; General Chemistry; Antarctic; Greenland; Antarc*; Antarctica; glacier; Ice Shelf
• Online Access: http://dx.doi.org/10.1038/s41467-021-23093-0; http://www.nature.com/articles/s41467-021-23093-0.pdf; http://www.nature.com/articles/s41467-021-23093-0

Abstract Approximately half of the freshwater discharged from the Greenland and Antarctic Ice Sheets enters the ocean subsurface as a result of basal ice melt, or runoff draining via the grounding line of a deep ice shelf or marine-terminating glacier. Around Antarctica and parts of northern Greenland, this freshwater then experiences prolonged residence times in large cavities beneath floating ice tongues. Due to the inaccessibility of these cavities, it is unclear how they moderate the freshwater associated supply of nutrients such as iron (Fe) to the ocean. Here, we show that subglacial dissolved Fe export from Nioghalvfjerdsbrae (the ‘79°N Glacier’) is decoupled from particulate inputs including freshwater Fe supply, likely due to the prolonged ~162-day residence time of Atlantic water beneath Greenland’s largest floating ice-tongue. Our findings indicate that the overturning rate and particle-dissolved phase exchanges in ice cavities exert a dominant control on subglacial nutrient supply to shelf regions.