Microbial Fe(III) reduction as a potential iron source from Holocene sediments beneath Larsen Ice Shelf

• Published in: Nature communications Vol. 10; no. 1; pp. 5786 - 10
• Main Authors: Jung, Jaewoo, Yoo, Kyu-Cheul, Rosenheim, Brad E, Conway, Tim M, Lee, Jae Il, Yoon, Ho Il, Hwang, Chung Yeon, Yang, Kiho, Subt, Christina, Kim, Jinwook
• Format: Journal Article
• Language: English
• Published: England Nature Publishing Group 19.12.2019; Nature Publishing Group UK; Nature Portfolio
• Subjects: Antarctic Regions; Bacteria - chemistry; Bacteria - isolation & purification; Bacteria - metabolism; Biogeochemistry; Carbon Sequestration; Climate Change; Geologic Sediments - chemistry; Geologic Sediments - microbiology; Glaciers; Holocene; Ice; Ice Cover - chemistry; Ice Cover - microbiology; Illite; Iron; Iron - chemistry; Land ice; Marine sediments; Metamorphism; Metamorphism (geology); Microorganisms; Minerals - analysis; Oxides; Oxygen - chemistry; Sea level; Seawater - chemistry; Seawater - microbiology; Sediments; Temperature; Water circulation; Water column; Antarctic Regions
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-019-13741-x

Recent recession of the Larsen Ice Shelf C has revealed microbial alterations of illite in marine sediments, a process typically thought to occur during low-grade metamorphism. In situ breakdown of illite provides a previously-unobserved pathway for the release of dissolved Fe to porewaters, thus enhancing clay-rich Antarctic sub-ice shelf sediments as an important source of Fe to Fe-limited surface Southern Ocean waters during ice shelf retreat after the Last Glacial Maximum. When sediments are underneath the ice shelf, Fe from microbial reductive dissolution of illite/Fe-oxides may be exported to the water column. However, the initiation of an oxygenated, bioturbated sediment under receding ice shelves may oxidize Fe within surface porewaters, decreasing dissolved Fe export to the ocean. Thus, we identify another ice-sheet feedback intimately tied to iron biogeochemistry during climate transitions. Further constraints on the geographical extent of this process will impact our understanding of iron-carbon feedbacks during major deglaciations.