Microbial Fe(III) reduction as a potential iron source from Holocene sediments beneath Larsen Ice Shelf
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(2+) to porewaters, thu...
Published in: | Nature Communications |
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Main Authors: | , , , , , , , , , |
Format: | Text |
Language: | English |
Published: |
Nature Publishing Group UK
2019
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Subjects: | |
Online Access: | http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6923428/ http://www.ncbi.nlm.nih.gov/pubmed/31857591 https://doi.org/10.1038/s41467-019-13741-x |
Summary: | 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(2+) 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(2+) 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(2+) 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. |
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