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 Fe2+ to porewaters, thus...
| Main Authors: | , , , , , , , , , |
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| Format: | Article in Journal/Newspaper |
| Language: | unknown |
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Digital Commons @ University of South Florida
2019
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| Subjects: | |
| Online Access: | https://digitalcommons.usf.edu/msc_facpub/2418 https://digitalcommons.usf.edu/cgi/viewcontent.cgi?article=3466&context=msc_facpub |
| 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 Fe2+ 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, Fe2+ 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 Fe2+ 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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