A Contemporary Microbially Maintained Subglacial Ferrous "Ocean"

• Published in: Science
• Main Authors: Mikucki, Jill A., Pearson, Ann, Johnston, David T., Turchyn, Alexandra V., Farquhar, James, Schrag, Daniel P., Anbar, Ariel D., Priscu, John C., Lee, Peter A.
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Association for the Advancement of Science (AAAS) 2009
• Subjects: Antarc*; Antarctic; Ice Sheet; Taylor Glacier
• Online Access: http://dx.doi.org/10.1126/science.1167350; https://www.science.org/doi/pdf/10.1126/science.1167350

An active microbial assemblage cycles sulfur in a sulfate-rich, ancient marine brine beneath Taylor Glacier, an outlet glacier of the East Antarctic Ice Sheet, with Fe(III) serving as the terminal electron acceptor. Isotopic measurements of sulfate, water, carbonate, and ferrous iron and functional gene analyses of adenosine 5′-phosphosulfate reductase imply that a microbial consortium facilitates a catalytic sulfur cycle. These metabolic pathways result from a limited organic carbon supply because of the absence of contemporary photosynthesis, yielding a subglacial ferrous brine that is anoxic but not sulfidic. Coupled biogeochemical processes below the glacier enable subglacial microbes to grow in extended isolation, demonstrating how analogous organic-starved systems, such as Neoproterozoic oceans, accumulated Fe(II) despite the presence of an active sulfur cycle.