Iron cycling in the anoxic cryo-ecosystem of Antarctic Lake Vida
© 2017, Springer International Publishing Switzerland. Iron redox cycling in metal-rich, hypersaline, anoxic brines plays a central role in the biogeochemical evolution of life on Earth, and similar brines with the potential to harbor life are thought to exist elsewhere in the solar system. To inves...
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ftlouisianastuir:oai:digitalcommons.lsu.edu:geo_pubs-1593 2023-06-11T04:07:11+02:00 Iron cycling in the anoxic cryo-ecosystem of Antarctic Lake Vida Proemse, Bernadette C. Murray, Alison E. Schallenberg, Christina McKiernan, Breege Glazer, Brian T. Young, Seth A. Ostrom, Nathaniel E. Bowie, Andrew R. Wieser, Michael E. Kenig, Fabien Doran, Peter T. Edwards, Ross 2017-07-01T07:00:00Z https://digitalcommons.lsu.edu/geo_pubs/594 https://doi.org/10.1007/s10533-017-0346-5 unknown LSU Digital Commons https://digitalcommons.lsu.edu/geo_pubs/594 doi:10.1007/s10533-017-0346-5 Faculty Publications Iron Lake Vida McMurdo dry valleys Redox text 2017 ftlouisianastuir https://doi.org/10.1007/s10533-017-0346-5 2023-05-28T18:16:59Z © 2017, Springer International Publishing Switzerland. Iron redox cycling in metal-rich, hypersaline, anoxic brines plays a central role in the biogeochemical evolution of life on Earth, and similar brines with the potential to harbor life are thought to exist elsewhere in the solar system. To investigate iron biogeochemical cycling in a terrestrial analog we determined the iron redox chemistry and isotopic signatures in the cryoencapsulated liquid brines found in frozen Lake Vida, East Antarctica. We used both in situ voltammetry and the spectrophotometric ferrozine method to determine iron speciation in Lake Vida brine (LVBr). Our results show that iron speciation in the anoxic LVBr was, unexpectedly, not free Fe(II). Iron isotope analysis revealed highly depleted values of −2.5‰ for the ferric iron of LVBr that are similar to iron isotopic signatures of Fe(II) produced by dissimilatory iron reduction. The presence of Fe(III) in LVBr therefore indicates dynamic iron redox cycling beyond iron reduction. Furthermore, extremely low δ18O–SO42− values (−9.7‰) support microbial iron-sulfur cycling reactions. In combination with evidence for chemodenitrification resulting in iron oxidation, we conclude that coupled abiotic and biotic redox reactions are driving the iron cycle in Lake Vida brine. Our findings challenge the current state of knowledge of anoxic brine chemistry and may serve as an analogue for icy brines found in the outer reaches of the solar system. Text Antarc* Antarctic Antarctica East Antarctica McMurdo Dry Valleys LSU Digital Commons (Louisiana State University) Antarctic East Antarctica McMurdo Dry Valleys Frozen Lake ENVELOPE(76.108,76.108,-69.415,-69.415) Lake Vida ENVELOPE(161.950,161.950,-77.383,-77.383) Biogeochemistry 134 1-2 17 27 |
institution |
Open Polar |
collection |
LSU Digital Commons (Louisiana State University) |
op_collection_id |
ftlouisianastuir |
language |
unknown |
topic |
Iron Lake Vida McMurdo dry valleys Redox |
spellingShingle |
Iron Lake Vida McMurdo dry valleys Redox Proemse, Bernadette C. Murray, Alison E. Schallenberg, Christina McKiernan, Breege Glazer, Brian T. Young, Seth A. Ostrom, Nathaniel E. Bowie, Andrew R. Wieser, Michael E. Kenig, Fabien Doran, Peter T. Edwards, Ross Iron cycling in the anoxic cryo-ecosystem of Antarctic Lake Vida |
topic_facet |
Iron Lake Vida McMurdo dry valleys Redox |
description |
© 2017, Springer International Publishing Switzerland. Iron redox cycling in metal-rich, hypersaline, anoxic brines plays a central role in the biogeochemical evolution of life on Earth, and similar brines with the potential to harbor life are thought to exist elsewhere in the solar system. To investigate iron biogeochemical cycling in a terrestrial analog we determined the iron redox chemistry and isotopic signatures in the cryoencapsulated liquid brines found in frozen Lake Vida, East Antarctica. We used both in situ voltammetry and the spectrophotometric ferrozine method to determine iron speciation in Lake Vida brine (LVBr). Our results show that iron speciation in the anoxic LVBr was, unexpectedly, not free Fe(II). Iron isotope analysis revealed highly depleted values of −2.5‰ for the ferric iron of LVBr that are similar to iron isotopic signatures of Fe(II) produced by dissimilatory iron reduction. The presence of Fe(III) in LVBr therefore indicates dynamic iron redox cycling beyond iron reduction. Furthermore, extremely low δ18O–SO42− values (−9.7‰) support microbial iron-sulfur cycling reactions. In combination with evidence for chemodenitrification resulting in iron oxidation, we conclude that coupled abiotic and biotic redox reactions are driving the iron cycle in Lake Vida brine. Our findings challenge the current state of knowledge of anoxic brine chemistry and may serve as an analogue for icy brines found in the outer reaches of the solar system. |
format |
Text |
author |
Proemse, Bernadette C. Murray, Alison E. Schallenberg, Christina McKiernan, Breege Glazer, Brian T. Young, Seth A. Ostrom, Nathaniel E. Bowie, Andrew R. Wieser, Michael E. Kenig, Fabien Doran, Peter T. Edwards, Ross |
author_facet |
Proemse, Bernadette C. Murray, Alison E. Schallenberg, Christina McKiernan, Breege Glazer, Brian T. Young, Seth A. Ostrom, Nathaniel E. Bowie, Andrew R. Wieser, Michael E. Kenig, Fabien Doran, Peter T. Edwards, Ross |
author_sort |
Proemse, Bernadette C. |
title |
Iron cycling in the anoxic cryo-ecosystem of Antarctic Lake Vida |
title_short |
Iron cycling in the anoxic cryo-ecosystem of Antarctic Lake Vida |
title_full |
Iron cycling in the anoxic cryo-ecosystem of Antarctic Lake Vida |
title_fullStr |
Iron cycling in the anoxic cryo-ecosystem of Antarctic Lake Vida |
title_full_unstemmed |
Iron cycling in the anoxic cryo-ecosystem of Antarctic Lake Vida |
title_sort |
iron cycling in the anoxic cryo-ecosystem of antarctic lake vida |
publisher |
LSU Digital Commons |
publishDate |
2017 |
url |
https://digitalcommons.lsu.edu/geo_pubs/594 https://doi.org/10.1007/s10533-017-0346-5 |
long_lat |
ENVELOPE(76.108,76.108,-69.415,-69.415) ENVELOPE(161.950,161.950,-77.383,-77.383) |
geographic |
Antarctic East Antarctica McMurdo Dry Valleys Frozen Lake Lake Vida |
geographic_facet |
Antarctic East Antarctica McMurdo Dry Valleys Frozen Lake Lake Vida |
genre |
Antarc* Antarctic Antarctica East Antarctica McMurdo Dry Valleys |
genre_facet |
Antarc* Antarctic Antarctica East Antarctica McMurdo Dry Valleys |
op_source |
Faculty Publications |
op_relation |
https://digitalcommons.lsu.edu/geo_pubs/594 doi:10.1007/s10533-017-0346-5 |
op_doi |
https://doi.org/10.1007/s10533-017-0346-5 |
container_title |
Biogeochemistry |
container_volume |
134 |
container_issue |
1-2 |
container_start_page |
17 |
op_container_end_page |
27 |
_version_ |
1768380039586381824 |