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dc.contributor.authorFox-Powell, Mark George
dc.contributor.authorHallsworth, John
dc.contributor.authorCousins, Claire Rachel
dc.contributor.authorCockell, Charles
dc.identifier.citationFox-Powell , M G , Hallsworth , J , Cousins , C R & Cockell , C 2016 , ' Ionic strength is a barrier to the habitability of Mars ' , Astrobiology , vol. 16 , no. 6 , pp. 427-442 .
dc.identifier.otherPURE: 242437212
dc.identifier.otherPURE UUID: 7da9abf5-1e9e-4729-b6b7-115b41622c6a
dc.identifier.otherScopus: 84973596194
dc.identifier.otherORCID: /0000-0002-3954-8079/work/60196602
dc.identifier.otherWOS: 000377210200005
dc.descriptionClaire R. Cousins is supported by a Royal Society of Edinburgh Personal Research Fellowship. Funding for this work was provided by the UK Space Agency as part of the Aurora Science program. Support was also provided by Science and Technology Facilities Council (STFC) Grant no. ST/M001261/1.en
dc.description.abstractThe thermodynamic availability of water (water activity) strictly limits microbial propagation on Earth, particularly in hypersaline environments. A considerable body of evidence indicates the existence of hypersaline surface waters throughout the history of Mars; therefore it is assumed that, as on Earth, water activity is a major limiting factor for martian habitability. However, the differing geological histories of Earth and Mars have driven variations in their respective aqueous geochemistry, with as-yet-unknown implications for habitability. Using a microbial community enrichment approach, we investigated microbial habitability for a suite of simulated martian brines. While the habitability of some martian brines was consistent with predictions made from water activity, others were uninhabitable even when the water activity was biologically permissive. We demonstrate experimentally that high ionic strength, driven to extremes on Mars by the ubiquitous occurrence of multivalent ions, renders these environments uninhabitable despite the presence of biologically available water. These findings show how the respective geological histories of Earth and Mars, which have produced differences in the planets' dominant water chemistries, have resulted in different physicochemical extremes which define the boundary space for microbial habitability.
dc.rightsCopyright Mary Ann Liebert, Inc. This work is made available online in accordance with the publisher’s policies. This is the author created, accepted version manuscript following peer review and may differ slightly from the final published version. The final published version of this work is available at
dc.subjectWater activityen
dc.subjectLife in extreme environmentsen
dc.subjectG Geography (General)en
dc.subjectQB Astronomyen
dc.titleIonic strength is a barrier to the habitability of Marsen
dc.typeJournal articleen
dc.contributor.institutionUniversity of St Andrews.School of Earth & Environmental Sciencesen
dc.contributor.institutionUniversity of St Andrews.St Andrews Centre for Exoplanet Scienceen
dc.contributor.institutionUniversity of St Andrews.Earth and Environmental Sciencesen
dc.description.statusPeer revieweden

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