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The Microbial Habitability of Weathered Volcanic Glass Inferred from Continuous Sensing Techniques

The Microbial Habitability of Weathered Volcanic Glass Inferred from Continuous Sensing Techniques
The Microbial Habitability of Weathered Volcanic Glass Inferred from Continuous Sensing Techniques
Basaltic glasses (hyaloclastite) are a widespread habitat for life in volcanic environments, yet their interior physical conditions are poorly characterized. We investigated the characteristics of exposed weathered basaltic glass from a surface outcrop in Iceland, using microprobes capable of continuous sensing, to determine whether the physical conditions in the rock interior are hospitable to microbial life. The material provided thermal protection from freeze-thaw and rapid temperature fluctuations, similar to data reported for other rock types. Water activity experiments showed that at moisture contents less than 13% wet weight, the glass and its weathering product, palagonite, had a water activity below levels suitable for bacterial growth. In pore spaces, however, these higher moisture conditions might be maintained for many days after a precipitation event. Gas exchange between the rock interior and exterior was rapid (<10?min) when the rocks were dry, but when saturated with water, equilibration took many hours. During this period, we demonstrated the potential for low oxygen conditions within the rock caused by respiratory stimulation of the heterotrophic community within. These conditions might exist within subglacial environments during the formation of the rocks or in micro-environments in the interior of exposed rocks. The experiments showed that microbial communities at the site studied here could potentially be active for 39% of the year, if the depth of the community within the outcrop maintains a balance between access to liquid water and adequate protection from freezing. In the absence of precipitation, the interior of weathered basaltic glass is an extreme and life-limiting environment for microorganisms on Earth and other planets.
Basaltic glass, Palagonite, Oxygen sensing, Cryptoendoliths, Life in extreme environments
1531-1074
651-664
Bagshaw, Elizabeth A.
d34b716f-8162-4788-81a8-03146d5528ed
Cockell, Charles S.
ecd7d75b-c42d-4fad-979c-c0781857ddbb
Magan, Naresh
c31cf01e-226d-4242-82b5-19821524eaf6
Wadham, Jemma L.
fccc19ee-c691-4f95-bbfd-41f4d4f32c57
Venugopalan, T.
73f464ae-796f-4923-8696-0af8f46896b7
Sun, Tong
f98abb53-dae7-4e34-9f2f-d9406c20d0f7
Mowlem, Matt
6f633ca2-298f-48ee-a025-ce52dd62124f
Croxford, Anthony J.
1543e5e5-944e-49b4-bf9b-131e103c7d22
Bagshaw, Elizabeth A.
d34b716f-8162-4788-81a8-03146d5528ed
Cockell, Charles S.
ecd7d75b-c42d-4fad-979c-c0781857ddbb
Magan, Naresh
c31cf01e-226d-4242-82b5-19821524eaf6
Wadham, Jemma L.
fccc19ee-c691-4f95-bbfd-41f4d4f32c57
Venugopalan, T.
73f464ae-796f-4923-8696-0af8f46896b7
Sun, Tong
f98abb53-dae7-4e34-9f2f-d9406c20d0f7
Mowlem, Matt
6f633ca2-298f-48ee-a025-ce52dd62124f
Croxford, Anthony J.
1543e5e5-944e-49b4-bf9b-131e103c7d22

Bagshaw, Elizabeth A., Cockell, Charles S., Magan, Naresh, Wadham, Jemma L., Venugopalan, T., Sun, Tong, Mowlem, Matt and Croxford, Anthony J. (2011) The Microbial Habitability of Weathered Volcanic Glass Inferred from Continuous Sensing Techniques. Astrobiology, 11 (7), 651-664.

Record type: Article

Abstract

Basaltic glasses (hyaloclastite) are a widespread habitat for life in volcanic environments, yet their interior physical conditions are poorly characterized. We investigated the characteristics of exposed weathered basaltic glass from a surface outcrop in Iceland, using microprobes capable of continuous sensing, to determine whether the physical conditions in the rock interior are hospitable to microbial life. The material provided thermal protection from freeze-thaw and rapid temperature fluctuations, similar to data reported for other rock types. Water activity experiments showed that at moisture contents less than 13% wet weight, the glass and its weathering product, palagonite, had a water activity below levels suitable for bacterial growth. In pore spaces, however, these higher moisture conditions might be maintained for many days after a precipitation event. Gas exchange between the rock interior and exterior was rapid (<10?min) when the rocks were dry, but when saturated with water, equilibration took many hours. During this period, we demonstrated the potential for low oxygen conditions within the rock caused by respiratory stimulation of the heterotrophic community within. These conditions might exist within subglacial environments during the formation of the rocks or in micro-environments in the interior of exposed rocks. The experiments showed that microbial communities at the site studied here could potentially be active for 39% of the year, if the depth of the community within the outcrop maintains a balance between access to liquid water and adequate protection from freezing. In the absence of precipitation, the interior of weathered basaltic glass is an extreme and life-limiting environment for microorganisms on Earth and other planets.

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More information

Published date: 16 September 2011
Keywords: Basaltic glass, Palagonite, Oxygen sensing, Cryptoendoliths, Life in extreme environments
Organisations: Ocean Technology and Engineering

Identifiers

Local EPrints ID: 198087
URI: https://eprints.soton.ac.uk/id/eprint/198087
ISSN: 1531-1074
PURE UUID: c420d4ae-4556-407b-8dd6-042f79190d80

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Date deposited: 29 Sep 2011 15:16
Last modified: 08 Nov 2017 12:45

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Contributors

Author: Elizabeth A. Bagshaw
Author: Charles S. Cockell
Author: Naresh Magan
Author: Jemma L. Wadham
Author: T. Venugopalan
Author: Tong Sun
Author: Matt Mowlem
Author: Anthony J. Croxford

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