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Extreme hydrochemical conditions in natural microcosms entombed within Antarctic ice

Extreme hydrochemical conditions in natural microcosms entombed within Antarctic ice
Extreme hydrochemical conditions in natural microcosms entombed within Antarctic ice
Cryoconite holes are near-vertical tubes that form in the surface of glaciers when solar-heated debris melts into the ice. Those that form in the McMurdo Dry Valleys of Antarctica are distinctive, in that they have ice lids and are closed to the atmosphere for periods of years to decades. Photoautotrophs and heterotrophs grow within this closed environment, perturbing the poorly buffered water chemistry, yet maintaining the potential for photosynthesis. Microbial excretion and decomposition of organic matter produces dissolved organic carbon (DOC): dissolved inorganic carbon ratios of ?1 : 2. Much of the dissolved nitrogen pool (80–100%) exists as dissolved organic nitrogen (DON). The DON:DOC ratio is ?1 : 11 (mol/mol), typical of organic particulate material at the Earth’s surface. The combination of photoautotrophy, heterotrophy and weak chemical buffering within these microcosms promotes values of pH, pCO2, O2 saturation and percentage total dissolved nitrogen as DON that reach 10·99, 10?7·6 atm, 160% and 100% respectively, which are a unique combination among the surface waters on Earth. These ice-sealed cryoconite holes could be important analogues of refugia on Snowball Earth and other icy planets.
cryconite, Antarctica, glacier ice, microcosms
1099-1085
379-387
Tranter, M.
a272a56a-ce28-4fa3-a4c4-1602b3ece6c1
Fountain, A.G.
96f25237-d3fd-4835-bd3e-bfe8ba401205
Fritsen, C.H.
39093ead-9922-4cbf-abf3-8c965c0fc336
Lyons, W.B.
532c919e-152c-460c-9b77-b79968fd766d
Priscu, J.C.
da851dd6-8d7c-401b-a153-8d136fcd4c59
Statham, P.J.
51458f15-d6e2-4231-8bba-d0567f9e440c
Welch, K.A.
be2e5488-7854-4cda-9ab4-bb2be246f891
Tranter, M.
a272a56a-ce28-4fa3-a4c4-1602b3ece6c1
Fountain, A.G.
96f25237-d3fd-4835-bd3e-bfe8ba401205
Fritsen, C.H.
39093ead-9922-4cbf-abf3-8c965c0fc336
Lyons, W.B.
532c919e-152c-460c-9b77-b79968fd766d
Priscu, J.C.
da851dd6-8d7c-401b-a153-8d136fcd4c59
Statham, P.J.
51458f15-d6e2-4231-8bba-d0567f9e440c
Welch, K.A.
be2e5488-7854-4cda-9ab4-bb2be246f891

Tranter, M., Fountain, A.G., Fritsen, C.H., Lyons, W.B., Priscu, J.C., Statham, P.J. and Welch, K.A. (2004) Extreme hydrochemical conditions in natural microcosms entombed within Antarctic ice. Hydrological Processes, 18 (2), 379-387. (doi:10.1002/hyp.5217).

Record type: Article

Abstract

Cryoconite holes are near-vertical tubes that form in the surface of glaciers when solar-heated debris melts into the ice. Those that form in the McMurdo Dry Valleys of Antarctica are distinctive, in that they have ice lids and are closed to the atmosphere for periods of years to decades. Photoautotrophs and heterotrophs grow within this closed environment, perturbing the poorly buffered water chemistry, yet maintaining the potential for photosynthesis. Microbial excretion and decomposition of organic matter produces dissolved organic carbon (DOC): dissolved inorganic carbon ratios of ?1 : 2. Much of the dissolved nitrogen pool (80–100%) exists as dissolved organic nitrogen (DON). The DON:DOC ratio is ?1 : 11 (mol/mol), typical of organic particulate material at the Earth’s surface. The combination of photoautotrophy, heterotrophy and weak chemical buffering within these microcosms promotes values of pH, pCO2, O2 saturation and percentage total dissolved nitrogen as DON that reach 10·99, 10?7·6 atm, 160% and 100% respectively, which are a unique combination among the surface waters on Earth. These ice-sealed cryoconite holes could be important analogues of refugia on Snowball Earth and other icy planets.

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Published date: 2004
Keywords: cryconite, Antarctica, glacier ice, microcosms

Identifiers

Local EPrints ID: 9878
URI: http://eprints.soton.ac.uk/id/eprint/9878
ISSN: 1099-1085
PURE UUID: 0cdc8b3b-7d19-4eab-a2bd-f6e88218a0f6

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Date deposited: 14 Oct 2004
Last modified: 15 Mar 2024 04:57

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Contributors

Author: M. Tranter
Author: A.G. Fountain
Author: C.H. Fritsen
Author: W.B. Lyons
Author: J.C. Priscu
Author: P.J. Statham
Author: K.A. Welch

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