Ikaite crystals in melting sea ice – implications for p CO 2 and pH levels in Arctic surface waters
A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air–sea CO 2 exchange. This has been complicated by the recent discoveries of ikaite (a polymorph of CaCO 3 ·6H 2 O) in Arctic and Antarctic sea ice, which indicate that multiple che...
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ftdoajarticles:oai:doaj.org/article:9c4bbbb1622c4e4e9e10a7805eed9264 2023-05-15T13:51:45+02:00 Ikaite crystals in melting sea ice – implications for p CO 2 and pH levels in Arctic surface waters R. J. G. Leakey F. C. Hawthorne D. Barber N. Halden K. Lennert M. Cooper R. N. Glud S. Rysgaard 2012-08-01T00:00:00Z https://doi.org/10.5194/tc-6-901-2012 https://doaj.org/article/9c4bbbb1622c4e4e9e10a7805eed9264 EN eng Copernicus Publications http://www.the-cryosphere.net/6/901/2012/tc-6-901-2012.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-6-901-2012 1994-0416 1994-0424 https://doaj.org/article/9c4bbbb1622c4e4e9e10a7805eed9264 The Cryosphere, Vol 6, Iss 4, Pp 901-908 (2012) Environmental sciences GE1-350 Geology QE1-996.5 article 2012 ftdoajarticles https://doi.org/10.5194/tc-6-901-2012 2022-12-31T00:03:59Z A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air–sea CO 2 exchange. This has been complicated by the recent discoveries of ikaite (a polymorph of CaCO 3 ·6H 2 O) in Arctic and Antarctic sea ice, which indicate that multiple chemical transformations occur in sea ice with a possible effect on CO 2 and pH conditions in surface waters. Here, we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from a melting 1.7 km 2 (0.5–1 m thick) drifting ice floe in the Fram Strait during summer. Our findings show that ikaite crystals are present throughout the sea ice but with larger crystals appearing in the upper ice layers. Ikaite crystals placed at elevated temperatures disintegrated into smaller crystallites and dissolved. During our field campaign in late June, melt reduced the ice floe thickness by 0.2 m per week and resulted in an estimated 3.8 ppm decrease of p CO 2 in the ocean surface mixed layer. This corresponds to an air–sea CO 2 uptake of 10.6 mmol m −2 sea ice d −1 or to 3.3 ton km −2 ice floe week −1 . This is markedly higher than the estimated primary production within the ice floe of 0.3–1.3 mmol m −2 sea ice d −1 . Finally, the presence of ikaite in sea ice and the dissolution of the mineral during melting of the sea ice and mixing of the melt water into the surface oceanic mixed layer accounted for half of the estimated p CO 2 uptake. Article in Journal/Newspaper Antarc* Antarctic Arctic Arctic Ocean Fram Strait Sea ice The Cryosphere Directory of Open Access Journals: DOAJ Articles Antarctic Arctic Arctic Ocean The Cryosphere 6 4 901 908 |
institution |
Open Polar |
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Directory of Open Access Journals: DOAJ Articles |
op_collection_id |
ftdoajarticles |
language |
English |
topic |
Environmental sciences GE1-350 Geology QE1-996.5 |
spellingShingle |
Environmental sciences GE1-350 Geology QE1-996.5 R. J. G. Leakey F. C. Hawthorne D. Barber N. Halden K. Lennert M. Cooper R. N. Glud S. Rysgaard Ikaite crystals in melting sea ice – implications for p CO 2 and pH levels in Arctic surface waters |
topic_facet |
Environmental sciences GE1-350 Geology QE1-996.5 |
description |
A major issue of Arctic marine science is to understand whether the Arctic Ocean is, or will be, a source or sink for air–sea CO 2 exchange. This has been complicated by the recent discoveries of ikaite (a polymorph of CaCO 3 ·6H 2 O) in Arctic and Antarctic sea ice, which indicate that multiple chemical transformations occur in sea ice with a possible effect on CO 2 and pH conditions in surface waters. Here, we report on biogeochemical conditions, microscopic examinations and x-ray diffraction analysis of single crystals from a melting 1.7 km 2 (0.5–1 m thick) drifting ice floe in the Fram Strait during summer. Our findings show that ikaite crystals are present throughout the sea ice but with larger crystals appearing in the upper ice layers. Ikaite crystals placed at elevated temperatures disintegrated into smaller crystallites and dissolved. During our field campaign in late June, melt reduced the ice floe thickness by 0.2 m per week and resulted in an estimated 3.8 ppm decrease of p CO 2 in the ocean surface mixed layer. This corresponds to an air–sea CO 2 uptake of 10.6 mmol m −2 sea ice d −1 or to 3.3 ton km −2 ice floe week −1 . This is markedly higher than the estimated primary production within the ice floe of 0.3–1.3 mmol m −2 sea ice d −1 . Finally, the presence of ikaite in sea ice and the dissolution of the mineral during melting of the sea ice and mixing of the melt water into the surface oceanic mixed layer accounted for half of the estimated p CO 2 uptake. |
format |
Article in Journal/Newspaper |
author |
R. J. G. Leakey F. C. Hawthorne D. Barber N. Halden K. Lennert M. Cooper R. N. Glud S. Rysgaard |
author_facet |
R. J. G. Leakey F. C. Hawthorne D. Barber N. Halden K. Lennert M. Cooper R. N. Glud S. Rysgaard |
author_sort |
R. J. G. Leakey |
title |
Ikaite crystals in melting sea ice – implications for p CO 2 and pH levels in Arctic surface waters |
title_short |
Ikaite crystals in melting sea ice – implications for p CO 2 and pH levels in Arctic surface waters |
title_full |
Ikaite crystals in melting sea ice – implications for p CO 2 and pH levels in Arctic surface waters |
title_fullStr |
Ikaite crystals in melting sea ice – implications for p CO 2 and pH levels in Arctic surface waters |
title_full_unstemmed |
Ikaite crystals in melting sea ice – implications for p CO 2 and pH levels in Arctic surface waters |
title_sort |
ikaite crystals in melting sea ice – implications for p co 2 and ph levels in arctic surface waters |
publisher |
Copernicus Publications |
publishDate |
2012 |
url |
https://doi.org/10.5194/tc-6-901-2012 https://doaj.org/article/9c4bbbb1622c4e4e9e10a7805eed9264 |
geographic |
Antarctic Arctic Arctic Ocean |
geographic_facet |
Antarctic Arctic Arctic Ocean |
genre |
Antarc* Antarctic Arctic Arctic Ocean Fram Strait Sea ice The Cryosphere |
genre_facet |
Antarc* Antarctic Arctic Arctic Ocean Fram Strait Sea ice The Cryosphere |
op_source |
The Cryosphere, Vol 6, Iss 4, Pp 901-908 (2012) |
op_relation |
http://www.the-cryosphere.net/6/901/2012/tc-6-901-2012.pdf https://doaj.org/toc/1994-0416 https://doaj.org/toc/1994-0424 doi:10.5194/tc-6-901-2012 1994-0416 1994-0424 https://doaj.org/article/9c4bbbb1622c4e4e9e10a7805eed9264 |
op_doi |
https://doi.org/10.5194/tc-6-901-2012 |
container_title |
The Cryosphere |
container_volume |
6 |
container_issue |
4 |
container_start_page |
901 |
op_container_end_page |
908 |
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1766255781116641280 |