Freezing-induced acidification of sea ice brine
The acidity of sea ice and snow plays a key role in the chemistry of the cryosphere; an important example lies in the photochemical catalytic release of reactive bromine in polar regions, facilitated at pHs below 6.5. We apply in-situ acid-base indicators to probe the microscopic acidity of the brin...
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ftnerc:oai:nora.nerc.ac.uk:537655 2024-09-30T14:43:07+00:00 Freezing-induced acidification of sea ice brine Veselý, L. Štůsek, R. Mikula, O. Yang, X. Heger, D. 2024-10-10 http://nora.nerc.ac.uk/id/eprint/537655/ https://www.sciencedirect.com/science/article/pii/S0048969724043420?via%3Dihub unknown Elsevier Veselý, L.; Štůsek, R.; Mikula, O.; Yang, X. orcid:0000-0002-3838-9758 Heger, D. 2024 Freezing-induced acidification of sea ice brine. Science of the Total Environment, 946, 174194. 14, pp. https://doi.org/10.1016/j.scitotenv.2024.174194 <https://doi.org/10.1016/j.scitotenv.2024.174194> Publication - Article PeerReviewed 2024 ftnerc https://doi.org/10.1016/j.scitotenv.2024.174194 2024-09-18T00:05:58Z The acidity of sea ice and snow plays a key role in the chemistry of the cryosphere; an important example lies in the photochemical catalytic release of reactive bromine in polar regions, facilitated at pHs below 6.5. We apply in-situ acid-base indicators to probe the microscopic acidity of the brine within the ice matrix in artificial sea water at a range of concentrations (0.35–70 PPT) and initial pHs (6–9). The results are supported by analogous measurements of the most abundant salts in seawater: NaCl, Na2SO4, and CaCO3. In the research herein, the acidity is expressed in terms of the Hammett acidity function, H2−. The obtained results show a pronounced acidity increase in sea water after freezing at −15 °C and during the subsequent cooling down to −50 °C. Importantly, we did not observe any significant hysteresis; the values of acidity upon warming markedly resembled those at the corresponding temperatures at cooling. The acidity increase is attributed to the minerals' crystallization, which is accompanied by a loss of the buffering capacity. Our observations show that lower salinity sea water samples (≤ 3.5 PPT) reach pH values below 6.5 at the temperature of −15 °C, whereas higher salinity ices attain such values only at −30 °C. The ensuing implications for polar chemistry and the relevance to the field measurements are discussed. Article in Journal/Newspaper Sea ice Natural Environment Research Council: NERC Open Research Archive Science of The Total Environment 946 174194 |
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Open Polar |
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Natural Environment Research Council: NERC Open Research Archive |
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ftnerc |
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unknown |
description |
The acidity of sea ice and snow plays a key role in the chemistry of the cryosphere; an important example lies in the photochemical catalytic release of reactive bromine in polar regions, facilitated at pHs below 6.5. We apply in-situ acid-base indicators to probe the microscopic acidity of the brine within the ice matrix in artificial sea water at a range of concentrations (0.35–70 PPT) and initial pHs (6–9). The results are supported by analogous measurements of the most abundant salts in seawater: NaCl, Na2SO4, and CaCO3. In the research herein, the acidity is expressed in terms of the Hammett acidity function, H2−. The obtained results show a pronounced acidity increase in sea water after freezing at −15 °C and during the subsequent cooling down to −50 °C. Importantly, we did not observe any significant hysteresis; the values of acidity upon warming markedly resembled those at the corresponding temperatures at cooling. The acidity increase is attributed to the minerals' crystallization, which is accompanied by a loss of the buffering capacity. Our observations show that lower salinity sea water samples (≤ 3.5 PPT) reach pH values below 6.5 at the temperature of −15 °C, whereas higher salinity ices attain such values only at −30 °C. The ensuing implications for polar chemistry and the relevance to the field measurements are discussed. |
format |
Article in Journal/Newspaper |
author |
Veselý, L. Štůsek, R. Mikula, O. Yang, X. Heger, D. |
spellingShingle |
Veselý, L. Štůsek, R. Mikula, O. Yang, X. Heger, D. Freezing-induced acidification of sea ice brine |
author_facet |
Veselý, L. Štůsek, R. Mikula, O. Yang, X. Heger, D. |
author_sort |
Veselý, L. |
title |
Freezing-induced acidification of sea ice brine |
title_short |
Freezing-induced acidification of sea ice brine |
title_full |
Freezing-induced acidification of sea ice brine |
title_fullStr |
Freezing-induced acidification of sea ice brine |
title_full_unstemmed |
Freezing-induced acidification of sea ice brine |
title_sort |
freezing-induced acidification of sea ice brine |
publisher |
Elsevier |
publishDate |
2024 |
url |
http://nora.nerc.ac.uk/id/eprint/537655/ https://www.sciencedirect.com/science/article/pii/S0048969724043420?via%3Dihub |
genre |
Sea ice |
genre_facet |
Sea ice |
op_relation |
Veselý, L.; Štůsek, R.; Mikula, O.; Yang, X. orcid:0000-0002-3838-9758 Heger, D. 2024 Freezing-induced acidification of sea ice brine. Science of the Total Environment, 946, 174194. 14, pp. https://doi.org/10.1016/j.scitotenv.2024.174194 <https://doi.org/10.1016/j.scitotenv.2024.174194> |
op_doi |
https://doi.org/10.1016/j.scitotenv.2024.174194 |
container_title |
Science of The Total Environment |
container_volume |
946 |
container_start_page |
174194 |
_version_ |
1811645061687934976 |