Field pH Determinations in Glacial Melt Waters
Abstract Laboratory pH analyses of glacial melt waters are unrepresentative of in situ values, due primarily to CO 2 gas exchange between the sample and the atmosphere, and solute enrichment from chemical reaction with sediment and colloidal particles. A method is presented which enables field pH me...
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Cambridge University Press (CUP)
1984
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Online Access: | http://dx.doi.org/10.1017/s0022143000008546 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000008546 |
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crcambridgeupr:10.1017/s0022143000008546 2024-03-03T08:46:05+00:00 Field pH Determinations in Glacial Melt Waters Metcalf, Richard C. 1984 http://dx.doi.org/10.1017/s0022143000008546 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000008546 en eng Cambridge University Press (CUP) Journal of Glaciology volume 30, issue 104, page 106-111 ISSN 0022-1430 1727-5652 Earth-Surface Processes journal-article 1984 crcambridgeupr https://doi.org/10.1017/s0022143000008546 2024-02-08T08:40:23Z Abstract Laboratory pH analyses of glacial melt waters are unrepresentative of in situ values, due primarily to CO 2 gas exchange between the sample and the atmosphere, and solute enrichment from chemical reaction with sediment and colloidal particles. A method is presented which enables field pH measurements that are reproducible within ±0.04 pH units to be made in glacial melt waters, using commonly available digital pH meters with combination electrodes. During initial spring snow melt in May 1981 at Gornergletscher, Switzerland, melt waters in the proglacial stream leaving the glacier terminus were oversaturated with respect to atmospheric p (CO 2 ), and rapidly increased pH during CO 2 outgassing at in situ temperature and pressure. Summer ice melt from glaciers which are temperate in the ablation zone are usually undersaturated by about ten times with respect to atmospheric p (CO 2 ), and rapidly lower their pH values to achieve equilibrium upon encountering the atmosphere, as observed at Gornergletscher during July and August 1981. Gornergletscher summer proglacial stream waters, sometimes show pH increases from rock weathering, with the rate limited by the transfer rate of CO 2 across the air-water interface to drive the weathering reactions. Throughout the year, any water parcel at equilibrium with atmospheric CO 2 is generally at an equilibrium pH value, if filtration prohibits solute enrichment. For these reasons, laboratory pH measurements are unacceptable for quantitative studies of melt-water chemistry and should be discontinued. Article in Journal/Newspaper Journal of Glaciology Cambridge University Press Journal of Glaciology 30 104 106 111 |
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Cambridge University Press |
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crcambridgeupr |
language |
English |
topic |
Earth-Surface Processes |
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Earth-Surface Processes Metcalf, Richard C. Field pH Determinations in Glacial Melt Waters |
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Earth-Surface Processes |
description |
Abstract Laboratory pH analyses of glacial melt waters are unrepresentative of in situ values, due primarily to CO 2 gas exchange between the sample and the atmosphere, and solute enrichment from chemical reaction with sediment and colloidal particles. A method is presented which enables field pH measurements that are reproducible within ±0.04 pH units to be made in glacial melt waters, using commonly available digital pH meters with combination electrodes. During initial spring snow melt in May 1981 at Gornergletscher, Switzerland, melt waters in the proglacial stream leaving the glacier terminus were oversaturated with respect to atmospheric p (CO 2 ), and rapidly increased pH during CO 2 outgassing at in situ temperature and pressure. Summer ice melt from glaciers which are temperate in the ablation zone are usually undersaturated by about ten times with respect to atmospheric p (CO 2 ), and rapidly lower their pH values to achieve equilibrium upon encountering the atmosphere, as observed at Gornergletscher during July and August 1981. Gornergletscher summer proglacial stream waters, sometimes show pH increases from rock weathering, with the rate limited by the transfer rate of CO 2 across the air-water interface to drive the weathering reactions. Throughout the year, any water parcel at equilibrium with atmospheric CO 2 is generally at an equilibrium pH value, if filtration prohibits solute enrichment. For these reasons, laboratory pH measurements are unacceptable for quantitative studies of melt-water chemistry and should be discontinued. |
format |
Article in Journal/Newspaper |
author |
Metcalf, Richard C. |
author_facet |
Metcalf, Richard C. |
author_sort |
Metcalf, Richard C. |
title |
Field pH Determinations in Glacial Melt Waters |
title_short |
Field pH Determinations in Glacial Melt Waters |
title_full |
Field pH Determinations in Glacial Melt Waters |
title_fullStr |
Field pH Determinations in Glacial Melt Waters |
title_full_unstemmed |
Field pH Determinations in Glacial Melt Waters |
title_sort |
field ph determinations in glacial melt waters |
publisher |
Cambridge University Press (CUP) |
publishDate |
1984 |
url |
http://dx.doi.org/10.1017/s0022143000008546 https://www.cambridge.org/core/services/aop-cambridge-core/content/view/S0022143000008546 |
genre |
Journal of Glaciology |
genre_facet |
Journal of Glaciology |
op_source |
Journal of Glaciology volume 30, issue 104, page 106-111 ISSN 0022-1430 1727-5652 |
op_doi |
https://doi.org/10.1017/s0022143000008546 |
container_title |
Journal of Glaciology |
container_volume |
30 |
container_issue |
104 |
container_start_page |
106 |
op_container_end_page |
111 |
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1792501976555061248 |