Characterisation and deployment of an immobilised pH sensor spot towards surface ocean pH measurements
The oceans are a major sink for anthropogenic atmospheric carbon dioxide, and the uptake causes changes to the marine carbonate system and has wide ranging effects on flora and fauna. It is crucial to develop analytical systems that allow us to follow the increase in oceanic pCO2 and corresponding r...
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Online Access: | https://eprints.soton.ac.uk/384032/ https://eprints.soton.ac.uk/384032/1/1-s2.0-S0003267015011654-main.pdf |
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ftsouthampton:oai:eprints.soton.ac.uk:384032 2023-08-27T04:12:13+02:00 Characterisation and deployment of an immobilised pH sensor spot towards surface ocean pH measurements Clarke, Jennifer S. Achterberg, Eric P. Rérolle, Victoire M.C. Abi Kaed Bey, Samer Floquet, Cedric F.A. Mowlem, Matthew C. 2015-10-15 text https://eprints.soton.ac.uk/384032/ https://eprints.soton.ac.uk/384032/1/1-s2.0-S0003267015011654-main.pdf en English eng https://eprints.soton.ac.uk/384032/1/1-s2.0-S0003267015011654-main.pdf Clarke, Jennifer S., Achterberg, Eric P., Rérolle, Victoire M.C., Abi Kaed Bey, Samer, Floquet, Cedric F.A. and Mowlem, Matthew C. (2015) Characterisation and deployment of an immobilised pH sensor spot towards surface ocean pH measurements. Analytica Chimica Acta, 897, 69-80. (doi:10.1016/j.aca.2015.09.026 <http://dx.doi.org/10.1016/j.aca.2015.09.026>). cc_by_4 Article PeerReviewed 2015 ftsouthampton https://doi.org/10.1016/j.aca.2015.09.026 2023-08-03T22:21:20Z The oceans are a major sink for anthropogenic atmospheric carbon dioxide, and the uptake causes changes to the marine carbonate system and has wide ranging effects on flora and fauna. It is crucial to develop analytical systems that allow us to follow the increase in oceanic pCO2 and corresponding reduction in pH. Miniaturised sensor systems using immobilised fluorescence indicator spots are attractive for this purpose because of their simple design and low power requirements. The technology is increasingly used for oceanic dissolved oxygen measurements. We present a detailed method on the use of immobilised fluorescence indicator spots to determine pH in ocean waters across the pH range 7.6–8.2. We characterised temperature (?0.046 pH/°C from 5 to 25 °C) and salinity dependences (?0.01 pH/psu over 5–35), and performed a preliminary investigation into the influence of chlorophyll on the pH measurement. The apparent pKa of the sensor spots was 6.93 at 20 °C. A drift of 0.00014 R (ca. 0.0004 pH, at 25 °C, salinity 35) was observed over a 3 day period in a laboratory based drift experiment. We achieved a precision of 0.0074 pH units, and observed a drift of 0.06 pH units during a test deployment of 5 week duration in the Southern Ocean as an underway surface ocean sensor, which was corrected for using certified reference materials. The temperature and salinity dependences were accounted for with the algorithm, R=0.00034?0.17·pH+0.15·S2+0.0067·T?0.0084·S·1.075R=0.00034?0.17·pH+0.15·S2+0.0067·T?0.0084·S·1.075. This study provides a first step towards a pH optode system suitable for autonomous deployment. The use of a short duration low power illumination (LED current 0.2 mA, 5 ?s illumination time) improved the lifetime and precision of the spot. Further improvements to the pH indicator spot operations include regular application of certified reference materials for drift correction and cross-calibration against a spectrophotometric pH system. Desirable future developments should involve novel fluorescence spots with ... Article in Journal/Newspaper Southern Ocean University of Southampton: e-Prints Soton Southern Ocean Analytica Chimica Acta 897 69 80 |
institution |
Open Polar |
collection |
University of Southampton: e-Prints Soton |
op_collection_id |
ftsouthampton |
language |
English |
description |
The oceans are a major sink for anthropogenic atmospheric carbon dioxide, and the uptake causes changes to the marine carbonate system and has wide ranging effects on flora and fauna. It is crucial to develop analytical systems that allow us to follow the increase in oceanic pCO2 and corresponding reduction in pH. Miniaturised sensor systems using immobilised fluorescence indicator spots are attractive for this purpose because of their simple design and low power requirements. The technology is increasingly used for oceanic dissolved oxygen measurements. We present a detailed method on the use of immobilised fluorescence indicator spots to determine pH in ocean waters across the pH range 7.6–8.2. We characterised temperature (?0.046 pH/°C from 5 to 25 °C) and salinity dependences (?0.01 pH/psu over 5–35), and performed a preliminary investigation into the influence of chlorophyll on the pH measurement. The apparent pKa of the sensor spots was 6.93 at 20 °C. A drift of 0.00014 R (ca. 0.0004 pH, at 25 °C, salinity 35) was observed over a 3 day period in a laboratory based drift experiment. We achieved a precision of 0.0074 pH units, and observed a drift of 0.06 pH units during a test deployment of 5 week duration in the Southern Ocean as an underway surface ocean sensor, which was corrected for using certified reference materials. The temperature and salinity dependences were accounted for with the algorithm, R=0.00034?0.17·pH+0.15·S2+0.0067·T?0.0084·S·1.075R=0.00034?0.17·pH+0.15·S2+0.0067·T?0.0084·S·1.075. This study provides a first step towards a pH optode system suitable for autonomous deployment. The use of a short duration low power illumination (LED current 0.2 mA, 5 ?s illumination time) improved the lifetime and precision of the spot. Further improvements to the pH indicator spot operations include regular application of certified reference materials for drift correction and cross-calibration against a spectrophotometric pH system. Desirable future developments should involve novel fluorescence spots with ... |
format |
Article in Journal/Newspaper |
author |
Clarke, Jennifer S. Achterberg, Eric P. Rérolle, Victoire M.C. Abi Kaed Bey, Samer Floquet, Cedric F.A. Mowlem, Matthew C. |
spellingShingle |
Clarke, Jennifer S. Achterberg, Eric P. Rérolle, Victoire M.C. Abi Kaed Bey, Samer Floquet, Cedric F.A. Mowlem, Matthew C. Characterisation and deployment of an immobilised pH sensor spot towards surface ocean pH measurements |
author_facet |
Clarke, Jennifer S. Achterberg, Eric P. Rérolle, Victoire M.C. Abi Kaed Bey, Samer Floquet, Cedric F.A. Mowlem, Matthew C. |
author_sort |
Clarke, Jennifer S. |
title |
Characterisation and deployment of an immobilised pH sensor spot towards surface ocean pH measurements |
title_short |
Characterisation and deployment of an immobilised pH sensor spot towards surface ocean pH measurements |
title_full |
Characterisation and deployment of an immobilised pH sensor spot towards surface ocean pH measurements |
title_fullStr |
Characterisation and deployment of an immobilised pH sensor spot towards surface ocean pH measurements |
title_full_unstemmed |
Characterisation and deployment of an immobilised pH sensor spot towards surface ocean pH measurements |
title_sort |
characterisation and deployment of an immobilised ph sensor spot towards surface ocean ph measurements |
publishDate |
2015 |
url |
https://eprints.soton.ac.uk/384032/ https://eprints.soton.ac.uk/384032/1/1-s2.0-S0003267015011654-main.pdf |
geographic |
Southern Ocean |
geographic_facet |
Southern Ocean |
genre |
Southern Ocean |
genre_facet |
Southern Ocean |
op_relation |
https://eprints.soton.ac.uk/384032/1/1-s2.0-S0003267015011654-main.pdf Clarke, Jennifer S., Achterberg, Eric P., Rérolle, Victoire M.C., Abi Kaed Bey, Samer, Floquet, Cedric F.A. and Mowlem, Matthew C. (2015) Characterisation and deployment of an immobilised pH sensor spot towards surface ocean pH measurements. Analytica Chimica Acta, 897, 69-80. (doi:10.1016/j.aca.2015.09.026 <http://dx.doi.org/10.1016/j.aca.2015.09.026>). |
op_rights |
cc_by_4 |
op_doi |
https://doi.org/10.1016/j.aca.2015.09.026 |
container_title |
Analytica Chimica Acta |
container_volume |
897 |
container_start_page |
69 |
op_container_end_page |
80 |
_version_ |
1775356110195130368 |