OSD Ocean Science Discussions OSD Ocean Sci. Discuss. 1812-0822 Göttingen, Germany 10.5194/os-2021-126 Technical Note: Calibration-Free pH Sensing of Ocean and Estuarine Waters Miranda Mugica Monica https://orcid.org/0000-0002-9116-8233 1 Day Christina 1 McHale Brandon 1 McGuinness Kay Louis 1 Lee Gareth 2 Pickup Daisy https://orcid.org/0000-0003-0003-7607 2 Lawrence Nathan Scott 1 ANB Sensors Ltd., 4 Penn Farm, Haslingfield Cambridge, CB23 1JZ, UK School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK 24 01 2022 2022 1 15 Copyright: © 2022 Monica Miranda Mugica et al. 2022 This work is licensed under the Creative Commons Attribution 4.0 International License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/4.0/ This article is available from https://os.copernicus.org/preprints/os-2021-126/ The full text article is available as a PDF file from https://os.copernicus.org/preprints/os-2021-126/os-2021-126.pdf

<p>An electrochemical based, all solid-state, calibration-free pH sensor is presented. The sensor is targeted for monitoring the pH of ocean and estuarine environments covering a salinity range from 10&ndash;35 ppt without the need for additional salinity measurements. The sensor performance is demonstrated in both laboratory and field conditions. The field tests were conducted in an estuarine environment close to Oban in Scotland where the sensor was deployed for a period of three days. The sensor was validated against a sampled solution and tested alongside a glass pH sensor. The data highlighted the efficiency of the sensor to monitor the tidal variations of pH in the estuarine environment.</p>

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