Articles | Volume 22, issue 3
https://doi.org/10.5194/os-22-1609-2026
https://doi.org/10.5194/os-22-1609-2026
Technical note
 | 
21 May 2026
Technical note |  | 21 May 2026

Obtaining accurate, high-frequency and long-term seawater pH data by using coupled lab-on-chip and optode sensing technologies

Anthony J. Lucio, Dirk Koopmans, Martin Arundell, Socratis Loucaides, and Allison Schaap

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Cited articles

Aßmann, S., Frank, C., and Körtzinger, A.: Spectrophotometric high-precision seawater pH determination for use in underway measuring systems, Ocean Sci., 7, 597–607, https://doi.org/10.5194/os-7-597-2011, 2011. 
Bagshaw, E. A., Wadham, J. L., Tranter, M., Beaton, A. D., Hawkings, J. R., Lamarche-Gagnon, G., and Mowlem, M. C.: Measuring pH in low ionic strength glacial meltwaters using ion selective field effect transistor (ISFET) technology, Limnol. Oceanogr.-Meth., 19, 222–233, https://doi.org/10.1002/lom3.10416, 2021. 
Bresnahan, P. J., Martz, T. R., Takeshita, Y., Johnson, K. S., and LaShomb, M.: Best practices for autonomous measurement of seawater pH with the Honeywell Durafet, Methods in Oceanography, 9, 44–60, https://doi.org/10.1016/j.mio.2014.08.003, 2014. 
Bresnahan, P. J., Takeshita, Y., Wirth, T., Martz, T. R., Cyronak, T., Albright, R., Wolfe, K., Warren, J. K., and Mertz, K.: Autonomous in situ calibration of ion-sensitive field effect transistor pH sensors, Limnol. Oceanogr.-Meth., 19, 132–144, https://doi.org/10.1002/lom3.10410, 2021. 
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Overall, this work provides the community with guidelines on how to achieve accurate (e.g., difference ~0.02 relative to validation samples), rapid (e.g., <1 minute per measurement) and long-term (e.g., 6-month) pH measurements, while balancing power requirements, by combining two complementary pH sensing technologies. We present a data correction method to account for sensor signal drift and demonstrate this in a challenging (i.e., significant biofouling) shallow water field deployment.
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