Seawater pH sensors measure the total concentration of hydrogen ions in a solution. The OOI pH sensor (Sunburst SAMI-pH) measures pH (total hydrogen scale) in the marine pH range of 7-9. For tens of millions of years, Earth’s oceans have maintained a relatively stable pH level. However, since the beginning of the industrial revolution in the 1800s, the surface ocean pH is estimated to have decreased from approximately 8.25 to 8.14. While this may seem to be a very small change in pH, it represents about a 30% increase in H+ ion concentration, and is already impacting marine organisms and the shellfish industry.
This instrument measures the following data products. Select a data product's name to learn more.
- PHSEN Thermistor Temperature (ABSTHRM)
- Optical Absorbance Signal Intensity at 434nm (PH434SI)
- Optical Absorbance Signal Intensity at 578nm (PH578SI)
- pH (PHWATER) DPS
The algorithm code used to generate this instrument's data products is also available in the ion-functions GitHub repository.
Instrument Models & Deployed Locations
The OOI includes the following instrument makes and models for this instrument type. Follow the links below to find out where in the OOI this instrument has been deployed. You'll also find quick links for each instrument to Data portal, where you can plot and access data.
Primary Science Discipline