pH

The sensor measures pH (total concentration of hydrogen ions) in the marine environments spanning the Cabled Array. For tens of millions of years, Earth's oceans have maintained a relatively stable pH level.  Instruments on the Cabled Array are pH SAMI sensors provided by Sunburst.

Since the beginning of the industrial revolution (1800s), however, 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% in H+ ion concentration and already is impacting marine organisms and, in particular, the shellfish industry.

Cabled Array pH sensors, that complement the pCO₂ measurements, are installed on Shallow Profiler Mooring profiling science pods and on the static Platform Interface Assemblies at Axial Base, the Offshore site, and at Slope Base. They are also a component of the Benthic Experiment Platform on the Oregon Offshore and Shelf sites.