pCO2 of seawater is measured using a colorimetric reaction by injecting a pH-dependent indicator solution into a sample of seawater and measuring the absorbance of that mixture at two wavelengths. The ratio of absorbance between those two wavelengths is then used to calculate pCO2. Optical Absorbance Ratio at 434nm refers to the ratio of absorbance of the seawater sample with and without the pH indicator solution at a wavelength of 434 nm.
The following instrument classes include this data product:
- pCO2 Water (PCO2W)