Autonomous pH and pCO₂ measurements in marine environments

The SAMI-C0₂ and SAMI-pH instruments demonstrate the power of using pH and Ar data to quantify the entire carbonate system. Shipboard systems are routinely used to measure pCO₂, pH, DIC and AT. The SAMI-C0 ₂ and SAMI-pH are both colorimetric, reagent-based sensors and have very similar designs. Both use a solenoid pump and a solenoid valve for fluid control. The solutions are pumped to a fiber optic flow cell where absorbance measurements are made. While the original SAMIs have made significant progress in autonomous pH and CO₂ sensing, five years of research and development has culminated in the SAMI2, which features the same data-collection capabilities in a smaller package that consumes less power and is easier to use. The ability of the SAMI instruments to operate autonomously for long time periods allows oceanographers and marine biologists to study the effects of increasing C0₂.