Program

Accurate characterization of carbonate chemistry is critical to understanding the changing chemistry of the ocean and the impacts of ocean acidification. Extensive efforts have been devoted to improving methodologies and instruments for determination of carbon parameters in seawater. Measurements of pH based on spectrophotometric principles have long been used in the field of chemistry. The techniques of pH determination were closely analogous to those that were recently developed for direct carbonate measurements. These techniques are fast, methodologically simple, suitable for analyses using autonomous instrumentation. Here we describe the development and testing of a new indicator-based sensor that provides pH_T values for seawater with repeatability better than 0.001. This pH_T sensor can be easily adapted into a carbonate sensor with minor modifications. The main components include a modular injection pump, a custom-designed flow cell, spectrophotometric detection system and control electronics. By applying these sensors in autonomous underway systems, we will be able to detect seawater acidification as well as obtain new information on ocean carbon cycles.