Development of a portable carbon system sensor for ocean acidification research

Lowering of seawater pH due to increased anthropogenic carbon dioxide, known as ocean acidification (OA), has garnered attention from scientists and lawmakers around the globe. A great deal of research involves projecting how OA will affect aquatic organisms and systems in the future. It is generally recognized that many of the laboratories engaged in OA research do not possess the facilities or expertise necessary to measure carbon system parameters at the precision required to produce reliable, actionable results. To address this deficiency, researchers and engineers from SRI and USF are undertaking a major advancement in carbon-system sensors. Drawing on our experience in developing and deploying our multi-parameter inorganic carbon analyzer (MICA) instruments, we are building a new system (MICA III) that is easy to use and requires virtually no supporting infrastructure. Advances in commercial technology and refinement of our methods enable us to dramatically reduce the size and cost of MICA instrumentation. MICA III measures three parameters: pH, dissolved inorganic carbon (DIC), and total alkalinity (TA). Our instrument includes innovative designs for temperature compensation and total alkalinity measurements, and uses an embedded display/user interface to produce a truly portable (about the size of a large briefcase) sensor for studies of OA and the CO
₂
system. Our goal is to develop an instrument that can be easily deployed by both chemists and non-chemists to produce carbon system data fully consistent with best-practice protocols. This article discusses overall objectives, highlights key design elements, and presents results from initial hardware evaluations.