Re-envisioning Carbon Dioxide Reference Materials in Seawater
by Dr. Regina Easley, Dr. Jason Waters, Dr. Michael Fong, Dr. Kimberly Harris, Dr. Rebecca Kraft, Mrs./Ms. Jennifer Carney, Dr. Michael Winchester, Dr. Elizabeth Jewett, Dr. Andrew Dickson

Abstract

The ocean is a sink for approximately a fourth of the excess carbon dioxide released into the atmosphere by human activities, causing changes in ocean chemistry and thus pH (ocean acidification). Ensuring a sustained and adequate supply of reference materials for monitoring the carbon dioxide system in seawater is a critical global need.  For the past 30 years, these reference materials have been value-assigned and provided by a sole supplier. With burgeoning demand for these materials and supply limitations stressed by the global COVID-19 pandemic, it is crucial to expand upon knowledge gained over the past few decades and work to create a robust network to supply and certify these materials. In this presentation, we will highlight some of the current challenges with the existing production model and will focus our discussion on plans to build the capacity to certify seawater reference materials for total dissolved inorganic carbon and total alkalinity at the National Institute of Standards and Technology (NIST). Additionally, we will explore ways in which NIST’s measurement services and partnerships can address future seawater CO2 measurement needs, expanding the reference material program to support additional measurands such as δ13C,14C, and pH. This new production model will leverage the measurement capabilities of NIST and other national metrology institutes in the areas of electroanalytical chemistry, stable isotope measurements, and gas metrology to provide metrological traceability to seawater CO2 reference materials. Furthermore, we envision integrating the reference material program into the existing metrological infrastructure, such as participation in key comparisons associated with the International Committee of Weights and Measures (CIPM) and establishment of a quality assurance program for the user community and/or secondary reference material producers, to ensure long-term quality. These efforts will not only support the existing oceanographic research community but also enhance efforts to expand support for monitoring carbon dioxide in coastal regions and to quantify the effectiveness of ocean carbon dioxide removal technologies.