AN 14 - Stable Isotope Ratio Measurement of Dissolved Inorganic Carbon (DIC)

There is an established need and methodology to measure dissolved inorganic carbon (carbonate and bicarbonate) concentrations in aqueous samples¹. Carbon/water cycle studies use this technique to aid in assessment of the capture/storage capacity of seawater and its role in stabilizing atmospheric CO₂ levels. Another such application is monitoring the performance of man-made sequestration projects where captured CO₂ is stored in deep saline aquifers. A powerful additional metric that has been underexploited is the stable isotope ratio of the DIC i.e. δ¹³C. Since different sources of CO₂, from plant respiration to fossil fuel combustion, have a characteristic δ¹³C value, measuring δ¹³C can provide important sourcing/tracing information about the origins of the DIC found in samples.