High-resolution Measurement of Seawater Carbonate

Since the start of the Industrial Revolution, the chemistry of seawater has been significantly changed by the absorption of fossil fuel CO2 (carbon dioxide) from the atmosphere. When CO2 is absorbed by seawater, it sets off a series of chemical reactions: carbonic acid (H2CO3) is formed, which then dissociates to H3O+ and bicarbonate (HCO3-). The H3O+ reacts with carbonate ions (CO32-), forming additional bicarbonate. The overall reaction is the production H3O+ and the consumption of carbonate, a process referred to as ocean acidification.While pH and local variability is relatively straightforward to measure in the field, carbonate concentration is difficult to measure directly. In order to address this limitation, our laboratory has developed a range of hand-held sensors to measure fine-scale carbonate changes in the field.