A rapid, precise potentiometric determination of total alkalinity in seawater by a newly developed flow-through analyzer designed for coastal regions

Abstract

A flow-through analyzer has been developed for the rapid, potentiometric determination of total alkalinity (TA) in seawater in order to capture large temporal and spatial variations of the CO 2 system in coastal zones, where the carbon cycle is still not well understood despite the potential large contribution of such areas to the global carbon cycle. This analyzer requires small amounts of seawater (3 ml min −1), and has realized continuous measurements of TA with a response time of 4–5 min, with long-term precision of about 0.1% (ca. 2 μmol kg −1), and accuracy of a similar level over a range of TA (more than 200 μmol kg −1) when appropriate standard solutions are used. This analyzer is fully automated and can achieve stable measurements (within 0.15%; 3 μmol kg −1) over 1–2 days without regular recalibration for drift, which will enable us to carry out continuous, in situ measurements of TA in coastal waters.