Abstract
A high‐accuracy, batch‐equilibration, static‐headspace technique for the determination of the fugacity of CO 2 ( f CO 2 ) in discrete water samples is described. The technique was designed for monitoring small changes of CO 2 in the ocean and has accuracy and precision ( 2 and C T , is comparable to or better than is generally attained using potentiometric titration. Compared with C T and total alkalinity measurements, the small sample volume and rapid analysis time makes it practical to perform analysis of multiple replicates in order to improve confidence in the result. The method is readily applicable to experimental studies such as incubations as well as to time‐series measurements of in situ biological metabolism. Because the analysis employsgas chromatography, the technique can be acapted to measure simultaneously a suite of gases dissolved in seawater.