Spectrophotometric determination of bicarbonate dissociation constants (K2) for freshwater, estuarine, and marine waters over a wide range of temperatures

This dataset presents the first spectrophotometric data of K2 at estuarine conditions (0≤Sp≤20; where Sp is practical salinity) and over a broad range of temperatures (275.15≤T≤308.15 K; where T is temperature in Kelvin). The spectrophotometric data from Schockman and Byrne (2021) and Schockman et al. (2024) were combined with the low-salinity data. This dataset was used to produce a set of pK2 (i.e., –log K2) values for the salinity range 0≤Sp≤41 and temperature range 275.15≤T≤308.15 K. The resulting set of pK2 values presented in the dataset was fitted as a function of SP and T to obtain a new pK2 parameterization on the total pH scale (Martín-Mayor et al., in review).