The most lasting contributions of geochemistry to broader science in the 20th century are: (i) the establishment of radiogenic age dating; (ii) the codification of thermodynamic data to reach geochemical temperatures and pressures, and (iii) the systematics of light stable-isotope fractionations. Here I discuss Dave Wesolowskis contributions to (ii), our codification of solution thermodynamics and extension to geochemical conditions. Several thermodynamic models for these extrapolations now exist, but perhaps the most commonly used is the HKF formalism, which allows equilibrium constants and solute activities to be calculated to 1000oC and 0.5GPa for aqueous solutions containing a wide array of common solutes, including biomolecules, and rock-forming minerals. Recently the limits of the HKF model were extended to 5.0 GPa and 1200oC via computational estimation of the dielectric constant of water to extreme conditions. These predictions outstrip the experimental data. Dave Wesolowski spent much of his career collecting data to complement and improve these thermodynamic models. In this presentation I review some of these accomplishments. These include the measurement of oxide mineral solubilities (particularly interesting for me are the aluminum (hydr)oxide phases) and measurement of the rates of dissolution of gibbsite with unparalleled precision using a high-temperature hydrogen electrode. He accomplished extraordinarily difficult measurements of ionization equilibria, complexation reactions and mass-transfer of material in hydrothermal settings. If Dave Wesolowski's goal was the make measurements in his life that would be cited in a hundred years, he certainly succeeded.

Not to be soon revised--Dave Wesolowski's accomplishments in understanding hydrothermal chemistry

255th National Meeting (2018)

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