Program > Browse abstracts by speaker > Stefansson Andri

Low-density hydrothermal fluids play a fundamental role in the chemical evolution of the Earth's crust, spanning environments from volcanic systems to low-temperature settings. These aqueous fluids exist as gas-like vapor and can contain a variety of elements; however, their solubility and molecular chemistry remain poorly understood. Here, we present the results of solubility measurements of various minerals including salts, sulfates and oxides at temperatures of 400-800°C and pressures of 25-300 bar. The experiments were conducted using state-of-the-art U-tube reactor systems that enable fast and reliable solubility measurements across a wide range of temperatures and pressures. The experimental results were analyzed assuming complete ion-pairing of the molecular species in the vapor phase followed by hydration (H2O addition) of such neutral gas moieties with increasing water pressure. As pressure increases, the hydration number was found to increase, while the stability of smaller solute-water clusters increases with increasing temperature. Based on the experimental results and data processing, thermodynamic values (ΔGr, ΔHr, ΔSr, ΔCp,r) have been obtained for the solubility of the hydrated neutral gas compounds as a function of temperature and pressure. These values are subsequently utilized to model solute transport behavior in upper crustal environment. The project has received funding from the European Union's Horizon 2020 under Grant Agreement #818169 (GeoPro).