Extending Noble Gas Solubilities in Water to Higher Temperatures for Environmental Application

Noble gas concentrations in natural waters are widely used todetermine ambient temperature conditions during the last intensive contact withthe atmosphere (equilibration). Such applications require accurate solubilityfunctions, which so far are available only for the common environmentaltemperature range between (0 and 35)degrees C. Nonetheless, environmental scenariosthat generate higher surface-water temperatures (such as volcanism) exist. Previoussolubility measurements beyond similar to 35 degrees C are sparse or outdated and weredetermined through equilibration of water with pure noble gases. This canpotentially render them not suitable for environmental applications whereequilibration with atmospheric air is considered. We therefore conducted new measurements for the solubilities of helium, neon,argon, krypton, and xenon in deionized water equilibrated with atmospheric air at similar to 1 bar for temperatures ranging from (25 to 80)degrees C. These measurements were combined with data from the literature that were obtained in a similar manner andfitted with acommonly used function to determine new noble gas solubility functions valid from (0 to 80)degrees C. We estimate relative standarduncertainties with a 0.99 level of confidence between 0.015 and 0.030 for the new functions, which are thus suitable for theinvestigation of environmental high-temperature equilibration scenarios. For temperatures beyond 35 degrees C, the new functions deviate significantly from previous studies.