Characterization of Air-Sea Gas Exchange Processes and Dissolved Gas/Ice Interactions Using Noble Gases

In order to constrain the processes controlling the cycles of biogeochemically important gases such as O2 and CO2, and thereby infer rates of biological activity in the upper ocean or the uptake of greenhouse gases, the noble gases are used to characterize and quantify the physical processes affecting the dissolved gases. The processes of vertical mixing, gas exchange, air injection, and radiative heating are investigated using a 2 year time-series of the noble gases, temperature, and meteorological data from Station S near Bermuda, coupled with a 1-dimensional upper ocean mixing model to stimulate the physical processes in the upper ocean. In order to obtain a high-frequency time-series of the noble gases to better parameterize the gas flux from bubbles, a moorable, sequential noble gas sampler was developed. Dissolved gas concentrations can be significantly modified by ice formation and melting, and due to the solubility of He and Ne in ice, the noble gases are shown to be unique tracers of these interactions. A three-phase equilibrium partitioning model was constructed to quantify these interactions in perennially ice-covered Lake Fryxell. Preliminary surveys in oceanic environments indicate that the noble gases may provide useful and unique information about interactions between water and ice.