| This study used measurements of dissolved neon, nitrogen, argon, and oxygen in the ocean to quantify the rates of upper ocean processes, focusing particularly on bubble-mediated gas exchange and biological O2 production. The effects of mixing, diffusive gas exchange and temperature change on the gases were also explored. The different physical properties of these gases cause them to respond differently to processes of interest, which allows the use of the gases as tracers. I began the project by developing a precise and accurate method to measure dissolved Ne using isotope dilution quadrupole mass spectrometry. Solubility experiments in the laboratory allowed me to define the equilibrium concentrations of Ne, N2 and Ar at a range of temperatures and salinities. At three locations around the globe, I found that all three gases were supersaturated in the surface, but that the gases deviated from each other at depth. Using a quasi-steady-state model, I showed that gas exchange by both diffusive and bubble-mediated mechanisms and temperature change were the main controls on gas saturations in the ocean. Finally, I collected a near-monthly time-series of Ne, N2, Ar, and O2 at station ALOHA over one annual cycle. Using a Price-Weller-Pinkel dynamic mixed layer model, I was able to constrain the rates of bubble-mediated gas exchange at the surface, but not the rate of mixing at the base of the euphotic zone. I also showed that the injection and exchange bubble mechanisms contribute fairly equally to the total flux of O2 through bubbles. The largest remaining errors in determining biological O2 production by gas mass balance are now uncertainties in the diffusive gas exchange parameterization and in cross-isopycnal mixing. |
