2022ApJ...926...72L

Planets with a few percent water by mass may have a high-pressure ice mantle separating the rocky interior from both the ocean and atmosphere. Here we examine whether the partitioning of O₂ into high-pressure ice can constrain the atmospheric abundance of O₂ produced by water photolysis in the atmosphere. We find that the partition coefficient of dissolved O₂ between high-pressure ice and liquid water is about unity. We show that the solubility of O₂ in high-pressure water ice yields an upper value for the atmospheric abundance of O₂ that depends on the ocean surface temperature. The atmospheric pressure of O₂ has a maximum of approximately 3000 bars. The latter drops to a few hundred bars as the surface temperature of the ocean approaches supercritical conditions.