Figure 5--Profiles of fluid pressure, gas saturation, and gas solubilization in a hydrostatic basin around a gas pool. The rapid change in pressure gradients induces greater solubilization of gas at the top of the reservoir, a larger diffusive flux, and a rapid desolubilization immediately above. The macroscopic image is a flux of leakage of a gas phase, when a closer view shows a very short distance of solubilization/diffusion of gas molecules in water, surrounded by buoyant flux of a gas phase. The consequence is a global chemical and isotopic fractionation.