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## Summary

The article discusses the process of ebullition (bubbling) in the simulation of aqueous methane (CH4) concentrations in soil levels. The key points are:

### Calculating Equilibrium Gaseous Partial Pressure
- The simulated aqueous CH4 concentration is used to estimate the expected equilibrium gaseous partial pressure (Ce), which is a function of temperature and depth below the water table.
- This is done by first estimating the Henry's law partitioning coefficient (kh^C) using the equations provided.
- The local pressure is calculated as the sum of ambient pressure, water pressure down to the local depth, and pressure from surface ponding.

### Ebullition Threshold and Bubble Composition
- When the CH4 partial pressure exceeds 15% of the local pressure, bubbling occurs to remove CH4 to below this value.
- The fraction of CH4 in the bubbles is taken as 57%.
- Bubbles are immediately added to the surface flux for saturated columns, and placed immediately above the water table interface in unsaturated columns.

The article provides the detailed equations and references used in the simulation of aqueous CH4 concentrations and the resulting ebullition process.