Conceptual Models > Incorporation PHREEQC in programming languages

Question about RM_SetComponentH2O


Dear all,

I am coupling a transport model with PhreeqcRM. However, I am confused about RM_SetComponentH2O in PhreeqcRM. In the transport model, water is reflected by pressure, whereas the concentration of water is needed when enabling RM_SetComponentH2O. Does anyone know how to deal with them when doing the coupling?
Thanks for your help in advance.

Best regards,

To use PhreeqcRM, you must provide to the reaction module either (1) the total concentrations of H and O, including H and O in water [SetComponentH2O(false)], or (2) the concentration of liquid H2O, the concentration of non-water H ("excess H"), and the concentration of non-water O ("excess O") [SetComponentH2O(true)]. By experience, either choice seems to work. The reason for option 2 is that the excess quantities tend to be several orders of magnitude smaller than the total H an O, but accurate values of total H and O are needed to calculate pH and pe. It was reasoned that numerical errors in transporting the total H and total O could lead to inaccurate pH and pe, whereas transporting the excess quantities would be more accurate.

Usually, the concentrations [either choice (1) or (2)] are transported in the same way as other element concentrations.

Concentration options are mg/L, mol/L, or mass fraction (SetUnitsSolution).

Total moles of each element in a cell (used to define the solution in a cell in PhreeqcRM) depends on the concentrations of the elements plus the representative volume, porosity, and saturation of the cell.


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