Solute Time Variable Boundary Condition

The HP1 code incorporates modules simulating
(1) transient water flow in variably-saturated media,
(2) transport of multiple components, and
(3) mixed equilibrium/kinetic geochemical reactions.
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Solute Time Variable Boundary Condition

Post by aliko » Wed Jan 03, 2018 9:28 am

I am wondering how its possible to apply time variable boundary condition which includes X mol/kgw of an insoluble mineral in water. For more clarification lets consider I have a mineral based fertilizer which is roughly insoluble (Log_k=-50) and at sowing day of planting it is applied. Firs I need to define this mineral in PHASES in phreeqc with its dissolution reaction ( Mineral(s) + nH+ = ...) and then when I equilibriate the incoming solution composition 3000=1 with this phase It does not apply during simulation and after several days an error regarding Activity of water does not converge appear.

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Re: Solute Time Variable Boundary Condition

Post by diederik » Wed Jan 10, 2018 6:39 am


Minerals as such can not be transported in HP. The components defined within the PHASES datablock are all treated as immobile phases. However, you can treat the insoluble mineral as an aqueous component and then it will be transported with the advection-dispersion equation. You can add then kinetic reactions to mimic slow dissolution, other geochemical reactions or different transport behavior (related to transport of colloids).

Note that I do not fully understand your question as an insoluble aqueous particle / mineral is something inert in your system - or is it involve in any other geochemical reaction?


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