A concentration jump at the beginning of transport with kinetic dissolution

[MichaelZ20]

After running the attached file of runoff formation at a dolomitic slope, I get at the graph a concentration jump at the beginning of the flow path.
How can I remove it?

[dlparkhurst]

Put an END statement after SOLUTION_SPREAD.

With your input file, the sequence of calculations is to run the initial solution calculation defined by SOLUTION_SPREAD, then a reaction calculation between solution 0, EQUILIBRIUM_PHASES 1, and KINETICS 1(in 120 steps), and finally, the TRANSPORT calculation. The reaction calculation is defined by default when a solution and another reaction (like EQUILIBRIUM_PHASES, EXCHANGE, KINETICS, REACTION_TEMPERATURE, and others) are defined within the same END-to-END block. If you put an END after SOLUTION_SPREAD, the default reaction is no longer defined because the reactions are not within the same block as the SOLUTION_SPREAD.

Note that the results of the reaction calculation for the solution 0 and equilibrium phase 1 are not SAVEd, so the original solution 0 and equilibrium_phase 1 are used in the TRANSPORT calculation. KINETICS is different in that the moles of kinetic reaction are continuously updated in the reaction calculation, and thus the TRANSPORT calculation in your original file may differ from the TRANSPORT calculation with the inserted END because the moles of kinetic reaction for cell 1 would be different.

[MichaelZ20]

David, thank you very much for your explanation!