ADVECTION only RT model with varying inflow solution compositions

[brathi]

Dear all,

I am trying to create a RT model with ADVECTION-only scheme using just 1 cell but the challenge is to introduce varying solution compositions at different times.
I am not sure how to approach this in PhreeqC but this is my vague idea:

A typical RT model could look like this:

SOLUTION 0   #incoming solution
SOLUTION 1   #background solution in cell 1
END

SURFACE 1   #background surface in cell 1
END

KINETICS 1   #background kinetic reactant in cell 1
END

ADVECTION
-cells    1
-shifts   1    # total shifts required are 240
-time_steps   720 second
- .... other entries

SELECTED_OUTPUT
-file    rt_adv.sel

USER_PUNCH
-.....
END

Could someone suggest how I can introduce SOLUTION 2 (which is different to SOLUTION 0 above) for 2 more shifts, followed by SOLUTION 3 for another 5 shifts and so on... and have the results appended in the selected_output file.

Thanks in advance for your help.