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Re: kinetic problem

Dear Dr.Parkhurst,
Here is another problem we met. The problem setup is:
100 meter 1d domain with 1 meter cells
5 m/ yr flow velocity
The aquifer initially have 0.8 mol/L K-fedlspar or 2% vol. The other 98% is quartz. The aquifer has 25% porosity
No initial values, but can precipitate gibbsite, kaolinite, and muscovite (K-mica)
The phase definition is taken from example 6 of phreeqc manual.

               Al(OH)3 + 3 H+ = Al+3 + 3 H2O
               log_k          8.049

               Al2Si2O5(OH)4 + 6 H+ = H2O + 2 H4SiO4 + 2 Al+3
               log_k          5.708

               KAl3Si3O10(OH)2 + 10 H+ = 3 Al+3 + 3 H4SiO4 + K+
               log_k          12.970

               KAlSi3O8 + 4 H2O + 4 H+ = Al+3 + 3 H4SiO4 + K+
               log_k          0.875

The incoming solution has the following compositions

       units      mol/kgw
	  temp	 25
	  PH         8.1
       Al         1.e-13
       K          2.74e-5
       Si         9.25e-5
	  Cl         7.62e-5
	  Na         1.509e-4
	Ca         8.843e-4
	  Mg         1.09e-4

The K-feldspar dissolution rate is 10^(-12.5) mol/sec/sq meter.

The scenario is kaolinite has slow rate (K-feldspar rate /100),
muscovite = K-feldspar rate/10000

The problem we got is: If there is no transport part in the simulation, it worked well.After adding one dimensional transport, the simulation can't converge.It warned that element Al and K has negative concentration in solution. Then it

stopped after bad RK step>500.

We attached the input files of transport and no-transport, so you can compare them.

Thank you very much.

Sincerely yours,
Hui Tan

Attachment: transport02.pqi
Description: Binary data

Attachment: Blackmesa-04-8.pqi
Description: Binary data

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