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Questions concerning Phreeqc



Hello!

I am using the Phreeqc interactive alpha version 2.4.2 and I have some
problems with the transport calculations. I know there must be something
wrong with the way I defined the input file. I hope I do not waste your time
and you can give me some assistance in this problem ?!

I am trying to model a 1D pure diffusive transport through a bentonite
column (no advection, no dispersion). My intention is first to calculate the
bentonite porewater including cation exchange, surface complexation,
equilibrium phases, and reaction. Next, the resulting porewater and changed
exchanger, surface, and phases in equilibrium with the porewater represent
the volume of the column cells and Sr is injected at one column end as
solution 0. In this way  I expect to see how Sr diffuses through the column,
how it is retarded by the exchanger surface and how the exchanger, the
surface, the amount of phases and the porewater composition change with
time.

My problem now is that 
1)   Sr is not transported into the cells. I tried to refine the grid, to
increase the time step and to increase the diffusion coefficent, but either
the calculation takes too long and finds no end or the results show no Sr in
the cells.
2)   the porewater should be in equilibrium with the defined reactions and
as long as no Sr is entering the cells the porewater composition should stay
constant. But I fear that the reactions are repeated with every time step
(e.g. the Na and Cl are changing continously). How can I define, that the
reactions are in equilibrium with the porewater as long as no influence from
outside takes place?

I attached the input file to this mail and I hope you have an idea about
what I did wrong. 

Thank you very much in advance and best regards,

Nicole Klennert




---------------------------------------------------------------------------
Dipl.-Geol. Nicole Klennert
Federal Institute for Geosciences and Natural Resources
Stilleweg 2
30655 Hannover
Germany

+49-(0)511-643-0 		(switchboard)
+49-(0)511-643-3719 	(direct)
+49-(0)511-643-3694 	(fax)

nicole.klennert@xxxxxx
www.bgr.de



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