Re: Aqueous species oscillations within transport calculation

["Fiona Hunter" <Fiona.Hunter@xxxxxxxxxxxxxxxxxx>]

Dear David
I've been running your beta test Phreeqc code as you suggested.  This
works much better...  I've attached an input file, a section of the
output file and a selected output file (k21, k21.out and k21.sel), for
advection of alkaline solution through the Boom Clay column.  I've
removed Pyrite  and Fe from the calculation to remove any redox changes
for Fe, increased the water mass to 1kg and increased the mineral
proportions accordingly.  For each kinetic phase, I've increased the
tolerance to 1e-5.  I've used the Llnl.dat database again.

However, my main concern is the selected output file.  I want to
monitor cell 32,  (i.e. the effluent coming out of the end of the
colum), this should initially be at around pH 8, increasing slowly as
the alkaline fluid advects through.  However, you can see from the
selected output file that the pH is initially recorded at pH 8.8, but
then drops to zero for several time steps, before returning to the
correct value of around pH 9, then drops to zero and so on. For example,
during transport step 9, cells 1-9 are at pH~13, but cells 10-32 at
pH=0; the pE also oscillates quite a lot over this interval.

I assume this is a problem with the new version of phreeqc, or is can
you see anything in my input file?  

Thanks again for your comprehensive reply this morning.  That has been
really useful!

Best regards
Fiona Hunter

~~~~~~~~~~~~~~~~~~~~~~~~~~
Dr Fiona Hunter    MRSC
Serco Assurance
Building 150
Harwell International Business Centre, Didcot
Oxfordshire OX11 0QJ 
Telephone: +44 (0)1635 280418
Facsimile: +44 (0)1635 280305
~~~~~~~~~~~~~~~~~~~~~~~~~~





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Attachment: k21.sel
Description: Binary data

Attachment: k21
Description: Binary data

Attachment: k21.out
Description: Binary data