Re: transport modeling question

["David L Parkhurst" <dlpark@xxxxxxxx>]

PHREEQC can do 1D transport calculations considering only diffusion.
However, all species have the same diffusion coefficient. I don't know if
this is a problem for you. If not, you should be able to set up a
simulation. You need to use the TRANSPORT data block, but you also need
SOLUTION and possibly other data blocks to describe the initial conditions
for the column. In TRANSPORT, you need to set "-flow_direction
diffusion_only" and specify a diffusion coefficient with "
-diffusion_coefficient".

David




David Parkhurst (dlpark@xxxxxxxx)
U.S. Geological Survey
Box 25046, MS 413
Denver Federal Center
Denver, CO 80225


                                                                                                                          
                      "Vicky Peacey"                                                                                      
                      <vpeacey@xxxxxx>         To:      "David L Parkhurst" <dlpark@xxxxxxxx>                             
                                               cc:                                                                        
In-Reply-To: <001901c16949$b4490d20$d5de6481@xxxxxxxxxxxx>
                      11/09/01 11:09           Subject: transport modeling question                                       
                      AM                                                                                                  
                                                                                                                          
                                                                                                                          



Dear Mr.Parkhurst,

Is it possible to do diffusion modeling using PHREEQC? I've tried using
POLLUTE, but it doesn't do upwards diffusion. I have a laboratory diffusion
cell and I am trying to model upwards diffusion of metals from the tailings
into a clean overlying water cover and then estimate diffusion coefficients
of metals. Initially, the water has a concentration of zero, and each day
the concentration of contaminants increased in the water cover, until an
equilibrium value was reached. I know the pore water and solid elemental
concentrations of contaminants in the tailings.

Thanks,
Vicky Peacey