I worked more on the input file and got somewhat satisfactory results simulating Part 1 of my problem, with sorbents accumulating on the sites from
pore volume to pore volume exactly as you said. Some efforts with this part of the model are still needed to find where the rest of uranium is ?hiding?. I got stuck, however, with Part 2 of the simulation that does not converge. Therefore, I am attaching my input file for your review with a humble request for help.
We are modeling advection of a uranium pregnant solution through a soil column followed by advection of atmospheric precipitation. Our soil column is defined by 5 unsaturated layers followed by two saturated layers. Each layer has a different soil moisture and/or pore water chemistry (7 different solutions) and different (seven) sorbing site concentrations. I have divided the soil column into 46 cells and related them with 46 Solutions: ?SOLUTION 1-11? for the upper layer ?SOLUTION 12-28? for the second layer etc.
Part 1, which consists of Simulation 1 through 4, simulates advection of the uranium pregnant solution (Solution 0) . We need to simulate the impact of Solution 0 on the chemistry of the soil moisture and the removal of uranium (present in solution 0) by surface complexation processes. Sorbing sites used in Part 1 are defined as Fea-w through Feg-w for the weak sites and Fea-s through Feg-s for the strong sites. Appropriate additions to the thermodynamic database have been made, and the data base is attached.
Part 2, which consists of Simulation 5 and 6, simulates the effect of atmospheric water ?flushing? out the uranium that was sorbed during the waste release event modeled by Part 1. I called atmospheric water again Solution 0 understanding that this will overwrite the first one which described the waste stream. In order that Simulation 6 uses the final solutions of Part 1, I saved them (in Simulation 4) as Solutions 1-46. Similarly, to have Simulation 6 using partially occupied sorbing sites I saved Surface 1-46 and Equilibrium_phases 1-46
Simulation 6 does not converge. I tried many versions combining Simulations 5 and 6 together as well as using the USE keyword for each solution and surface (USE surface 1, USE surface 2 etc). I also tried relaxing converging criteria within the KNOBS keyword, but this did not help either.
Thank you for the assistance you provided thus far and I will greatly appreciate any additional help you can give. Please contact me for more information, if needed.
----- Original Message -----
From: "David L Parkhurst" <dlpark@xxxxxxxx>
To: "Marek Zaluski" <zaluskim@xxxxxxxxxx>
Sent: Tuesday, October 07, 2003 8:15 AM
Subject: Re: PHREEQCI
> If it still doesn't make sense, send the input file and I'll take a quick
> David Parkhurst (dlpark@xxxxxxxx)
> U.S. Geological Survey
> Box 25046, MS 413
> Denver Federal Center
> Denver, CO 80225
> Project web page: https://wwwbrr.cr.usgs.gov/projects/GWC_coupled
> "Marek Zaluski"
> <zaluskim@xxxxxx. To: "David L Parkhurst" <dlpark@xxxxxxxx>
> com> cc:
> Subject: Re: PHREEQCI
> 10/06/2003 09:48
> Thank you for your reply!
> Now when I've been assured that "sorbents will accumulate on the sites from
> pore volume to pore volume", I will further examine my input file.
> Obviously, I must be doing something wrong.
> Again, thanks!
> ----- Original Message -----
> From: "David L Parkhurst" <dlpark@xxxxxxxx>
> To: "Marek Zaluski" <zaluskim@xxxxxxxxxx>
> Sent: Monday, October 06, 2003 8:19 AM
> Subject: Re: PHREEQCI
> > > My selective output file lists steps as specified by "punch_cells" and
> > "punch_frequency" commands preceded by 15 lines (all numbered "step
> > I can trace last 7 lines (out 15 in question) to some parameters of my
> > seven layers. The fist 8 lines are conundrum for me. The PHREEQC manual
> > for SELECTED_OUTPUT refer to lines "?99" as other calculations. Would
> > please enlighten me what are these calculations whose results are
> > in lines marked -99?
> > Starting with the simulation in which SELECTED_OUTPUT is defined, every
> > calculation adds a line to the selected-output file. A calculation
> > initial solution calculations and reaction calculations. I think the -99
> > for step are probably initial solution calculations. If you move the
> > SELECTED_OUTPUT definition to the simulation where ADVECTION is defined,
> > you will not get the initial lines in the selected-output file.
> > The results for uranium sorbed within each layer after one and two pore
> > volumes are identical. It seems to me that the logistics of ADVECTION
> > word does not account for the reduced site concentration that exist after
> > the first pore volume moved through. Am I interpreting it correctly, and
> > if so, is there any way to account for the reduction in site
> > for the advancement of the second pore volume?
> > I can't tell what your problem is. The sites (SURFACE or EXCHANGE) are
> > immobile and remain in the cell for which they were defined. However,
> > sorbants will accumulate on the sites from pore volume to pore volume.
> > Remember that a time step only advects the solution one cell; a pore
> > would require 46 steps if you have 46 cells.
> > David
> > David Parkhurst (dlpark@xxxxxxxx)
> > U.S. Geological Survey
> > Box 25046, MS 413
> > Denver Federal Center
> > Denver, CO 80225
> > Project web page: https://wwwbrr.cr.usgs.gov/projects/GWC_coupled
Description: Binary data
MinteqaForHanfordBwith exchange and Fea-gB.dat
Description: Binary data
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