[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Modeling Waite et al. 1994 in Phreeqc




> Am I correct that as in the mass action equation only the H+ activity has
an
exponent of 2, Phreeqc should provide similar results to Waite et al.?

I think you are right. The mole-fraction activity for surface species would
not affect the mass-action equation in this case.

> I set it up as follows but I run into problems that the total H balance
of the
system is distorted. I would be glad if you have any suggestions.



I don't have a copy of Waite and others close at hand and I have pretty
much forgotten their paper. How is the total H distorted? Thinking about
what phreeqc does, there is a mole balance equation for H and =Fe sites. I
think the sum of the species in the calculated distribution of species must
conserve both H and sites, so I don't know where the error would be.

What are you comparing to? If you are comparing to calculations by Waite, I
wonder if there is an error in their total H condition when they use the
funny mass-action equation. I am not sure if they used that mass-action for
a good reason or just by necessity because they didn't use a more
reasonable activity convention for bidentate sorbed species.

Let me  know a little more about the total H balance being "distorted" and
I'll try to give you a better answer.

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




Project Home Page
Complete Water Resources Division Software
USGS Home Page
Water Resources Division Home Page
NRP Home Page
Help Page
USGS Privacy Statement       

Please note that some U.S. Geological Survey (USGS) information accessed through this page may be preliminary in nature and presented prior to final review and approval by the Director of the USGS. This information is provided with the understanding that it is not guaranteed to be correct or complete and conclusions drawn from such information are the sole responsibility of the user.

Any use of trade, product, or firm names in this publication is for descriptive purposes only and does not imply endorsement by the U.S. Government. 


The URL of this page is: https://wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc/mail/msg00628.html
Email:dlpark@usgs.gov
Last modified: $Date: 2005-09-13 21:04:21 -0600 (Tue, 13 Sep 2005) $
Visitor number 1732 since Jan 22, 1998.