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

pH to high

Thanks for your recent help on executing phreeqci.
I have another problem that I hope you can help me with:  I have mixed a groundwater with 129 ppm SO4-2 (specified as S) with Fe_metal and observed that the water reaches saturation with respect to several Fe oxide and sulfide phases and as well as As2S3.  As expected, pe drops like a rock.  Magenite has the greatest degree of saturation of the Fe phases.
Allowing magnetite, pyrite, and orpiment to "exist" shows that only magnetite ppts, leaving pH high but perhaps unrealistically high (12+) so that HS- is trivial relative to other S species and the sulfides do not form.
Do I need to define reactions for the other S species and the orpiment, pyrite, etc.?
Also, can you comment on reaction precipitation sequence?

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/msg00246.html
Last modified: $Date: 2005-09-13 21:04:21 -0600 (Tue, 13 Sep 2005) $
Visitor number 3140 since Jan 22, 1998.