Dr. Parkhurst, I was hoping you might be able to provide some insight for a warning message I am getting running a pyrite oxidation simulation. I am modeling injecting oxygenated water into a basalt aquifer containing 0.1% pyrite to simulate what may occur during aquifer storage and recovery operations. For my initial simulation I have not included possible precipitation of ferrihydrite. There is no iron in my initial solution so the only source of iron is what is released due to the oxidation of pyrite. At the point in the simulation where iron concentrations plateau as oxygen is depleted I get the following warning: WARNING: Element Fe has negative moles in solution, -2.943717e-005. Erroneous mole balance occurs as moles are added to produce zero moles. Caused by KINETICS or REACTION. May be due to large time steps in early part of KINETICS simulation. Using solution 2. Richland Water (9/25/00) Using kinetics 2. Kinetics defined in simulation 2. The final iron concentration in solution however is equal to the total amount of pyrite that has dissolved during the simulation as would be expected. Since I have no reactions that would remove iron, I'm not sure how I could have negative moles in solution. I have tried decreasing my time step but this does not seem to help. Any help would be greatly appreciated. Cheryl Ross _____________________________ Cheryl Ross, M.Sc. Hydrogeochemist Golder Associates Inc. 18300 NE Union Hill Rd., Suite 200 Redmond, WA 98052 Office: 425-883-0777 Fax: 425-882-5498
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:
Last modified: $Date: 2005-09-13 21:04:21 -0600 (Tue, 13 Sep 2005) $
Visitor number 1518 since Jan 22, 1998.