> Iam happy to send you my 1st e-mail. I want your help to show me how I can use WATEQ and what WATEQ can tell me if I used it with my data about high saline water. I have no information about this programme I need to know the steps by which I can use the results to identify my water analysis results. WATEQ is a speciation code, that is, it calculates the distribution of elements among aqueous species (ion pairs and complexes). The usual reason for doing the calculation is to obtain saturation indices for minerals and partial pressures of gases, which whether minerals (and gases) should dissolve or precipitate in the solution. The program needs a complete major element chemical analysis (Ca, Mg, Na, SO4, Cl, alkalinity, and field pH) to make the calculation. I would suggest using PhreeqcI instead of WATEQ if you are running on a Windows computer. You can download PhreeqcI from https://wwwbrr.cr.usgs.gov/projects/GWC_coupled/phreeqc. It has more features that WATEQ and is interactive. High salinity may be a problem. Both WATEQ and PhreeqcI use an ion-association model. It is not accurate at high ionic strengths. The range of applicability is up to 0.1 to 1.0 molal ionic strength, depending on the composition of the waters. Another approach, called the specific interaction or Pitzer approach, is better for higher ionic strengths. However, this approach is limited to major ions and does not allow for redox or alumino-silicate reactions. We have a program called PHRQPITZ at the same web site, but it is old and difficult to use. You may be able to use other geochemical models that include the Pitzer approach (TEQUIL, EQ3/6, Geochemists Workbench), but I'm not sure these programs are easily available. David David Parkhurst (dlpark@xxxxxxxx) U.S. Geological Survey Box 25046, MS 413 Denver Federal Center Denver, CO 80225
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