Keywords SOLUTION SPECIES

For all reactions being put in data sets manually, the used master species, if not yet existent, have to be defined using the keyword SOLUTION MASTER SPECIES. 

If elements, species, stability constants, and/or solubility constants that are unavailable in an existing data set, should be used for one task only, it is advisable to define them directly in the input file rather than to change the data set itself. As a declaration in an input file always has a higher rank, it overwrites information of a data set. Like in a data set, the keyword SOLUTION MASTER SPECIES has to be used to define the element (e.g. C), the ionic form (e.g. C03-2), the contribution of the element to alkalinity (e.g. 2.0), the mole mass of the species for... 

Aqueous Species The keyword SOLUTION MASTER SPECIES allows us to define new basis species. To see how this is done, the easiest thing is to look into phreeqc.dat to see how others are defined. Since it has not previously been defined, we have a choice... 

Other aqueous arsenic species are then entered using the SOLUTION SPECIES keyword. Again copy the format given in phreeqc.dat. For As(OH>3, this is... 

The unit used for the input of concentrations can be defined with the keyword units. Possible units are mass or moles per liter solution, moles per kg solution or moles per kg water. Concentrations thereby can be given in g, mg, ug (not pg) or mol, mmol, and umol. Temperature (temp) is denoted in °C. The density (density) can be entered in g/cm3, with a default of 0.9998. That information is especially important for highly mineralized waters, like e.g. seawater. To input the measured Eh value a conversion to the pE value is necessary (see chapter 1.1.5.2.2, Eq. 65). If no pE value is given, pE is assumed to be 4 by default. A redox couple (redox) can be defined to calculate the pE value that will be used to model the species distribution of redox sensitive elements if no pE is given. 

First of all both solutions, the acid mine water and the groundwater, are defined in the PHREEQC input file and mixed applying the keyword MIX. Then this solution is saved as solution 3 (SAVE SOLUTION) and the job is finished by END. A second job follows, which uses again SOLUTION 2 (groundwater) and SOLUTION 3 (1 1 diluted water) via the key word USE, once again mixes both solutions 1 1, and saves the result as SOLUTION 4, etc. SELECTED OUTPUT facilitates the further data processing in EXCEL by providing the pH values and the molalities of all uranium species. The key word itself has to be repeated for every job, as well as the definition of the desired parameters pH and molalities. 

---