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Re: alkalinity question




> Do I just enter this number in the alkalinity space, or do I have to
somehow specify alkalinity as mg/L CaCO3 somewhere in the program?

Each database has a default for conversion of alkalinity from mg/L to
equivalents/L. For phreeqc.dat, wateq4f.dat, and llnl.dat, the default
conversion is based on CaCO3. For minteq.dat it is HCO3. The 4th entry for
Alkalinity in SOLUTION_MASTER_SPECIES gives the default conversion, either
as a formula or as a gram equivalent wt. To be safe, you can always define
the conversion explicitly in the SOLUTION data block.

SOLUTION
      Alkalinity 150. mg/L as Ca.5(CO3).5 # (or "as CaCO3")

The 0.5 accounts for the fact that there are 2 equivalents per mole of
CaCO3. The program also accepts "CaCO3" and uses the correct gram
equivalent weight of 50.0.

David




David Parkhurst (dlpark@xxxxxxxx)
U.S. Geological Survey
Box 25046, MS 413
Denver Federal Center
Denver, CO 80225


                                                                                                                          
                      "Vicky Peacey"                                                                                      
                      <vpeacey@xxxxxx>         To:      "David L Parkhurst" <dlpark@xxxxxxxx>                             
                                               cc:                                                                        
In-Reply-To: <001101c172bb$7febdfa0$d5de6481@xxxxxxxxxxxx>
                      11/21/01 11:36           Subject: alkalinity question                                               
                      AM                                                                                                  
                                                                                                                          
                                                                                                                          



Hi, I'm using the WATEQ database in PHREEQC and alkalinity is one of the
parameters I wish to enter to perform a speciation calculation. I have
measured alkalinity in my water as mg/L CaCO3. Do I just enter this number
in the alkalinity space, or do I have to somehow specify alkalinity as mg/L
CaCO3 somewhere in the program?

Thanks
Vicky Peacey







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