> 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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