New user question

[tcotterell]

Hey there! I am using PHREEQC to see what minerals will precipitate by way of evaporation of a mine water. The data I have includes total dissolved metals and total metals, and no pe/redox information, or density of the water. Can I still run a simulation without that information? Should I use the total metals or just total dissolved? Thank you in advance for your help!

[dlparkhurst]

Use the dissolved concentrations to calculate saturation indices. Hopefully, you have a pH and if the pH is 5 or above, an alkalinity.

[tcotterell]

Thank you for your input!
I do have a couple more questions and have been trying to find answers to them all morning. I am looking at ground water chemistry from a piezometer in bedrock, adjacent to a large tailings pile, that periodically gets influxes of high TDS and sulfate concentrations. I want to look at my solution description by inputting the information that I have. Can I use conductivity in the solution input? And how would I do that? I tried to put "specific conductance" with it's value and got an error message. Also, I have bicarbonate and carbonate concentrations but am not sure how to use them in the solution input. Bicarbonate has a value of 359 mg/L and carbonate is at 0.5 mg/L. I tried to us "bicarbonate", "HCO3" and "alkalinity" in the solution input and have only gotten errors.

[dlparkhurst]

You cannot enter specific conductance. The databases phreeqc.dat, Amm.dat, and pitzer.dat will calculate specific conductance, so you can compare the calculated value with your measured value.

For alkalinity, I would probably just ignore the CO3-2 part because it is small. It depends on the lab, sometimes the HCO3- is the total alkalinity, sometimes not. If it is just the HCO3- part of the alkalinity, then to be complete, you would calculate total alkalinity (the value needed by PHREEQC) as

Code: [Select]

Alk, as HCO3- = HCO3- + CO3-2*61/60*2

Make sure the program uses the correct equivalent weight for Alkalinity. By default, phreeqc.dat uses 50, the gram equivalent weight for Alkalinity reported as CaCO3, which is common for labs in the US. To be sure, regardless of the database, use the following:

Code: [Select]

SOLUTION
Alkalinity 360 as HCO3