How to Specify the Carbonate System?

There are three alternatives to determine the carbonate system:

The corresponding input panels are part of the main input window.

Input of DIC

aqion_DIC_input

The right screenshot shows the DIC input panel (in mg/L Carbon or in mmol/L). Unfortunately, DIC does not belong to the list of common water analysis parameters. An alternative is then the alkalinity (if provided).

If neither DIC nor alkalinity data is available, then you can enter any initial DIC value (say, 1 mM or 1 mg/L) and let the program calculate the unknown DIC by charge-balance adjustment with DIC. [Warning: This method requires that the measured pH and all major ions are sufficiently accurate. Otherwise, the calculated DIC will not be very reliable.]

Input of Alkalinity

aqion_DIC_input

Instead of DIC the carbonate system can be specified by the measured alkalinity (also known as total alkalinity or M alkalinity). This quantity is closely related to the carbonate hardness (CH) and the Acid Neutralizing Capacity:

Alkalinity  =  CH  ≈  ANC to pH 4.3 … 4.5

After calculation, all relevant parameters of the carbonate system (alkalinity, ANC, and the complete carbonate speciation) are displayed in the output tables.

Two remarks:

[last modified: 2015-07-05]