Output Table: Water Composition

aqion main output table (physico-chemical parameters and elements)

aqion displays the results of the hydrochemical calculations in different ways. One example is shown in the right screen­shot. In this table, three aqueous solutions (each in one column) are shown and compared:1

Input – the input water itself (raw data)

Output 1 – the solution in chemical equilibrium (and after charge-balance adjustment)

Output 2 – the same like Output 1, but with mineral-water interaction (incl. redox reactions)

The values in the last two columns differ only when mineral phases precipitate and/or dissolve or when redox reactions are present. [In this example, no minerals precipi­tate,2 but some minor redox reactions take place that change the redox potential.]

Physico-Chemical Parameters

The table shown above contains the following physico-chemical parameters (rows from top to bottom):

pH pH value of the solution
pe pe value of the solution
Eh redox potential in mV (related to standard hydrogen electrode)
T temperature of the solution in °C
Ionic strength ionic strength in mmol/L
TDS total dissolved solids in mg/L
EC electrical conductivity in µS/cm (at sampling temperature)3
EC_25 temperature-compensated value EC25 in µS/cm at 25
Alkalinity total alkalinity (M alkalinity) in meq/L or ppm CaCO34
CH carbonate hardness or temporary hardness in meq/L or ppm CaCO34
TH total hardness in meq/L or ppm CaCO35
C.B.E. charge-balance error (CBE) in percent6

Element Concentrations – The lower section of the table lists the total element concentrations in mg/L (or in mmol/L if the upper checkbox mol is activated).

Upper Menu Bar

mol checkbox to switch between concentration units: mg/L ⇔ mmol/L
digits specifies the number of digits after the decimal point
Ions opens a table of all ions and aqueous complexes (complete speciation)7
Minerals opens a table of the precipitated or dissolved mineral phases (if any) and the saturation indices
Export writes the table(s) into text files (for Excel or other programs)
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Lower Menu Bar

Save Out 1 stores8 the calculated solution shown in column Output 1
Save Out 2 stores8 the calculated solution shown in column Output 2
Last line jumps to the last table row (relevant only for large tables)
« back returns to the main window
next » displays next panel with relevant data of the carbonate system (buffer capacities, alkalinity, CO2 partial pressure) and the calcite-carbonate system (SI, LSI)

Remarks & Footnotes

  1. The idea behind Output 1 and Output 2 is explained here

  2. An example of mineral precipitation is given here

  3. The program provides three calculation methods for EC, which can be selected in Settings in the upper menu bar of the main window. 

  4. To switch between units “meq/L” and “ppm CaCO3”, click the upper mol checkbox.  2

  5. Also named “general hardness” GH (reminiscent of the German “Gesamthärte” = total hardness). 

  6. The CBE is non-zero only in the first column (input water); after charge-balance adjustment CBE becomes zero – see the last two columns. 

  7. Another example for aqueous speciation is presented here

  8. The calculated solutions in Output 1 and Output 2 can be saved for successive combination of reaction processes. This, however, is only allowed in aqion PRO.  2

[last modified: 2020-12-30]