The Input Panel

aqion main input panel

Program Start

Just after program start, aqion opens with the main input panel for chemical data – as shown on the right.

There are two possibilities to enter an aqueous solution:

by typing-in the chemical data (of a water analysis) via the keyboard
by loading an existing input water via the button Open (on the bottom menu bar)

In the following we describe the first option.

Input Data

The input window enable you to enter the following parameters (from top to bottom):¹

Filename. The default filename of the empty input panel is “new”. You can change this name before you save the input solution. Example: water_A3 will be saved as file water_A3.sol (in the user directory aqion/INP)²³

pH and T [°C]. pH value (default: 7.0) and water temperature (default: 25).

mol. This checkbox switches the concentration units from mg/L to mmol/L (and vice versa); it acts for all elements at once. (Also, you can change the concentration unit for each element separately by clicking on the light gray drop-down list next to the respective element.) Fields with molar units are highlighted in pale yellow.

Minerals. This checkbox opens the mineral table to enter:

the initial amount (in mmol/L) and/or
the saturation index (SI)

These data are stored together with the element concentrations in the same input-water file.

Element Concentrations. The major elements are arranged in two columns:

cations (left): Ca, Mg, Na, K, Al, Mn, total ammonia
anions (right): chloride, sulfate, nitrate, phosphate

The light gray drop-down list on the right side of each element selects the concentration unit: g/L, mg/L, µg/L, mol/L, mmol/L or µmol/L.

DIC – Dissolved Inorganic Carbon. DIC plays a key role in hydrochemistry and natural waters at all. It is a (non-trivial) topic of its own and will be discussed here.

Fe(2) / Fe(3). Iron forms compounds and species in the +2 (ferrous) and +3 (ferric) oxidation states. You can enter the iron concentrations in two ways:

either as total iron (Fe_total)
or as Fe(2) and Fe(3)

Given Fe_total, aqion converts the total concentration into Fe(2) and Fe(3) in accordance with the redox potential.

More Elements. This checkbox opens a panel with additional elements:

cations (left): Si, As, Sr, Cu, Cr, Ni, Zn, Pb, U
anions (right): B, F, Br

Redox Potential. This checkbox enables the input of the redox potential:

either as Eh in mV
or as pe value

Once this option is checked the aqueous system is forced to attain the chosen redox potential or pe value by exchange of O₂ (“Open System”).

In most cases, it is not necessary to specify the redox potential explicitly. The calculations are then performed at the state of redox equilibrium (or at 240 mV, i.e. pe value 4, as default). In any case, you’ll find the information about pe or Eh for every reaction step in the output tables.

Comments. Optionally, comments can be entered in two lines; they are then stored together with the data.

Evaluation Temperature. The evaluation temperature can be entered when the corresponding checkbox is checked. This optional parameter is used in calculations of calcite saturation only.⁴ If no evaluation temperature is entered the program uses the water temperature from the input field above.

Top Menu Bar

File

Reset solution to “pure water” – same as button H2O
Open/select input water – same as button Open
Save input water – same as button Save

Run

Charge balance, physico-chem parameters … – same as button Start
Reactions, pH calculator, titration curves – same as button Reac
Mixing of two waters – same as button Mix
Calcite-carbonate system

Settings

Config panel for minerals
Config panel for conductivity model (EC) and
Config panel for redox reactions of nitrogen

Extras ⁵

Dosing of chemicals to attain a target pH – shortcut Alt-P
Prepare solutions (Buffer Maker) – shortcut Alt-B

Info

Link to www.aqion.de
Upgrade to aqion PRO

Bottom Menu Bar

Open	Opens the standard dialog to select an existing solution (input water) which are stored in directory `INP`.	Alt-O
Save	Saves the input water (by storing the data file in directory `INP`). Note: Saving is not required to run the hydrochemical calculations.	Alt-V
H2O	Clears the entire panel. The empty window represents pure water with pH 7 and 25.¹	Alt-H
Mix	Mixing of two waters.	Alt-M
Reac	Opens the reaction panel to add chemicals (acids, bases, salts) and/or to perform titration calculations.⁶	Alt-R
Start	Starts the hydrochemical calculations (chemical equilibrium and speciation, charge balance, calcite saturation etc.)⁶	Alt-S
End	Closes the program.

Remarks / Footnotes

The “empty” template represents the simplest of all aqueous solutions: pure water (H₂O) with pH 7 at 25. This is often the starting point for pH calculations of acids, bases and salts with the reaction module (via button Reac). ↩ ↩²
All input solutions of aqion have the file extension sol. ↩
The input solutions can be used in PhreeqC as input files as well (the syntax is the same). ↩
For example: The water sample has 20, but we are interested in the calcite saturation parameters at the evaluation temperature 60. ↩
only for aqion PRO ↩
Start vs. Reac – see here ↩ ↩²

[last modified: 2020-12-30]