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Parameters

 

Please Note: Parameter-related functionality is only available in HGA+.

 

Parameters are those properties whose values describe the state of a particular station or sample. There are three general kinds of parameters in Hydro GeoAnalyst:

Station parameters are those parameters that describe a station and its properties.  All of the fields in the Station Table are station parameters; for example: station name, x- and y-coordinates, and site description.

 

Sample parameters are those parameters that describe a sample and its properties. Similarly, all of the fields in the Sample Table are sample parameters; for example: sample ID, station, and sample date.

 

Analytical parameters are associated with sampling results and describe the value or measurement of a particular constituent (e.g. calcium concentration, pH, temperature, etc.).

 

Generally in Hydro GeoAnalyst, unless otherwise specifically stated, the term parameter refers to analytical parameters.  Analytical parameters may be further subdivided into various groups as discussed below.  

 

Viewing Parameters and Results

When viewing the Sample List, results for the selected sample are shown in the Results pane. Results are shown by parameter type in the tab at the top of the results pane (as denoted by circled area 1):

Measured parameters are those values that are explicitly stored in the database and typically have been measured either in the field or in an analytical laboratory.

 

Calculated parameters are those values that have been calculated using the HGA+ built-in functions.  These are calculated dynamically and are not stored in the database.

 

Modeled parameters are those values that have been estimated using PHREEQC in an imported AquaChem 2014 project.  This tab is only shown for projects that used PHREEQC and have been imported into the current version Hydro GeoAnalyst.  Note that support for  PHREEQC in Hydro GeoAnalyst is planned for a subsequent release.

 

Measured parameters can be filtered in the Results tab using the parameter group dropdown (as denoted by circled area 2), discussed below.

 

 

Parameters and the Parameter Editor

Information about all measured parameters is stored in the Parameter Table, and includes the relevant chemical and descriptive attributes as follows (using bicarbonate as an example):

Short Name: a unique, typically short or abbreviated, name that is easily recognizable (e.g. HCO3) and used as a look up name and a primary key.

Display Name: a longer descriptive name (e.g. bicarbonate) used for labeling in plots and tables.

CAS: Chemical Abstracts Service (CAS) Registry number (e.g. 56240-83-6), a unique number assigned by CAS, a division of the American Chemical Society

Description: typically a more descriptive name that may include a list of alternate names (e.g. bicarbonate; hydrogencarbonate)

Formula: chemical formula (e.g. HCO3)

Molecular Weight: combined atomic weights of all constituent atoms that compose the parameter (e.g. HCO3 = 1x1.00794 + 1x12.0107 + 3x15.9994 = 61 g/mol)

Valency: the ionic/electric charge of the parameter in solution (e.g. -1).

 

For more information, see the Parameter Editor section.

 

 

 

Parameter Groups

Measured parameters may be grouped into categories called parameter groups to facilitate viewing, analyzing, plotting, and tabulating your data. Some parameter groups are automatically created for you by Hydro GeoAnalyst, including:

All Measured Parameters: all of the measured parameters in your project

Analyzed Parameters: parameters with results for the active sample(s)

Ions: parameters with a non-zero valence

Cations: parameters with a positive valence

Anions: parameters with a negative valence

Required Parameters: parameters that are used in a supported formula and are required

Used in Standard: parameters in your project that are present in an active Water Quality Standard.

 

Custom Parameter Groups may be created in the Parameter Group Editor.

 

Parameter Selection Window

The parameter selection window is used throughout Hydro GeoAnalyst to allow you to easily find and select one or more parameters:

 

 

The main portion of the window displays a list of parameters that can be selected.  In many cases, you can select more than one parameter by holding the <CRTL> key to add individual items to your selection or the <SHIFT> key to add a range of items to your list.

You can filter the list in one of two ways:

Parameter Group dropdown menu: which will restrict the listed parameters to the selected parameter group or

Filter bar: allows you to filter the parameter list using a search term

 

PHREEQC Parameter Selection Window

The PHREEQC parameter selection window is used to select and add modeled parameters from the default thermodynamic database in the project:

 

The dropdown menu allows you to select the type of modeled parameter:

Activities: allows you to select and add one or more parameter for the log activity of a parameter that has been mapped to an Element/Master Species entry in the default thermodynamic database

Saturation Indices: allows you to select and add one or more parameter for the saturation index of species that are included in the Phases block of the default thermodynamic database

Other: allows you to select and add one or more common parameters that are modeled in PHREEQC (Alkalinity, Ionic Strength, Mass H2O, Percent Error

 

The main portion of the window displays a list of parameters that can be selected and added to the project. You can select more than one parameter by holding the <CRTL> key to add individual items to your selection or the <SHIFT> key to add a range of items to your list.

Please Note: you must add modeled parameters before using PHREEQC to calculate saturation indices and activities or running a PHREEQC (basic) simulation or the results will not be saved to the database.

 

 


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