AquaChem
AquaChem: piper diagrams, stiff diagrams, ternary
diagrams and other aqueous geochemistry graph utilities
Main Features
- Automatic unit conversions
(mg/l, mol/l, mmol/l, ppm, meq, SiO2 in Si or H2Si3)
- Flexible data input methods
(import from ASCII file or manual keyboard entry)
- Standard database functionality for performing queries
- Built-in selection of common geochemical calculations and
analysis methods
- Comprehensive selection of graphical techniques for representing
and interpreting geochemical data
- Graphical interface to PHREEQC for geochemical modeling
(PHREEQC executable included!)
AquaChem is a fully-integrated software package developed
specifically for graphical and numerical analysis of geochemical data
sets. It features a powerful database that can be customized and
configured to include an unlimited number of attributes per sample, and a
built-in database of inorganic chemicals that are commonly used for
geochemical analyses, calculations and plotting.
AquaChem covers a wide range of calculations frequently used for the
analysis, interpretation and comparison of hydrochemical data ranging from
simple unit transformation and charge balance to more complex
geothermometer calculations. These powerful analytical capabilities are
complimented by a comprehensive selection of commonly used graphical
techniques to portray the chemical characteristics of geochemical and
water quality data for single samples and groups of samples. The fully
customizable graphical features facilitate the understanding and
interpretation of the many complex interactions between the groundwater
and aquifer materials. AquaChem's graphical plotting techniques include
Piper, Stiff, Durov, Langelier-Ludwig, Schoeller and ternary diagrams,
radial plots, scatter graphs, frequency histograms, pie charts,
geothermometer plots and time series graphs.
In addition, AquaChem features a built-in graphical interface to the
popular geochemical modeling program PHREEQC for calculating equilibrium
concentrations (or activities) of chemical species in solution and
saturation indices of solid phases in equilibrium with a solution.
Once you start using AquaChem, you will see that it is truly one of the
most powerful tools available for anyone dealing with the interpretation,
analysis and modeling of simple or complex geochemical data sets.
Database Features
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Data Struture
AquaChem is built around a
customizable database that can be configured to include up to 100
numeric attributes per sample (e.g. chemical elements, gas
concentration, isotopic composition, physical parameters, etc).
Each sample can be characterized
according to five basic parameter groups including:
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Header Information (Sample ID,
Site, Location, Date, Geology, etc.),
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Physical Data (Coordinates, sample
depth, head, pH, Conductivity, etc.),
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Cations (Ca, Mg, Na, K, etc.),
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Anions (Cl, Br, SO4, NO3, etc.),
and
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Uncharged Compounds (Al, As, CO2,
etc.)
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Each of these parameter groups
contains pre-defined parameters which can be used to create a data
structure that is customized for your sampling and reporting
requirements. The built-in database contains most major cations and
anions and the chemical properties of each. Additional parameters
that are not included can be easily added to the database together
with guideline exceedence values for each parameter.
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The AquaChem database offers standard
database functionality for performing queries or adding and
subtracting samples from the selected data set. A powerful search
engine allows you to find and group data records according to
virtually any search criterion associated with the data set. The
selected samples can be easily saved in sub-groups or temporarily
isolated from the other records for further data processing and
interpretation by AquaChem. |
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Analysis
AquaChem uses the common measured values (cations
and anions) for each sample to calculate additional geochemical
parameters including Water Type, Sum of Anions, Sum of Cations, Ion
Balance, TDS, Hardness, Alkalinity, Common Ratios, and dissolved
minerals. In addition, AquaChem also performs more advanced
calculations including: |
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- Basic statistical calculations such as average
value, dispersion and linear correlation matrix.
- Similarity analysis to calculate a linear
regression between a single sample and all other samples of the
record list.
- Mixing of two samples can be performed and the
results written to the database and a new sample record.
- Chemical facies can be calculated based on the
elements which are present by more than 20% of the total of all
elements in equivalent concentration.
- Geothermometric calculations can be performed
to estimate the original temperature at depth of sampled water.
- Upper and lower tolerance and guideline limit
exceedences can be identified for every numeric parameter in the
sample set.
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AquaChem also produces printed reports for each record
or for the entire database containing general sample information, isotope
summaries, and a list of samples. All sample records can be exported to a
tab-delimited ASCII file.
Graphical Display Features
AquaChem's powerful graphical tools
utilize 15 plotting techniques commonly used by hydrogeologists and
geochemists for analyzing and interpreting aqueous geochemical data sets
for hundreds and even thousands of different samples. These graphical
methods and the various display options are discussed below.
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Common Features for all Graphs
One of the most powerful features of AquaChem is
the ability to simulataneously display and modify multiple plots,
and to easily identify selected data points within each plot. This
unique feature allows you to perform a comprehensive analysis of the
data using several interpretation methods. Futhermore, each sample
record in the database is directly linked to the graphs, so that any
changes to the data are immediately updated on the graphs. This also
allows you to easily identify specific sample records on each plot.
Other common features include:
- Fully customizable axes scale settings and unit
selections for applicable graphs
- Complete selection of Windows True Type fonts
for plot titles, legends, axis labels, and symbol labels
- Proportional symbol sizes using concentration
value for any measured or calculated parameter
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Site Map
Diagrams
Detailed site maps can be imported from DXF files
and overlayed with sample point locations. This provides a familiar
point of reference when you are analyzing sample data by
simultaneously displaying several plot types on the same screen. The
symbols representing the sample locations can be customized
according to shape and color. In addition, the map plot can be used
to display the location of different water facies, or the symbols
can scaled according to the concentration of a selected measured
element. The highlighted sample points indicate samples that are
selected in the database and are also highlighted on all other open
graphical displays.
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Stiff
Diagrams
The Stiff diagrams are plotted for individual
samples as a method of graphically comparing the concentration of
selected anions and cations for several individual samples. The
shape formed by the Stiff diagrams will quickly identify samples
that have similar compositions and are particularly useful when used
as map symbols to show the geographic location of different water
facies.
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Radial
Diagrams
The radial diagrams are plotted for individual
samples as a method of graphically comparing the concentrations of
measured parameters for several individual samples. The shape formed
by the radial diagrams will quickly identify samples that have
similar compositions and are particularly useful when used as map
symbols to show the geographic location of different water facies.
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Pie Charts
The pie charts are used to plot the concentrations
ratio of the major ions (or any combination of parameters) for
individual samples. As with the Stiff and radial diagrams, the pie
chart is used to graphically compare the concentration ratios of
several measured parameters for several different samples. The color
and patterns used to identify each parameter are customizable.
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Piper
Diagrams
The Piper diagram plots the major ions as
percentages of milliequivalents in two base triangles. The total
cations and the total anions are set equal to 100% and the data
points in the two triangles are projected onto an adjacent grid.
This plot reveals useful properties and relationships for large
sample groups. The main purpose of the Piper diagram is to show
clustering of data points to indicate samples that have similar
compositions.
The Piper diagram can be used to plot all samples
in the open database or selected sample groups. In addition, the
symbols representing the sample values can be customized according
to shape and color. Other options include individual multiplication
factors for each selected ion to prevent data point accumulation
along a base line. The highlighted sample points indicate samples
that are selected in the database and are also highlighted on all
other open graphical displays.
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Durov
Diagrams
The Durov diagram is an alternative to the Piper
diagram. The Durov diagram plots the major ions as percentages of
milliequivalents in two base triangles. The total cations and the
total anions are set equal to 100% and the data points in the two
triangles are projected onto a square grid which
lies perpendicular to the third axis in each triangle. This plot
reveals useful properties and relationships for large sample groups.
The main purpose of the Durov diagram is to show clustering of data
points to indicate samples that have similar compositions.
The Durov diagram can be used to plot all samples
in the open database or selected sample groups. In addition, the
symbols representing the sample values can be customized according
to shape and color. Other options include individual multiplication
factors for each selected ion to prevent data point accumulation
along a base line. The highlighted sample points indicate samples
that are selected in the database and are also highlighted on all
other open graphical displays.
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Ternary
Diagrams
A ternary diagram is also used to identify trends
and relationships between groups of samples. However, it is
generally easier to understand than Piper or Durov diagrams since it
involves fewer parameters and does not project data points onto a
grid. Like the Piper diagram, the ternary diagram plots the ions as
percentages of their concentration values. However, the ternary
diagram is not limited to using only meq units.
The ternary diagram can be used to plot all
samples in the open database or selected sample groups. In addition,
the symbols representing the sample values can be customized
according to shape and color. Other options include individual
multiplication factors for each selected ion to prevent data point
accumulation along a base line. The highlighted sample points
indicate samples that are selected in the database and are also
highlighted on all other open graphical displays.
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Langelier-Ludwig
Diagram
The Langelier-Ludwig square diagram is similar to
the projection areas of the Piper and Durov diagrams. Suitable
groupings of cations and anions are selected and plotted as
percentages of milliequivalents. By convention, the sums of the
selected cations are plotted on the y-axis, and the sum of the
selected anions are plotted on the x-axis. Each axis ranges from 0
to 50 meq%.
All major elements can be displayed in one plot
with the Langelier-Ludwig diagram. However, like the Piper and Durov
diagrams, it displays relative ratios rather than absolute
concentrations.
The Langelier-Ludwig diagram can be used to plot
all samples in the open database or selected sample groups. In
addition, the symbols representing the sample values can be
customized according to shape and color. The highlighted sample
points indicate samples that are selected in the database and are
also highlighted on all other open graphical displays.
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Schoeller
Diagrams
These semi-logarithmic diagrams were developed to
represent major ion analyses in meq/l and to demonstrate different
hydrochemical water types on the same diagram. This type of
graphical representation has the advantage that, unlike the
trilinear diagrams, actual sample concentrations are displayed and
compared.
The Schoeller diagram can be used to plot all
samples in the open database or selected sample groups only. Up to
10 different parameters can be included along the x-axis and the
symbols representing the sample points can be customized according
to shape and color. The highlighted lines indicate specific samples
that are selected in the database and are also highlighted on all
other open graphical displays.
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Scatter
Plots
The X-Y scatter plots are the most simple initial
approach to the interpretation of geochemical data. Single plots of
ion relationship and parameters that show significant data can be
easily created and patterns are quickly identified and easily
understood. Both normal scale and log scales are supported for the x
and y axes and multiplication factors can be applied to either the x
or y element. Element ratios and sums may also be included for
either axes.
The scatter plot can be used to plot all samples
in the open database or selected sample groups. The symbols
representing the sample points can be customized according to shape
and color. The highlighted data points indicate specific samples
that are selected in the database and are also highlighted on all
other open graphical displays.
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Frequency
Histograms
Frequency histograms are most commonly used to
check the number f populations within a given range of measured
values. It allows you to view a large number of samples without the
diagram becoming too cluttered with data points. The frequency of
samples within the given ranges can be plotted according to
percentages or numbers of samples.
The frequency histogram can be used to plot all
samples in the open database or selected sample groups. The range of
values can be customized up to 10 or more groups and the individual
samples can be identified at the associated value along the x-axis.
The highlighted data points indicate specific samples that are
selected in the database and are also highlighted on all other open
graphical displays.
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Time Series Graphs
The evolution of physical and chemical parameters
for a given sampling location is a standard technique for
interpreting hydrochemical and hydrogeological processes in natural
waters. AquaChem allows you to plot time-series graphs for any
numeric parameter in your database and axes are customizable to suit
your display requirements.
The time series graph can be used to plot all
samples in the open database or selected sample groups. The symbols
representing the sample points can be customized according to shape
and color. The highlighted data points indicate specific samples
that are selected in the database and are also highlighted on all
other open graphical displays.
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Geothermometer Plots
Geothermometer plots can be used to test the
quality of geotherometer estimates for a given geological and
hydrogeological condition.
The Giggenbach Triangle
The Giggenbach triangle is composed of three
zones; (1) immature waters along the base; (2) partially
equilibrated waters in the middle; and (3) fully equilibrated waters
along the upper curve. Depending on where the composition of a given
sample lies within this triangle, you can estimate the extent of
rock-water equilibrium based on the concentrations of K, Mg and Na.
Log(K)-1000/T Plots
The linear log(K)-1000/T plots can be used for
samples from boreholes where you know the insitu temperature of the
formation. It can be used to; (i) check the usability of
thermometers on a set of samples; (ii) plot the chemistry versus
formation temperature; (iii) search for the geothermometer with the
best fit; and (iv) develop new chemical geothermometers for
parameters which show linear behaviour.
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Printing
Results
AquaChem prints all reports and graphical displays
to any printer or plotter supported by Windows 95/NT. The printing
utility allows you to size and arrange the location of an unlimited
number of open graphical displays on the page. This is particularly
useful for comparing Stiff and radial diagrams from multiple
samples, or for using several different graphical displays to
interpret groups of samples in each plot. Two lines of titles can be
added at the top of the page while a single line of footer
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The PHREEQC Interface
PHREEQC is a program for performing aqueous geochemical
calculations and modeling including:
- Speciation and saturation-index calculations;
- Reaction-path and advective-transport calculations involving
specified irreversible reactions, mixing of solutions, mineral and gas
equilibria, surface complexation reactions, and ion-exchange reactions;
and
- Inverse modeling to find sets of mineral and gas mole transfers that
account for composition differences between waters, within specified
compositional uncertainties.
As the name might suggest, PHREEQC is written in the C programming
language and is derived from the Fortran program PHREEQE (Parkhurst et
al.). PHREEQC is essentially an upgrade from the previous versions of
PHREEQE since it retains all of the functionality and incorporates many
improvements and new features. A detailed description of the improvements
and the history of PHREEQE is provided at
http://water.usgs.gov/cgi-bin/man_wrdapp?phreeqc.
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Creating PHREEQC Input
Files
AquaChem provides a direct interface to PHREEQC
for creating the input files and running the simulations. A full
working version of PHREEQC is included with AquaChem and can be
executed directly from the interface.
In order to run a geochemical simulation using
PHREEQC, you must specify at least one solution to use in the
simulation. The main advantage of the AquaChem interface is that it
provides a direct link between PHREEQC input and output files and
the AquaChem database files. This database link allows for
instantaneous preparation of hundreds of solutions using samples
from the database. Alternatively, you can also use the interface to
load modeled solutions from previous simulations, or to manually
prepare solutions. These features will save you an incredible amount
of time and hassle when you are dealing with a large number of
samples (e.g. simultaneously speciation of samples).
The AquaChem PHREEQC interface also provides a
link between the specified solutions and other PHREEQC operations
including:
- Adding reactions to the solutions
- Defining mineral phases for equilibration with
the solutions
- Mixing solutions,
- Adding gas phases to the solutions,
- Specifying ion exchanges,
- Performing 1-D transport simulations, and
- Inverse modeling
Once the properties of the solutions have been
defined, you simply execute the PHREEQC program directly from the
AquaChem interface and the simulation calculations will take place.
If addition modifications are required, AquaChem allows you to edit
the PHREEQC input text file directly from the interface.
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Importing PHREEQC Results
AquaChem allows you to import the PHREEQC modeling
output file (.pun file) into your database for creating graphs and
tables for reports and for statistically analysing the results. When
the appropriate PHREEQC simulation output file is selected and
imported, the results will be displayed in a spreadsheet. These
results canbe copied and pasted to other Windows applications or
imported into your AquaChem database. |
Documentation
AquaChem is accompanied by a comprehensive user's manual
containing easy-to-follow instructions and a step-by-step tutorial. Free
technical support is provided by phone, fax or email.
Hardware Requirements
- PC 486DX or Pentium
- 16Mb RAM
- 15Mb free disk space
- XVGA display (1024x768) and mouse
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