Major-Ion and Conductance Toolbo

Overview
This product is a CD containing a Microsoft Excel spreadsheet in which you enter your major-ion concentrations,
specific conductance, pH, and a few other constituents if they are available. The spreadsheet will automatically compute several numbers
that can be used to review or to interpret the major ion data. A new, proprietary algorithm computes specific conductance from the major-ion
concentrations over a wide range of concentrations and specific conductance. The algorithm has been tested from about 30 to 54,000 microsiemens
per centimeter at 25 degrees Celsius and appears to be accurate within a few percent. The CD also contains files with (1) user instructions
with explanation of the computations and other output, (2) a general overview of major-ion review, and (3) a disclaimer.

The concentration-conductance relationship adds considerable rigor to the quality assurance review of major-ion and conduct-

ance data. In some cases, likely errors can be can be identified. It may be possible to identify likely errors down to the field specific

conductance, laboratory specific conductance, cations, anions, or to specific groups of cations or anions. An expert system will

in some cases, show a brief text comment that offers the most likely error. If there are no errors within the default criteria, the

expert system will leave the cells empty. Some of the default criteria are based on U.S. Geological Survey criteria
(Blackburn, 1992). Other criteria are based on the judgment of Ronald L. Miller. Most criteria can be changed from
the default limits to accommodate data of different quality from different laboratories or time periods.

Some features

● For each water sample, each constituent's value is entered into its own cell in a horizontal row with identifying information. To do a
meaningful quality assurance check, it is best to have at least sodium, potassium, calcium, magnesium, chloride, sulfate, alkalinity,
specific conductance, and pH. For some water samples, concentrations of other constituents, such as strontium, lithium,
ammonium, iron, manganese, nitrate, fluoride, bromide, phosphate, and dissolved organic carbon (DOC) are needed to get good ionic balances.

● The program computes a total dissolved solid concentration as the sum of the measured concentrations. Silica may be a significant

part of the dissolved solids that can be entered into the spreadsheet to improve comparisons to laboratory measures of total dissolved solids (TDS)
as a residue left after the evaporation of the water from a known volume of sample water.

● Up to 24 calculations may be done on the input data. They include the percentage difference between lab and field specific conduct-

ance, cation sum, anion sum, ionic sum predicted from specific conductance (using major-ion data for water type), percentage differ-

ence between the cation sum and the predicted ionic sum, percentage difference between the anion sum and the predicted ionic sum,

specific conductance predicted from major-ion concentrations, percentage difference between the field specific conductance and the

predicted specific conductance, percentage difference between the laboratory specific conductance and the predicted specific conduct-

ance, percent mineral imbalance (PMI) developed by Miller and Sutcliffe (1984, p. 34) and two terms DIA and DIIA associated with PMI,

calculated TDS, ratio of the calculated TDS to the TDS measured by evaporation of sample water, the dominant cation (based on milli-

equivalents per liter), the dominant anion, and a few other calculations.

The expert system has 12 columns in which possible errors or comments about constituent values are shown if an apparent inconsistency
with the rest of the sample data exists. If no apparent inconsistencies exist, within the critieria, the cell is left empty.

§Definition - A major constituent (some of which are ions) are those constituents commonly present at concentrations exceeding 1.0
milligrams per liter (Hem, 1992, p. 54, http://pubs.usgs.gov/wsp/wsp2254/html/pdf.html )