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At least 127 records · Page 7Linked to original sources
USGS1976

WATEQF; a FORTRAN IV version of WATEQ : a computer program for calculating chemical equilibrium of natural waters

WATEQF is a FORTRAN IV computer program that models the thermodynamic speciation of inorganic ions and complex species in solution for a given water analysis. The original version (WATEQ) was written in 1973 by A. H. Truesdell and B. F. Jones in Programming Language/one (PL/1.) With but a few exceptions, the thermochemical data, speciation, coefficients, and general calculation procedure of WATEQF is identical to the PL/1 version. This report notes the differences between WATEQF and WATEQ, demonstrates how to set up the input data to execute WATEQF, provides a test case for comparison, and makes available a listing of WATEQF. (Woodard-USGS)

Water-Resources Investigations Report↗
USGS1965

Determination of uranium in natural waters

A method is described for the determination of very low concentrations of uranium in water. The method is based on the fluorescence of uranium in a pad prepared by fusion of the dried solids from the water sample with a flux of 10 percent NaF 45.5 percent Na2CO3 , and 45.5 percent K2CO3 . This flux permits use of a low fusion temperature and yields pads which are easily removed from the platinum fusion dishes for fluorescence measurements. Uranium concentrations of less than 1 microgram per liter can be determined on a sample of 10 milliliters, or less. The sensitivity and accuracy of the method are dependent primarily on the purity of reagents used, the stability and linearity of the fluorimeter, and the concentration of quenching elements in the water residue. A purification step is recommended when the fluorescence is quenched by more than 30 percent. Equations are given for the calculation of standard deviations of analyses by this method. Graphs of error functions and representative data are also included.

Water Supply Paper↗
USGS1979

Concentration and fractionation of hydrophobic organic acid constituents from natural waters by liquid chromatography

A scheme is presented which used adsorption chromatography with pH gradient elution and size-exclusion chromatography to concentrate and separate hydrophobic organic acids from water. A review of chromatographic processes involved in the flow scheme is also presented. Organic analytes which appear in each aqueous fraction are quantified by dissolved organic carbon analysis. Hydrophobic organic acids in a water sample are concentrated on a porous acrylic resin. These acids usually constitute approximately 30-50 percent of the dissolved organic carbon in an unpolluted water sample and are eluted with an aqueous eluent (dilute base). The concentrate is then passed through a column of polyacryloylmorpholine gel, which separates the acids into high- and low-molecular-weight fractions. The high- and low-molecular-weight eluates are reconcentrated by adsorption chromatography, then are eluted with a pH gradient into strong acids (predominately carboxylic acids) and weak acids (predominately phenolic compounds). For standard compounds and samples of unpolluted waters, the scheme fractionates humic substances into strong and weak acid fractions that are separated from the low molecular weight acids. A new method utilizing conductivity is also presented to estimate the acidic components in the methanol fraction.

Water Supply Paper↗
USGS1940

Natural water loss in selected drainage basins

Determinations of areal rainfall, run-off, and water loss, comprising largely evaporation from land surfaces and transpiration by vegetation, are essential in indicating the hydrologic characteristics of river basins. This report is primarily a statistical study that presents the results of computations of annual water loss, or annual rainfall minus annual run-off, for river basins in the humid or semiarid regions east of the Rocky Mountains. The basic period for which the computations are made is the water year or year ending September 30. As it is impractical to present in this report all the basic data used in arriving at the results, only sample computations are given. The various steps in the computations and the probable accuracy of the results are discussed. The drainage areas for which data are presented are those above river-measuring stations that have records for 3 years or more. For each area there are determinations of annual rainfall, annual run-off, and annual water loss for each year of record .as well as the means for the period of record. Results are given for about 200 drainage areas with an aggregate period of record of more than 2,000 years. As an illustration of the magnitude involved, the annual water loss from the eastern streams draining directly into the Atlantic Ocean varies more or less closely with latitude from about 20 inches as an average in northern New England to about 30 inches in Georgia. As the annual water loss from a basin is affected by the temperature, a supplemental study was made of the relation between water loss and temperature. For 28 drainage areas selected in various parts 8f eastern and central United States, average temperatures were computed for each year of the period shown in table 1. The results indicate a relation between average annual water loss and average annual temperature.

Water Supply Paper↗
USGS1989

Mineral saturation states in natural waters and their sensitivity to thermodynamic and analytical errors

Saturation indices computed with WATEQ4F chemical analyses from a groundwater in crystalline bedrock and a surface water receiving acid mine drainage are frequently at or above saturation with respect to calcite, fluorite, barite, gibbsite and ferrihydrite. Deep granitic groundwaters from Stripa, Sweden, are supersaturated with respect to calcite and fluorite. Acid mine waters from the Leviathan Mine drainage basin in California are supersaturated with respect to barite by about a factor of three. These mine waters also are 10 times supersaturated with respect to the most soluble form of ferric hydroxide but are near saturation with respect to microcrystalline gibbsite. A sensitivity analysis has been performed by varying the analytic and thermodynamic parameters for which the saturation indices are most sensitive. For calcite, fluorite and barite, the supersaturation effect appears to be real because it is only slightly decreased by sources of uncertainty. Apparent supersaturation for gibbsite is most likely caused by the degree of crystallinity on solubility behavior. Apparent supersaturation for ferric hydroxide is likely caused by small colloidal particles (< 0.1 µ m) in the water sample that cannot be removed by standard field filtration, although several other possible explanations cannot be easily excluded.

Science Geological Bulletin↗
USGS1993

Methods of analysis by the U.S. Geological Survey National Water Quality Laboratory-Determination of low-level silver by graphite furnace atomic absorption spectrophotometry

Increased awareness of the quality of water in the United States has led to the development of a method for determining low levels (0.2-5.0 microg/L) of silver in water samples. Use of graphite furnace atomic absorption spectrophotometry provides a sensitive, precise, and accurate method for determining low-level silver in samples of low ionic-strength water, precipitation water, and natural water. The minimum detection limit determined for low-level silver is 0.2 microg/L. Precision data were collected on natural-water samples and SRWS (Standard Reference Water Samples). The overall percent relative standard deviation for natural-water samples with silver concentrations more than 0.2 microg/L was less than 40 percent throughout the analytical range. For the SRWS with concentrations more than 0.2 microg/L, the overall percent relative standard deviation was less than 25 percent throughout the analytical range. The accuracy of the results was determined by spiking 6 natural-water samples with different known concentrations of the silver standard. The recoveries ranged from 61 to 119 percent at the 0.5-microg/L spike level. At the 1.25-microg/L spike level, the recoveries ranged from 92 to 106 percent. For the high spike level at 3.0 microg/L, the recoveries ranged from 65 to 113 percent. The measured concentrations of silver obtained from known samples were within the Branch of Quality Assurance accepted limits of 1 1/2 standard deviations on the basis of the SRWS program for Inter-Laboratory studies.

Open-File Report↗