Publications

The U.S. Geological Survey computer model to simulate two-dimensional solute transport and dispersion in ground water (Konikow and Bredehoeft, 1978; Goode and Konikow, 1989) has been modified to improve management of input and output data and to provide progressive run-time information. All opening and closing of files are now done automatically by the program. Names of input data files...

Particulate matter was collected at Rio Vista, California, in two study periods; the first, from January 3 to May 26, 1983; the second from October 31, 1983 to November 29, 1984. Concentrations of suspended particulate matter were measured gravimetrically on silver membrane filters. The pooled standard deviation on replicated samples was 1.4 mg/L, giving a coefficient of variation of 5.7...

The U.S. Geological Survey conducted hydrologic investigations in San Francisco Bay between October 1991 and November 1993. Dissolved inorganic plant nutrients, nitrate, nitrite, ammonium, silica, and reactive phosphorus were measured in surface and in near-bottom waters at previously established locations in both northern and southern reaches of the bay. Salinity, turbidigy, and...

The commonly used analytical solution developed by Neuman for a homogeneous, water-table aquifer assumes that the drainage of pores in the zone above the water table due to lowering of the water table occurs instantaneously. Noninstantaneous drainage of pores in the unsaturated zone accounts for the finding that both type-curve analysis and volume-balance calculations yield values of...

The number- and weight-averaged molecular weights of a number of aquatic fulvic acids, a commercial humic acid, and unfractionated organic matter from four natural water samples were measured by high-pressure size exclusion chromatography (HPSEC). Molecular weights determined in this manner compared favorably with those values reported in the literature. Both recent literature values and...

Sorption of tetra- and pentachlorobenzene by sediment from a glacial outwash aquifer on Cape Cod, MA, was evaluated. Particle size and mineralogical fractions (separated based on paramagnetic susceptibility) were characterized with respect to sediment organic carbon (SOC), mineralogy, surface area, metal oxide coatings, and spatial variability. SOC increases by a factor of 10 as particle...

No abstract available.

No abstract available.

Ground-water quality was assessed in a 5,000-square-mile area of the High Plains aquifer in south-central Kansas that is susceptible to nonpoint-source contamination from agricultural and petroleum-production activities. Of particular interest was the presence of agricultural chemicals and petroleum-derived hydrocarbons that might have been associated with brines that formerly were...

NETPATH is an interactive Fortran 77 computer program used to interpret net geochemical mass-balance reactions between an initial and final water along a hydrologic flow path. Alternatively, NETPATH computes the mixing proportions of two to five initial waters and net geochemical reactions that can account for the observed composition of a final water. The program utilizes previously...

A geohydrologic investigation was performed by the U.S. Geological Survey, in cooperation with the U.S. Environmental Protection Agency, to determine the distribution of volatile organic compounds in a fractured-rock aquifer near the Southeast Rockford Groundwater Contamination Site in Rockford, Ill. The geologic units of concern are the St. Peter Sandstone and Glenwood Formation; the...

No abstract available.