Publications

No abstract available.

Water and streambed-sediment samples were collected on March 9 and 10,1987 from one site upstream and three sites downstream of the discharge from a municipal wastewater-treatment plant on Rowlett Creek near Dallas, Texas. To extract and separate organic compounds, purgeand-trap, closed-loop stripping, and pH-adjusted solvent extraction methods were used for water samples; and a Soxhlet-solvent ex

As part of its primary responsibility concerning water as a national resource, the U.S. Geological Survey collects and analyzes samples of ground water and surface water to determine water quality. This report describes the method used since June 1987 to determine selected total-recoverable carbamate pesticides present in water samples. High- performance liquid chromatography is used to separate N

This Services Catalog contains information about field supplies and analytical services available from the National Water Quality Laboratory in Denver, Colo., and field supplies available from the Quality Water Service Unit in Ocala, Fla., to members of the U.S. Geological Survey's Water Resources Division. To assist personnel in the selection of analytical services, this catalog lists sample volu

The National Water Quality Laboratory determines organic and inorganic constituents in samples of surface and ground water, river and lake sediment, aquatic plant and animal material, and precipitation collected throughout the United States and its territories by the U.S. Geological Survey. In water year 1994, the Laboratory produced more than 900,000 analytical results for about 65,000 samples. T

The National Water Quality Laboratory (NWQL) offers a variety of analytical services for the determination of constituents in samples of water, sediment, and biological material. As technology has advanced, many new methods have been introduced but not always incorporated into plans and schedules developed in the districts. The strengths and weaknesses of many different techniques are discussed an

Organic explosives are determined in samples of ground water and surface water with emphasis on identifying and quantifying trinitrotoluene (TNT) metabolites. Water samples are filtered to remove suspended particulate material and passed through a polystyrene divinylbenzene-packed cartridge by a vacuum-extraction system. The target analytes subsequently are eluted with acetonitrile. A high-perf

No abstract available.

On March 15, 1979, four moderate earthquakes (ML 4.9, 5.3, 4.5, 4.8) occurred in the Homestead Valley area of the Mojave Desert (Figure 1). At that time, they were noteworthy for a vigorous aftershock sequence and for off-fault epicentral locations that formed a cruciform pattern (Hutton, et al., 1980; Stein and Lisowski, 1983). More recently, there is renewed interest in the Homestead Valley sequ

All inorganic and organic methods for analyzing samples of water and fluvial sediment, which have been approved for use by the U.S. Geological Survey from 1954 to the present (1994), are listed. Descriptive method names include references to published reports for easy retrieval of methodology. The year each method was approved is listed as well as the year the method was discontinued. Inorganic an

Twenty-two bottom-sediment samples were collected from Town Lake in Austin, Texas, in 1991 and 1992 and analyzed for chlorinated insecticides by a reconnaissance-quality, electron-capture gas chromatography screening method developed by the U.S. Geological Survey (USGS). Four different chlorinated insecticides (aldrin, chlordane, dieldrin, and p,p'-DDT) and two degradation products of p,p'-DDT (p,

Graphite furnace atomic absorption spectrophotometry is a sensitive, precise, and accurate method for the determination of chromium in natural water samples. The detection limit for this analytical method is 0.4 microg/L with a working linear limit of 25.0 microg/L. The precision at the detection limit ranges from 20 to 57 percent relative standard deviation (RSD) with an improvement to 4.6 percen