Publications

The Little River, an ephemeral stream that drains a watershed of approximately 88 km2 in northern Florida, disappears into a series of sinkholes along the Cody Scarp and flows directly into the carbonate Upper Floridan aquifer, the source of water supply in northern Florida. The changes in the geochemistry of ground water caused by a major recharge pulse from the sinking stream were...

The contribution of hydroxylated atrazine degradation products (HADPs) to the total atrazine load (i.e., atrazine plus stable metabolites) in streams needs to be determined in order to fully assess the impact of atrazine contamination on stream ecosystems and human health. The objectives of this study were (1) to determine the contribution of HADPs to the total atrazine load in streams...

A natural-gradient tracer test was conducted in an unconfined sand and gravel aquifer on Cape Cod, Massachusetts. Molybdate was included in the injectate to study the effects of variable groundwater chemistry on its aqueous distribution and to evaluate the reliability of laboratory experiments for identifying and quantifying reactions that control the transport of reactive solutes in...

Metal concentrations of the soluble fraction of the cytoplasm (cytosol) and the whole body were determined in the caddisfly Hydropsyche spp. (Trichoptera). Metal accumulation in the cytosol and the whole body were compared in samples collected along 380 kms of a contamination gradient in the Clark Fork river in four consecutive years (1992–1995), and from a contaminated tributary (Flint...

Two experiments were performed to investigate flow beneath an ephemeral stream and to estimate streambed infiltration rates. Discharge and stream-area measurements were used to determine infiltration rates. Stream and subsurface temperatures were used to interpret subsurface flow through variably saturated sediments beneath the stream. Spatial variations in subsurface temperatures...

From July 1994 through May 1997, the U.S. Geological Survey in cooperation with the Department of Energy, sampled 86 wells completed in the Snake River Plain aquifer at and near the Idaho N ationa1 Engineering and Environmental Laboratory (INEEL). The wells were sampled for a variety of constituents including one- and two-carbon halocarbons. Concentrations of dichlorodifluoromethane (CFC...

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No abstract available.

A long-term perspective of erosion and deposition in San Francisco Bay is vital to understanding and managing wetland change, harbor and channel siltation, and other sediment-related phenomena such as particle and particle-associated substance (pollutants, trace metals, etc.) transport and deposition. A quantitative comparison of historical hydrographic surveys provides this perspective...

This report documents the application of nonlinear-regression methods to a numerical model of ground-water flow in the Albuquerque Basin, New Mexico. In the Albuquerque Basin, ground water is the primary source for most water uses. Ground-water withdrawal has steadily increased since the 1940's, resulting in large declines in water levels in the Albuquerque area. A ground-water flow...

The lithology and fracture network of the bedrock aquifer in the Mirror Lake area were characterized from hydrogeologic data collected from 1979-95 in Grafton County, N.H. The collection of these data is an integral part of an ongoing multidisciplinary study by the U.S. Geological Survey to characterize groundwater flow and solute transport in fractured rock. The data provide a physical...

No abstract available.