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Pulse-chase experiments show that two marine bivalves take optimal advantage of different types of particulate food by varying food retention time in a flexible two-phase digestive system. For example, carbon is efficiently assimilated from bacteria by subjecting nearly all the ingested bacteria to prolonged digestion. Prolonging digestion also enhances assimilation...

An important part of the water supply in the western United States is derived from runoff fed by mountain snowmelt Snow accumulation responds to both precipitation and temperature variations, and forms an interesting climatic index, since it integrates these influences over the entire late fall-spring period. Here, effects of cool...

No abstract available....

No abstract available...

Biogeochemical studies in small watersheds provide an analytical approach to understand how ecosystems respond to natural climatic variations and human-induced environmental change. Small watersheds, usually less than 5 km2, are small enough to permit characterization and understanding of ecosystem processes within relatively simple, homogeneous biological and physical settings; yet they are large enough to...

Laboratory, field, and digital solute-transport- modeling studies demonstrate that microorganisms indigenous to the shallow ground-water system at Laurel Bay Exchange, Marine Corps Air Station Beaufort, South Carolina, can degrade petroleum hydrocarbons in gasoline released at the site. Microorganisms in aquifer sediments incubated in the laboratory under aerobic and anaerobic conditions...

Bottomland hardwood forests are distributed along rivers and streams throughout the central and eastern United States, with the greatest concentration in the Southeast. Past and projected losses of bottomland hardwoods and degradation of remaining stands suggest that habitat management and/or restoration strategies that target multiple species and multiple uses will...

A 4-year investigation of the Upper Floridan aquifer and ground-water flow system in Leon County, Florida, and surrounding counties of north-central Florida and southwestern Georgia began in 1990. The purpose of the investigation was to describe the ground-water flow system and to delineate the contributing areas to selected City of...

The Upper Mississippi River Basin is diverse in ways that can control the areal distribution and flow of water and the distribution and concentration of constituents that affect water quality. A review of the environmental setting of the Upper Mississippi River Basin study unit of the National Water-Quality Assessment Program...

The occurrence of volatile organic compounds (VOCs) in water is of national concern because of their relatively high aqueous solubility, mobility, and persistence, because many are known or suspected carcinogens, because of their widespread use, and because they have been found in drinking-water supplies. Because of this national concern, VOCs...

Methods for estimating low-flow frequency characteristics at ungaged sites were developed for two areas in northern Florida. In the Yellow, Blackwater, Escambia, and Perdido River Basins study area (northwestern Florida), regional regression equations were developed for estimating the 7- and 30-day, 2- and 10-year low-flow characteristic (Q7,2, Q7,10, Q30,2, and...

Large chloride concentrations in Arkansas River water have the potential to degrade water quality in the adjacent Equus beds aquifer between Hutchinson and Wichita, Kansas. The aquifer is an important source of water for municipal, industrial, agricultural, and domestic uses. A three-dimensional, finite-difference, ground-water flow-model program (MODFLOW) was used with...

Investigations were conducted in Arizona during the early 1980's to obtain hydrologic data in order to deliver 30,000 acre-feet of water annually to the Ak-Chin Indian Reservation. A recharge experiment produced infiltration rates for an ephemeral stream channel that ranged from 0.64 to 1.09 cubic feet per second per 1,000...

Estimates of flow-duration and low-flow characteristics for the period of record at continuous-record streamflow stations are essential in hydrologic studies and water-resources management. This report provides flow-duration information, in the form of characteristics of the cumulative distribution function of the daily streamflow record, for 215 continuous-record streamflow stations. The report...

The U.S. Geological Survey (USGS), in cooperation with the Tennessee Department of Agriculture, began a long-term scientific investigation in 1989 to evaluate the effect of agricultural activities on water quality and the effectiveness of agricultural best management practices in the Beaver Creek watershed, West Tennessee. In 1993 as a part...

No abstract available....

Physical and chemical-related properties, concentrations of chemical constituents, which included major ions and nutrients, and concentrations of fecal-coliform bacteria were determined for 17 sites on 11 streams in St. Tammany Parish, Louisiana, during the period April-August 1995. The streams were sampled to assess the effects of different streamflow conditions...

The city of Sarasota, Florida, operates a downtown well field that pumps mineralized water from ground water sources to supply a reverse osmosis plant. Because of the close proximity of the well field to Sarasota Bay and the high sulfate and chloride concentrations of ground-water supplies, a growing concern exists...

Hydrologic and water-quality data were collected from a precipitation-collection station and from two small watersheds on Catoctin Mountain, north-central Maryland, as part of investigations of acidic deposition and episodic acidification, and their effects on streamwater quality. Detailed descriptions of the site instrumentation in the watersheds, field data-collection techniques, and laboratory...

This report presents the results of a study conducted at Picatinny Arsenal, Morris County, New Jersey, to (1) determine whether streambed sediments in Green Pond Brook and its tributaries are contaminated with inorganic or organic constituents, (2) determine the extent of contamination in those reaches, and (3) characterize the quality...

The surface-water hydrology in Clear, Clarks, and Clover Creek Basins in central Pierce County, Washington, is described with a conceptual model of the runoff processes and then simulated with the Hydrological Simulation Program-FORTRAN (HSPF), a continuous, deterministic hydrologic model. The study area is currently undergoing a rapid conversion of rural,...

Commercial and industrial activities in the Railroad Industrial Area in Fairbanks, Alaska, have resulted in accidental releases of chemicals to the subsurface. Such releases have generated concern regarding local ground-water quality and the potential impact on nearby water-supply wells. Consequently, a study is being conducted to characterize the environmental and...

This report describes the status of ground-water resources at U.S. Navy Support Facility, Diego Garcia. Data presented are from January 1994 through March 1996, with a focus on data from January through March 1996 (first quarter of 1996). A complete database of ground-water withdrawals and chloride-concentration records since 1985 is...

Ground-water resources are the only source of water in most of the San Juan structural basin and are mainly used for municipal, industrial, domestic, and stock purposes. Industrial use increased dramatically during the late 1970's and early 1980's because of increased exploration and development of uranium and coal resources....