Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
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New reference materials for nitrogen-isotope-ratio measurements
Three new reference materials were manufactured for calibration of relative stable nitrogen‐isotope‐ratio measurements:USGS25 (ammonium sulfate) δ615″=−30 per milUSGS26 (ammonium sulfate) δ615″=+54 per milUSGS32 (potassium nitrate) δ615″=+180 per milwhere δN′, relative to atmospheric nitrogen, is an approximate value subject to change following interlaboratory comparisons. These materials are isot
Authors
John K. Böhlke, C. J. Gwinn, T. B. Coplen
Application of borehole geophysics in defining the wellhead protection area for a fractured crystalline bedrock aquifer
Wellbore geophysical techniques were used to characterize fractures and flow in a bedrock aquifer at a site near Blackwater Brook in Dover, New Hampshire. The primary focus ofthis study was the development of a model to assist in evaluating the area surrounding a planned water supply well where contaminants introduced at the land surface might be induced to flow towards a pumping well. Well logs a
Authors
J.H. Vernon, F.L. Paillet, W.H. Pedler, W.J. Griswold
An efficient numerical solution of the transient storage equations for solute transport in small streams
Several investigators have proposed solute transport models that incorporate the effects of transient storage. Transient storage occurs in small streams when portions of the transported solute become isolated in zones of water that are immobile relative to water in the main channel (e.g., pools, gravel beds). Transient storage is modeled by adding a storage term to the advection-dispersion equatio
Authors
Robert L. Runkel, Steven C. Chapra
The effect of streambed topography on surface-subsurface water exchange in mountain catchments
A numerical hydrological simulation suggested that water exchange between stream channels and adjacent aquifers is enhanced by convexities and concavities in streambed topography. At St. Kevin Gulch, an effluent stream in the Rocky Mountains of Colorado, subsurface hydraulic gradients and movement of ionic tracers indicated that stream water was locally recharged into well-defined flow paths throu
Authors
Judson W. Harvey, Kenneth E. Bencala
A perspective on stream-catchment connections
Ecological study of the hyporheic zone is leading to recognition of a need for additional hydrologic understanding. Some of this understanding can be obtained by viewing the hyporheic zone as a succession of isolated boxes adjacent to the stream. Further understanding, particularly relevant to catchment-scale ecology, may come from studies focussed on the fluid mechanics of the flow-path connectio
Authors
Kenneth E. Bencala
Monte Carlo simulations of multiphase flow incorporating spatial variability of hydraulic properties
To study the effect of spatial variability of sediment hydraulic properties on multiphase flow, oil infiltration into a hypothetical glacial outwash aquifer, followed by oil extraction, was simulated using a cross-sectional multiphase flow model. The analysis was simplified by neglecting capillary hysteresis. The first simulation used a uniform mean permeability and mean retention curve. This was
Authors
Hedeff I. Essaid, Kathryn M. Hess
Nonpoint source contamination of the Mississippi river and its tributaries by herbicides
A study of the Mississippi River and its tributaries during July-August 1991, October-November 1991, and April-May 1992 has indicated that the entire navigable reach of the river is contaminated with a complex mixture of agrochemicals and their transformation products derived from nonpoint sources. Twenty-three compounds were identified, including triazine, chloroacetanilide, thiocarbamate, phenyl
Authors
W. E. Pereira, F. D. Hostettler
Stable isotope enrichment in paleowaters of the southeast Atlantic coastal plain, United States
Paleowaters from the Floridan aquifer system in the southeastern Atlantic coastal plain have higher D/H and 18O/16O ratios than local Holocene ground water. Maximum δ18O enrichments in ground water having adjusted radiocarbon ages of 20,000 to 26,000 years are 0.7 to 2.3 per mil. The trend in isotopic enrichment in paleowaters is the reverse of that normally observed in continental glacial age gro
Authors
Niel Plummer
Meromixis in hypersaline Mono Lake, California. 3. Biogeochemical response to stratification and overturn
Mono Lake is a terminal, saline lake that became ectogenically meromictic in 1982–1983 and remained stratified until November 1988. During this period, the monimolimnion remained anoxic and nearly isothermal, while the upper mixolimnion was well oxygenated and exhibited a seasonal thermal regime. Dissolved sulfide and methane increased in the monimolimnion as a result of diffusive flux from the se
Authors
Laurence G. Miller, R. Jellison, Ronald S. Oremland, Charles W. Culbertson
Isolation and chemical characterization of dissolved and colloidal organic matter
Commonly used techniques for the concentration and isolation of organic matter from water, such as preparative chromatography, ultrafiltration and reverse osmosis, and the methods used to analyze the organic matter obtained by these methods are reviewed. The development of methods to obtain organic matter that is associated with fractions of the dissolved organic carbon other than humic substances
Authors
G. Aiken, J. Leenheer
Sorption of N2 and EGME vapors on some soils, clays, and mineral oxides and determination of sample surface areas by use of sorption data
Vapor sorption isotherms of ethylene glycol monoethyl ether (EGME) at room temperature and isotherms of N2 gas at liquid nitrogen temperature were determined for various soils and minerals. The N2 monolayer capacities [Qm (N2)] were calculated from the BET equation and used to determine the surface areas. To examine whether EGME is an appropriate adsorbate for determination of surface areas, the a
Authors
C. T. Chiou, D.W. Rutherford, M. Manes
Atrazine degradation in a small stream in Iowa
A study was conducted during 1990 through an 11.2-km reach of Roberts Creek in northeastern Iowa to determine the fate of atrazine in a surface water environment Water samples were collected at ~1-month intervals from April through November during stable low to medium flow conditions and analyzed for atrazine and two of its initial biotic degradation products, desethylatrazine and deisopropylatraz
Authors
D.W. Kolpin, S. J. Kalkhoff