Publications
Dive into our publications and explore the science from the Environmental Health Program (Toxic Substances Hydrology and Contaminant Biology).
Filter Total Items: 3787
Anaerobic mineralization of vinyl chloride in Fe(III)-reducing, aquifer sediments
Within anaerobic aquifer systems, reductive dehalogenation of polychlorinated ethenes commonly results in the accumulation of vinyl chloride, which is highly toxic and carcinogenic to humans. Anaerobic reduction of vinyl chloride is considered to be slow and incomplete. Here, we provide the first evidence for anaerobic oxidation of vinyl chloride under Fe(III)reducing conditions. Addition of chela
Authors
P. M. Bradley, F. H. Chapelle
Effects of sampling strategies on estimates of annual mean herbicide concentrations in midwestern rivers
The effects of 10 sampling strategies on estimates of annual mean concentrations of the herbicides atrazine, alachlor, and cyanazine in selected midwestern rivers were tested. The accuracy of the strategies was computed by comparing time-weighted annual mean herbicide concentrations calculated from water samples collected from 17 locations on midwestern rivers, with simulated annual mean concentra
Authors
W.A. Battaglin, L.E. Hay
Comparison of denitrification activity measurements in groundwater using cores and natural-gradient tracer tests
The transport of many solutes in groundwater is dependent upon the relative rates of physical flow and microbial metabolism. Quantifying rates of microbial processes under subsurface conditions is difficult and is most commonly approximated using laboratory studies with aquifer materials. In this study, we measured in situ rates of denitrification in a nitrate-contaminated aquifer using small-scal
Authors
R. L. Smith, S. P. Garabedian, M. H. Brooks
Reactive solute transport in streams: 1. Development of an equilibrium- based model
An equilibrium-based solute transport model is developed for the simulation of trace metal fate and transport in streams. The model is formed by coupling a solute transport model with a chemical equilibrium submodel based on MINTEQ. The solute transport model considers the physical processes of advection, dispersion, lateral inflow, and transient storage, while the equilibrium submodel considers t
Authors
Robert L. Runkel, Kenneth E. Bencala, Robert E. Broshears, Steven C. Chapra
Fate of linear alkylbenzene sulfonate in the Mississippi River
The 2 800-km reach of the Mississippi River between Minneapolis, MN, and New Orleans, LA, was examined for the occurrence and fate of linear alkylbenzene sulfonate (LAS), a common anionic surfactant found in municipal sewage effluents. River water and bottom sediment were sampled in the summer and fall of 1991 and in the spring of 1992. LAS was analyzed using solid-phase extraction/derivatization/
Authors
C.F. Tabor, L.B. Barber
Direct simulation of groundwater age
A new method is proposed to simulate groundwater age directly, by use of an advection-dispersion transport equation with a distributed zero-order source of unit (1) strength, corresponding to the rate of aging. The dependent variable in the governing equation is the mean age, a mass-weighted average age. The governing equation is derived from residence-time-distribution concepts for the case of st
Authors
Daniel J. Goode
Reactive solute transport in streams: 2. Simulation of a pH modification experiment
We present an application of an equilibrium-based solute transport model to a pH-modification experiment conducted on the Snake River, an acidic, metal-rich stream located in the Rocky Mountains of Colorado. During the experiment, instream pH decreased from 4.2 to 3.2, causing a marked increase in dissolved iron concentrations. Model application requires specification of several parameters that ar
Authors
Robert L. Runkel, Diane M. McKnight, Kenneth E. Bencala, Steven C. Chapra
Observed and simulated movement of bank-storage water
Detailed hydrologic and water-chemistry data were collected that document the movement of bank-storage water during March 7-April 17, 1990, in an alluvial aquifer adjacent to the Cedar River, Iowa. Hydrologic data included 745 daily ground-water-level measurements from 27 observation wells. Water-chemistry data indicate that bank-storage water had smaller specific conductance and larger concentrat
Authors
P. J. Squillace
The relationships among three habitat scales and stream benthic invertebrate community structure
1. The relationships between three habitat scales and lotic invertebrate species composition were investigated for the 15 540 km2 Yakima River basin in south-central Washington, U.S.A.
2. The three spatial scales were sample (the sampled riffle), reach (a length of ten–twenty stream widths) and segment (a length of stream of nearly uniform slope and valley form having no change in stream order).
3
Authors
J.L. Carter, S.V. Fend, S.S. Kennelly
Near field receiving water monitoring of trace metals in clams (Macoma balthica) and sediments near the Palo Alto and San Jose/Sunnyvale Water Quality Control Plants in South San Francisco Bay: December 1994 - December 1995
No abstract available.
Authors
S. N. Luoma, D.J. Cain, C. Brown, M. Hornberger, R. Bouse
U.S. Geological Survey Nitrogen-Cycling Workshop: Denver, Colorado October 30 - November 2, 1995
No abstract available.
Authors
Frank J. Triska
Using a geographic information system and scanning technology to create high-resolution land-use data sets
A geographic information system (GIS) procedure was developed to compile low-altitude aerial photography, digitized data, and land-use data from U.S. Department of Agriculture Consolidated Farm Service Agency (CFSA) offices into a high-resolution (approximately 5 meters) land-use GIS data set. The aerial photography consisted of 35-mm slides which were scanned into tagged information file format (
Authors
Craig A. Harvey, Dana W. Kolpin, William A. Battaglin