Copper speciation and binding by organic matter in copper-contaminated streamwater
R.F. Breault, J.A. Colman, G. R. Aiken, D. McKnight
1996, Environmental Science & Technology (30) 3477-3486
Fulvic acid binding sites (1.3−70 μM) and EDTA (0.0017−0.18 μM) accounted for organically bound Cu in seven stream samples measured by potentiometric titration. Cu was 84−99% organically bound in filtrates with 200 nM total Cu. Binding of Cu by EDTA was limited by competition from other trace...
Bacterial dissimilatory reduction of arsenic(V) to arsenic(III) in anoxic sediments
P.R. Dowdle, A.M. Laverman, R.S. Oremland
1996, Applied and Environmental Microbiology (62) 1664-1669
Incubation of anoxic salt marsh sediment slurries with 10 mM As(V) resulted in the disappearance over time of the As(V) in conjunction with its recovery as As(III). No As(V) reduction to As(III) occurred in heat- sterilized or formalin-killed controls or in live sediments incubated in air. The rate of As(V)...
Identification of a new sulfonic acid metabolite of metolachlor in soil
D.S. Aga, E.M. Thurman, M.E. Yockel, L.R. Zimmerman, T.D. Williams
1996, Environmental Science & Technology (30) 592-597
An ethanesulfonic acid metabolite of metolachlor (metolachlor ESA) was identified in soil-sample extracts by negative-ion, fast-atom bombardment mass spectrometry (FAB-MS) and FAB tandem mass spectrometry (FAB-MS/MS). Production fragments from MS/MS analysis of the deprotonated molecular ion of metolachlor ESA in the soil extract can be reconciled with the structure of...
Processes affecting the fate of monoaromatic hydrocarbons in an aquifer contaminated by crude oil
R.P. Eganhouse, T.F. Dorsey, C.S. Phinney, A.M. Westcott
1996, Environmental Science & Technology (30) 3304-3312
Crude oil spilled from a subsurface pipeline in north-central Minnesota has dissolved in the groundwater, resulting in the formation of a plume of aliphatic, aromatic, and alicyclic hydrocarbons. Comparison of paired oil and groundwater samples collected along the central axis of the residual oil body shows that the trailing edge...
Little Ice Age evidence from a south-central North American ice core, U.S.A.
D. L. Naftz, R.W. Klusman, R. L. Michel, P. F. Schuster, M.M. Ready, Howard E. Taylor, T.M. Yanosky, E.A. McConnaughey
1996, Arctic and Alpine Research (28) 35-41
In the past, ice-core records from mid-latitude glaciers in alpine areas of the continental United States were considered to be poor candidates for paleoclimate records because of the influence of meltwater on isotopic stratigraphy. To evaluate the existence of reliable paleoclimatic records, a 160-m ice core, containing about 250 yr...
Localized alteration of the paintbrush nonwelded hydrologic unit within the exploratory studies facility
Z. E. Peterman, R.W. Spengler, F.R. Singer, S.C. Beason
1996, Conference Paper, High Level Radioactive Waste Management - Proceedings of the Annual International Conference
The mound-like feature in the lower part of the PTn, composed of highly disrupted strata and open-system alteration were the result of intense water-rock interaction. This feature was formed by fumarolic activity during cooling of the 12.8 Ma Topopah Spring Tuff and prior to deposition of the pre-Pah Canyon bedded...
Simulation of phosphate transport in sewage-contaminated groundwater, Cape Cod, Massachusetts
K.G. Stollenwerk
1996, Applied Geochemistry (11) 317-324
Sewage-contaminated groundwater currently discharges to Ashumet Pond, located on Cape Cod, Massachusetts. Phosphate concentrations as high as 60 μmol l−1 have been measured in groundwater entering Ashumet Pond, and there is concern that the rate of eutrophication could increase. Phosphate in the sewage...
Distributions and fate of chlorinated pesticides, biomarkers and polycyclic aromatic hydrocarbons in sediments along a contamination gradient from a point-source in San Francisco Bay, California
W. E. Pereira, F. D. Hostettler, J. B. Rapp
1996, Marine Environmental Research (41) 299-314
The distribution and fate of chlorinated pesticides, biomarkers, and polycyclic aromatic hydrocarbons (PAHs) in surficial sediments along a contamination gradient in the Lauritzen Canal and Richmond Harbor in San Francisco Bay was investigated. Compounds were identified and quantified using gas chromatography-ion trap mass spectrometry. Biomarkers and PAHs were derived primarily...
Acetochlor in the hydrologic system in the midwestern United States, 1994
D.W. Kolpin, B.K. Nations, D. A. Goolsby, E.M. Thurman
1996, Environmental Science & Technology (30) 1459-1464
The herbicide acetochlor [2-chloro-N-(ethoxymethyl)-N-(2-ethyl-6-methylphenyl)acetamide] was given conditional registration in the United States by the U.S. Environmental Protection Agency in March 1994. This registration provided a rare opportunity to investigate the occurrence of a pesticide during its first season of extensive use in the midwestern United States. Water samples collected and...
Occurrence of selected pesticides and their metabolites in near-surface aquifers of the midwestern United States
D.W. Kolpin, Thurman E. Michael, D. A. Goolsby
1996, Environmental Science & Technology (30) 335-340
The occurrence and distribution of selected pesticides and their metabolites were investigated through the collection of 837 water-quality samples from 303 wells across the Midwest. Results of this study showed that five of the six most frequently detected compounds were pesticide metabolites. Thus, it was common for a metabolite to...
Reactive solute transport in an acidic stream: Experimental pH increase and simulation of controls on pH, aluminum, and iron
R. E. Broshears, R.L. Runkel, B. A. Kimball, Diane M. McKnight, K.E. Bencala
1996, Environmental Science & Technology (30) 3016-3024
Solute transport simulations quantitatively constrained hydrologic and geochemical hypotheses about field observations of a pH modification in an acid mine drainage stream. Carbonate chemistry, the formation of solid phases, and buffering interactions with the stream bed were important factors in explaining the behavior of pH, aluminum, and iron. The precipitation...
Properties and variability of soil and trench fill at an arid waste-burial site
Brian J. Andraski
1996, Soil Science Society of America Journal (60) 54-66
Arid sites commonly are assumed to be ideal for long-term isolation of wastes. Information on properties and variability of desert soils is limited, however, and little is known about how the natural site environment is altered by installation of a waste facility. During fall construction of two test trenches next...
Integrated borehole logging methods for wellhead protection applications
Frederick L. Paillet, W.H. Pedler
1996, Engineering Geology (42) 155-165
Modeling of ground water infiltration and movement in the wellhead area is a critical part of an effective wellhead protection program. Such models depend on an accurate description of the aquifer in the wellhead area so that reliable estimates of contaminant travel times can be used in defining a protection...
Inferring shallow groundwater flow in saprolite and fractured rock using environmental tracers
P.G. Cook, D. K. Solomon, W. E. Sanford, E. Busenberg, Niel Plummer, R.J. Poreda
1996, Water Resources Research (32) 1501-1509
The Ridge and Valley Province of eastern Tennessee is characterized by (1) substantial topographic relief, (2) folded and highly fractured rocks of various lithologies that have low primary permeability and porosity, and (3) a shallow residuum of medium permeability and high total porosity. Conceptual models of shallow groundwater flow and...
Evaluating the reliability of the stream tracer approach to characterize stream-subsurface water exchange
Judson W. Harvey, Brian J. Wagner, Kenneth E. Bencala
1996, Water Resources Research (32) 2441-2451
Stream water was locally recharged into shallow groundwater flow paths that returned to the stream (hyporheic exchange) in St. Kevin Gulch, a Rocky Mountain stream in Colorado contaminated by acid mine drainage. Two approaches were used to characterize hyporheic exchange: sub-reach-scale measurement of hydraulic heads and hydraulic conductivity to compute...
Episodic acidification of a coastal plain stream in Virginia
A. K. O’Brien, K.N. Eshleman
1996, Water, Air, & Soil Pollution (89) 291-316
This study investigates the episodic acidification of Reedy Creek, a wetland-influenced coastal plain stream near Richmond, Virginia. Primary objectives of the study were to quantify the episodic variability of acid- base chemistry in Reedy Creek, to examine the seasonal variability in episodic response and to explain the hydrological and geochemical...
A sample-freezing drive shoe for a wire line piston core sampler
F. Murphy, W.N. Herkelrath
1996, Ground Water Monitoring and Remediation (16) 86-90
Loss of fluids and samples during retrieval of cores of saturated, noncohesive sediments results in incorrect measures of fluid distributions and an inaccurate measure of the stratigraphic position of the sample. To reduce these errors, we developed a hollow drive shoe that freezes in place the...
Trace metal speciation in natural waters: Computational vs. analytical
D. Kirk Nordstrom
1996, Water, Air, & Soil Pollution (90) 257-267
Improvements in the field sampling, preservation, and determination of trace metals in natural waters have made many analyses more reliable and less affected by contamination. The speciation of trace metals, however, remains controversial. Chemical model speciation calculations do not necessarily agree with voltammetric, ion exchange, potentiometric, or other analytical speciation...
The accuracy of seismic estimates of dynamic strains: an evaluation using strainmeter and seismometer data from Piñon Flat Observatory, California
Joan S. Gomberg, Duncan Carr Agnew
1996, Bulletin of the Seismological Society of America (86) 212-220
The dynamic strains associated with seismic waves may play a significant role in earthquake triggering, hydrological and magmatic changes, earthquake damage, and ground failure. We determine how accurately dynamic strains may be estimated from seismometer data and elastic-wave theory by comparing such estimated...
The relationships among three habitat scales and stream benthic invertebrate community structure
J.L. Carter, S.V. Fend, S.S. Kennelly
1996, Freshwater Biology (35) 109-124
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...
Observed and simulated movement of bank-storage water
P. J. Squillace
1996, Ground Water (34) 121-134
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...
Trends in the chemistry of precipitation and surface water in a national network of small watersheds
Brent T. Aulenbach, R. P. Hooper, O.P. Bricker
1996, Hydrological Processes (10) 151-181
Trends in precipitation and surface water chemistry at a network of 15 small watersheds ( < 10 km2) in the USA were evaluated using a statistical test for monotonic trends (the seasonal Kendall test) and a graphical smoothing technique for the visual identification of trends. Composite precipitation samples were collected...
Reactive solute transport in streams: 2. Simulation of a pH modification experiment
Robert L. Runkel, Diane M. McKnight, Kenneth E. Bencala, Steven C. Chapra
1996, Water Resources Research (32) 419-430
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...
Water supply implications of herbicide sampling
J. K. Stamer
1996, Journal - American Water Works Association (88) 76-85
Hydrologic conditions may affect concertrations of organonitrogen herbicides and may be important considerations in complying with drinking water regulations.The temporal distribution of the herbicides alachlor, atrazine, cyanazine, and metolachlor was documented from September 1991 through August 1992 in the Platte River at Louisville, Neb., the drainage of the Central Nebraska...
Trends in nutrients
A.L. Heathwaite, P.J. Johnes, N.E. Peters
1996, Hydrological Processes (10) 263-293
The roles of nitrogen (N) and phosphorus (P) as key nutrients determining the trophic status of water bodies are examined, and evidence reviewed for trends in concentrations of N and P species which occur in freshwaters, primarily in northern temperate environments. Data are reported for...
