Channel degradation in southeastern Nebraska Rivers
Kenneth L. Wahl, Linda S. Weiss
Ward Rim J., editor(s)
1995, Conference Paper, Watershed Management Symposium - Proceedings
Many stream channels in southeastern Nebraska were dredged and straightened during 1904-15. The resulting channels were both shorter and steeper than the original channels. Tests for time trends were conducted using the nonparametric Kendall tau test to see if the channels have responded to these changes. Tests were conducted on...
Mantle helium in ground waters of eastern North America: Time and space constraints on sources
T. Torgersen, S. Drenkard, M. Stute, P. Schlosser, A. Shapiro
1995, Geology (23) 675-678
Mantle helium in continental environments is generally considered to be the result of active volcanism and/or active extension. The latest episodes of volcanism in northeastern North America are the track of the New England hotspot (95–190 Ma) and the closure of the Iapetus sea (before 300 Ma). Thus, the identification...
Characterization of a high-transmissivity zone by well test analysis: Steady state case
Claire R. Tiedeman, Paul A. Hsieh, Sarah B. Christian
1995, Water Resources Research (31) 27-37
A method is developed to analyze steady horizontal flow to a well pumped from a confined aquifer composed of two homogeneous zones with contrasting transmissivities. Zone 1 is laterally unbounded and encloses zone 2, which is elliptical in shape and is several orders of magnitude more transmissive than zone 1....
Year-to-year fluctuation of the spring phytoplankton bloom in south San Francisco Bay: An example of ecological variability at the land-sea interface
James E. Cloern, Alan D. Jassby
1995, Book chapter, Ecological time
Estuaries are transitional ecosystems at the interface of the terrestrial and marine realms. Their unique physiographic position gives rise to large spatial variability, and to dynamic temporal variability resulting, in part, from a variety of forces and fluxes at the oceanic and terrestrial boundaries. River flow, in particular, is an...
Phosphate dynamics in an acidic mountain stream: Interactions involving algal uptake, sorption by iron oxide, and photoreduction
Cathy M. Tate, Robert E. Broshears, Diane M. McKnight
1995, Limnology and Oceanography (40) 938-946
Acid mine drainage streams in the Rocky Mountains typically have few algal species and abundant iron oxide deposits which can sorb phosphate. An instream injection of radiolabeled phosphate (32P0,) into St. Kevin Gulch, an acid mine drainage stream, was used to test the ability of a dominant algal species, Ulothrix...
Mercury cycling in the Allequash Creek watershed, northern Wisconsin
D. P. Krabbenhoft, J.M. Benoit, Christopher L. Babiarz, J.P. Hurley, A.W. Andren
1995, Water, Air, & Soil Pollution (80) 425-433
Although there have been recent significant gains in our understanding of mercury (Hg) cycling in aquatic environments, few studies have addressed Hg cycling on a watershed scale in particular, attention to Hg species transfer between watershed components (upland soils, groundwater, wetlands, streams, and lakes) has been lacking. This study describes...
A comparison of two nitrification inhibitors used to measure nitrification rates in estuarine sediments
J.M. Caffrey, L.G. Miller
1995, FEMS Microbiology Ecology (17) 213-219
Nitrification rates were measured using intact sediment cores from South San Francisco Bay and two different nitrification inhibitors: acetylene and methyl fluoride. Sediment oxygen consumption and ammonium and nitrate fluxes were also measured in these cores. Four experiments were conducted in the spring, and one in the fall of 1993....
Determination of water retention in stratified porous materials
J. Constantz
1995, Transport in Porous Media (18) 217-229
Predicted and measured water-retention values,θ(ψ), were compared for repacked, stratified core samples consisting of either a sand with a stone-bearing layer or a sand with a clay loam layer in various spatial orientations. Stratified core samples were packed in submersible pressure outflow cells, then water-retention...
Sewage contamination in the upper Mississippi River as measured by the fecal sterol, coprostanol
J.H. Writer, J.A. Leenheer, L. B. Barber, G.L. Amy, S.C. Chapra
1995, Water Research (29) 1427-1436
The molecular sewage indicator, coprostanol, was measured in bed sediments of the Mississippi River for the purpose of determining sewage contamination. Coprostanol is a non-ionic, non-polar, organic molecule that associates with sediments in surface waters, and concentrations of coprostanol in bed sediments provide an indication of long-term sewage loads. Because...
Strong-acid, carboxyl-group structures in fulvic acid from the Suwannee River, Georgia. 1. Minor structures
J.A. Leenheer, R.L. Wershaw, M.M. Reddy
1995, Environmental Science & Technology (29) 393-398
An investigation of the strong-acid characteristics (pKa 3.0 or less) of fulvic acid from the Suwannee River, Georgia, was conducted. Quantitative determinations were made for amino acid and sulfur-containing acid structures, oxalate half-ester structures, malonic acid structures, keto acid structures, and aromatic carboxyl-group structures. These determinations were made by using...
Paleohydrologic record from lake brine on the southern High Plains, Texas
Ward E. Sanford, Warren W. Wood
1995, Geology (23) 229-232
The timing of changes in the stage and salinity of Double Lakes of Lynn County, Texas, was estimated using dissolved-chloride profiles across an underlying shale layer. Lake conditions over the past 30 to 50 ka can be inferred from the chloride profiles by using the advective velocity of the pore...
Pesticides in near-surface aquifers: An assessment using highly sensitive analytical methods and tritium
D.W. Kolpin, D. A. Goolsby, E.M. Thurman
1995, Journal of Environmental Quality (24) 1125-1132
In 1992, the U.S. Geological Survey (USGS) determined the distribution of pesticides in near-surface aquifers of the midwestern USA to be much more widespread than originally determined during a 1991 USGS study. The frequency of pesticide detection increased from 28.4% during the 1991 study to 59.0% during the 1992 study....
Hydrochemical processes during snowmelt in a subalpine watershed, Colorado, USA
N.E. Peters, G.H. Leavesley
1995, Biogeochemistry of seasonally snow-covered catchments. Proc. symposium, Boulder, 1995 (228) 313-319
Snowmelt is the primary hydrologic event in the studied subalpine watershed, generating streamflow for 3 months from a 1-month snowmelt period which commenced in mid-April 1992 and mid-May 1993. The melting rate of the snowpack varied diurnally and was asymmetrical, increasing rapidly to a maximum at the onset of daily...
Preferential flow and segregation of porewater solutes in Wetland sediment
J. W. Harvey, R.M. Chambers, J.R. Hoelscher
1995, Estuaries (18) 568-578
Sediment macropores (with effective diameters larger than 100 ??m) comprise 11% of the bulk sediment volume in a tidal freshwater wetland vegetated with Peltandra virginica. In order to determine effects of macroporous sediment structure on solute transport, we conducted a solute tracer experiment in the sediment. The effective transport volume...
Pb2+ and Zn2+ adsorption by a natural aluminum- and iron-bearing surface coating on an aquifer sand
J.A. Coston, C. C. Fuller, J.A. Davis
1995, Geochimica et Cosmochimica Acta (59) 3535-3547
Pb2+ and Zn2+ adsorption was studied in batch experiments with material collected from a shallow, unconfined aquifer of glacial outwash sand and gravel in Falmouth, Massachusetts, USA. The aquifer solids contain primarily quartz (95% w/w), with minor amounts of alkali feldspars and ferromagnetic minerals. Pb2+ and...
Little River revisited - thirty-five years after Hack and Goodlett
W. R. Osterkamp, C.R. Hupp, M.R. Schening
1995, Geomorphology (13) 1-20
In possibly the first detailed study to relate geomorphology, vegetation, and hydrology at a watershed scale, Hack and Goodlett (1960) documented variation in the eastern forest with topograhic positions of cove, side slope, and nose. Runoff identified as convergent, parallel, or divergent,...
Simulation models for conservative and nonconservative solute transport in streams
R.L. Runkel
1995, Effects of scale on interpretation and management of sediment and water quality. Proc. symposium, Boulder, 1995 (226) 153-159
Solute transport in streams is governed by a suite of hydrologic and chemical processes. Interactions between hydrologic processes and chemical reactions may be quantified through a combination of field-scale experimentation and simulation modeling. Two mathematical models that simulate conservative and nonconservative solute transport in streams are presented. A model for...
Prediction of areas where irrigation drainage may induce selenium contamination of water
R. L. Seiler
1995, Journal of Environmental Quality (24) 973-979
The U.S. Department of the Interior has investigated 25 areas in the western USA to determine whether irrigation drainage has caused harmful effects on wildlife or has reduced subsequent beneficial uses of the water. A database of chemical analyses of water, sediment, and biota from the...
Strong-acid, carboxyl-group structures in fulvic acid from the Suwannee River, Georgia. 2. Major structures
J.A. Leenheer, R.L. Wershaw, M.M. Reddy
1995, Environmental Science & Technology (29) 399-405
Polycarboxylic acid structures that account for the strong-acid characteristics (pKa1 near 2.0) were examined for fulvic acid from the Suwannee River. Studies of model compounds demonstrated that pKa values near 2.0 occur only if the a-ether or a-ester groups were in cyclic structures with two to three additional electronegative functional...
Rapid toluene mineralization by aquifer microorganisms at Adak, Alaska: Implications for intrinsic bioremediation in cold environments
P. M. Bradley, F. H. Chapelle
1995, Environmental Science & Technology (29) 2778-2781
No abstract available. ...
The structural and geochemical evolution of the continental crust: Support for the oceanic plateau model of continental growth
D. Abbott, Walter D. Mooney
1995, Reviews of Geophysics (33) 231-242
The problem of the origin of the continental crust can be resolved into two fundamental questions: (1) the location and mechanisms of initial mantle extraction of the primitive crust and (2) the processes by which this primitive crust is converted into the continental crust that presently exists....
Hydrologic effects of increased urbanization
Joel R. Guay
Espey William H.Combs Phil G., editor(s)
1995, Conference Paper, International Water Resources Engineering Conference - Proceedings
Urban areas in Perris Valley, California, have more than tripled during the last 20 years, resulting in increased storm-runoff volumes and peak discharges. To quantify the effects of increased urbanization, rainfall-runoff models of the basin were developed to simulate runoff for 1970-75 and 1990-93 conditions. Hourly rainfall data for 1949-93...
Fate, bioavailability and toxicity of silver in estuarine environments
S. N. Luoma, Y.B. Ho, G.W. Bryan
1995, Marine Pollution Bulletin (31) 44-54
The chemistry and bioavailability of Ag contribute to its high toxicity in marine and estuarine waters. Silver is unusual, in that both the dominant speciation reaction in seawater and the processes important in sorbing Ag in sediments favour enhanced bioavailability. Formation of a stable chloro complex favours dispersal of dissolved...
Spatial trends in Pearson Type III statistical parameters
R.W. Lichty, M.R. Karlinger
1995, Journal of Hydraulic Engineering (121) 672-678
Spatial trends in the statistical parameters (mean, standard deviation, and skewness coefficient) of a Pearson Type III distribution of the logarithms of annual flood peaks for small rural basins (less than 90 km2) are delineated using a climate factor CT, (T=2-, 25-, and 100-yr recurrence intervals), which quantifies the effects...
Partition of nonpolar organic pollutants from water to soil and sediment organic matters
Daniel E. Kile, C. T. Chiou, H. Zhou
1995, Environmental Science & Technology (29) 1401-1406
The partition coefficients (Koc) of carbon tetrachloride and 1,2-dichlorobenzene between normal soil/sediment organic matter and water have been determined for a large set of soils, bed sediments, and suspended solids from the United States and the People's Republic of China. The Koc values for both solutes are quite invariant either...
