Electromagnetic methods for mapping freshwater lenses on Micronesian atoll islands
S. S. Anthony
1992, Journal of Hydrology (137) 99-111
The overall shape of freshwater lenses can be determined by applying electromagnetic methods and inverse layered-earth modeling to the mapping of atoll island freshwater lenses. Conductivity profiles were run across the width of the inhabited islands at Mwoakilloa, Pingelap, and Sapwuahfik atolls of the Pohnpei State, Federated States...
Energy budgets and resistances to energy transport in sparsely vegetated rangeland
William D. Nichols
1992, Agricultural and Forest Meteorology (60) 221-247
Partitioning available energy between plants and bare soil in sparsely vegetated rangelands will allow hydrologists and others to gain a greater understanding of water use by native vegetation, especially phreatophytes. Standard methods of conducting energy budget studies result in measurements of latent and sensible heat fluxes above the plant canopy...
U-Pb dating of uranium deposits in collapse breccia pipes of the Grand Canyon region
K.R. Ludwig, K. R. Simmons
1992, Economic Geology (87) 1747-1765
Two major periods of uranium mineralization are indicated by U-Pb isotope dating of uranium ores from collapse breeeia pipes in the Grand Canyon region, northern Arizona. The Hack 2 and 3, Kanab North, and EZ 1 and 2 orebodies apparently formed in the interval of 200 + or - 20...
Evaluation of the depth-integration method of measuring water discharge in large rivers
J. A. Moody, B.M. Troutman
1992, Journal of Hydrology (135) 201-236
The depth-integration method of measuring water discharge makes a continuous measurement of the water velocity from the water surface to the bottom at 20 to 40 locations or verticals across a river. It is especially practical for large rivers where river traffic makes it impractical to use boats...
Floodplain storage of mine tailings in the Belle Fourche river system: a sediment budget approach
D. C. Marron
1992, Earth Surface Processes and Landforms (17) 675-685
Arsenic‐contaminated mine tailings that were discharged into Whitewood Creek at Lead, South Dakota, from 1876 to 1978, were deposited along the floodplains of Whitewood Creek and the Belle Fourche River. The resulting arsenic‐contaminated floodplain deposit consists mostly of overbank sediments and filled abandoned meanders along White‐wood Creek, and overbank and...
Effects of uranium mining discharges on water quality in the Puerco River basin, Arizona and New Mexico
P. C. Van Metre, J. R. Gray
1992, Hydrological Sciences Journal (37) 463-480
From 1967 until 1986, uranium mine dewatering increased dissolved gross alpha, gross beta, uranium and radium activities and dissolved selenium and molybdenum concentrations in the Puerco River as indicated by time trends, areal patterns involving distance from the mines and stream discharge. Additionally, increased dissolved uranium concentrations were identified in...
The dynamic relationship between ground water and the Columbia River: Using deuterium and oxygen-18 as tracers
K. A. McCarthy, W. D. McFarland, J.M. Wilkinson, L. D. White
1992, Journal of Hydrology (135) 1-12
Deuterium and oxygen-18 were used as natural tracers to investigate the hydraulic relationship between the Columbia River and the Blue Lake gravel aquifer near Portland, Oregon. A time series of stable-isotope data collected from surface and ground waters during a March 1990 aquifer test confirms that the river and aquifer...
Herbicide transport in rivers: Importance of hydrology and geochemistry in nonpoint-source contamination
P. J. Squillace, E.M. Thurman
1992, Environmental Science & Technology (26) 538-545
Alachlor, atrazine, cyanazine, metolachlor, and metribuzin were measured at six sites during 1984 and 1985 in large subbasins within the Cedar River, IA. A computer model separated the Cedar River discharge hydrograph into groundwater and overland-flow components. The concentration of herbicides in the river when groundwater was the...
Determination of subsurface fluid contents at a crude-oil spill site
K.M. Hess, W.N. Herkelrath, H.I. Essaid
1992, Journal of Contaminant Hydrology (10) 75-96
Measurement of the fluid-content distribution at sites contaminated by immiscible fluids, including crude oil, is needed to better understand the movement of these fluids in the subsurface and to provide data to calibrate and verify numerical models and geophysical methods. A laboratory...
Riparian vegetation recovery patterns following stream channelization: A geomorphic perspective
Cliff R. Hupp
1992, Ecology (73) 1209-1226
Hundreds of kilometres of West Tennessee streams have been channelized since the turn of the century. After a stream is straightened, dredged, or cleared, basinwide ecologic, hydrologic, and geomorphic processes bring about an integrated, characteristic recovery sequence. The rapid pace of channel responses to channelization provides an opportunity to document...
Isolation of hydrophilic organic acids from water using nonionic macroporous resins
G. R. Aiken, Diane M. McKnight, K. A. Thorn, E.M. Thurman
1992, Organic Geochemistry (18) 567-573
A method has been developed for the isolation of hydrophilic organic acids from aquatic environments using Amberlite∗ XAD-4 resin. The method uses a two column array of XAD-8 and XAD-4 resins in series. The hydrophobic organic acids, composed primarily of...
Enzymatic uranium precipitation
Y.A. Gorby, Derek R. Lovley
1992, Environmental Science & Technology (26) 205-207
No abstract available....
Semiempirical model of soil water hysteresis
J. R. Nimmo
1992, Soil Science Society of America Journal (56) 1723-1730
In order to represent hysteretic soil water retention curves accurately using as few measurements as possible, a new semiempirical model has been developed. It has two postulates related to physical characteristics of the medium, and two parameters, each with a definite physical interpretation, whose values are determined empirically for a...
Laboratory investigations on the role of sediment surface and ground water chemistry in transport of bacteria through a contaminated Sandy Aquifer
M. A. Scholl, R.W. Harvey
1992, Environmental Science & Technology (26) 1410-1417
No abstract available. ...
Large lake basins of the southern High Plains: Ground-water control of their origin?
W.W. Wood, W. E. Sanford, C.C. Reeves Jr.
1992, Geology (20) 535-538
The origin of the ∼40-50 topographically large lake basins on the southern High Plains of Texas and New Mexico has been an enigma. Previous workers have considered deflation or evaporite dissolution at depth and subsequent collapse as the most probable mechanisms. However, the eolian hypotheses have been unable to provide...
Patterns and rates of ground-water flow on Long Island, New York
Herbert T. Buxton, Edward Modica
1992, Groundwater (30) 857-866
Increased ground-water contamination from human activities on Long Island has prompted studies to define the pattern and rate of ground-water movement. A two-dimensional, fine-mesh, finite-element model consisting of 11,969 nodes and 22,880 elements was constructed to represent ground-water flow along a north-south section through central Long Island. The model represents...
Humic substances and trace metals associated with Fe and Al oxides deposited in an acidic mountain stream
Diane M. McKnight, R.L. Wershaw, K.E. Bencala, G. W. Zellweger, G. L. Feder
1992, Science of Total Environment (117-118) 485-498
Hydrous iron and aluminum oxides are deposited on the streambed in the confluence of the Snake River and Deer Creek, two streams in the Colorado Rocky Mountains. The Snake River is acidic and has high concentrations of dissolved Fe and Al. These metals precipitate at the confluence with the pristine,...
Inhibition of existing denitrification enzyme activity by chloramphenicol
M. H. Brooks, R. L. Smith, D.L. Macalady
1992, Applied and Environmental Microbiology (58) 1746-1753
Chloramphenicol completely inhibited the activity of existing denitrification enzymes in acetylene-block incubations with (i) sediments from a nitrate-contaminated aquifer and (ii) a continuous culture of denitrifying groundwater bacteria. Control flasks with no antibiotic produced significant amounts of nitrous oxide in the same time period. Amendment with chloramphenicol after nitrous oxide...
An improved method for field extraction and laboratory analysis of large, intact soil cores
J.A. Tindall, K. Hemmen, J.F. Dowd
1992, Journal of Environmental Quality (21) 259-263
Various methods have been proposed for the extraction of large, undisturbed soil cores and for subsequent analysis of fluid movement within the cores. The major problems associated with these methods are expense, cumbersome field extraction, and inadequate simulation of unsaturated flow conditions. A field and laboratory procedure is presented that...
Influence of soil organic matter composition on the partition of organic compounds
D.W. Rutherford, C. T. Chiou, D.E. Klle
1992, Environmental Science & Technology (26) 336-340
No abstract available. ...
Atrazine mineralization potential of alluvial-aquifer sediments under aerobic conditions
P.B. McMahon, F. H. Chapelle, M.L. Jagucki
1992, Environmental Science & Technology (26) 1556-1559
No abstract available....
Sources of nitrogen and phosphorus to Northern San Francisco Bay
S.W. Hager, L. E. Schemel
1992, Estuaries (15) 40-52
We studied nutrient sources to the Sacramento River and Suisun Bay (northern San Francisco Bay) and the influence which these sources have on the distributions of dissolved inorganic nitrogen (DIN) and dissolved reactive phosphorus (DRP) in the river and bay. We found that agricultural return flow drains and a...
Triggered earthquakes and deep well activities
C. Nicholson, R. L. Wesson
1992, Pure and Applied Geophysics PAGEOPH (139) 561-578
Earthquakes can be triggered by any significant perturbation of the hydrologic regime. In areas where potentially active faults are already close to failure, the increased pore pressure resulting from fluid injection, or, alternatively, the massive extraction of fluid or gas, can induce sufficient stress and/or strain changes that, with time,...
Bioremediation of uranium contamination with enzymatic uranium reduction
Derek R. Lovley, Elizabeth J.P. Phillips
1992, Environmental Science & Technology (26) 2228-2234
Enzymatic uranium reduction by Desulfovibrio desulfuricans readily removed uranium from solution in a batch system or when D. desulfuricans was separated from the bulk of the uranium-containing water by a semipermeable membrane. Uranium reduction continued at concentrations as high as 24 mM. Of a variety of potentially inhibiting anions and...
D4Z: A new renumbering for iterative solution of ground-water flow and solute-transport equations
K.L. Kipp, T.F. Russell, J.S. Otto
1992, Conference Paper, Finite Elements in Water Resources, Proceedings of the International Conference
D4 zig-zag (D4Z) is a new renumbering scheme for producing a reduced matrix to be solved by an incomplete LU preconditioned, restarted conjugate-gradient iterative solver. By renumbering alternate diagonals in a zig-zag fashion, a very low sensitivity of convergence rate to renumbering direction is obtained. For two demonstration problems involving...
