Microbial control of silver mineralization at a sea-floor hydrothermal site on the northern Gorda Ridge
Robert A. Zierenberg, Peter Schiffman
1990, Nature (348) 155-157
THE Sea Cliff hydrothermal field, on the northern Gorda Ridge, contains mounds and chimneys of hydrothermally precipitated sulphide and sulphate minerals typical of sea-floor hydrothermal vent sites1. In addition, large areas of the sea floor are covered by subhorizontal hydrothermal crusts. Samples of the crust recovered by submersible are composed...
Field methods for measurement of ground water redox chemical parameters
Katherine Walton-Day, Donald L. Macalady, Myron H. Brooks, Vernon T. Tate
1990, Groundwater Monitoring & Remediation (10) 81-89
An inexpensive, versatile, and portable system is presented, which facilitates rapid field determinations of redox potentials, pH, conductivity, ferrous and total iron, nitrite, specific conductance, dissolved oxygen, and temperature. Accuracy is facilitated by on‐site measurements of most parameters using specially constructed flow‐through cells and, for several...
Historical Landsat data comparisons: illustrations of land surface change
Matthew D. Cross
1990, Report
The U.S. Geological Survey's (USGS) EROS Data Center (EDC) has archived two decades of Landsat data, providing a rich collection of information about the dynamics of the Earth's land surface. Major changes to the surface features of the planet can be detected, measured, and studied using Landsat data. The effects...
Establishment of bottomland oak plantations on the Yazoo National Wildlife Refuge complex
J. A. Allen
1990, Southern Journal of Applied Forestry (14) 206-210
Stocking, height and diameter growth, and invasion of both herbaceous and woody plant species are reported for 5 direct seeded and 5 planted seedling stands of bottomland oaks, all of which were between 4 and 8 years old. Stocking was generally higher in the planted seedling stands. Both height and...
The Ag-Mn-Pb-Zn vein, replacement, and skarn deposits of Uchucchacua, Peru; studies of structure, mineralogy, metal zoning, Sr isotopes, and fluid inclusions
M. Andrew Bussell
1990, Economic Geology (85) 1348-1383
Uchucchacua is an Ag-Mn-Pb-Zn vein, replacement, and skarn mineral district in the central Andes of Peru. Host rocks are massive Jumasha Formation shelf limestones of Turonian age that have been folded into an asymmetric northeast-verging anticline of Andean trend. Strata near the fold crest are cut by minor dacitic intrusions...
Multiple scales of patchiness and patch structure: a hierarchical framework for the study of heterogeneity
Natasha B. Kotliar, John A. Wiens
1990, Oikos (59) 253-260
We develop a hierarchical model of heterogeneity that provides a framework for classifying patch structure across a range of scales. Patches at lower levels in the hierarchy are more simplistic and correspond to the traditional view of patches. At levels approaching the upper bounds of the hierarchy the internal structure...
Influence of exchange flow between the channel and hyporheic zone on nitrate production in a small mountain stream
Frank J. Triska, John H. Duff, Ronald J. Avanzino
1990, Canadian Journal of Fisheries and Aquatic Sciences (47) 2099-2111
Variation in local exchange of flows between the channel and hyporheic zone produced temporally shifting concentration gradients of dissolved oxygen, nitrate, and ammonium in subsurface waters of a small, gravel-cobble bed stream. Channel water advected laterally supplied dissolved oxygen, and groundwater supplied ammonium to support hyporheic nitrification. Nitrate production was...
Transferring models: the case of the physical habitat simulation system
Robert T. Milhous
1990, Book, Transferring models to users
No abstract available....
Simulation of lake evaporation with application to modeling lake level variations of Harney‐Malheur Lake, Oregon
Steven W. Hostetler, Patrick J Bartlein
1990, Water Resources Research (26) 2603-2612
A physically based eddy diffusion model for simulating the seasonal variation in lake temperature and evaporation is presented and validated. Because no lake‐specific fitting of the parameters of the model is necessary, the model can be used to simulate evaporation in studies of climate change and lake...
Subsurface energy storage and transport for solar-powered geysers on Triton
Randolph L. Kirk, Robert H. Brown, Laurence A. Soderblom
1990, Science (250) 424-429
The location of active geyser-like eruptions and related features close to the current subsolar latitude on Triton suggests a solar energy source for these phenomena. Solidstate greenhouse calculations have shown that sunlight can generate substantially elevated subsurface temperatures. A variety of models for the storage of solar energy in a...
Water movement through an experimental soil liner
I.G. Krapac, K. Cartwright, S.V. Panno, B.R. Hensel, K.R. Rehfeldt, B.L. Herzog
1990, Waste Management and Research (9) 195-204
A field-scale soil liner was constructed to test whether compacted soil barriers in cover and liner systems could be built to meet the U.S. EPA saturated hydraulic conductivity requirement (⩽ 1 × 10−7 cm s−1). The 8 × 15 × 0.9 m liner was constructed in 15 cm compacted lifts using...
Paleontological analysis of a lacustrine carbonaceous uranium deposit at the Anderson mine, Date Creek basin, west-central Arizona (U.S.A.)
J. K. Otton, J.P. Bradbury, R. M. Forester, J.H. Hanley
1990, Ore Geology Reviews (5) 541-552
The Tertiary sedimentary sequence of the Date Creek basin area of Arizona is composed principally of intertonguing alluvial-fan and lacustrine deposits. The lacustrine rocks contain large intermediate- to, locally, high-grade uranium deposits that form one of the largest uranium resources in the United States (an estimated 670,000 tons of U3O8 at...
Chemistry and palynology of carbon seams and associated rocks from the Witwatersrand goldfields, South Africa
L.B. Ebert, E. I. Robbins, K.D. Rose, R.V. Kastrup, J.C. Scanlon, L.A. Gebhard, A.R. Garcia
1990, Ore Geology Reviews (5) 423-444
Carbon seams in the Witwatersrand System of South Africa host some of the richest gold concentrations in the world. A study of the microscopic characteristics in thin sections and acid residues, and of the chemical and physical nature of the carbon-bearing phases, was undertaken to gain some understanding of the...
Palynological assessment of organic tissues and metallic minerals in the Jerritt Canyon gold deposit, Nevada (U.S.A.)
E. I. Robbins, J. P. D’Agostino, J.L. Haas Jr., R.R. Larson, F.T. Dulong
1990, Ore Geology Reviews (5) 399-422
Organic tissues and metallic minerals were studied in acid residues and thin section of the Jerritt Canyon (Bell Mine) gold deposit. The purpose was to compare gold-bearing and gold-free rocks, characterize their differences, and assess a possible relationship between the invisible gold and the organic tissues in these early Paleozoic,...
Opportunities to protect instream flows and wetland uses of water in Florida
Nina Burkardt
1990, Report
This document combines the efforts of several individuals, agencies, and organizations toward a common objective: the identification, description, and preliminary evaluation of promising opportunities for protecting instream uses of water under existing laws in Florida. this report is intended for the use of State and Federal planning and management personnel who...
A sensitivity analysis of nine diversity and seven similarity indices
Terrence P. Boyle, Gary M. Smillie, Jana C. Anderson, David R. Beeson
1990, Research Journal of the Water Pollution Control Federation (62) 749-762
Indices summarizing community structure are used to evaluate fundamental community ecology, species interaction, biogeographical factors, and environmental stress. Some of these indices are insensitive to gross community changes induced by contaminants of pollution. Sixteen indices commonly used to assess the status of aquatic communities in water quality studies were evaluated...
Tests of a habitat suitability model for black-capped chickadees
Richard L. Schroeder
1990, Report
The black-capped chickadee (Parus atricapillus) Habitat Suitability Index (HSI) model provides a quantitative rating of the capability of a habitat to support breeding, based on measures related to food and nest site availability. The model assumption that tree canopy volume can be predicted from measures of tree height and...
Volcanism in Northwest Ishtar Terra, Venus
Lisa R. Gaddis, Ronald Greeley
1990, Icarus (87) 327-338
Soviet Venera 15/16 radar images and topographic data for an area in NW Ishtar Terra, Venus (74°N, 313°E) contain evidence for the existence of a complex volcanic center. Located at the intersection of Akna and Freyja Montes (both elevated ∼4 to 7 km above the planetary reference radius of 6051...
Coda duration magnitudes in central California: An empirical approach
Caryl A. Michaelson
1990, Bulletin of the Seismological Society of America (80) 1190-1204
A new empirical coda magnitude MD is presented for the central California seismic network (CALNET), in which station corrections are introduced to reduce the influence of hypocenter and station distributions. The new magnitude scale is obtained by relating the lapse-time τ^ to local magnitudes ML using data from 55 earthquakes with 1.1 ≦ ML ≤ 5.6...
Stoichiometry of mineral reactions from mass balance computations for acid mine waters, Iron Mountain, California
Charles N. Alpers, D. Kirk Nordstrom
1990, Book chapter, Acid-mine drainage : Designing for closure
No abstract available....
Photosynthetic pathways in freshwater aquatic plants
Jon E. Keeley
1990, Trends in Ecology and Evolution (5) 330-333
Recent studies show that generalizations about photosynthetic pathways, derived from terrestrial plant studies, do not apply to aquatic plants. Crassulacean acid metabolism (CAM) photosynthesis is of selective value not only in arid environments, where it enhances water-use efficiency, but also in aquatic plants of oligotrophic waters, where it enhances competitive...
Effects of winter undernutrition on body composition and physiological profiles of white-tailed deer
Glenn D. DelGiudice, L. David Mech, Ulysses S. Seal
1990, Journal of Wildlife Management (54) 539-550
We examined the effects of undernutrition and recovery on body composition and blood and urinary profiles of 6 captive white-tailed deer (Odocoileus virginianus) between 18 December 1984 and 3 May 1985. Deer were weighed, and blood and urine were collected every 2 weeks from 10 January to 3 May. At...
Neck-band retention for Canada geese in the Mississippi flyway
Michael D. Samuel, Nondor T. Weiss, Donald H. Rusch, Scott R. Craven, Robert E. Trost, F. Dale Caswell
1990, Journal of Wildlife Management (54) 612-621
We used capture, harvest, and observation histories of Canada geese (Branta canadensis) banded in the Mississippi flyway, 1974-88, to examine the problem of neck-band retention. Methods for the analysis of survival data were used to estimate rates of neck-band retention and to evaluate factors associated with neck-band loss. Sex, age...
Survival and band recovery rates of mallards in New Zealand
James D. Nichols, Murray Williams, Tom Caithness
1990, Journal of Wildlife Management (54) 629-636
Mallards (Anas platyrhynchos) were banded at 4 discrete study areas in New Zealand. We used hunting season recoveries in conjunction with band recovery models to estimate annual survival and recovery rates and to test hypotheses about sources of variation in these rates. Recovery rates varied among the 4 areas and...
Selected geographic analysis projects: U. S. Fish and Wildlife Service's National Wetlands Research Center
Floyd O. Stayner, James D. Scurry, James B. Johnston, Mary C. Watzin, Pasquale F. Roscigno
1990, Conference Paper, Proceedings of the first national U.S. Fish and Wildlife Service geographic information systems workshop, June 4-7, 1990
No abstract available....
