Sampling benthic macroinvertebrates in a large flood-plain river: Considerations of study design, sample size, and cost
L.A. Bartsch, W. B. Richardson, T.J. Naimo
1998, Environmental Monitoring and Assessment (52) 425-439
Estimation of benthic macroinvertebrate populations over large spatial scales is difficult due to the high variability in abundance and the cost of sample processing and taxonomic analysis. To determine a cost-effective, statistically powerful sample design, we conducted an exploratory study of the spatial variation of benthic macroinvertebrates in a 37...
Well log evaluation of gas hydrate saturations
T. S. Collett
1998, Conference Paper, Transactions of the SPWLA Annual Logging Symposium (Society of Professional Well Log Analysts)
The amount of gas sequestered in gas hydrates is probably enormous, but estimates are highly speculative due to the lack of previous quantitative studies. Gas volumes that may be attributed to a gas hydrate accumulation within a given geologic setting are dependent on a number of reservoir parameters; one of...
Numerical analysis of the hydrogeologic controls in a layered coastal aquifer system, Oahu, Hawaii, USA
D.S. Oki, W. R. Souza, E.L. Bolke, G.R. Bauer
1998, Hydrogeology Journal (6) 243-263
The coastal aquifer system of southern Oahu, Hawaii, USA, consists of highly permeable volcanic aquifers overlain by weathered volcanic rocks and interbedded marine and terrestrial sediments of both high and low permeability. The weathered volcanic rocks and sediments are collectively known as caprock, because they impede...
Response of shoal grass, Halodule wrightii, to extreme winter conditions in the Lower Laguna Madre, Texas
D.W. Hicks, C.P. Onuf, J.W. Tunnell
1998, Aquatic Botany (62) 107-114
Effects of a severe freeze on the shoal grass, Halodule wrightii, were documented through analysis of temporal and spatial trends in below-ground biomass. The coincidence of the second lowest temperature (-10.6??C) in 107 years of record, 56 consecutive hours below freezing, high winds and extremely low water levels exposed the...
Choosing indicators of natural resource condition: A case study in Arches National Park, Utah, USA
J. Belnap
1998, Environmental Management (22) 635-642
Heavy visitor use in many areas of the world have necessitated development of ways to assess visitation impacts. Arches National Park recently completed a Visitor Experience and Resource Protection (VERP) plan. Integral to this plan was developing a method to identify biological indicators that would both measure visitor impacts and...
Response of nesting ducks to predator exclosures and water conditions during drought
Lewis M. Cowardin, Pamela J. Pietz, John T. Lokemoen, H. Thomas Sklebar
1998, Journal of Wildlife Management (62) 152-163
We investigated whether small predator exclosures might be a useful tool for increasing duck recruitment. During a period of increasing drought from 1987 to 1991, we monitored populations of dabbling ducks on 9 51-km2 study areas, 3 of which contained a centrally located 25-ha predator exclosure and 3 of which...
Hydrothermal uranium deposits containing molybdenum and fluorite in the Marysvale volcanic field, west-central Utah
C. G. Cunningham, J.D. Rasmussen, T. A. Steven, R. O. Rye, P. D. Rowley, S.B. Romberger, J. Selverstone
1998, Mineralium Deposita (33) 477-494
Uranium deposits containing molybdenum and fluorite occur in the Central Mining Area, near Marysvale, Utah, and formed in an epithermal vein system that is part of a volcanic/hypabyssal complex. They represent a known, but uncommon, type of deposit; relative to other commonly described volcanic-related uranium deposits, they are young,...
Geohydrologic unit boundaries along the Colorado Front Range
Sharon Rafferty
1998, Report
This digital geospatial data set consists of geohydrologic unit boundaries shown in the report "Structure, outcrop, and subcrop of the bedrock aquifers along the western margin of the Denver Basin, Colorado" (Robson and others, 1998)....
Abnormally high formation pressures, Potwar Plateau, Pakistan
B. E. Law, S.H.A. Shah, M.A. Malik
1998, AAPG Memoir 247-258
Abnormally high formation pressures in the Potwar Plateau of north-central Pakistan are major obstacles to oil and gas exploration. Severe drilling problems associated with high pressures have, in some cases, prevented adequate evaluation of reservoirs and significantly increased drilling costs. Previous investigations of abnormal pressure in the Potwar Plateau have...
Seawater intrusion in aquifers underlying the oxnard plain, Ventura County, California
John A. Izbicki, Eric G. Reichard, Tracy Nishikawa, Peter Martin
1998, Report - University of California Water Resources Center (95) 65-77
[No abstract available]...
Selecting habitat management strategies on refuges
Richard L. Schroeder, Wayne J. King, John E. Cornely
1998, Information and Technology Report 1998-0003
This report is a joint effort of the Biological Resources Division, U.S. Geological Survey and the U.S. Fish and Wildlife Service (FWS) to provide National Wildlife Refuge (NWR) managers guidance on the selection and evaluation of habitat management strategies to meet stated objectives. The FWS recently completed a handbook on...
Interdecadal variations of annual precipitation in the central United States
Q. Hu, C.M. Woodruff, S.E. Mudrick
1998, Bulletin of the American Meteorological Society (79) 221-229
Century-long annual precipitation time series at 168 stations in the central United States are analyzed with special attention given to interdecadal variations. The results show statistically significant precipitation variations of interdecadal timescales in the region. In particular, one variation has a quasi 20-yr period, and another one possesses a quasi...
Modeling tidal hydrodynamics of San Diego Bay, California
P.-F. Wang, R. T. Cheng, K. Richter, E.S. Gross, D. Sutton, J. W. Gartner
1998, Journal of the American Water Resources Association (34) 1123-1140
In 1983, current data were collected by the National Oceanic and Atmospheric Administration using mechanical current meters. During 1992 through 1996, acoustic Doppler current profilers as well as mechanical current meters and tide gauges were used. These measurements not only document tides and tidal currents in San Diego Bay, but...
Survival of plains cottonwood (Populus deltoides subsp. monilifera) and saltcedar (Tamarix ramosissima) seedlings in response to flooding
D.N. Gladwin, J. E. Roelle
1998, Wetlands (18) 669-674
We examined the response of first year saltcedar (Tamarix ramosissima) and plains cottonwood (Populus deltoides subsp.monilifera) seedlings to flooding in fall (25 days) and spring (28 days) using potgrown plants (12–18 individuals/26.5-liter pot). Seedlings were initially counted in all pots prior to fall treatment. Survival was calculated as...
Diel variability of mercury phase and species distributions in the Florida Everglades
D. P. Krabbenhoft, J.P. Hurley, M.L. Olson, L.B. Cleckner
1998, Biogeochemistry (40) 311-325
Preliminary studies of mercury (Hg) cycling in the Everglades revealed that dissolved gaseous mercury (DGM), total mercury (Hg(T)), and reactive mercury (Hg(R)) show reproducible, diel trends. Peak water-column DGM concentrations were observed on or about noon, with a 3 to 7 fold increase over night-time concentrations. Production of DGM appears...
Herbivore effects on plant species density at varying productivity levels
L. Gough, J.B. Grace
1998, Ecology (79) 1586-1594
Artificially increasing primary productivity decreases plant species richness in many habitats; herbivory may affect this outcome, but it has rarely been directly addressed in fertilization studies. This experiment was conducted in two Louisiana coastal marshes to examine the effects of nutrient enrichment and sediment addition on herbaceous plant communities with...
Evidence for Proterozoic and late Cretaceous-early Tertiary ore-forming events in the Coeur d'Alene district, Idaho and Montana
D. L. Leach, A. H. Hofstra, S. E. Church, L.W. Snee, R. B. Vaughn, R. E. Zartman
1998, Economic Geology (93) 347-359
New 40 Ar/ 39 Ar age spectra on sericite and lead isotope data on tetrahedrite, siderite, galena, bournonite, and stibnite, together with previously published isotopic, geochemical, and geologic studies provide evidence for two major vein-forming events in the Coeur d'Alene district and surrounding areas of the Belt basin. The data suggest that the zinc-...
Tectonic controls on fault-zone permeability in a geothermal reservoir at Dixie Valley, Nevada
Stephen Hickman, Mark Zoback, Richard Benoit
1998, Conference Paper, Proceedings of the SPE/ISRM Rock Mechanics in Petroleum Engineering Conference
To determine factors controlling permeability variations within and adjacent to a fault-hosted geothermal reservoir at Dixie Valley, Nevada, we conducted borehole televiewer observations of wellbore failure (breakouts and cooling cracks) together with hydraulic fracturing stress measurements in six wells drilled into the Stillwater fault zone at depths of 2 to...
The Cascadia Subduction Zone: Two contrasting models of lithospheric structure
T.V. Romanyuk, R. Blakely, Walter D. Mooney
1998, Physics and Chemistry of the Earth (23) 297-301
The Pacific margin of North America is one of the most complicated regions in the world in terms of its structure and present day geodynamic regime. The aim of this work is to develop a better understanding of lithospheric structure of the Pacific Northwest, in particular the Cascadia subduction zone...
Geology of Akutan Island, Alaska
Donald H. Richter, Christopher F. Waythomas, Robert G. McGimsey, Peter L. Stelling
1998, Open-File Report 98-135
No abstract available....
An economical, portable apparatus for conducting static thermal and chemical toxicity tests on amphibian eggs and larvae
M.R. Jennings
1998, California Fish and Game (84) 40-43
Analysis of lake-bottom sediment to estimate historical nonpoint-source phosphorus loads
K. E. Juracek
1998, Journal of the American Water Resources Association (34) 1449-1463
ABSTRACT Bottom sediment in Hillsdale Lake, Kansas, was analyzed to estimate the annual load of total phosphorus deposited in the lake from nonpoint sources. Topographic, bathymetric, and sediment-core data were used to estimate the total mass of phosphorus in the lake-bottom sediment. Available streamflow and...
Operational modeling system with dynamic-wave routing
A. L. Ishii, T.J. Charlton, T.W. Ortel, C.C. Vonnahme
Loucks E, editor(s)
1998, Conference Paper, Proceedings of the Annual Water Resources Planning and Management Conference
A near real-time streamflow-simulation system utilizing continuous-simulation rainfall-runoff generation with dynamic-wave routing is being developed by the U.S. Geological Survey in cooperation with the Du Page County Department of Environmental Concerns for a 24-kilometer reach of Salt Creek in Du Page County, Illinois. This system is needed in order to...
Palynology of latest Neogene (Middle Miocene to late Pliocene) strata in the Delmarva Peninsula of Maryland and Virginia
L. Sirkin, J. P. Owens
1998, Northeastern Geology and Environmental Sciences (20) 117-132
Palynology of Miocene and Pliocene formations in the Delmarva Peninsula of Maryland and Virginia reveals a significant representation of exotic pollen interspersed in pollen assemblages that are otherwise comparable to those from the modern vegetation of the Mid-Alantic coastal plain region. The late Tertiary arboreal pollen (AP) assemblages are dominated...
Simulating cholinesterase inhibition in birds caused by dietary insecticide exposure
M.S. Corson, M.A. Mora, W.E. Grant
1998, Ecological Modelling (105) 299-323
We describe a stochastic simulation model that simulates avian foraging in an agricultural landscape to evaluate factors affecting dietary insecticide exposure and to predict post-exposure cholinesterase (ChE) inhibition. To evaluate the model, we simulated published field studies and found that model predictions of insecticide decay and ChE inhibition reasonably approximated...
