Entrainment of riparian gravel and cobbles in an alluvial reach of a regulated canyon river
John G. Elliott, Lauren A. Hammack
2000, Regulated Rivers: Research & Management (16) 37-50
Many canyon rivers have channels and riparian zones composed of alluvial materials and these reaches, dominated by fluvial processes, are sensitive to alterations in streamflow regime. Prior to reservoir construction in the mid-1960s, banks and bars in alluvial reaches of the Gunnison River in the Black Canyon National Monument, Colorado,...
Wildlife tradeoffs based on landscape models of habitat
C. Loehle, M.S. Mitchell
2000, Conference Paper, NCASI Proceedings
It is becoming increasingly clear that the spatial structure of landscapes affects the habitat choices and abundance of wildlife. In contrast to wildlife management based on preservation of critical habitat features such as nest sites on a beach or mast trees, it has not been obvious how to incorporate spatial...
Reproductive longevity and fecundity associated with nonannual spawning in cui-ui
G.G. Scoppettone, P.H. Rissler, M.E. Buettner
2000, Transactions of the American Fisheries Society (129) 658-669
The cui-ui Chasmistes cujus, a long-lived (40 years or more) and highly fecund catostomid, is often prevented from spawning in drought years. We studied the effect of cui-ui age on egg viability and the effect of nonannual spawning on fecundity in relation to length, age, and growth rate. Egg hatching...
Aquifer response to stream-stage and recharge variations. II. Convolution method and applications
P. M. Barlow, L.A. DeSimone, A.F. Moench
2000, Journal of Hydrology (230) 211-229
In this second of two papers, analytical step-response functions, developed in the companion paper for several cases of transient hydraulic interaction between a fully penetrating stream and a confined, leaky, or water-table aquifer, are used in the convolution integral to calculate aquifer heads, streambank seepage rates, and bank storage that...
The southwestern Alaska mercury belt and its relationship to the circum-Pacific metallogenic mercury province
J. E. Gray, C. A. Gent, L.W. Snee
2000, Polarforschung (68) 187-196
A belt of small but numerous mercury deposits extends for about 500 km in the Kuskokwim River region of southwestern Alaska. The southwestern Alaska mercury belt is part of widespread mercury deposits of the circumPacific region that are similar to other mercury deposits throughout the world because they are epithermal...
Modelling carbon responses of tundra ecosystems to historical and projected climate: Sensitivity of pan-Arctic carbon storage to temporal and spatial variation in climate
A. D. McGuire, Joy S. Clein, J. M. Melillo, D. W. Kicklighter, R.A. Meier, C. J. Vorosmarty, Mark C. Serreze
2000, Global Change Biology (6) 141-159
Historical and projected climate trends for high latitudes show substantial temporal and spatial variability. To identify uncertainties in simulating carbon (C) dynamics for pan-Arctic tundra, we compare the historical and projected responses of tundra C storage from 1921 to 2100 between simulations by the Terrestrial Ecosystem Model (TEM) for the...
Geophysical, archaeological and historical evidence support a solar-output model for climate change
C. A. Perry, K.J. Hsu
2000, Conference Paper, Proceedings of the National Academy of Sciences of the United States of America
Although the processes of climate change are not completely understood, an important causal candidate is variation in total solar output. Reported cycles in various climate-proxy data show a tendency to emulate a fundamental harmonic sequence of a basic solar-cycle length (11 years) multiplied by 2(N) (where N equals a positive...
A crustal model of the ultrahigh-pressure Dabie Shan orogenic belt, China, derived from deep seismic refraction profiling
Chun-Yong Wang, Rong-Sheng Zeng, Walter D. Mooney, B. R. Hacker
2000, Journal of Geophysical Research B: Solid Earth (105) 10857-10869
We present a new crustal cross section through the east-west trending ultrahigh-pressure (UHP) Dabie Shan orogenic belt, east central China, based on a 400-km-long seismic refraction profile. Data from our profile reveal that the cratonal blocks north and south of the orogen are composed of 35-km-thick crust consisting of three...
Synthetic aperture radar interferometry of Okmok volcano, Alaska: radar observations
Zhong Lu, Dorte Mann, Jeffrey T. Freymueller, David Meyer
2000, Journal of Geophysical Research B: Solid Earth (105) 10791-10806
ERS-1/ERS-2 synthetic aperture radar interferometry was used to study the 1997 eruption of Okmok volcano in Alaska. First, we derived an accurate digital elevation model (DEM) using a tandem ERS-1/ERS-2 image pair and the preexisting DEM. Second, by studying changes in interferometric coherence we found that the newly erupted lava...
Dynamics of nutrient cycling and related benthic nutrient and oxygen fluxes during a spring phytoplankton bloom in South San Francisco Bay (USA)
C. Grenz, J. E. Cloern, S.W. Hager, B.E. Cole
2000, Marine Ecology Progress Series (197) 67-80
Benthic oxygen uptake and nutrient releases of N, P and Si were measured weekly at 2 sites in South San Francisco Bay around the 1996 spring bloom. Exchanges across the sediment-water interface were estimated from whole core incubations performed in the laboratory at in situ temperature and in dark. Fluxes changed significantly...
Pollen-based biomes for Beringia 18,000, 6000 and 0 14C yr BP
M. E. Edwards, P. M. Anderson, L.B. Brubaker, T. A. Ager, A.A. Andreev, N.H. Bigelow, L.C. Cwynar, Wendy R. Eisner, S. P. Harrison, F.-S. Hu, D. Jolly, A.V. Lozhkin, G. M. MacDonald, Cary J. Mock, J.C. Ritchie, A.V. Sher, R.W. Spear, J.W. Williams, G. Yu
2000, Journal of Biogeography (27) 521-554
The objective biomization method developed by Prentice et al. (1996) for Europe was extended using modern pollen samples from Beringia and then applied to fossil pollen data to reconstruct palaeovegetation patterns at 6000 and 18,000 14C yr BP. The predicted modern distribution of tundra, taiga and cool conifer forests in...
Models of downdip frictional coupling for the Cascadia Megathrust
D. Stanley, A. Villasenor
2000, Geophysical Research Letters (27) 1551-1554
We have developed models of downdip frictional coupling along two transects across the Cascadia subduction zone in northern Washington and central Oregon. The models involve complicated downdip coupling profiles. Although not unique, our models closely predict available GPS shortening rates and vertical uplift data. We are able to explain relatively...
Simulated influences of Lake Agassiz on the climate of central North America 11,000 years ago
S. W. Hostetler, P. J. Bartlein, P.U. Clark, E.E. Small, A.M. Solomon
2000, Nature (405) 334-337
Eleven thousand years ago, large lakes existed in central and eastern North America along the margin of the Laurentide Ice Sheet. The large-scale North American climate at this time has been simulated with atmospheric general circulation models, but these relatively coarse global models do not resolve potentially important features of...
Strong motion from surface waves in deep sedimentary basins
William B. Joyner
2000, Bulletin of the Seismological Society of America (90) S95-S112
It is widely recognized that long-period surface waves generated by conversion of body waves at the boundaries of deep sedimentary basins make an important contribution to strong ground motion. The factors controlling the amplitude of such motion, however, are not widely understood. A study of pseudovelocity response spectra of strong-motion...
Deep magmatic structures of Hawaiian volcanoes, imaged by three-dimensional gravity models
J. Kauahikaua, T. Hildenbrand, M. Webring
2000, Geology (28) 883-886
A simplified three-dimensional model for the island of Hawai'i, based on 3300 gravity measurements, provides new insights on magma pathways within the basaltic volcanoes. Gravity anomalies define dense cumulates and intrusions beneath the summits and known rift zones of every volcano. Linear gravity anomalies project southeast from Kohala and Mauna...
Functional groups and elemental analyses of cuticular morphotypes of Cordaites principalis (Germar) Geinitz, Carboniferous Maritimes Basin, Canada
E.L. Zodrow, Maria Mastalerz, W. H. Orem, Z. Simunek, A.R. Bashforth
2000, International Journal of Coal Geology (45) 1-19
Well-preserved cuticles were isolated from Cordaites principalis (Germar) Geinitz leaf compressions, i.e., foliage from extinct gymnosperm trees Coniferophyta: Order Cordaitales. The specimens were collected from the Sydney. Stellarton and Bay St. George subbasins of the once extensive Carboniferous Maritimes Basin of Atlantic Canada. Fourier transformation of infrared spectra (FTIR) and...
Estimation of potential loss of two pesticides in runoff in Fillmore County, Minnesota using a field-scale process-based model and a geographic information system
Paul D. Capel, Zhang Hua
2000, Conference Paper, Agrochemical fate and movement
In assessing the occurrence, behavior, and effects of agricultural chemicals in surface water, the scales of study (i.e., watershed, county, state, and regional areas) are usually much larger than the scale of agricultural fields, where much of the understanding of processes has been developed. Field-scale areas are characterized by relatively...
Considerations involved with the use of semipermeable membrane devices for monitoring environmental contaminants
J. D. Petty, C.E. Orazio, J.N. Huckins, R.W. Gale, J.A. Lebo, J.C. Meadows, K. R. Echols, W.L. Cranor
2000, Journal of Chromatography A (879) 83-95
Semipermeable membrane devices (SPMDs) are used with increasing frequency, and throughout the world as samplers of organic contaminants. The devices can be used to detect a variety of lipophilic chemicals in water, sediment/soil, and air. SPMDs are designed to sample nonpolar, hydrophobic chemicals. The maximum concentration factor achievable for a...
Mobilization of major inorganic ions during experimental diagenesis of characterized peats
A.M. Bailey, A.D. Cohen, W. H. Orem, J.H. Blackson
2000, Chemical Geology (166) 287-300
Laboratory experiments were undertaken to study changes in concentrations of major inorganic ions during simulated burial of peats to about 1.5 km. Cladium, Rhizophora, and Cyrilla peats were first analyzed to determine cation distributions among fractions of the initial materials and minerals in residues from wet oxidation. Subsamples of the...
Studies in neotropical paleobotany. XIV. A palynoflora from the middle Eocene Saramaguacán formation of Cuba
A. Graham, D. Cozadd, A. Areces-Mallea, N. O. Frederiksen
2000, American Journal of Botany (87) 1526-1539
An assemblage of 46 fossil pollen and spore types is described from a core drilled through the middle Eocene Saramaguacán Formation, Camagüey Province, eastern Cuba. Many of the specimens represent unidentified or extinct taxa but several can be identified to family (Palmae, Bombacaceae, Gramineae, Moraceae, Myrtaceae) and some to genus...
Regional Crustal Structures and Their Relationship to the Distribution of Ore Deposits in the Western United States, Based on Magnetic and Gravity Data
T.G. Hildenbrand, B. Berger, R.C. Jachens, S. Ludington
2000, Economic Geology (95) 1583-1603
Upgraded gravity and magnetic databases and associated filtered-anomaly maps of western United States define regional crustal fractures or faults that may have guided the emplacement of plutonic rocks and large metallic ore deposits. Fractures, igneous intrusions, and hydrothermal circulation tend to be localized along boundaries of crustal blocks, with geophysical...
Using submarine lava pillars to record mid-ocean ridge eruption dynamics
Tracy Gregg, Daniel J. Fornari, Michael R. Perfit, W. Ian Ridley, Mark D. Kurz
2000, Earth and Planetary Science Letters (178) 195-214
Submarine lava pillars are hollow, glass-lined, basaltic cylinders that occur at the axis of the mid-ocean ridge, and within the summit calderas of some seamounts. Typically, pillars are ~1-20 m tall and 0.25-2.0 m in diameter, with subhorizontal to horizontal glassy selvages on their exterior walls. Lava pillars form gradually...
Drainage-basis-scale geomorphic analysis to determine refernce conditions for ecologic restoration-Kissimmee River, Florida
A.G. Warne, L.A. Toth, W.A. White
2000, Geological Society of America Bulletin (112) 884-899
Major controls on the retention, distribution, and discharge of surface water in the historic (precanal) Kissimmee drainage basin and river were investigated to determine reference conditions for ecosystem restoration. Precanal Kissimmee drainage-basin hydrology was largely controlled by landforms derived from relict, coastal ridge, lagoon, and shallow-shelf features; widespread carbonate solution...
Modeling biotic habitat high risk areas
Don G. Despain, P. Beier, C. Tate, B.M. Durtsche, T. Stephens
2000, Journal of Sustainable Forestry (11) 89-117
Fire, especially stand replacing fire, poses a threat to many threatened and endangered species as well as their habitat. On the other hand, fire is important in maintaining a variety of successional stages that can be important for approach risk assessment to assist in prioritizing areas for allocation of fire...
Chapter 4. Predicting post-fire erosion and sedimentation risk on a landscape scale
L. H. MacDonald, R. Sampson, D. Brady, L. Juarros, Deborah A. Martin
2000, Journal of Sustainable Forestry (11) 57-87
Historic fire suppression efforts have increased the likelihood of large wildfires in much of the western U.S. Post-fire soil erosion and sedimentation risks are important concerns to resource managers. In this paper we develop and apply procedures to predict post-fire erosion and sedimentation risks on a pixel-, catchment-, and landscape-scale...
