Earthquake and volcano clustering via stress transfer at Yucca Mountain, Nevada
T. Parsons, G. A. Thompson, A.H. Cogbill
2006, Geology (34) 785-788
The proposed national high-level nuclear waste repository at Yucca Mountain is close to Quaternary cinder cones and faults with Quaternary slip. Volcano eruption and earthquake frequencies are low, with indications of spatial and temporal clustering, making probabilistic assessments difficult. In an effort to identify the most likely intrusion sites, we...
A holistic approach to taxonomic evaluation of two closely related endangered freshwater mussel species, the oyster mussel Epioblasma capsaeformis and tan riffleshell Epioblasma florentina walkeri (Bivalvia: Unionidae)
J. W. Jones, R. J. Neves, S.A. Ahlstedt, E.M. Hallerman
2006, Journal of Molluscan Studies (72) 267-283
Species in the genus Epioblasma have specialized life history requirements and represent the most endangered genus of freshwater mussels (Unionidae) in the world. A genetic characterization of extant populations of the oyster mussel E. capsaeformis and tan riffleshell E. florentina walkeri sensu late was conducted to assess taxonomic validity and...
Multiphase, multicomponent parameter estimation for liquid and vapor fluxes in deep arid systems using hydrologic data and natural environmental tracers
Edward M. Kwicklis, Andrew V. Wolfsberg, Philip H. Stauffer, Michelle Ann Walvoord, Michael J. Sully
2006, Vadose Zone Journal (5) 934-950
Multiphase, multicomponent numerical models of long-term unsaturated-zone liquid and vapor movement were created for a thick alluvial basin at the Nevada Test Site to predict present-day liquid and vapor fluxes. The numerical models are based on recently developed conceptual models of unsaturated-zone moisture movement in thick alluvium that explain present-day...
Nitrogen sources and cycling in the San Francisco Bay estuary: A nitrate dual isotopic composition approach
Scott D. Wankel, C. Kendall, C.A. Francis, A. Paytan
2006, Limnology and Oceanography (51) 1654-1664
We used the dual isotopic composition of nitrate (δ15N and δ18O) within the estuarine system of San Francisco (SF) Bay, California, to explore the utility of this approach for tracing sources and cycling of nitrate (NO2−). Surface water samples from 49 sites within the estuary were sampled during July–August 2004....
Evaluating uncertainty in predicting spatially variable representative elementary scales in fractured aquifers, with application to Turkey Creek Basin, Colorado
Tristan P. Wellman, Eileen P. Poeter
2006, Water Resources Research (42)
Computational limitations and sparse field data often mandate use of continuum representation for modeling hydrologic processes in large‐scale fractured aquifers. Selecting appropriate element size is of primary importance because continuum approximation is not valid for all scales. The traditional approach is to select elements by identifying a single representative elementary...
Acoustic bed velocity and bed load dynamics in a large sand bed river
D. Gaeuman, R. B. Jacobson
2006, Journal of Geophysical Research F: Earth Surface (111)
Development of a practical technology for rapid quantification of bed load transport in large rivers would represent a revolutionary advance for sediment monitoring and the investigation of fluvial dynamics. Measurement of bed load motion with acoustic Doppler current profiles (ADCPs) has emerged as a promising approach for evaluating bed load...
Estimating locations and magnitudes of earthquakes in southern California from modified Mercalli intensities
W. H. Bakun
2006, Bulletin of the Seismological Society of America (96) 1278-1295
Modified Mercalli intensity (MMI) assignments, instrumental moment magnitudes M, and epicenter locations of thirteen 5.6 ??? M ??? 7.1 "training-set" events in southern California were used to obtain the attenuation relation MMI = 1.64 + 1.41M - 0.00526 * ??h - 2.63 * log ??h, where ??h is the hypocentral...
Sediment distribution and transport across the continental shelf and slope under idealized wind forcing
S.A. Condie, C. R. Sherwood
2006, Progress in Oceanography (70) 255-270
Resuspension, transport, and deposition of sediments over the continental shelf and slope are complex processes and there is still a need to understand the underlying spatial and temporal dynamical scales. As a step towards this goal, a two-dimensional slice model (zero gradients in the alongshore direction) based on the primitive...
Proximate and landscape factors influence grassland bird distributions
M.A. Cunningham, Douglas H. Johnson
2006, Ecological Applications (16) 1062-1075
Ecologists increasingly recognize that birds can respond to features well beyond their normal areas of activity, but little is known about the relative importance of landscapes and proximate factors or about the scales of landscapes that influence bird distributions. We examined the influences of tree cover at both proximate and...
A trait-based test for habitat filtering: Convex hull volume
W.K. Cornwell, D.W. Schwilk, D. D. Ackerly
2006, Ecology (87) 1465-1471
Community assembly theory suggests that two processes affect the distribution of trait values within communities: competition and habitat filtering. Within a local community, competition leads to ecological differentiation of coexisting species, while habitat filtering reduces the spread of trait values, reflecting shared ecological tolerances. Many statistical tests for the effects...
Dietary exposure of largemouth bass to OCPs changes expression of genes important for reproduction
Natalia Garcia-Reyero, D.S. Barber, T. S. Gross, K. G. Johnson, M. S. Sepulveda, N.J. Szabo, N. D. Denslow
2006, Aquatic Toxicology (78) 358-369
Dieldrin and p,p???-DDE are ubiquitous contaminants known to act as endocrine disruptors, causing impaired development and reproduction in fish and wildlife. In order to elucidate the mechanisms by which dieldrin and p,p???-DDE cause endocrine disruption in largemouth bass (Micropterus salmoides), fish were exposed subchronically through the diet to both contaminants....
Comparison of selenium bioaccumulation in the clams Corbicula fluminea and Potamocorbula amurensis: A bioenergetic modeling approach
B.-G. Lee, J.-S. Lee, S. N. Luoma
2006, Environmental Toxicology and Chemistry (25) 1933-1940
Selenium uptake from food (assimilation efficiency) and dissolved phase (influx rate) as well as loss kinetics (efflux rate) were compared between two bivalves, Corbicula fluminea and Potamocorbula amurensis. The effects of salinity and temperature on these kinetic parameters for both clam species also were evaluated. The Asiatic clam, C. fluminea,...
Derivation of planetary topography using multi-image shape-from-shading
Volker Lohse, Christian Heipke, Randolph L. Kirk
2006, Planetary and Space Science (54) 661-674
In many cases, the derivation of high-resolution digital terrain models (DTMs) from planetary surfaces using conventional digital image matching is a problem. The matching methods need at least one stereo pair of images with sufficient texture. However, many space missions provide only a few stereo images and planetary surfaces often...
Peak flow responses to landscape disturbances caused by the cataclysmic 1980 eruption of Mount St. Helens, Washington
Jon J. Major, Linda E. Mark
2006, Geological Society of America Bulletin (118) 938-958
Years of discharge measurements that precede and follow the cataclysmic 1980 eruption of Mount St. Helens, Washington, provide an exceptional opportunity to examine the responses of peak flows to abrupt, widespread, devastating landscape disturbance. Multiple basins surrounding Mount St. Helens (300–1300 km2 drainage areas) were variously disturbed by: (1) a debris...
Usoi dam wave overtopping and flood routing in the Bartang and Panj Rivers, Tajikistan
J. C. Risley, J. S. Walder, R.P. Denlinger
2006, Natural Hazards (38) 375-390
The Usoi dam was created in the winter of 1911 after an enormous seismogenic rock slide completely blocked the valley of the Bartang River in the Pamir Mountains of southeastern Tajikistan. At present the dam impounds 17 million cubic meters of water in Lake Sarez. Flood volume and discharge estimates...
Rupture models for the A.D. 900-930 Seattle fault earthquake from uplifted shorelines
Uri S. ten Brink, J. Song, R.C. Bucknam
2006, Geology (34) 585-588
A major earthquake on the Seattle fault, Washington, ca. A.D. 900-930 was first inferred from uplifted shorelines and tsunami deposits. Despite follow-up geophysical and geological investigations, the rupture parameters of the earthquake and the geometry of the fault are uncertain. Here we estimate the fault geometry, slip direction, and magnitude...
Effects of permafrost melting on CO2 and CH4 exchange of a poorly drained black spruce lowland
K.P. Wickland, Robert G. Striegl, J. C. Neff, T. Sachs
2006, Journal of Geophysical Research G: Biogeosciences (111)
[1] Permafrost melting is occurring in areas of the boreal forest region where large amounts of carbon (C) are stored in organic soils. We measured soil respiration, net CO2 flux, and net CH4 flux during May–September 2003 and March 2004 in a black spruce lowland in interior Alaska to...
Integration of P- and SH-wave high-resolution seismic reflection and micro-gravity techniques to improve interpretation of shallow subsurface structure: New Madrid seismic zone
C.E. Bexfield, J.H. McBride, Andre J. M. Pugin, D. Ravat, S. Biswas, W.J. Nelson, T.H. Larson, S.L. Sargent, M.A. Fillerup, B.E. Tingey, L. Wald, M.L. Northcott, J.V. South, M.S. Okure, M.R. Chandler
2006, Tectonophysics (420) 5-21
Shallow high-resolution seismic reflection surveys have traditionally been restricted to either compressional (P) or horizontally polarized shear (SH) waves in order to produce 2-D images of subsurface structure. The northernmost Mississippi embayment and coincident New Madrid seismic zone (NMSZ) provide an ideal laboratory to study the experimental use of integrating...
Relationship between shrubs and foods in mountain plover habitat in Park County, Colorado
S.C. Schneider, Michael B. Wunder, F.L. Knopf
2006, Southwestern Naturalist (51) 197-202
We explored habitat use in terms of vegetation structure and potential forage availability for mountain plovers (Charadrius montanus) in Park County, Colorado. We quantified the percentage cover of bare ground, percentage cover of shrubs (Chrysothamnus visadiflorus), linear distance to nearest shrub, arthropod biomass, and grasshopper density for 102 plots of...
Seasonal dynamics of microbial community composition and function in oak canopy and open grassland soils
M. P. Waldrop, M.K. Firestone
2006, Microbial Ecology (52) 470-479
Soil microbial communities are closely associated with aboveground plant communities, with multiple potential drivers of this relationship. Plants can affect available soil carbon, temperature, and water content, which each have the potential to affect microbial community composition and function. These same variables change seasonally, and thus plant control on microbial...
Essential elements of online information networks on invasive alien species
Annie Simpson, Elizabeth A. Sellers, Andrea Grosse, Y. Xie
2006, Conference Paper
In order to be effective, information must be placed in the proper context and organized in a manner that is logical and (preferably) standardized. Recently, invasive alien species (IAS) scientists have begun to create online networks to share their information concerning IAS prevention and control. At a special networking session...
Mechanical deformation model of the western United States instantaneous strain-rate field
F. F. Pollitz, M. Vergnolle
2006, Geophysical Journal International (167) 421-444
We present a relationship between the long-term fault slip rates and instantaneous velocities as measured by Global Positioning System (GPS) or other geodetic measurements over a short time span. The main elements are the secularly increasing forces imposed by the bounding Pacific and Juan de Fuca (JdF) plates on the...
Nitrogen loads through baseflow, stormflow, and underflow to Rehoboth Bay, Delaware
J.A. Volk, K.B. Savidge, J.R. Scudlark, A.S. Andres, W.J. Ullman
2006, Journal of Environmental Quality (35) 1742-1755
A detailed study of water and nitrogen (N) discharge from a small, representative subwatershed of Rehoboth Bay, Delaware, was conducted to determine total N loads to the bay. The concentrations of ammonium (NH 4+), nitrate + nitrite (NO3- + NO2-), and dissolved and particulate organic N were determined in baseflow...
Stochastic uncertainty analysis for unconfined flow systems
Gaisheng Liu, Dongxiao Zhang, Zhiming Lu
2006, Water Resources Research (42)
A new stochastic approach proposed by Zhang and Lu (2004), called the Karhunen‐Loeve decomposition‐based moment equation (KLME), has been extended to solving nonlinear, unconfined flow problems in randomly heterogeneous aquifers. This approach is on the basis of an innovative combination of Karhunen‐Loeve decomposition, polynomial expansion, and perturbation methods. The random...
Simulating the effects of frequent fire on southern california coastal shrublands
A.D. Syphard, J. Franklin, Jon E. Keeley
2006, Ecological Applications (16) 1744-1756
Fire disturbance is a primary agent of change in the mediterranean-climate chaparral shrublands of southern California, USA. However, fire frequency has been steadily increasing in coastal regions due to ignitions at the growing wildland-urban interface. Although chaparral is resilient to a range of fire frequencies, successively short intervals between fires...
