Dynamic replacement and loss of soil carbon on eroding cropland
J.W. Harden, J. M. Sharpe, W.J. Parton, D.S. Ojima, T. L. Fries, Thomas G. Huntington, S. M. Dabney
1999, Global Biogeochemical Cycles (13) 885-901
Links between erosion/sedimentation history and soil carbon cycling were examined in a highly erosive setting in Mississippi loess soils. We sampled soils on (relatively) undisturbed and cropped hillslopes and measured C, N, 14C, and CO2 flux to characterize carbon storage and dynamics and to parameterize Century and spreadsheet 14C models for different erosion...
Gas hydrate accumulation at the Hakon Mosby Mud Volcano
G.D. Ginsburg, A.V. Milkov, V.A. Soloviev, A.V. Egorov, G.A. Cherkashev, P.R. Vogt, K. Crane, T.D. Lorenson, M.D. Khutorskoy
1999, Geo-Marine Letters (19) 57-67
Gas hydrate (GH) accumulation is characterized and modeled for the Hakon Mosby mud volcano, ca. 1.5 km across, located on the Norway-Barents-Svalbard margin. Pore water chemical and isotopic results based on shallow sediment cores as well as geothermal and geomorphological data suggest that the GH accumulation is of a concentric...
Geological implications of a permeability-depth curve for the continental crust
S. E. Ingebritsen, C. E. Manning
1999, Geology (27) 1107-1110
The decrease in permeability (k) of the continental crust with depth (z), as constrained by geothermal data and calculated fluid flux during metamorphism, is given by log k = −14 − 3.2 log z, where k is in meters squared and z is in kilometers. At moderate...
Simulation modeling of population viability for the leopard darter (Percidae: Percina pantherina)
L.R. Williams, A.A. Echelle, C.S. Toepfer, M.G. Williams, W.L. Fisher
1999, Southwestern Naturalist (44) 470-477
We used the computer program RAMAS to perform a population viability analysis for the leopard darter, Percina pantherina. This percid fish is a threatened species confined to five isolated rivers in the Ouachita Mountains of Oklahoma and Arkansas. A base model created from life history data indicated a 6% probability...
Nearshore versus offshore copper loading in Lake Superior sediments: Implications for transport and cycling
J.J. Kolak, D.T. Long, W.C. Kerfoot, T.M. Beals, Steven J. Eisenreich
1999, Journal of Great Lakes Research (25) 611-624
A thorough understanding of the fate and transport of metals in Lake Superior is necessary in order to predict the ability of Lake Superior to recover from anthropogenic perturbations (copper mining). Sediment cores were collected from nearshore and offshore sites in...
Response of North American freshwater lakes to simulated future climates
S. W. Hostetler, E.E. Small
1999, Conference Paper, Journal of the American Water Resources Association
We apply a physically based lake model to assess the response of North American lakes to future climate conditions as portrayed by the transient trace-gas simulations conducted with the Max Planck Institute (ECHAM4) and the Canadian Climate Center (CGCM1) atmosphere-ocean general circulation models (A/OGCMs). To quantify spatial patterns of lake...
Precipitation structure in the Sierra Nevada of California during winter
G.R. Pandey, D.R. Cayan, K.P. Georgakakos
1999, Journal of Geophysical Research D: Atmospheres (104) 12019-12030
Influences of upper air characteristics along the coast of California upon winter-time (November-April) precipitation in the Sierra Nevada are investigated. Precipitation events in the Sierra Nevada region occur mostly during wintertime, irrespective of station location (leeside or windside) and elevation. Most precipitation episodes in the region are associated with moist...
Radiometric calibration of spacecraft using small lunar images
Hugh H. Kieffer, James M. Anderson, Kris J. Becker
1999, Conference Paper, Proceedings of SPIE - The International Society for Optical Engineering
In this study, the data reduction steps that can be used to extract the lunar irradiance from low resolution images of the Moon are examined and the attendant uncertainties are quantitatively assessed. The response integrated over an image is compared to a lunar irradiance model being developed from terrestrial multi-band...
The role of groundwater chemistry in the transport of bacteria to water-supply wells
R.W. Harvey, D.W. Metge
1999, Conference Paper, IAHS-AISH Publication
Static mini-columns and in situ injection and recovery tests were used to assess the effects of modest changes in groundwater chemistry upon the pH-dependence of bacterial attachment, a primary determinant of bacterial mobility in drinking water aquifers. In uncontaminated groundwater (<1 mg l-1 dissolved organic carbon, DOC), bacterial attachment to...
Socioeconomic impacts of climate change on U.S. water supplies
K.D. Frederick, G. E. Schwarz
1999, Conference Paper, Journal of the American Water Resources Association
A greenhouse warming would have major effects on water supplies and demands. A framework for examining the socioeconomic impacts associated with changes in the long-term availability of water is developed and applied to the hydrologic implications of the Canadian and British Hadley2 general circulation models (GCMs) for the 18 water...
Spatial variability of turbulent fluxes in the roughness sublayer of an even-aged pine forest
G. Katul, C.-I. Hsieh, D. Bowling, K. Clark, N. Shurpali, A. Turnipseed, J. Albertson, K. Tu, D. Hollinger, B. M. Evans, B. Offerle, D. Anderson, D. Ellsworth, C. Vogel, R. Oren
1999, Boundary-Layer Meteorology (93) 1-28
The spatial variability of turbulent flow statistics in the roughness sublayer (RSL) of a uniform even-aged 14 m (= h) tall loblolly pine forest was investigated experimentally. Using seven existing walkup towers at this stand, high frequency velocity, temperature, water vapour and carbon dioxide concentrations were measured at 15.5...
The initial subevent of the 1994 Northridge, California, earthquake: Is earthquake size predictable?
Debi Kilb, J. Gomberg
1999, Journal of Seismology (3) 409-420
We examine the initial subevent (ISE) of the M 6.7, 1994 Northridge, California, earthquake in order to discriminate between two end-member rupture initiation models: the ‘preslip’ and ‘cascade’ models. Final earthquake size may be predictable from an ISE's seismic signature in the preslip model but not in the cascade model....
Plate deformation at depth under northern California: Slab gap or stretched slab?
Uri S. ten Brink, N. Shimizu, P.C. Molzer
1999, Tectonics (18) 1084-1098
Plate kinematic interpretations for northern California predict a gap in the underlying subducted slab caused by the northward migration of the Pacific-North America-Juan de Fuca triple junction. However, large-scale decompression melting and asthenospheric upwelling to the base of the overlying plate within the postulated gap are not supported by geophysical...
Explaining spatial variability in mean annual runoff in the conterminous United States
David M. Wolock, Gregory J. McCabe
1999, Climate Research (11) 149-159
The hydrologic concepts needed in a water-balance model to estimate the spatial variation in mean annual runoff for the 344 climate divisions in the conterminous United States (U.S.) were determined. The concepts that were evaluated were the climatic supply of water (precipitation), climatic demand for water (potential evapotranspiration), seasonality in...
Simulating the water balance of the Aral Sea with a coupled regional climate-lake model
E.E. Small, L.C. Sloan, S. Hostetler, F. Giorgi
1999, Journal of Geophysical Research D: Atmospheres (104) 6583-6602
Before coupled atmosphere-lake models can be used to study the response of large lake systems to climatic forcings, we must first evaluate how well they simulate the water balance and associated lake atmosphere interactions under present-day conditions. We evaluate the hydrology simulated by a lake model coupled to NCAR's regional...
Geotechnical characteristics and slope stability in the Gulf of Cadiz
H. Lee, J. Baraza
1999, Marine Geology (155) 173-190
Sedimentological and geotechnical analyses of thirty-seven core samples from the Gulf of Cadiz continental margin were used to define the regional variability of sediment properties and to assess slope stability. Considering the sediment property data set as a whole, there is an association between grain size, plasticity and water content....
Negative pH, efflorescent mineralogy, and consequences for environmental restoration at the iron mountain superfund site, California
D. Kirk Nordstrom, Charles N. Alpers
1999, Proceedings of the National Academy of Sciences of the United States of America (96) 3455-3462
The Richmond Mine of the Iron Mountain copper deposit contains some of the most acid mine waters ever reported. Values of pH have been measured as low as -3.6, combined metal concentrations as high as 200 g/liter, and sulfate concentrations as high as 760 g/liter. Copious quantities of soluble metal...
SAR studies in the Yuma Desert, Arizona: Sand penetration, geology, and the detection of military ordnance debris
G. G. Schaber
1999, Remote Sensing of Environment (67) 320-347
Synthetic Aperture Radar (SAR) images acquired over part of the Yuma Desert in southwestern Arizona demonstrate the ability of C-band (5.7-cm wavelength), L-band (24.5 cm), and P-band (68 cm) AIRSAR signals to backscatter from increasingly greater depths reaching several meters in blow sand and sandy alluvium. AIRSAR images obtained within...
Ventifacts at the Pathfinder landing site
N.T. Bridges, R. Greeley, A. F. C. Haldemann, Kenneth E. Herkenhoff, M. Kraft, T. J. Parker, A. W. Ward
1999, Journal of Geophysical Research E: Planets (104) 8595-8615
About half of the rocks at the Mars Pathfinder Ares Vallis landing site appear to be ventifacts, rocks abraded by windborne particles. Comparable resolution images taken by the Imager for Mars Pathfinder (IMP) camera and the Viking landers show that ventifacts are more abundant at the Pathfinder site. The ventifacts...
Stasis and extinction of Silurian (Llandovery-Wenlock) trilobite associations related to oceanic cyclicity
Donald G. Mikulic, Joanne Kluessendorf
1999, Journal of Paleontology (73) 320-325
Silurian trilobites of the central United States belong to a series of temporally-successive associations which appeared abruptly, maintained taxonomic stasis for a time, and then disappeared abruptly. Their disappearance resulted from global perturbations of short-term duration and moderate magnitude, which caused substantial taxonomic replacement but no reorganization of major ecosystems....
Health impacts of domestic coal use in China
R. B. Finkelman, H. E. Belkin, B. Zheng
1999, Conference Paper, Proceedings of the National Academy of Sciences of the United States of America
Domestic coal combustion has had profound adverse effects on the health of millions of people worldwide. In China alone several hundred million people commonly burn raw coal in unvented stoves that permeate their homes with high levels of toxic metals and organic compounds. At least 3,000 people in Guizhou Province...
Genetic and morphometric assessment of an unusual tortoise (Gopherus agassizii) population in the Black Mountains of Arizona
A.M. McLuckie, T. Lamb, C.R. Schwalbe, R.D. Mccord
1999, Journal of Herpetology (33) 36-44
Under recent regulatory designation of the U.S. Fish and Wildlife Service, desert tortoises (Gopherus agassizii) occurring east and south of the Colorado River constitute the Sonoran population, whereas those to the west and north form the Mojave population. These management units, distinguished by significant genetic, morphometric, and ecological differences, represent...
Site response for Seattle and source parameters of earthquakes in the Puget Sound Region
A. Frankel, D. Carver, E. Cranswick, M. Meremonte, T. Bice, D. Overturf
1999, Bulletin of the Seismological Society of America (89) 468-483
We analyzed seismograms from 21 earthquakes (ML 2.0-4.9) recorded by digital seismographs we deployed in urban Seattle to determine site response and earthquake stress drops. The seismometers were situated on a wide variety of geologic units, including artificial fill (e.g., Kingdome, Harbor Island), Pleistocene...
Estimates of suspended-sediment flux and bedform activity on the inner portion of the Eel continental shelf
D.A. Cacchione, P.L. Wiberg, J. Lynch, J. Irish, P. Traykovski
1999, Marine Geology (154) 83-97
Energetic waves, strong bottom currents, and relatively high rates of sediment discharge from the Eel River combined to produce large amounts of suspended-sediment transport on the inner continental shelf near the Eel River during the winter of 1995-1996. Bottom-boundary-layer (BBL) measurements at a depth of ~50 m using the GEOPROBE...
The thin hot plume beneath Iceland
R. M. Allen, G. Nolet, W. J. Morgan, K. Vogfjord, B. H. Bergsson, P. Erlendsson, G.R. Foulger, S. Jakobsdottir, B.R. Julian, M. Pritchard, S. Ragnarsson, R. Stefansson
1999, Geophysical Journal International (137) 51-63
We present the results of a seismological investigation of the frequency-dependent amplitude variations across Iceland using data from the HOTSPOT array currently deployed there. The array is composed of 30 broad-band PASSCAL instruments. We use the parameter t(*), defined in the usual manner from spectral ratios (Halderman and Davis 1991),...
