Application of synchrotron methods to assess the uptake of roadway-derived Zn by earthworms in an urban soil
S.M. Lev, E. R. Landa, K. Szlavecz, R. Casey, J. Snodgrass
2008, Mineralogical Magazine (72) 191-195
The impact of human activities on biogeochemical cycles in terrestrial environments is nowhere more apparent than in urban landscapes. Trace metals, collected on roadways and transported by storm water, may contaminate soils and sediments associated with storm water management systems. These systems will accumulate metals and associated sediments may reach...
Representing general theoretical concepts in structural equation models: The role of composite variables
J.B. Grace, K.A. Bollen
2008, Environmental and Ecological Statistics (15) 191-213
Structural equation modeling (SEM) holds the promise of providing natural scientists the capacity to evaluate complex multivariate hypotheses about ecological systems. Building on its predecessors, path analysis and factor analysis, SEM allows for the incorporation of both observed and unobserved (latent) variables into theoretically-based probabilistic models. In this paper we...
Are fractal dimensions of the spatial distribution of mineral deposits meaningful?
G. L. Raines
2008, Natural Resources Research (17) 87-97
It has been proposed that the spatial distribution of mineral deposits is bifractal. An implication of this property is that the number of deposits in a permissive area is a function of the shape of the area. This is because the fractal density functions of deposits are dependent on the...
Evidence for fish dispersal from spatial analysis of stream network topology
N.P. Hitt, P. L. Angermeier
2008, Journal of the North American Benthological Society (27) 304-320
Developing spatially explicit conservation strategies for stream fishes requires an understanding of the spatial structure of dispersal within stream networks. We explored spatial patterns of stream fish dispersal by evaluating how the size and proximity of connected streams (i.e., stream network topology) explained variation in fish assemblage structure and how...
Temporal downscaling of decadal sediment load estimates to a daily interval for use in hindcast simulations
N. K. Ganju, N. Knowles, D. H. Schoellhamer
2008, Journal of Hydrology (349) 512-523
In this study we used hydrologic proxies to develop a daily sediment load time-series, which agrees with decadal sediment load estimates, when integrated. Hindcast simulations of bathymetric change in estuaries require daily sediment loads from major tributary rivers, to capture the episodic delivery of sediment during multi-day freshwater flow pulses....
Eruption dynamics at Mount St. Helens imaged from broadband seismic waveforms: Interaction of the shallow magmatic and hydrothermal systems
G.P. Waite, B. A. Chouet, P.B. Dawson
2008, Journal of Geophysical Research B: Solid Earth (113)
The current eruption at Mount St. Helens is characterized by dome building and shallow, repetitive, long-period (LP) earthquakes. Waveform cross-correlation reveals remarkable similarity for a majority of the earthquakes over periods of several weeks. Stacked spectra of these events display multiple peaks between 0.5 and 2 Hz that are common...
Soil nutrient-landscape relationships in a lowland tropical rainforest in Panama
F.K. Barthold, R.F. Stallard, H. Elsenbeer
2008, Forest Ecology and Management (255) 1135-1148
Soils play a crucial role in biogeochemical cycles as spatially distributed sources and sinks of nutrients. Any spatial patterns depend on soil forming processes, our understanding of which is still limited, especially in regards to tropical rainforests. The objective of our study was to investigate the effects of landscape properties,...
Using HEM surveys to evaluate disposal of by-product water from CBNG development in the Powder River Basin, Wyoming
B.A. Lipinski, J.I. Sams, B. D. Smith, W. Harbert
2008, Geophysics (73)
Production of methane from thick, extensive coal beds in the Powder River Basin of Wyoming has created water management issues. Since development began in 1997, more than 650 billion liters of water have been produced from approximately 22,000 wells. Infiltration impoundments are used widely to dispose of by-product water from...
Modeling unobserved sources of heterogeneity in animal abundance using a Dirichlet process prior
R.M. Dorazio, B. Mukherjee, L. Zhang, M. Ghosh, H.L. Jelks, F. Jordan
2008, Biometrics (64) 635-644
In surveys of natural populations of animals, a sampling protocol is often spatially replicated to collect a representative sample of the population. In these surveys, differences in abundance of animals among sample locations may induce spatial heterogeneity in the counts associated with a particular sampling protocol. For some species, the...
Influences of calcium availability and tree species on Ca isotope fractionation in soil and vegetation
B.D. Page, T.D. Bullen, M.J. Mitchell
2008, Biogeochemistry (88) 1-13
The calcium (Ca) isotope system is potentially of great use for understanding biogeochemical processes at multiple scales in forest ecosystems, yet remains largely unexplored for this purpose. In order to further our understanding of Ca behavior in forests, we examined two nearly adjacent hardwood-dominated catchments with differing soil Ca concentrations,...
Tamarix as habitat for birds: Implications for riparian restoration in the Southwestern United States
M. K. Sogge, S.J. Sferra, E. H. Paxton
2008, Restoration Ecology (16) 146-154
Exotic vegetation has become a major habitat component in many ecosystems around the world, sometimes dramatically changing the vegetation community structure and composition. In the southwestern United States, riparian ecosystems are undergoing major changes in part due to the establishment and spread of the exotic Tamarix (saltcedar, tamarisk). There are...
Comparisons of shear-wave slowness in the Santa Clara Valley, California using blind interpretations of data from invasive and noninvasive methods
D.M. Boore, M.W. Asten
2008, Bulletin of the Seismological Society of America (98) 1983-2003
Many groups contributed to a blind interpretation exercise for the determination of shear-wave slowness beneath the Santa Clara Valley. The methods included invasive methods in deep boreholes as well as noninvasive methods using active and passive sources, at six sites within the valley (with most investigations being conducted at a...
The influence of alewife year-class strength on prey selection and abundance of age-1 Chinook salmon in Lake Michigan
D.M. Warner, C.S. Kiley, R.M. Claramunt, D.F. Clapp
2008, Transactions of the American Fisheries Society (137) 1683-1700
We used growth and diet data from a fishery-independent survey of Chinook salmon Oncorhynchus tshawytscha, acoustic estimates of prey density and biomass, and statistical catch-at-age modeling to study the influence of the year-class strength of alewife Alosa pseudoharengus on the prey selection and abundance of age-1 Chinook salmon in Lake...
A fully distributed implementation of mean annual streamflow regional regression equations
K.L. Verdin, B. Worstell
2008, Journal of the American Water Resources Association (44) 1537-1547
Estimates of mean annual streamflow are needed for a variety of hydrologic assessments. Away from gage locations, regional regression equations that are a function of upstream area, precipitation, and temperature are commonly used. Geographic information systems technology has facilitated their use for projects, but traditional approaches using the polygon overlay...
Distribution of icy particles across Enceladus' surface as derived from Cassini-VIMS measurements
R. Jaumann, K. Stephan, G. B. Hansen, R. N. Clark, B. J. Buratti, R. H. Brown, K. H. Baines, S.F. Newman, G. Bellucci, G. Filacchione, A. Coradini, D. P. Cruikshank, C.A. Griffith, C. A. Hibbitts, T. B. McCord, R.M. Nelson, P. D. Nicholson, Christophe Sotin, R. Wagner
2008, Icarus (193) 407-419
The surface of Enceladus consists almost completely of water ice. As the band depths of water ice absorptions are sensitive to the size of particles, absorptions can be used to map variations of icy particles across the surface. The Visual and Infrared Mapping Spectrometer (VIMS) observed Enceladus with a high...
Assigning king eiders to wintering regions in the Bering Sea using stable isotopes of feathers and claws
S. Oppel, A.N. Powell
2008, Marine Ecology Progress Series (373) 149-156
Identification of wintering regions for birds sampled during the breeding season is crucial to understanding how events outside the breeding season may affect populations. We assigned king eiders captured on breeding grounds in northern Alaska to 3 broad geographic wintering regions in the Bering Sea using stable carbon and nitrogen...
Remote sensing and GIS approach for water-well site selection, southwest Iran
K. Rangzan, A. Charchi, E. Abshirini, J. Dinger
2008, Environmental & Engineering Geoscience (14) 315-326
The Pabdeh-Lali Anticline of northern Khuzestan province is located in southwestern Iran and occupies 790 km2. This structure is situated in the Zagros folded belt. As a result of well-developed karst systems in the anticlinal axis, the water supply potential is high and is drained by many peripheral springs. However,...
Great Basin paleontological database
N. Zhang, R. B. Blodgett, A. H. Hofstra
2008, Geosphere (4) 520-535
The U.S. Geological Survey has constructed a paleontological database for the Great Basin physiographic province that can be served over the World Wide Web for data entry, queries, displays, and retrievals. It is similar to the web-database solution that we constructed for Alaskan paleontological data (www.alaskafossil.org). The first phase of...
A study of methods to estimate debris flow velocity
A.B. Prochaska, P.M. Santi, J.D. Higgins, S.H. Cannon
2008, Landslides (5) 431-444
Debris flow velocities are commonly back-calculated from superelevation events which require subjective estimates of radii of curvature of bends in the debris flow channel or predicted using flow equations that require the selection of appropriate rheological models and material property inputs. This research investigated difficulties associated with the use of...
Biomorphodynamics: Physical-biological feedbacks that shape landscapes
A.B. Murray, M.A.F. Knaapen, M. Tal, M. L. Kirwan
2008, Water Resources Research (44)
Plants and animals affect morphological evolution in many environments. The term "ecogeomorphology" describes studies that address such effects. In this opinion article we use the term "biomorphodynamics" to characterize a subset of ecogeomorphologic studies: those that investigate not only the effects of organisms on physical processes and morphology but also...
Summer season variability of the north residual cap of Mars as observed by the Mars Global Surveyor Thermal Emission Spectrometer (MGS-TES)
Wendy M. Calvin, Timothy N. Titus
2008, Planetary and Space Science (56) 212-226
Previous observations have noted the change in albedo in a number of North Pole bright outliers and in the distribution of bright ice deposits between Mariner 9, Viking, and Mars Global Surveyor (MGS) data sets. Changes over the summer season as well as between regions at the same season (Ls)...
(U-Th)/He dating of kimberlites-A case study from north-eastern Kansas
T.J. Blackburn, D.F. Stockli, R. W. Carlson, P. Berendsen
2008, Earth and Planetary Science Letters (275) 111-120
Dating kimberlite intrusive rocks by radiogenic isotope geochronology often is a difficult task, complicated by both the lack of dateable minerals within kimberlite as well as significant sample alteration that can degrade samples and alter parent-daughter ratios. This study presents a new geochronologic tool for timing the emplacement of kimberlites...
Regulating continent growth and composition by chemical weathering
C.-T.A. Lee, D. M. Morton, M.G. Little, R. Kistler, U.N. Horodyskyj, W.P. Leeman, A. Agranier
2008, Proceedings of the National Academy of Sciences of the United States of America (105) 4981-4986
Continents ride high above the ocean floor because they are underlain by thick, low-density, Si-rich, and Mg-poor crust. However, the parental magmas of continents were basaltic, which means they must have lost Mg relative to Si during their maturation into continents. Igneous differentiation followed by lower crustal delamination and chemical...
Using sequential self-calibration method to identify conductivity distribution: Conditioning on tracer test data
B.X. Hu, C. He
2008, Mathematical Geosciences (40) 845-859
An iterative inverse method, the sequential self-calibration method, is developed for mapping spatial distribution of a hydraulic conductivity field by conditioning on nonreactive tracer breakthrough curves. A streamline-based, semi-analytical simulator is adopted to simulate solute transport in a heterogeneous aquifer. The simulation is used as the forward modeling step. In...
Investigation of flow and transport processes at the MADE site using ensemble Kalman filter
Gaisheng Liu, Y. Chen, Dongxiao Zhang
2008, Advances in Water Resources (31) 975-986
In this work the ensemble Kalman filter (EnKF) is applied to investigate the flow and transport processes at the macro-dispersion experiment (MADE) site in Columbus, MS. The EnKF is a sequential data assimilation approach that adjusts the unknown model parameter values based on the observed data with time. The classic...
