Evaluation and comparison of gross primary production estimates for the Northern Great Plains grasslands
Li Zhang, Bruce K. Wylie, Thomas R. Loveland, Eugene A. Fosnight, Larry L. Tieszen, Lei Ji, Tagir Gilmanov
2007, Remote Sensing of Environment (106) 173-189
Two spatially-explicit estimates of gross primary production (GPP) are available for the Northern Great Plains. An empirical piecewise regression (PWR) GPP model was developed from flux tower measurements to map carbon flux across the region. The Moderate Resolution Imaging Spectrometer (MODIS) GPP model is a process-based model that uses...
Isotopic analysis of N and O in nitrite and nitrate by sequential selective bacterial reduction to N2O
John Karl Bohlke, Richard L. Smith, Janet E. Hannon
2007, Analytical Chemistry (79) 5888-5895
Nitrite is an important intermediate species in the biogeochemical cycling of nitrogen, but its role in natural aquatic systems is poorly understood. Isotopic data can be used to study the sources and transformations of NO2- in the environment, but methods for independent isotopic analyses of NO2- in the presence of...
Investigation of magnesium isotope fractionation during basalt differentiation: Implications for a chondritic composition of the terrestrial mantle
F.-Z. Teng, M. Wadhwa, Rosalind T. Helz
2007, Earth and Planetary Science Letters (261) 84-92
To investigate whether magnesium isotopes are fractionated during basalt differentiation, we have performed high-precision Mg isotopic analyses by multi-collector inductively coupled plasma mass spectrometry (MC-ICP-MS) on a set of well-characterized samples from Kilauea Iki lava lake, Hawaii, USA. Samples from the Kilauea Iki...
Alternative community structures in a kelp-urchin community: A qualitative modeling approach
G. Montano-Moctezuma, H.W. Li, P.A. Rossignol
2007, Ecological Modelling (205) 343-354
Shifts in interaction patterns within a community may result from periodic disturbances and climate. The question arises as to the extent and significance of these shifting patterns. Using a novel approach to link qualitative mathematical models and field data, namely using the inverse matrix to identify the community matrix, we...
Multiple-methods investigation of recharge at a humid-region fractured rock site, Pennsylvania, USA
C.S. Heppner, J. R. Nimmo, G.J. Folmar, W.J. Gburek, D. W. Risser
2007, Hydrogeology Journal (15) 915-927
Lysimeter-percolate and well-hydrograph analyses were combined to evaluate recharge for the Masser Recharge Site (central Pennsylvania, USA). In humid regions, aquifer recharge through an unconfined low-porosity fractured-rock aquifer can cause large magnitude water-table fluctuations over short time scales. The unsaturated hydraulic characteristics of the subsurface porous...
High arsenic concentrations and enriched sulfur and oxygen isotopes in a fractured-bedrock ground-water system
G. Lipfert, W.C. Sidle, A.S. Reeve, R. A. Ayuso, A.J. Boyce
2007, Chemical Geology (242) 385-399
Ground water with high arsenic concentrations (up to 26.6????mol L- 1) has sulfate enriched in 34S and 18O in the fractured-bedrock, ground-water system of the Kelly's Cove watershed, Northport, Maine, USA. The ranges of sulfur and oxygen isotope values in aqueous sulfate, ??34S[SO4] and ??18O[SO4], at the Kelly's Cove watershed...
Use of a wetland index to evaluate changes in riparian vegetation after livestock exclusion
M. C. Coles-Ritchie, D.W. Roberts, J. L. Kershner, R.C. Henderson
2007, Journal of the American Water Resources Association (43) 731-743
A method was developed to characterize ecological integrity of riparian sites based on the abundance of hydric species. This wetland index can be calculated with species data, or with community type data as performed here. Classified riparian community types were used to describe vegetation at 14 livestock exclosures and adjacent...
Summer microhabitat use of fluvial bull trout in Eastern Oregon streams
R. Al-Chokhachy, P. Budy
2007, North American Journal of Fisheries Management (27) 1068-1081
The management and recovery of populations of bull trout Salvelinus confluentus requires a comprehensive understanding of habitat use across different systems, life stages, and life history forms. To address these needs, we collected microhabitat use and availability data in three fluvial populations of bull trout in eastern Oregon. We evaluated...
Estimating biomass of submersed vegetation using a simple rake sampling technique
K.P. Kenow, J.E. Lyon, R. K. Hines, A. Elfessi
2007, Hydrobiologia (575) 447-454
We evaluated the use of a simple rake sampling technique for predicting the biomass of submersed aquatic vegetation. Vegetation sampled from impounded areas of the Mississippi River using a rake sampling technique, was compared with vegetation harvested from 0.33-m2 quadrats. The resulting data were used to model the relationship between...
Advantages of wet work for near-surface seismic reflection
R. D. Miller, R.D. Markiewicz, T.R. Rademacker, R. Hopkins, R.J. Rawcliffe, J. Paquin
2007, Conference Paper, SEG Technical Program Expanded Abstracts
Benefits of shallow water settings (0.1 to 0.5 m) are pronounced on shallow, high-resolution seismic reflection images and, for examples discussed here, range from an order of magnitude increased signal-to-noise ratio to resolution potential elevated by more than 8 times. Overall data quality of high-resolution seismic reflection data at three...
A method to estimate groundwater depletion from confining layers
Leonard F. Konikow, Christopher E. Neuzil
2007, Water Resources Research (43)
Although depletion of storage in low‐permeability confining layers is the source of much of the groundwater produced from many confined aquifer systems, it is all too frequently overlooked or ignored. This makes effective management of groundwater resources difficult by masking how much water has been derived from storage and, in...
Modeling the movement of a pH perturbation and its impact on adsorbed zinc and phosphate in a wastewater‐contaminated aquifer
Douglas B. Kent, J.A. Wilkie, J.A. Davis
2007, Water Resources Research (43)
[1] Chemical conditions were perturbed in an aquifer with an ambient pH of 5.9 and wastewater-derived adsorbed zinc (Zn) and phosphate (P) contamination by injecting a pulse of amended groundwater. The injected groundwater had low concentrations of dissolved Zn and P, a pH value of...
Spectral element modelling of fault-plane reflections arising from fluid pressure distributions
M. Haney, R. Snieder, J.-P. Ampuero, R. Hofmann
2007, Geophysical Journal International (170) 933-951
The presence of fault-plane reflections in seismic images, besides indicating the locations of faults, offers a possible source of information on the properties of these poorly understood zones. To better understand the physical mechanism giving rise to fault-plane reflections in compacting sedimentary basins, we numerically model the full elastic wavefield...
Paleoearthquakes on the southern San Andreas Fault, Wrightwood, California, 3000 to 1500 B.C.: A new method for evaluating paleoseismic evidence and earthquake horizons
K.M. Scharer, R.J. Weldon II, T. E. Fumal, G. P. Biasi
2007, Bulletin of the Seismological Society of America (97) 1054-1093
We present evidence of 11–14 earthquakes that occurred between 3000 and 1500 b.c. on the San Andreas fault at the Wrightwood paleoseismic site. Earthquake evidence is presented in a novel form in which we rank (high, moderate, poor, or low) the quality of all...
Distribution of breeding shorebirds on the Arctic Coastal Plain of Alaska
James A. Johnson, Richard B. Lanctot, Brad A. Andres, Jonathan Bart, Stephen C. Brown, Steven J. Kendall, David C. Payer
2007, Arctic (60) 277-293
Available information on the distribution of breeding shorebirds across the Arctic Coastal Plain of Alaska is dated, fragmented, and limited in scope. Herein, we describe the distribution of 19 shorebird species from data gathered at 407 study plots between 1998 and 2004. This information was collected using a single-visit rapid...
Does avian species richness in natural patch mosaics follow the forest fragmentation paradigm?
D.C. Pavlacky Jr., S.H. Anderson
2007, Animal Conservation (10) 57-68
As one approaches the north-eastern limit of pinyon (Pinus spp.) juniper (Juniperus spp.) vegetation on the Colorado Plateau, USA, woodland patches become increasingly disjunct, grading into sagebrush (Artemisia spp.)-dominated landscapes. Patterns of avian species richness in naturally heterogeneous forests may or may not respond to patch discontinuity in the same...
A simulation-based approach for estimating premining water quality: Red Mountain Creek, Colorado
Robert L. Runkel, Briant A Kimball, Katherine Walton-Day, Philip L. Verplanck
2007, Applied Geochemistry (22) 1899-1918
Regulatory agencies are often charged with the task of setting site-specific numeric water quality standards for impaired streams. This task is particularly difficult for streams draining highly mineralized watersheds with past mining activity. Baseline water quality data obtained prior to mining are often non-existent and application of generic water quality...
Multi-interferogram method for measuring interseismic deformation: Denali Fault, Alaska
Juliet Biggs, Tim Wright, Zhong Lu, Barry Parsons
2007, Geophysical Journal International (170) 1165-1179
Studies of interseismic strain accumulation are crucial to our understanding of continental deformation, the earthquake cycle and seismic hazard. By mapping small amounts of ground deformation over large spatial areas, InSAR has the potential to produce continental-scale maps of strain accumulation on active faults. However, most InSAR studies to date...
Analysis of impacts of urban land use and land cover on air quality in the Las Vegas region using remote sensing information and ground observations
G. Xian
2007, International Journal of Remote Sensing (28) 5427-5445
Urban development in the Las Vegas Valley of Nevada (USA) has expanded rapidly over the past 50 years. The air quality in the valley has suffered owing to increases from anthropogenic emissions of carbon monoxide, ozone and criteria pollutants of particular matter. Air quality observations show that pollutant concentrations have...
Population estimates of Hyla cinerea (Schneider) (Green Tree frog) in an urban environment
L. Pham, S. Boudreaux, S. Karhbet, B. Price, A. S. Ackleh, J. Carter, N. Pal
2007, Southeastern Naturalist (6) 203-216
Hyla cinerea (Green Treefrog) is a common wetlands species in the southeastern US. To better understand its population dynamics, we followed a relatively isolated population of Green Treefrogs from June 2004 through October 2004 at a federal office complex in Lafayette, LA. Weekly, Green Treefrogs were caught, measured, marked with...
Joint inversion of high-frequency surface waves with fundamental and higher modes
Y. Luo, J. Xia, J. Liu, Q. Liu, S. Xu
2007, Journal of Applied Geophysics (62) 375-384
Joint inversion of multimode surface waves for estimating the shear (S)-wave velocity has received much attention in recent years. In this paper, we first analyze sensitivity of phase velocities of multimodes of surface waves for a six-layer earth model, and then we invert surface-wave dispersion curves of the theoretical model...
Three new percid fishes (Percidae: Percina) from the Mobile Basin drainage of Alabama, Georgia, and Tennessee
J.D. Williams, D.A. Neely, S. J. Walsh, N.M. Burkhead
2007, Zootaxa 1-28
Three new species of Percina are described from upland drainages of the Mobile Basin. Two of the three species are narrowly distributed: P. kusha, the Bridled Darter, is currently known only from the Conasauga River drainage in Georgia and Tennessee and Etowah River drainage in Georgia, both tributaries of the...
MODIS imagery as a tool for synoptic water quality assessments in the southern California coastal ocean
N.P. Nezlin, P.M. DiGiacomo, B.H. Jones, K.M. Reifel, J.A. Warrick, S.C. Johnson, M.J. Mengel
2007, Conference Paper, Proceedings of SPIE - The International Society for Optical Engineering
The dynamics of rainstorm plumes in the coastal waters of southern California was studied during the Bight'03 Regional Water Quality Program surveys. Measurements of surface salinity and bacterial counts collected from research vessels were compared to MODIS-Aqua satellite imagery. The spectra of normalized water-leaving radiation (nLw) were different in plumes...
Revised landsat-5 thematic mapper radiometric calibration
G. Chander, B. L. Markham, J. A. Barsi
2007, IEEE Geoscience and Remote Sensing Letters (4) 490-494
Effective April 2, 2007, the radiometric calibration of Landsat-5 (L5) Thematic Mapper (TM) data that are processed and distributed by the U.S. Geological Survey (USGS) Center for Earth Resources Observation and Science (EROS) will be updated. The lifetime gain model that was implemented on May 5, 2003, for the reflective...
Crustal structure of Wrangellia and adjacent terranes inferred from geophysical studies along a transect through the northern Talkeetna Mountains
J.M.G. Glen, J. Schmidt, L. Pellerin, D.K. McPhee, J.M. O’Neill
2007, Special Paper of the Geological Society of America 21-41
Recent investigations of the Talkeetna Mountains in south-central Alaska were undertaken to study the region's framework geophysics and to reinterpret structures and crustal composition. Potential field (gravity and magnetic) and magnetotelluric (MT) data were collected along northwest-trending profiles as part of the U.S. Geological Survey's Talkeetna Mountains transect project. The...
