Acid rain effects on aluminum mobilization clarified by inclusion of strong organic acids
G.B. Lawrence, J.W. Sutherland, C.W. Boylen, S. W. Nierzwicki-Bauer, B. Momen, Barry P. Baldigo, H. A. Simonin
2007, Environmental Science & Technology (41) 93-98
Assessments of acidic deposition effects on aquatic ecosystems have often been hindered by complications from naturally occurring organic acidity. Measurements of pH and ANCG, the most commonly used indicators of chemical effects, can be substantially influenced by the presence of organic acids. Relationships between pH and inorganic Al, which is...
Multiobjective analysis of a public wellfield using artificial neural networks
E.A. Coppola Jr., F. Szidarovszky, D. Davis, S. Spayd, M.M. Poulton, E. Roman
2007, Ground Water (45) 53-61
As competition for increasingly scarce ground water resources grows, many decision makers may come to rely upon rigorous multiobjective techniques to help identify appropriate and defensible policies, particularly when disparate stakeholder groups are involved. In this study, decision analysis was conducted on a public water supply wellfield to balance water...
A three-dimensional geophysical model of the crust in the Barents Sea region: Model construction and basement characterization
O. Ritzmann, N. Maercklin, Faleide J. Inge, H. Bungum, Walter D. Mooney, Shane T. Detweiler
2007, Geophysical Journal International (170) 417-435
BARENTS50, a new 3-D geophysical model of the crust in the Barents Sea Region has been developed by the University of Oslo, NORSAR and the U.S. Geological Survey. The target region comprises northern Norway and Finland, parts of the Kola Peninsula and the East European lowlands. Novaya Zemlya, the...
Estimating fishing mortality, natural mortality, and selectivity using recoveries from tagging young fish
H. Jiang, C. Brownie, J.E. Hightower, K. H. Pollock
2007, North American Journal of Fisheries Management (27) 773-781
Current methods for estimation of age- and year-specific instantaneous mortality rates based on multiyear, multiple-age tagging studies assume that it is feasible to tag fish in a wide range of ages. For some species, however, only the youngest one or two age-classes are readily available for tagging. Given the practical...
Aeromagnetic mapping of the structure of Pine Canyon caldera and Chisos Mountains intrusion, Big Bend National Park, Texas
B. J. Drenth, C. A. Finn
2007, Geological Society of America Bulletin (119) 1521-1534
Analysis of aeromagnetic and gravity data reveals new details of the structure, igneous geology, and temporal evolution of the prominent, enigmatic ca.32 Ma Pine Canyon caldera and the Chisos Mountains (Big Bend National Park, Texas). The main caldera-filling Pine Canyon Rhyolite, the oldest member of the South Rim Formation, is...
Identifying sources of nitrogen to Hanalei Bay, Kauai, utilizing the nitrogen isotope signature of macroalgae
E. Derse, K.L. Knee, Scott D. Wankel, Carol Kendall, Carl J. Berg Jr., A. Paytan
2007, Environmental Science & Technology (41) 5217-5223
Sewage effluent, storm runoff, discharge from polluted rivers, and inputs of groundwater have all been suggested as potential sources of land derived nutrients into Hanalei Bay, Kauai. We determined the nitrogen isotopic signatures (δ15N) of different nitrate sources to Hanalei Bay...
Time-optimum packet scheduling for many-to-one routing in wireless sensor networks
W.-Z. Song, F. Yuan, R. LaHusen, B. Shirazi
2007, International Journal of Parallel, Emergent and Distributed Systems (22) 355-370
This paper studies the wireless sensor networks (WSN) application scenario with periodical traffic from all sensors to a sink. We present a time-optimum and energy-efficient packet scheduling algorithm and its distributed implementation. We first give a general many-to-one packet scheduling algorithm for wireless networks, and then prove that it is...
Rapid assessment of postfire plant invasions in coniferous forests of the western United States
J.P. Freeman, T.J. Stohlgren, M.E. Hunter, Philip N. Omi, E.J. Martinson, G.W. Chong, C. S. Brown
2007, Ecological Applications (17) 1656-1665
Fire is a natural part of most forest ecosystems in the western United States, but its effects on nonnative plant invasion have only recently been studied. Also, forest managers are engaging in fuel reduction projects to lessen fire severity, often without considering potential negative ecological consequences such as nonnative plant...
The influence of major dams on hydrology through the drainage network of the Sacramento River basin, California
M.B. Singer
2007, River Research and Applications (23) 55-72
This paper reports basinwide patterns of hydrograph alteration via statistical and graphical analysis from a network of long-term streamflow gauges located various distances downstream of major dams and confluences in the Sacramento River basin in California, USA. Streamflow data from 10 gauging stations downstream of major dams were divided into...
The restricted gemuk group: A triassic to lower cretaceous succession in southwestern Alaska
Marti L. Miller, D. C. Bradley, T. K. Bundtzen, R. B. Blodgett, E.A. Pessagno Jr., R. D. Tucker, A. G. Harris
2007, Special Paper of the Geological Society of America 273-305
New data from an Upper Triassic to Lower Cretaceous deep marine succession-the herein reinstated and restricted Gemuk Group-provide a vital piece of the puzzle for unraveling southwestern Alaska's tectonic history. First defined by Cady et al. in 1955, the Gemuk Group soon became a regional catchall unit that ended up...
Habitat classification modeling with incomplete data: Pushing the habitat envelope
P.L. Zarnetske, T.C. Edwards Jr., Gretchen G. Moisen
2007, Ecological Applications (17) 1714-1726
Habitat classification models (HCMs) are invaluable tools for species conservation, land-use planning, reserve design, and metapopulation assessments, particularly at broad spatial scales. However, species occurrence data are often lacking and typically limited to presence points at broad scales. This lack of absence data precludes the use of many statistical techniques...
Differential impacts of the southern pine beetle, Dendroctonus frontalis, on Pinus palustris and Pinus taeda
N.A. Friedenberg, B.M. Whited, D. H. Slone, S.J. Martinson, M.P. Ayres
2007, Canadian Journal of Forest Research (37) 1427-1437
Patterns of host use by herbivore pests can have serious consequences for natural and managed ecosystems but are often poorly understood. Here, we provide the first quantification of large differential impacts of the southern pine beetle, Dendroctonus frontalis Zimmermann, on loblolly pine, Pinus taeda L., and longleaf pine, Pinus palustris...
Modeling grain size variations of aeolian gypsum deposits at White Sands, New Mexico, using AVIRIS imagery
H.A. Ghrefat, P.C. Goodell, B.E. Hubbard, R.P. Langford, R.E. Aldouri
2007, Geomorphology (88) 57-68
Visible and Near-Infrared (VNIR) through Short Wavelength Infrared (SWIR) (0.4-2.5????m) AVIRIS data, along with laboratory spectral measurements and analyses of field samples, were used to characterize grain size variations in aeolian gypsum deposits across barchan-transverse, parabolic, and barchan dunes at White Sands, New Mexico, USA. All field samples contained a...
Avifaunal responses to fire in southwestern montane forests along a burn severity gradient
N.B. Kotliar, P.L. Kennedy, K. Ferree
2007, Ecological Applications (17) 491-507
The effects of burn severity on avian communities are poorly understood, yet this information is crucial to fire management programs. To quantify avian response patterns along a burn severity gradient, we sampled 49 random plots (2001-2002) at the 17 351-ha Cerro Grande Fire (2000) in New Mexico, USA. Additionally, pre-fire...
Biogeographic affinity helps explain productivity-richness relationships at regional and local scales
S. Harrison, J.B. Grace
2007, Conference Paper, American Naturalist
The unresolved question of what causes the observed positive relationship between large-scale productivity and species richness has long interested ecologists and evolutionists. Here we examine a potential explanation that we call the biogeographic affinity hypothesis, which proposes that the productivity-richness relationship is a function of species' climatic tolerances that in...
Propagation of the Hawaiian-Emperor volcano chain by Pacific plate cooling stress
W.D. Stuart, G.R. Foulger, M. Barall
2007, Special Paper of the Geological Society of America (430) 497-506
The lithosphere crack model, the main alternative to the mantle plume model for age-progressive magma emplacement along the Hawaiian-Emperor volcano chain, requires the maximum horizontal tensile stress to be normal to the volcano chain. However, published stress fields calculated from Pacific lithosphere tractions and body forces...
Three-dimensional P wave velocity model for the San Francisco Bay region, California
C.H. Thurber, T.M. Brocher, H. Zhang, V.E. Langenheim
2007, Journal of Geophysical Research B: Solid Earth (112)
[1] A new three-dimensional P wave velocity model for the greater San Francisco Bay region has been derived using the double-difference seismic tomography method, using data from about 5,500 chemical explosions or air gun blasts and approximately 6,000 earthquakes. The model region covers 140 km NE-SW by 240...
A critical assessment of the Burning Index in Los Angeles County, California
F.P. Schoenberg, H.-C. Chang, Jon E. Keeley, J. Pompa, J. Woods, H. Xu
2007, International Journal of Wildland Fire (16) 473-483
The Burning Index (BI) is commonly used as a predictor of wildfire activity. An examination of data on the BI and wildfires in Los Angeles County, California, from January 1976 to December 2000 reveals that although the BI is positively associated with wildfire occurrence, its predictive value is quite limited....
Survival of breeding Pacific common eiders on the Yukon-Kuskokwim Delta, Alaska
H.M. Wilson, Paul L. Flint, Christine L. Moran, A.N. Powell
2007, Journal of Wildlife Management (71) 403-410
Populations of Pacific common eiders (Somateria mollissima v-nigrum) breeding in Alaska, USA, have declined markedly over the past 40 years. We studied survival of adult female Pacific common eiders using capture—recapture of nesting hens at 3 sites on the Yukon-Kuskokwim Delta (YKD), Alaska from 1994 to 2004. We used data...
Estimated variability of National Atmospheric Deposition Program/Mercury Deposition Network measurements using collocated samplers
G.A. Wetherbee, D.A. Gay, R.C. Brunette, C.W. Sweet
2007, Environmental Monitoring and Assessment (131) 49-69
The National Atmospheric Deposition Program/Mercury Deposition Network (MDN) provides long-term, quality-assured records of mercury in wet deposition in the USA and Canada. Interpretation of spatial and temporal trends in the MDN data requires quantification of the variability of the MDN measurements. Variability is quantified for MDN data from collocated samplers...
Putting it all together: Exhumation histories from a formal combination of heat flow and a suite of thermochronometers
M. A. d'Alessio, C.F. Williams
2007, Journal of Geophysical Research B: Solid Earth (112)
A suite of new techniques in thermochronometry allow analysis of the thermal history of a sample over a broad range of temperature sensitivities. New analysis tools must be developed that fully and formally integrate these techniques, allowing a single geologic interpretation of the rate and timing of exhumation and burial...
Heat transport in the Red Lake Bog, Glacial Lake Agassiz Peatlands
J.M. McKenzie, D. I. Siegel, Donald O. Rosenberry, P.H. Glaser, Clifford I. Voss
2007, Hydrological Processes (21) 369-378
We report the results of an investigation on the processes controlling heat transport in peat under a large bog in the Glacial Lake Agassiz Peatlands. For 2 years, starting in July 1998, we recorded temperature at 12 depth intervals from 0 to 400 cm within a vertical peat profile at...
Upper cretaceous microbial petroleum systems in north-central Montana
Paul G. Lillis
2007, Mountain Geologist (44) 11-35
Cenomanian to Campanian rocks of north-central Montana contain shallow economic accumulations of dry natural gas derived from microbial methanogenesis. The methanogens utilized carbon dioxide derived from organic matter in the marginal marine sediments and hydrogen from in situ pore water to generate methane. The most recent USGS assessment of the shallow...
Physically based estimation of soil water retention from textural data: General framework, new models, and streamlined existing models
John R. Nimmo, William N. Herkelrath, Luna Laguna
2007, Vadose Zone Journal (6) 766-773
Numerous models are in widespread use for the estimation of soil water retention from more easily measured textural data. Improved models are needed for better prediction and wider applicability. We developed a basic framework from which new and existing models can be derived to facilitate improvements. Starting from the assumption...
The USGS national geothermal resource assessment: An update
C.F. Williams, M.J. Reed, S.P. Galanis Jr., J. DeAngelo
2007, Conference Paper, Transactions - Geothermal Resources Council
The U. S. Geological Survey (USGS) is working with the Department of Energy's (DOE) Geothermal Technologies Program and other geothermal organizations on a three-year effort to produce an updated assessment of available geothermal resources. The new assessment will introduce significant changes in the models for geothermal energy recovery factors, estimates...
