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...
Nitrification in the euphotic zone as evidenced by nitrate dual isotopic composition: Observations from Monterey Bay, California
Scott D. Wankel, Carol Kendall, J.T. Pennington, Francisco P. Chavez, Adina Paytan
2007, Global Biogeochemical Cycles (21)
Coupled measurements of nitrate (NO3−), nitrogen (N), and oxygen (O) isotopic composition (δ15NNO3 and δ18ONO3) were made in surface waters of Monterey Bay to investigate multiple N cycling processes occurring within surface waters. Profiles collected throughout the year at three sites exhibit a wide range of values, suggesting simultaneous...
Strategies to predict metal mobility in surficial mining environments
Kathleen S. Smith
2007, Reviews in Engineering Geology (17) 25-45
This report presents some strategies to predict metal mobility at mining sites. These strategies are based on chemical, physical, and geochemical information about metals and their interactions with the environment. An overview of conceptual models, metal sources, and relative mobility of metals under different geochemical conditions is presented, followed by...
Holocene climates and connections between the San Francisco Bay Estuary and its watershed: A review
F. Malamud-Roam, M. Dettinger, B. Lynn Ingram, Malcolm K. Hughes, Joan Florsheim
2007, San Francisco Estuary and Watershed Science (5)
Climate over the watershed of the San Francisco Bay Delta estuary system varies on a wide range of space and time scales, and affects downstream estuarine ecosystems. The historical climate has included mild to severe droughts and torrential rains accompanied by flooding, providing important lessons for present-day resource managers. Paleoclimate...
Empirical evaluation of decision support systems: Needs, definitions, potential methods, and an example pertaining to waterfowl management
R.S. Sojda
2007, Environmental Modelling and Software (22) 269-277
Decision support systems are often not empirically evaluated, especially the underlying modelling components. This can be attributed to such systems necessarily being designed to handle complex and poorly structured problems and decision making. Nonetheless, evaluation is critical and should be focused on empirical testing whenever possible. Verification and validation, in...
A coupled remote sensing and simplified surface energy balance approach to estimate actual evapotranspiration from irrigated fields
G.B. Senay, Michael Budde, J. P. Verdin, Assefa M. Melesse
2007, Sensors (7) 979-1000
Accurate crop performance monitoring and production estimation are critical for timely assessment of the food balance of several countries in the world. Since 2001, the Famine Early Warning Systems Network (FEWS NET) has been monitoring crop performance and relative production using satellite-derived data and simulation models in Africa, Central America,...
Fix success and accuracy of GPS radio collars in old-growth temperate coniferous forests
Kimberly A. Sager-Fradkin, Kurt J. Jenkins, Robert L. Hoffman, P. Happe, J. Beecham, R.G. Wright
2007, Journal of Wildlife Management (71) 1298-1308
Global Positioning System (GPS) telemetry is used extensively to study animal distribution and resource selection patterns but is susceptible to biases resulting from data omission and spatial inaccuracies. These data errors may cause misinterpretation of wildlife habitat selection or spatial use patterns. We used both stationary test collars and collared...
The oxygen-18 isotope approach for measuring aquatic metabolism in high-productivity waters
Craig R. Tobias, John Karl Bohlke, Judson W. Harvey
2007, Limnology and Oceanography (52) 1439-1453
We examined the utility of δ18O2 measurements in estimating gross primary production (P), community respiration (R), and net metabolism (P : R) through diel cycles in a productive agricultural stream located in the midwestern U.S.A. Large diel swings in O2(±200 µmol L−1) were accompanied by large diel variation in δ18O2 (±10‰). Simultaneous...
Winter movement dynamics of black brant
Mark S. Lindberg, David H. Ward, T. Lee Tibbitts, John Roser
2007, Journal of Wildlife Management (71) 534-540
Although North American geese are managed based on their breeding distributions, the dynamics of those breeding populations may be affected by events that occur during the winter. Birth rates of capital breeding geese may be influenced by wintering conditions, mortality may be influenced by timing of migration and wintering distribution,...
Biodegradation of organic chemicals in soil/water microcosms system: Model development
L. Liu, J.A. Tindall, M.J. Friedel, W. Zhang
2007, Water, Air, & Soil Pollution (178) 131-143
The chemical interactions of hydrophobic organic contaminants with soils and sediments may result in strong binding and slow subsequent release rates that significantly affect remediation rates and endpoints. In order to illustrate the recalcitrance of chemical to degradation on sites, a sorption mechanism of intraparticle sequestration was postulated to operate...
Sandhill crane abundance and nesting ecology at Grays Lake, Idaho
J. E. Austin, A.R. Henry, I.J. Ball
2007, Journal of Wildlife Management (71) 1067-1079
We examined population size and factors influencing nest survival of greater sandhill cranes (Grus canadensis tabida) at Grays Lake National Wildlife Refuge, Idaho, USA, during 1997-2000. Average local population of cranes from late April to early May, 1998-2000, was 735 cranes, 34% higher than that reported for May 1970-1971. We...
Life history and ecological characteristics of the Santa Ana sucker, Catostomus santaanae
Michael K. Saiki, Barbara A. Martin, Glen W. Knowles, Patrick W. Tennant
2007, California Fish and Game (93) 87-101
This study was conducted to document the life history and ecological characteristics of the Santa Ana sucker, Catostomus santaanae, within its native range in southern California. Electrofishing surveys were conducted at 3-month intervals from December 1998 to December 1999 at one site on the San Gabriel River and two sites on the Santa...
Holocene sea-level oscillations and environmental changes on the Eastern Black Sea shelf
E.V. Ivanova, I.O. Murdmaa, A.L. Chepalyga, T. M. Cronin, I.V. Pasechnik, O.V. Levchenko, S. S. Howe, A.V. Manushkina, E.A. Platonova
2007, Palaeogeography, Palaeoclimatology, Palaeoecology (246) 228-259
A multi-proxy study of four sediment cores from the Eastern (Caucasian) Black Sea shelf revealed five transgressive-regressive cycles overprinted on the general trend of glacioeustatic sea-level rise during the last 11,000??14C yr. These cycles are well represented in micro-and macrofossil assemblages, sedimentation rates, and grain size variations. The oldest recovered...
Development of a mercury speciation, fate, and biotic uptake (BIOTRANSPEC) model: Application to Lahontan Reservoir (Nevada, USA)
N. Gandhi, S.P. Bhavsar, M.L. Diamond, James S. Kuwabara, Mark C. Marvin-DePasquale, David P. Krabbenhoft
2007, Environmental Toxicology and Chemistry (26) 2260-2273
A mathematically linked mercury transport, speciation, kinetic, and simple biotic uptake (BIOTRANSPEC) model has been developed. An extension of the metal transport and speciation (TRANSPEC) model, BIOTRANSPEC estimates the fate and biotic uptake of inorganic (Hg(II)), elemental (Hg(0)) and organic (MeHg) forms of mercury and their species in the dissolved,...
Biotic and abiotic controls of argentine ant invasion success at local and landscape scales
S.B. Menke, Robert N. Fisher, W. Jetz, D.A. Holway
2007, Ecology (88) 3164-3173
Although the ecological success of introduced species hinges on biotic interactions and physical conditions, few experimental studies - especially on animals - have simultaneously investigated the relative importance of both types of factors. The lack of such research may stem from the common assumption that native and introduced species exhibit...
Effect of horseshoe crab spawning density on nest disturbance and exhumation of eggs: A simulation study
D. R. Smith
2007, Estuaries and Coasts (30) 287-295
Because the Delaware Bay horseshoe crab (Limulus polyphemus) population is managed to provide for dependent species, such as migratory shorebirds, there is a need to understand the process of egg exhumation and to predict eggs available to foraging shorebirds. A simple spatial model was used to simulate horseshoe crab spawning...
Mid-Holocene change in types of degassing volcanoes, using indium in Antarctic ice as a tracer of volcanic source type
T. Hinkley, A. Matsumoto
2007, Geophysical Research Letters (34)
Proportions of trace metals in Antarctic ice samples indicate that the type of volcanoes that dominated atmospheric emissions changed at about the middle of the Holocene from relatively mafic, deep source volcanoes to more silicic, shallower-source volcanoes. We base this inference on the strong contrast in the abundances of the...
Year-class formation of upper St. Lawrence River northern pike
B.M. Smith, J.M. Farrell, H.B. Underwood, S.J. Smith
2007, North American Journal of Fisheries Management (27) 481-491
Variables associated with year-class formation in upper St. Lawrence River northern pike Esox lucius were examined to explore population trends. A partial least-squares (PLS) regression model (PLS 1) was used to relate a year-class strength index (YCSI; 1974-1997) to explanatory variables associated with spawning and nursery areas (seasonal water level...
A GIS-based groundwater travel time model to evaluate stream nitrate concentration reductions from land use change
K. E. Schilling, C.F. Wolter
2007, Environmental Geology (53) 433-443
Excessive nitrate-nitrogen (nitrate) loss from agricultural watersheds is an environmental concern. A common conservation practice to improve stream water quality is to retire vulnerable row croplands to grass. In this paper, a groundwater travel time model based on a geographic information system (GIS) analysis of readily available soil and topographic...
Deglacial climate variability in central Florida, USA
Debra A. Willard, C.E. Bernhardt, G. R. Brooks, T. M. Cronin, T. Edgar, R. Larson
2007, Palaeogeography, Palaeoclimatology, Palaeoecology (251) 366-382
Pollen and ostracode evidence from lacustrine sediments underlying modern Tampa Bay, Florida, document frequent and abrupt climatic and hydrological events superimposed on deglacial warming in the subtropics. Radiocarbon chronology on well-preserved mollusk shells and pollen residue from core MD02-2579 documents continuous sedimentation in a variety of non-marine habitats in a...
Characterisation and modelling of washover fans
Chantal Donnelly, Asbury H. Sallenger Jr.
2007, Conference Paper, Coastal Sediments '07 - Proceedings of 6th International Symposium on Coastal Engineering and Science of Coastal Sediment Processes
Pre- and post-storm topography and aerial photography, collected in regions where new washover fans were formed, were studied to determine the extent of morphologic, vegetative and anthropogenic control on washover shape and extent. When overwash is funnelled through a gap in a dune ridge and then spreads laterally on the...
A new ghost-node method for linking different models and initial investigations of heterogeneity and nonmatching grids
J.E. Dickinson, S.C. James, S. Mehl, M. C. Hill, S. A. Leake, G.A. Zyvoloski, C.C. Faunt, A.-A. Eddebbarh
2007, Advances in Water Resources (30) 1722-1736
A flexible, robust method for linking parent (regional-scale) and child (local-scale) grids of locally refined models that use different numerical methods is developed based on a new, iterative ghost-node method. Tests are presented for two-dimensional and three-dimensional pumped systems that are homogeneous or that have simple heterogeneity. The parent and...
Evidence for a physical linkage between galactic cosmic rays and regional climate time series
C. A. Perry
2007, Advances in Space Research (40) 353-364
The effects of solar variability on regional climate time series were examined using a sequence of physical connections between total solar irradiance (TSI) modulated by galactic cosmic rays (GCRs), and ocean and atmospheric patterns that affect precipitation and streamflow. The solar energy reaching the Earth's surface and its oceans is...
Optimal use of resources structures home ranges and spatial distribution of black bears
M.S. Mitchell, R. A. Powell
2007, Animal Behaviour (74) 219-230
Research has shown that territories of animals are economical. Home ranges should be similarly efficient with respect to spatially distributed resources and this should structure their distribution on a landscape, although neither has been demonstrated empirically. To test these hypotheses, we used home range models that optimize resource use according...
Sorted bed forms as self-organized patterns: 2. complex forcing scenarios
Giovanni Coco, A. Brad Murray, Malcom O. Green, E. Robert Thieler, T.M. Hume
2007, Journal of Geophysical Research F: Earth Surface (112)
We employ a numerical model to study the development of sorted bed forms under a variety of hydrodynamic and sedimentary conditions. Results indicate that increased variability in wave height decreases the growth rate of the features and can potentially give rise to complicated, a priori unpredictable, behavior. This happens because...
