The role of hydrologic regimes on dissolved organic carbon composition in an agricultural watershed
P.J. Hernes, R.G.M. Spencer, R.Y. Dyda, B.A. Pellerin, P.A.M. Bachand, B.A. Bergamaschi
2008, Geochimica et Cosmochimica Acta (72) 5266-5277
Willow Slough, a seasonally irrigated agricultural watershed in the Sacramento River valley, California, was sampled weekly in 2006 in order to investigate seasonal concentrations and compositions of dissolved organic carbon (DOC). Average DOC concentrations nearly doubled from winter baseflow (2.75 mg L-1) to summer irrigation (5.14 mg L-1), while a...
Scientific results from Gulf of Mexico Gas Hydrates Joint Industry Project Leg 1 drilling: Introduction and overview
C. Ruppel, R. Boswell, E. Jones
2008, Marine and Petroleum Geology (25) 819-829
The Gulf of Mexico Gas Hydrates Joint Industry Project (JIP) is a consortium of production and service companies and some government agencies formed to address the challenges that gas hydrates pose for deepwater exploration and production. In partnership with the U.S. Department of Energy and with scientific assistance from the...
Gas and gas hydrate distribution around seafloor seeps in Mississippi Canyon, Northern Gulf of Mexico, using multi-resolution seismic imagery
W.T. Wood, P. E. Hart, D. R. Hutchinson, N. Dutta, F. Snyder, R.B. Coffin, J.F. Gettrust
2008, Marine and Petroleum Geology (25) 952-959
To determine the impact of seeps and focused flow on the occurrence of shallow gas hydrates, several seafloor mounds in the Atwater Valley lease area of the Gulf of Mexico were surveyed with a wide range of seismic frequencies. Seismic data were acquired with a deep-towed, Helmholz resonator source (220-820...
Environment and paleoecology of a 12 ka mid-North American Younger Dryas forest chronicled in tree rings
Irina P. Panyushkina, Steven W. Leavitt, Todd A. Thompson, Allan F. Schneider, Todd Lange
2008, Quaternary Research (70) 433-441
Until now, availability of wood from the Younger Dryas abrupt cooling event (YDE) in N. America ca. 12.9 to 11.6 ka has been insufficient to develop high-resolution chronologies for refining our understanding of YDE conditions. Here we present a multi-proxy tree-ring chronology (ring widths, “events” evidenced by microanatomy and macro...
Littoral zones as sources of biodegradable dissolved organic carbon in lakes
E.G. Stets, J.B. Cotner
2008, Canadian Journal of Fisheries and Aquatic Sciences (65) 2454-2460
A survey of 12 lakes in Minnesota, USA, was conducted to examine the factors controlling variability in biodegradable dissolved organic carbon (BDOC) concentration. The principal question addressed was whether BDOC concentration was more strongly related to lake trophic status or morphometric parameters. BDOC concentration was determined by incubating filtered lake...
Electromagnetic surveying of seafloor mounds in the northern Gulf of Mexico
M. Ellis, R.L. Evans, D. Hutchinson, P. Hart, J. Gardner, R. Hagen
2008, Marine and Petroleum Geology (25) 960-968
Seafloor controlled source electromagnetic data, probing the uppermost 30 m of seafloor sediments, have been collected with a towed magnetic dipole-dipole system across two seafloor mounds at approximately 1300 m water depth in the northern Gulf of Mexico. One of these mounds was the focus of??a recent gas hydrate research...
Cosmogenic exposure-age chronologies of Pinedale and Bull Lake glaciations in greater Yellowstone and the Teton Range, USA
J. M. Licciardi, K. L. Pierce
2008, Quaternary Science Reviews (27) 814-831
We have obtained 69 new cosmogenic 10Be surface exposure ages from boulders on moraines deposited by glaciers of the greater Yellowstone glacial system and Teton Range during the middle and late Pleistocene. These new data, combined with 43 previously obtained 3He and 10Be ages from deposits of the northern Yellowstone...
Estimating fish body condition with quantile regression
B.S. Cade, J.W. Terrell, M.T. Porath
2008, North American Journal of Fisheries Management (28) 349-359
We used quantile regression to compare the body condition of walleye Sander vitreus and white bass Morone chrysops before (1980-1988) and after (1989-2004) the establishment of alewives Alosa pseudoharengus in Lake McConaughy, Nebraska. Higher quantiles (percentiles = 100% x quantiles [0, 1]) of weight (W) at the same total length...
Population structure and genetic diversity of black redhorse (Moxostoma duquesnei) in a highly fragmented watershed
S.M. Reid, C.C. Wilson, N.E. Mandrak, L.M. Carl
2008, Conservation Genetics (9) 531-546
Dams have the potential to affect population size and connectivity, reduce genetic diversity, and increase genetic differences among isolated riverine fish populations. Previous research has reported adverse effects on the distribution and demographics of black redhorse (Moxostoma duquesnei), a threatened fish species in Canada. However, effects on genetic diversity and...
Effects of a natural dam-break flood on geomorphology and vegetation on the Elwha River, Washington, U.S.A.
S.A. Acker, T.J. Beechie, P.B. Shafroth
2008, Northwest Science (82) 210-223
Ephemeral dams caused by landslides have been observed around the world, yet little is known about the effects of their failure on landforms and vegetation. In 1967, a landslide-dam-break flood in a pristine reach of the Elwha River valley filled the former channel and diverted the river. The reach is...
Are wildlife detector dogs or people better at finding Desert Tortoises (Gopherus agassizii)?
K.E. Nussear, T. C. Esque, J.S. Heaton, Mary E. Cablk, K.K. Drake, C. Valentin, J.L. Yee, P.A. Medica
2008, Herpetological Conservation and Biology (3) 103-115
Our ability to study threatened and endangered species depends on locating them readily in the field. Recent studies highlight the effectiveness of trained detector dogs to locate wildlife during field surveys, including Desert Tortoises in a semi-natural setting. Desert Tortoises (Gopherus agassizii) are cryptic and difficult to detect during surveys,...
Monitoring volcanic threats using ASTER satellite data
K. A. Duda, R. Wessels, M. Ramsey, J. Dehn
2008, Conference Paper, International Geoscience and Remote Sensing Symposium (IGARSS)
This document summarizes ongoing activities associated with a research project funded by the national aeronautics and space administration (NASA) focusing on volcanic change detection through the use of satellite imagery. This work includes systems development as well as improvements in data analysis methods. Participating organizations include the NASA land processes...
Mercury sedimentation in lakes in western Whatcom County, Washington, USA and its relation to local industrial and municipal atmospheric sources
A.J. Paulson, D. Norton
2008, Water, Air, & Soil Pollution (189) 5-19
Concentrations of mercury (Hg) were measured in six dated cores from four lakes in western Whatcom County, Washington, USA, that were at various bearings from a chlor-alkali plant, two municipal waste incinerators and a municipal sewage sludge incinerator. The importance of atmospheric emissions of Hg from these local municipal and...
Environmental tracers as indicators of karst conduits in groundwater in South Dakota, USA
Andrew J. Long, J.F. Sawyer, L.D. Putnam
2008, Hydrogeology Journal (16) 263-280
Environmental tracers sampled from the carbonate Madison aquifer on the eastern flank of the Black Hills, South Dakota, USA indicated the approximate locations of four major karst conduits. Contamination issues are a major concern because these conduits are characterized by direct connections to sinking streams, high groundwater velocities, and proximity...
A comparison of winter mercury accumulation at forested and no-canopy sites measured with different snow sampling techniques
S.J. Nelson, K.B. Johnson, K.C. Weathers, C.S. Loftin, I.J. Fernandez, J. S. Kahl, D. P. Krabbenhoft
2008, Applied Geochemistry (23) 384-398
Atmospheric mercury (Hg) is delivered to ecosystems via rain, snow, cloud/fog, and dry deposition. The importance of snow, especially snow that has passed through the forest canopy (throughfall), in delivering Hg to terrestrial ecosystems has received little attention in the literature. The snowpack...
Evapotranspiration rates and crop coefficients for a restored marsh in the Sacramento-San Joaquin Delta, California, USA
Judith Z. Drexler, Frank E. Anderson, Richard L. Snyder
2008, Hydrological Processes (22) 725-735
The surface renewal method was used to estimate evapotranspiration (ET) for a restored marsh on Twitchell Island in the Sacramento–San Joaquin Delta, California, USA. ET estimates for the marsh, together with reference ET measurements from a nearby climate station, were used to determine crop coefficients over a 3‐year period during...
Compressional and shear-wave velocity versus depth relations for common rock types in northern California
T.M. Brocher
2008, Conference Paper, Bulletin of the Seismological Society of America
This article presents new empirical compressional and shear-wave velocity (Vp and Vs) versus depth relationships for the most common rock types in northern California. Vp versus depth relations were developed from borehole, laboratory, seismic refraction and tomography, and density measurements, and were converted to Vs versus depth relations using new...
Analysis of trade-offs between threats of invasion by nonnative brook trout (Salvelinus fontinalis) and intentional isolation for native westslope cutthroat trout (Oncorhynchus clarkii lewisi)
D.P. Peterson, B.E. Rieman, J. B. Dunham, K.D. Fausch, M.K. Young
2008, Canadian Journal of Fisheries and Aquatic Sciences (65) 557-573
Native salmonid fishes often face simultaneous threats from habitat fragmentation and invasion by nonnative trout species. Unfortunately, management actions to address one may create or exacerbate the other. A consistent decision process would include a systematic analysis of when and where intentional use or removal of barriers is the most...
Individual variation affects departure rate from the natal pond in an ephemeral pond-breeding anuran
N.D. Chelgren, D.K. Rosenberg, S.S. Heppell, A.I. Gitelman
2008, Canadian Journal of Zoology (86) 260-267
Frogs exhibit extreme plasticity and individual variation in growth and behavior during metamorphosis, driven by interactions of intrinsic state factors and extrinsic environmental factors. In northern red-legged frogs (Rana aurora Baird and Girard, 1852), we studied the timing of departure from the natal pond as it relates to date and...
Testing small-aperture array analysis on well-located earthquakes, and application to the location of deep tremor
Rocca M. La, D. Galluzzo, S. Malone, W. McCausland, G. Saccorotti, Pezzo E. Del
2008, Bulletin of the Seismological Society of America (98) 620-635
We have here analyzed local and regional earthquakes using array techniques with the double aim of quantifying the errors associated with the estimation of propagation parameters of seismic signals and testing the suitability of a probabilistic location method for the analysis of nonimpulsive signals. We have applied the zero-lag cross-correlation...
The release of dissolved actinium to the ocean: A global comparison of different end-members
W. Geibert, M. Charette, G. Kim, W.S. Moore, J. Street, M. Young, A. Paytan
2008, Marine Chemistry (109) 409-420
The measurement of short-lived 223Ra often involves a second measurement for supported activities, which represents 227Ac in the sample. Here we exploit this fact, presenting a set of 284 values on the oceanic distribution of 227Ac, which was collected when analyzing water samples for short-lived radium isotopes by the radium...
Estimation of successful breeding pairs for wolves in the Northern Rocky Mountains, USA
M.S. Mitchell, D.E. Ausband, C.A. Sime, E.E. Bangs, J.A. Gude, M.D. Jimenez, C.M. Mack, T.J. Meier, M.S. Nadeau, D.W. Smith
2008, Journal of Wildlife Management (72) 881-891
Under the Endangered Species Act, documenting recovery and federally mandated population levels of wolves (Canis lupus) in the Northern Rocky Mountains (NRM) requires monitoring wolf packs that successfully recruit young. United States Fish and Wildlife Service regulations define successful breeding pairs as packs estimated to contain an adult male and...
National, holistic, watershed-scale approach to understand the sources, transport, and fate of agricultural chemicals
P. D. Capel, K. A. McCarthy, J.E. Barbash
2008, Journal of Environmental Quality (37) 983-993
This paper is an introduction to the following series of papers that report on in-depth investigations that have been conducted at five agricultural study areas across the United States in order to gain insights into how environmental processes and agricultural practices interact to determine the transport and fate of agricultural...
Stand structure and dynamics of sand pine differ between the Florida panhandle and peninsula
P.B. Drewa, W.J. Platt, C. Kwit, T.W. Doyle
2008, Plant Ecology (196) 15-25
Size and age structures of stand populations of numerous tree species exhibit uneven or reverse J-distributions that can persist after non-catastrophic disturbance, especially windstorms. Among disjunct populations of conspecific trees, alternative distributions are also possible and may be attributed to more localized variation in disturbance. Regional differences in structure and...
Influence of dams on river-floodplain dynamics in the Elwha River, Washington
K.K. Kloehn, T.J. Beechie, S.A. Morley, H.J. Coe, J.J. Duda
2008, Northwest Science (82) 224-235
The Elwha dam removal project presents an ideal opportunity to study how historic reduction and subsequent restoration of sediment supply alter river-floodplain dynamics in a large, forested river floodplain. We used remote sensing and onsite data collection to establish a historical record of floodplain dynamics and a baseline of current...
