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...
Source and transport controls on the movement of nitrate to public supply wells in selected principal aquifers of the United States
P.B. McMahon, J.K. Böhlke, L. J. Kauffman, K.L. Kipp, M.K. Landon, C. A. Crandall, K.R. Burow, C. J. Brown
2008, Water Resources Research (44)
In 2003–2005, systematic studies in four contrasting hydrogeologic settings were undertaken to improve understanding of source and transport controls on nitrate movement to public supply wells (PSW) in principal aquifers of the United States. Chemical, isotopic, and age tracer data show that agricultural fertilizers and urban septic leachate were the...
Influence of wind and lake morphometry on the interaction between two rivers entering a stratified lake
S. Morillo, J. Imberger, J.P. Antenucci, P. F. Woods
2008, Journal of Hydraulic Engineering (134) 1579-1589
The interaction of two rivers flowing into Coeur d’Alene Lake (United States) was investigated with a field experiment and three-dimensional numerical simulations. The focus was on the influence of basin morphology, wind speed, and wind direction on the fate and transport of the inflowing water. Data from...
Computing nonhydrostatic shallow-water flow over steep terrain
R.P. Denlinger, D. R. H. O’Connell
2008, Journal of Hydraulic Engineering (134) 1590-1602
Flood and dambreak hazards are not limited to moderate terrain, yet most shallow-water models assume that flow occurs over gentle slopes. Shallow-water flow over rugged or steep terrain often generates significant nonhydrostatic pressures, violating the assumption of hydrostatic pressure made in most shallow-water codes. In this paper,...
A model of earthquake triggering probabilities and application to dynamic deformations constrained by ground motion observations
J. Gomberg, K. Felzer
2008, Journal of Geophysical Research B: Solid Earth (113)
We have used observations from Felzer and Brodsky (2006) of the variation of linear aftershock densities (i.e., aftershocks per unit length) with the magnitude of and distance from the main shock fault to derive constraints on how the probability of a main shock triggering a single aftershock at a point,...
Fish assemblages in a western Iowa stream modified by grade control structures
M.E. Litvan, C.L. Pierce, T.W. Stewart, C.J. Larson
2008, North American Journal of Fisheries Management (28) 1398-1413
Over 400 riprap grade control structures (GCSs) have been built in streams of western Iowa to reduce erosion and protect bridges, roads, and farmland. In conjunction with a companion study evaluating fish passage over GCSs in Turkey Creek, we evaluated the differences in fish assemblage and habitat characteristics in reaches...
Three-dimensional P-wave velocity structure and precise earthquake relocation at Great Sitkin Volcano, Alaska
Jeremy Pesicek, Clifford H. Thurber, Heather R. DeShon, Stephanie G. Prejean, Haijiang Zhang
2008, Bulletin of the Seismological Society of America (98) 2428-2448
Waveform cross-correlation with bispectrum verification is combined with double-difference tomography to increase the precision of earthquake locations and constrain regional 3D P-wave velocity heterogeneity at Great Sitkin volcano, Alaska. From 1999 through 2005, the Alaska Volcano Observatory (AVO) recorded ∼1700 earthquakes in the vicinity of Great Sitkin, including two ML 4.3 earthquakes that...
Differences in aggression, activity and boldness between native and introduced populations of an invasive crayfish
L.M. Pintor, A. Sih, M.L. Bauer
2008, Oikos (117) 1629-1636
Aggressiveness, along with foraging voracity and boldness, are key behavioral mechanisms underlying the competitive displacement and invasion success of exotic species. However, do aggressiveness, voracity and boldness of the invader depend on the presence of an ecologically similar native competitor in the invaded community? We conducted four behavioral assays to...
Deepwater demersal fish community collapse in Lake Huron
S.C. Riley, E.F. Roseman, S. J. Nichols, T. P. O’Brien, C.S. Kiley, J.S. Schaeffer
2008, Transactions of the American Fisheries Society (137) 1879-1890
Long-term fish community surveys were carried out in the Michigan waters of Lake Huron using bottom trawls from 1976 to 2006. Trends in abundance indices for common species (those caught in 10% or more of trawl tows) were estimated for two periods: early (1976-1991) and late (1994-2006). All common species...
Survival of postfledging Forster's terns in relation to mercury exposure in San Francisco Bay
Joshua T. Ackerman, Collin A. Eagles-Smith, John Y. Takekawa, S. A. Iverson
2008, Ecotoxicology (17) 789-801
We examined factors influencing mercury concentrations in 90 fledgling Forster's terns (Sterna forsteri) and evaluated whether mercury influenced postfledging survival in San Francisco Bay, California. Mercury concentrations (??SE) in chicks 21-29 days old (just before fledging) were 0.33 ?? 0.01 ??g g-1 ww for blood and 6.44 ?? 0.28 ??g...
Soil modification by invasive plants: Effects on native and invasive species of mixed-grass prairies
N.R. Jordan, D.L. Larson, S.C. Huerd
2008, Biological Invasions (10) 177-190
Invasive plants are capable of modifying attributes of soil to facilitate further invasion by conspecifics and other invasive species. We assessed this capability in three important plant invaders of grasslands in the Great Plains region of North America: leafy spurge (Euphorbia esula), smooth brome (Bromus inermis) and crested wheatgrass (Agropyron...
A new method for synthesizing fluid inclusions in fused silica capillaries containing organic and inorganic material
I.-M. Chou, Y. Song, R.C. Burruss
2008, Geochimica et Cosmochimica Acta (72) 5217-5231
Considerable advances in our understanding of physicochemical properties of geological fluids and their roles in many geological processes have been achieved by the use of synthetic fluid inclusions. We have developed a new method to synthesize fluid inclusions containing organic and inorganic material in fused silica capillary tubing. We have...
Origin of pockmarks and chimney structures on the flanks of the Storegga Slide, offshore Norway
C. K. Paull, W. Ussler III, W.S. Holbrook, T.M. Hill, R. Keaten, Jurgen Mienert, H. Haflidason, J.E. Johnson, W.J. Winters, T.D. Lorenson
2008, Geo-Marine Letters (28) 43-51
Seafloor pockmarks and subsurface chimney structures are common on the Norwegian continental margin north of the Storegga Slide scar. Such features are generally inferred to be associated with fluid expulsion, and imply overpressures in the subsurface. Six long gravity and piston cores taken from the interior of three pockmarks were...
Contribution of sediment fluxes and transformations to the summer nitrogen budget of an Upper Mississippi River backwater system
W.F. James, W. B. Richardson, D.M. Soballe
2008, Hydrobiologia (598) 95-107
Routing nitrate through backwaters of regulated floodplain rivers to increase retention could decrease loading to nitrogen (N)-sensitive coastal regions. Sediment core determinations of N flux were combined with inflow-outflow fluxes to develop mass balance approximations of N uptake and transformations in a flow-controlled backwater of the Upper Mississippi River (USA)....
Impacts of short-term acid and aluminum exposure on Atlantic salmon (Salmo salar) physiology: A direct comparison of parr and smolts
M.Y. Monette, S. D. McCormick
2008, Aquatic Toxicology (86) 216-226
Episodic acidification resulting in increased acidity and inorganic aluminum (Ali) is known to impact anadromous salmonids and has been identified as a possible cause of Atlantic salmon population decline. Sensitive life-stages such as smolts may be particularly vulnerable to impacts of short-term (days–week) acid/Al exposure, however the extent and mechanism(s)...
Pumice in the interglacial Whidbey Formation at Blowers Bluff, central Whidbey Island, WA, USA
D. P. Dethier, J.D. Dragovich, A.M. Sarna-Wojcicki, R.J. Fleck
2008, Quaternary International (178) 229-237
A new 40Ar/39Ar age of 128??9 ka and chemical analyses of pumice layers from interglacial alluvium at Blowers Bluff, Whidbey Island, WA, show that the deposits are part of the Whidbey Formation, a widespread, mainly subsurface unit. Glass chemistry of the dated dacitic pumice does not match any analyzed northern...
Comparison of Mexican wolf and coyote diets in Arizona and New Mexico
R. Carrera, W. Ballard, P. Gipson, B.T. Kelly, P.R. Krausman, M.C. Wallace, C. Villalobos, D.B. Wester
2008, Journal of Wildlife Management (72) 376-381
Interactions between wolves (Canis lupus) and coyotes (C. latrans) can have significant impacts on their distribution and abundance. We compared diets of recently translocated Mexican wolves (C. l. baileyi) with diets of resident coyotes in Arizona and New Mexico, USA. We systematically collected scats during 2000 and 2001. Coyote diet...
Cost-effective management alternatives for Snake river chinook salmon: A biological-economic synthesis
D.L. Halsing, M.R. Moore
2008, Conservation Biology (22) 338-350
The mandate to increase endangered salmon populations in the Columbia River Basin of North America has created a complex, controversial resource-management issue. We constructed an integrated assessment model as a tool for analyzing biological-economic trade-offs in recovery of Snake River spring- and summer-run chinook salmon (Oncorhynchus tshawytscha). We merged 3...
Demography and ecology of mangrove diamondback terrapins in a wilderness area of Everglades National Park, Florida, USA
K.M. Hart, C.C. McIvor
2008, Copeia 200-208
Diamondback Terrapins (Malaclemys terrapin) are distributed in brackish water habitats along the U.S. east coast from Massachusetts to Texas, but many populations may be in decline. Whereas ample morphological, behavioral, and reproductive information has been collected for terrapins living in temperate salt marsh habitats, comparatively little is known about mangrove...
Diurnal variability in turbidity and coral fluorescence on a fringing reef flat: Southern Molokai, Hawaii
G.A. Piniak, C. D. Storlazzi
2008, Estuarine, Coastal and Shelf Science (77) 56-64
Terrigenous sediment in the nearshore environment can pose both acute and chronic stresses to coral reefs. The reef flat off southern Molokai, Hawaii, typically experiences daily turbidity events, in which trade winds and tides combine to resuspend terrigenous sediment and transport it alongshore. These chronic turbidity events could play a...
The effects of layers in dry snow on its passive microwave emissions using dense media radiative transfer theory based on the quasicrystalline approximation (QCA/DMRT)
D. Liang, X. Xu, L. Tsang, K.M. Andreadis, E.G. Josberger
2008, IEEE Transactions on Geoscience and Remote Sensing (46) 3663-3671
A model for the microwave emissions of multilayer dry snowpacks, based on dense media radiative transfer (DMRT) theory with the quasicrystalline approximation (QCA), provides more accurate results when compared to emissions determined by a homogeneous snowpack and other scattering models. The DMRT model accounts for adhesive aggregate effects, which leads...
Sulfide-driven arsenic mobilization from arsenopyrite and black shale pyrite
W. Zhu, L.Y. Young, N. Yee, M. Serfes, E.D. Rhine, J.R. Reinfelder
2008, Geochimica et Cosmochimica Acta (72) 5243-5250
We examined the hypothesis that sulfide drives arsenic mobilization from pyritic black shale by a sulfide-arsenide exchange and oxidation reaction in which sulfide replaces arsenic in arsenopyrite forming pyrite, and arsenide (As-1) is concurrently oxidized to soluble arsenite (As+3). This hypothesis was tested in a series of sulfide-arsenide exchange experiments...
Postearthquake relaxation after the 2004 M6 Parkfield, California, earthquake and rate-and-state friction
J.C. Savage, J. Langbein
2008, Journal of Geophysical Research B: Solid Earth (113)
An unusually complete set of measurements (including rapid rate GPS over the first 10 days) of postseismic deformation is available at 12 continuous GPS stations located close to the epicenter of the 2004 M6.0 Parkfield earthquake. The principal component modes for the relaxation of the ensemble of those 12 GPS...
Aboveground predation by an American badger (Taxidea taxus) on black-tailed prairie dogs (Cynomys ludovicianus)
D.A. Eads, E. Biggins
2008, Western North American Naturalist (68) 396-401
During research on black-tailed prairie dogs (Cynomys ludovicianus), we repeatedly observed a female American badger (Taxidea taxus) hunting prairie dogs on a colony in southern Phillips County, Montana. During 1-14 June 2006, we observed 7 aboveground attacks (2 successful) and 3 successful excavations of prairie dogs. The locations and circumstances...
Distribution, abundance, and range of the round goby, Apollina melanostoma, in the Duluth-Superior Harbor and St. Louis River estuary, 1998-2004
M.A. Bergstrom, Lori M. Evrard, A.F. Mensinger
2008, Journal of Great Lakes Research (34) 535-543
Round gobies were first discovered in the Duluth-Superior Harbor, Lake Superior, in 1995. Anecdotal sightings by anglers and others suggested that the infestation was growing and expanding; however, direct evidence of the distribution and expansion rate in the harbor was largely unknown. Distribution and range of the round goby, Apollonia...
