Robust 24 ± 6 ka 40Ar/39Ar age of a low-potassium tholeiitic basalt in the Lassen region of NE California
Brent D. Turrin, L.J. Patrick Muffler, Michael A. Clynne, Duane E. Champion
2007, Quaternary Research (68) 96-110
40Ar/39Ar ages on the Hat Creek Basalt (HCB) and stratigraphically related lava flows show that latest Pleistocene tholeiitic basalt with very low K2O can be dated reliably. The HCB underlies ∼ 15 ka glacial gravel and overlies four andesite and basaltic andesite lava flows that yield 40Ar/39Ar ages of 38 ± 7 ka (Cinder Butte; 1.65%...
Response of brown treesnakes to reduction of their rodent prey
J.E. Gragg, G.H. Rodda, J. A. Savidge, Gary C. White, K. Dean-Bradley, A.R. Ellingson
2007, Journal of Wildlife Management (71) 2311-2317
Trapping brown treesnakes (Boiga irregularis; BTS) with live-mouse (Mus domesticus) lures is the principal control technique for this invasive species on Guam. Lure-based trapping is also used on other islands as a precaution against undetected arrivals and in response to verified BTS sightings. However, the effectiveness of lure-based trapping on...
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...
Elements of the iron and manganese cycles in Lake Baikal
L.Z. Granina, E. Callender
2007, Geochemistry International (45) 918-925
Using data obtained in recent years, we considered the external mass balance and characteristics of internal iron and manganese cycles in Lake Baikal (biological uptake, remineralization, sedimentary and diffusive fluxes, accumulation in sediments, time of renewal, etc.). Some previous results and common concepts were critically reevaluated. ?? Pleiades Publishing, Ltd....
Nitrate in aquifers beneath agricultural systems
M. R. Burkart, J.D. Stoner
Tanik A.Ozturk I.Yazgan M.S.Heath R., editor(s)
2007, Conference Paper, Water Science and Technology
Research from several regions of the world provides spatially anecdotal evidence to hypothesize which hydrologic and agricultural factors contribute to groundwater vulnerability to nitrate contamination. Analysis of nationally consistent measurements from the U.S. Geological Survey's NAWQA program confirms these hypotheses for a substantial range of agricultural systems. Shallow unconfined aquifers...
Red-shouldered hawk occupancy surveys in central Minnesota, USA
C. Henneman, M.A. McLeod, D. E. Andersen
2007, Journal of Wildlife Management (71) 526-533
Forest-dwelling raptors are often difficult to detect because many species occur at low density or are secretive. Broadcasting conspecific vocalizations can increase the probability of detecting forest-dwelling raptors and has been shown to be an effective method for locating raptors and assessing their relative abundance. Recent advances in statistical techniques...
Quasi-horizontal circulation cells in 3D seawater intrusion
E. Abarca, J. Carrera, X. Sanchez-Vila, Clifford I. Voss
2007, Journal of Hydrology (339) 118-129
The seawater intrusion process is characterized by the difference in freshwater and seawater density that causes freshwater to float on seawater. Many confined aquifers have a large horizontal extension with respect to thickness. In these cases, while buoyancy acts in the vertical direction, flow is confined between the upper and...
Distribution of selected halogenated organic compounds among suspended particulate, colloid, and aqueous phases in the Mississippi River and major tributaries
Colleen E. Rostad, S.R. Daniel
2007, Archives of Environmental Contamination and Toxicology (53) 151-158
Suspended particulate, colloid, and aqueous phases were separated and analyzed to determine spatial variation of specific organic compound transport associated with each phase in a dynamic river system. Sixteen sites along the Mississippi River and its major tributaries were sampled at low-flow conditions to maximize the possibility of equilibrium. Across...
Assessing functional equivalency of nekton habitat in enhanced habitats: Comparison of terraced and unterraced marsh ponds
M.K. La Peyre, B. Gossman, J.A. Nyman
2007, Estuaries and Coasts (30) 526-536
A primary goal of many coastal restoration programs is to increase nekton habitat in terms of both quantity and quality. Using shallow water ponds rehabilitated with a technique called marsh terracing, we examined the quality of nekton habitat created, using and comparing several metrics including nekton density and diversity, functional...
Spectral reflectance and emissivity features of broad leaf plants: Prospects for remote sensing in the thermal infrared (8.0-14.0 μm)
Beatriz Ribeiro da Luz, James K. Crowley
2007, Remote Sensing of Environment (109) 393-405
Field emissivity measurements were made of leaves collected from nine deciduous tree and agricultural plant species. The data show, for the first time, that it is possible to discriminate subtle spectral emissivity features of leaves from the natural background emission. Under conditions of controlled measurement geometry (leaves arranged to...
Climate variability controls on unsaturated water and chemical movement, High Plains aquifer, USA
J.J. Gurdak, R. T. Hanson, P.B. McMahon, B. W. Bruce, J.E. McCray, G.D. Thyne, R.C. Reedy
2007, Vadose Zone Journal (6) 533-547
Responses in the vadose zone and groundwater to interannual, interdecadal, and multidecadal climate variability have important implications for groundwater resource sustainability, yet they are poorly documented and not well understood in most aquifers of the USA. This investigation systematically examines the role of interannual to...
Quantifying fluid and bed dynamics for characterizing benthic physical habitat in large rivers
D. Gaeuman, R. B. Jacobson
2007, Journal of Applied Ichthyology (23) 359-364
Sturgeon use benthic habitats in and adjacent to main channels where environmental conditions can include bedload sediment transport and high near-bed flow velocities. Bed velocity measurements obtained with acoustic Doppler instruments provide a means to assess the concentration and velocity of sediment moving near the streambed, and are thus indicative...
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...
1400 yr multiproxy record of climate variability from the northern Gulf of Mexico
J.N. Richey, R.Z. Poore, B.P. Flower, T. M. Quinn
2007, Geology (35) 423-426
A continuous decadal-scale resolution record of climate variability over the past 1400 yr in the northern Gulf of Mexico was constructed from a box core recovered in the Pigmy Basin, northern Gulf of Mexico. Proxies include paired analyses of Mg/Ca and δ18O in the white variety of the planktic foraminifer...
Possible use of foresight, understanding, and planning by wolves hunting muskoxen
L. David Mech
2007, Arctic (60) 145-149
On Ellesmere Island in 2006, arctic wolves (Canis lupus arctos) were observed making a two-pronged approach to a herd of muskoxen (Ovibos moschatus) and, on another occasion, ambushing muskoxen. Both observations seemed to provide evidence that the wolves were using foresight, understanding, and planning. Although the possible use of insight...
Winter behavior and ecology of the Alder Flycatcher (Empidonax alnorum) in Peru
M.S. Foster
2007, Ornitologia Neotropical (18) 171-186
The winter ecology and behavior of Alder Flycatchers (Empidonax alnorum) were studied along the Manu, a white-water meander river in Manu National Park, Madre de Dios, Peru?? during October and November, 1993 to 1997. The birds occupied territories in primary-succession habitats on growing point bars. They were most common in...
Comparative toxicity of chlorpyrifos, diazinon, malathion and their oxon derivatives to larval Rana boylii
D. W. Sparling, G. Fellers
2007, Environmental Pollution (147) 535-539
Organophosphorus pesticides (OPs) are ubiquitous in the environment and are highly toxic to amphibians. They deactivate cholinesterase, resulting in neurological dysfunction. Most chemicals in this group require oxidative desulfuration to achieve their greatest cholinesterase-inhibiting potencies. Oxon derivatives are formed within liver cells but also by bacterial decay of parental pesticides....
Ground water stratification and delivery of nitrate to an incised stream under varying flow conditions
John Karl Bohlke, M. E. O’Connell, K.L. Prestegaard
2007, Journal of Environmental Quality (36) 664-680
Ground water processes affecting seasonal variations of surface water nitrate concentrations were investigated in an incised first-order stream in an agricultural watershed with a riparian forest in the coastal plain of Maryland. Aquifer characteristics including sediment stratigraphy, geochemistry, and hydraulic properties were examined in combination with chemical and isotopic analyses...
Surface temperature patterns in complex terrain: Daily variations and long-term change in the central Sierra Nevada, California
J.D. Lundquist, D.R. Cayan
2007, Journal of Geophysical Research D: Atmospheres (112)
A realistic description of how temperatures vary with elevation is crucial for ecosystem studies and for models of basin-scale snowmelt and spring streamflow. This paper explores surface temperature variability using temperature data from an array of 37 sensors, called the Yosemite network, which traverses both slopes of the Sierra Nevada...
Report of the IAU/IAG Working Group on cartographic coordinates and rotational elements: 2006
P.K. Seidelmann, B.A. Archinal, M. F. A’Hearn, A. Conrad, G.J. Consolmagno, D. Hestroffer, J.L. Hilton, G.A. Krasinsky, G. Neumann, J. Oberst, P. Stooke, E.F. Tedesco, D.J. Tholen, P.C. Thomas, I.P. Williams
2007, Celestial Mechanics and Dynamical Astronomy (98) 155-180
Every three years the IAU/IAG Working Group on Cartographic Coordinates and Rotational Elements revises tables giving the directions of the poles of rotation and the prime meridians of the planets, satellites, minor planets, and comets. This report introduces improved values for the pole and rotation rate of Pluto, Charon, and...
Genetic variability in spotted seatrout (Cynoscion nebulosus), determined with microsatellite DNA markers
R. Ward, K. Bowers, R. Hensley, B. Mobley, E. Belouski
2007, Fishery Bulletin (105) 197-206
Variation in the allele frequencies of five microsatellite loci was surveyed in 1256 individual spotted seatrout (Cynoscion nebulosus) obtained from 12 bays and estuaries from Laguna Madre, Texas, to Charlotte Harbor, Florida, to St. John's River on the Florida Atlantic Coast. Texas and Louisiana collection sites were resampled each year...
Habitat relationships of birds overwintering in a managed coastal prairie
H.Q. Baldwin, J.B. Grace, W.C. Barrow Jr., F.C. Rohwer
2007, Wilson Journal of Ornithology (119) 189-197
Grassland birds are considered to be rapidly declining in North America. Management approaches for grassland birds frequently rely on prescribed burning to maintain habitat in suitable condition. We evaluated the relationships among years since burn, vegetation structure, and overwintering grassland bird abundance in coastal prairie. Le Conte's Sparrows (Ammodramus leconteii)...
Post-middle Miocene origin of modern landforms in the eastern Piedmont of Virginia
Robert E. Weems, Lucy E. Edwards
2007, Stratigraphy (4) 35-48
Diverse late middle Miocene dinoflagellate floras, obtained from two sites along the western edge of the Atlantic Coastal Plain in central Virginia, indicate that the eastern Virginia Piedmont was covered by marine waters about 12-13 Ma. This transgression extended farther westward across the Virginia Piedmont than any other transgression that...
Mercury accumulation in periphyton of eight river ecosystems
A.H. Bell, B. C. Scudder
2007, Journal of the American Water Resources Association (43) 957-968
In 2003, the U.S. Geological Survey (USGS) National Water-Quality Assessment (NAWQA) program and U.S. Environmental Protection Agency studied total mercury (THg) and methylmercury (MeHg) concentrations in periphyton at eight rivers in the United States in coordination with a larger USGS study on mercury cycling in rivers. Periphyton samples were collected...
Sub-sampling genetic data to estimate black bear population size: A case study
C.A. Tredick, M.R. Vaughan, D.F. Stauffer, S.L. Simek, T. Eason
2007, Ursus (18) 179-188
Costs for genetic analysis of hair samples collected for individual identification of bears average approximately US$50 [2004] per sample. This can easily exceed budgetary allowances for large-scale studies or studies of high-density bear populations. We used 2 genetic datasets from 2 areas in the southeastern United States to explore how...
