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184534 results.

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Page 2642, results 66026 - 66050

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Not all publications have extents, not all extents are completely accurate
ATR-FTIR spectroscopic characterization of coexisting carbonate surface complexes on hematite
J.R. Bargar, J. D. Kubicki, R. Reitmeyer, J.A. Davis
2005, Geochimica et Cosmochimica Acta (69) 1527-1542
The speciation of carbonate adsorbed to hematite in air-equilibrated aqueous solutions has been studied using ATR-FTIR spectroscopy. Samples were measured over a range of pH conditions, at 0.1 M NaCl and at low ionic strength, and in H2O and D2O solutions to permit a multispecies analysis of the data. Second-derivative...
Selenium impacts on razorback sucker, Colorado River, Colorado: II. Eggs
S. J. Hamilton, K.M. Holley, K.J. Buhl, F.A. Bullard
2005, Ecotoxicology and Environmental Safety (61) 32-43
Effects on hatching and development of fertilized eggs in adult razorback sucker (Xyrauchen texanus) exposed to selenium in flooded bottomland sites near Grand Junction, Colorado, were determined. After 9 months exposure, fish were collected and induced to spawn and eggs collected for inorganic element analyses. A 9-day egg study was...
Selenium impacts on razorback sucker, Colorado River, Colorado: I. Adults
S. J. Hamilton, K.M. Holley, K.J. Buhl, F.A. Bullard, L.K. Weston, S.F. McDonald
2005, Ecotoxicology and Environmental Safety (61) 7-31
Adult razorback sucker (Xyrauchen texanus) were exposed to various selenium concentrations in ponds and isolated river channels of the Colorado River near Grand Junction, CO, to determine effects on their growth and residue accumulation over an 11-month period. Adults at Horsethief ponds were fed a commercial diet, whereas fish at...
Age and extent of the Ilopango TBJ Tephra inferred from a Holocene chronostratigraphic reference section, Lago De Yojoa, Honduras
P.J. Mehringer Jr., A.M. Sarna-Wojcicki, L.K. Wollwage, P. Sheets
2005, Quaternary Research (63) 199-205
Eruption of central El Salvador's Ilopango Volcano early in the first millennium A.D. caused death, cultural devastation, and exodus of southern Mesoamericans. It also left a time-stratigraphic marker in western El Salvador and adjacent Guatemala - the Ilopango Tierra Blanca Joven, or TBJ tephra. Mineral suites and major element abundances...
Animating the biodynamics of soil thickness using process vector analysis: A dynamic denudation approach to soil formation
D.L. Johnson, J.E.J. Domier, D.N. Johnson
2005, Geomorphology (67) 23-46
This paper expands the dynamic denudation framework of landscape evolution by providing new process insights and details on how soil and its signature morphological feature, the biomantle, form and function in the environment. We examine soils and their biomantles from disparate parts of the world, from the tropics through midlatitudes...
Influence of the Atchafalaya River on recent evolution of the chenier-plain inner continental shelf, northern Gulf of Mexico
A.E. Draut, G.C. Kineke, D.W. Velasco, M. A. Allison, R.J. Prime
2005, Continental Shelf Research (25) 91-112
This study examines the influence of the Atchafalaya River, a major distributary of the Mississippi River, on stratigraphic evolution of the inner continental shelf in the northern Gulf of Mexico. Sedimentary, geochemical, and shallow acoustic data are used to identify the western limit of the distal Atchafalaya subaqueous delta, and...
Soil biota can change after exotic plant invasion: Does this affect ecosystem processes?
Jayne Belnap, Susan L. Phillips, S. K. Sherrod, A. Moldenke
2005, Ecology (86) 3007-3017
Invasion of the exotic annual grass Bromus tectorum into stands of the native perennial grass Hilaria jamesii significantly reduced the abundance of soil biota, especially microarthropods and nematodes. Effects of invasion on active and total bacterial and fungal biomass were variable, although populations generally increased after 50+ years of invasion....
Prey vulnerability to peacock cichlids and largemouth bass based on predator gape and prey body depth
Jeffrey E. Hill, Leo G. Nico, Charles E. Cichra, Carter R. Gilbert
2005, Proceedings of the Southeastern Association of Fish and Wildlife Agencies (58) 47-56
The interaction of prey fish body depth and predator gape size may produce prey assemblages dominated by invulnerable prey and excessive prey-to-predator biomass ratios. Peacock cichlids (Cichla ocellaris) were stocked into southeast Florida canals to consume excess prey fish biomass, particularly spotted tilapia (Tilapia mariae). The ecomorphologically similar largemouth bass...
Linkages between climate, growth, competition at sea and production of sockeye salmon populations in Bristol Bay, 1955-2000
Jennifer L. Nielsen, Gregory T. Ruggerone
Sarah Behr, Helen Wiggins, Alison York, editor(s)
2005, Conference Paper, Proceedings of the open science meeting study of environmental Arctic change (SEARCH)
Bristol Bay, Alaska, supports one of the largest and most valuable salmon fisheries in the world. Salmon abundance in Bristol Bay and other northern areas more than doubled after the 1976–77 marine climate shift. However, in 1997–98, a major El Niño event led to unusual oceanographic conditions and Bristol Bay...
Environmental stresses and skeletal deformities in fish from the Willamette River, Oregon
Daniel L. Villeneuve, Lawrence R. Curtis, Jeffrey J. Jenkins, Kara E. Warner, Fred Tilton, Michael L. Kent, Virginia G. Watral, Michael E. Cunningham, Douglas F. Markle, Doolalai Sethajintanin, Oraphin Krissanakriangkrai, Eugene R. Johnson, Robert Grove
2005, Environmental Science & Technology (39) 3495-3506
The Willamette River, one of 14 American Heritage Rivers, flows through the most densely populated and agriculturally productive region of Oregon. Previous biological monitoring of the Willamette River detected elevated frequencies of skeletal deformities in fish from certain areas of the lower (Newberg pool [NP], rivermile [RM] 26−55) and middle...
Observer variability in pinniped counts: Ground-based enumeration of walruses at haul-out sites
Mark S. Udevitz, C.V. Jay, M.B. Cody
2005, Marine Mammal Science (21) 108-120
Pinnipeds are often monitored by counting individuals at haul-out sites, but the often large numbers of densely packed individuals at these sites are difficult to enumerate accurately. Errors in enumeration can induce bias and reduce precision in estimates of population size and trend. We used data from paired observers monitoring...
Manganese concentration in lobster (Homarus americansus) gills as an index of exposure to reducing conditions in Western Long Island Sound
Andrew F. J. Draxler, Robert M. Sherrell, Daniel Wieczorek, Michele G. Lavigne, Anthony J. Paulson
2005, Journal of Shellfish Research (24) 815-819
We examined the accumulation of manganese (Mn) in gill tissues of chemically naïve lobsters heldin situ at six sites in Long Island Sound (LIS) for up to six weeks to evaluate the possible contribution of eutrophication-driven habitat quality factors to the 1999 mass mortality of American lobsters (Homarus americanus). These western...
Late Neogene and Quaternary evolution of the northern Albemarle Embayment (mid-Atlantic continental margin, USA)
D. Mallinson, S. Riggs, E.R. Thieler, S. Culver, K. Farrell, D.S. Foster, D.R. Corbett, B. Horton, J.F. Wehmiller
2005, Marine Geology (217) 97-117
Seismic surveys in the eastern Albemarle Sound, adjacent tributaries and the inner continental shelf define the regional geologic framework and provide insight into the sedimentary evolution of the northern North Carolina coastal system. Litho- and chronostratigraphic data are derived from eight drill sites on the Outer Banks barrier islands, and...
Changes in the water surface profile of the Colorado River in Grand Canyon, Arizona, between 1923 and 2000
Christopher S. Magirl, Robert H. Webb, Peter G. Griffiths
2005, Water Resources Research (41)
In 1923, a U.S. Geological Survey expedition surveyed the water surface profile of the Colorado River through Grand Canyon with theodolite and stadia rod. In 2000, lidar overflights collected topographic data centered on the river corridor, allowing construction of a new water surface profile and detection of change in the...
RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine) biodegradation in aquifer sediments under manganese-reducing conditions
Paul M. Bradley, Richard S. Dinicola
2005, Bioremediation Journal (9) 1-8
A shallow, RDX (hexahydro-1,3,5-trinitro-1,3,5-triazine)–contaminated aquifer at Naval Submarine Base Bangor has been characterized as predominantly manganese-reducing, anoxic with local pockets of oxic conditions. The potential contribution of microbial RDX degradation to localized decreases observed in aquifer RDX concentrations was assessed in sediment microcosms amended with [U-14C] RDX. Greater than 85%...
Evidence from Opportunity’s Microscopic Imager for water on Meridiani Planum
Kenneth E. Herkenhoff, S. W. Squyres, R. Arvidson, D.S. Bass, J. F. Bell, P. Bertelsen, B. L. Ehlmann, W. Farrand, Lisa R. Gaddis, R. Greeley, J. Grotzinger, A. G. Hayes, S.F. Hviid, J. R. Johnson, B. Jolliff, K.M. Kinch, A. H. Knoll, M.B. Madsen, J.N. Maki, S. M. McLennan, H.Y. McSween, D. W. Ming, J. W. Rice Jr., L. Richter, M. Sims, P. H. Smith, Laurence A. Soderblom, Nicole Spanovich, R. Sullivan, S. Thompson, T. Wdowiak, C. Weitz, P. Whelley
2005, Science (306) 1727-1730
The Microscopic Imager on the Opportunity rover analyzed textures of soils and rocks at Meridiani Planum at a scale of 31 micrometers per pixel. The uppermost millimeter of some soils is weakly cemented, whereas other soils show little evidence of cohesion. Rock outcrops are laminated on...
Spatial data acquisition and integration
J. Jensen, A. Saalfeld, F. Broome, D. Cowen, K. Price, D. Ramsey, L. Lapine, E. Lynn Usery
2005, Book chapter, A research agenda for geographic information science
No abstract available....
Ecoregions and ecoregionalization: geographical and ecological perspectives
Thomas R. Loveland, James W. Merchant
2005, Environmental Management (34) S1-S13
Ecoregions, i.e., areas exhibiting relative homogeneity of ecosystems, are units of analysis that are increasingly important in environmental assessment and management. Ecoregions provide a holistic framework for flexible, comparative analysis of complex environmental problems. Ecoregions mapping has intellectual foundations in both geography and ecology. However, a hallmark of ecoregions mapping...
Survival and migration behavior of juvenile salmonids at McNary Dam, 2004, Final report of research
Russell W. Perry, Amy C. Braatz, Scott D. Fielding, Joel N. Lucchesi, John M. Plumb, Noah S. Adams, Dennis W. Rondorf
2005, Report
During 2004, the USGS Columbia River Research Laboratory conducted a study at McNary Dam using radio telemetry to estimate passage and survival parameters of juvenile salmonids. Our primary objective was to estimate these parameters under ambient environmental and operational conditions, and thus project-wide treatments were not implemented. The primary dam...