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Page 3238, results 80926 - 80950

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Molecular genetic status of Aleutian Canada Geese from Buldir and the Semidi Islands, Alaska
Barbara J. Pierson, John M. Pearce, Sandra L. Talbot, Gerald F. Shields, Kim T. Scribner
2000, The Condor (102) 172-180
We conducted genetic analyses of Aleutian Canada Geese (Branta canadensis leucopareia) from Buldir Island in the western Aleutians and the Semidi Islands in the eastern portion of their breeding range. We compared data from seven microsatellite DNA loci and 143 base pairs of the control region of mitochondrial DNA from...
Lead exposure in American black ducks after implementation of non-toxic shot
M.D. Samuel, E. Frank Bowers
2000, Journal of Wildlife Management (64) 947-953
Lead poisoning from the ingestion of spent shotgun pellets has been recognized as an important disease of North American waterfowl since Bellrose's (1959) research >40 years ago. Nation-wide regulations banning the use of lead shot for waterfowl hunting were established in 1991. We compared the prevalence of lead exposure in...
White sturgeon spawning areas in the lower Snake River
M.J. Parsley, K.M. Kappenman
2000, Northwest Science (74) 192-201
We documented 17 white sturgeon Acipenser transmontanus spawning locations in the Snake River from the mouth to Lower Granite Dam (river km 0 to 173). Spawning locations were determined by the collection of fertilized eggs on artificial substrates or in plankton nets. We collected 245 eggs at seven locations in...
Nitrite fixation by humic substances: Nitrogen-15 nuclear magnetic resonance evidence for potential intermediates in chemodenitrification
K. A. Thorn, M.A. Mikita
2000, Soil Science Society of America Journal (64) 568-582
Studies have suggested that NO− 2, produced during nitrification and denitrification, can become incorporated into soil organic matter and, in one of the processes associated with chemodenitrification, react with organic matter to form trace N gases, including N2O. To gain an understanding of the nitrosation chemistry on a molecular level, soil...
Effect of stream channel size on the delivery of nitrogen to the Gulf of Mexico
R. B. Alexander, R. A. Smith, G. E. Schwarz
2000, Nature (403) 758-761
An increase in the flux of nitrogen from the Mississippi river during the latter half of the twentieth century has caused eutrophication and chronic seasonal hypoxia in the shallow waters of the Louisiana shelf in the northern Gulf of Mexico. This has led to reductions in species diversity, mortality of...
Metalliferous coals of the Westphalian A Joggins Formation, Cumberland basin, Nova Scotia, Canada: Petrology, geochemistry, and palynology
J.C. Hower, J.H. Calder, C.F. Eble, A.C. Scott, J.D. Robertson, L.J. Blanchard
2000, International Journal of Coal Geology (42) 185-206
Five coals of Westphalian A (early Middle Pennsylvanian) age were sampled from the Joggins Formation section exposed along Chignecto Bay at Joggins, Nova Scotia. Coal beds along the bay were mined beginning in the early 17th century, yet there have been few detailed published investigation of the coal beds of...
Crustal deformation associated with glacial fluctuations in the eastern Chugach Mountains, Alaska
Jeanne Sauber, George Plafker, Bruce F. Molnia, Mark A. Bryant
2000, Journal of Geophysical Research B: Solid Earth (105) 8055-8077
The changes of the solid Earth in south central Alaska in response to two major glacial fluctuations on different temporal and spatial scales have been estimated and we evaluated their influence on the stress state and ongoing tectonic deformation of the region. During the recent (1993–1995) Bering Glacier surge, a...
Toxicity of acidified chitosan for cultured rainbow trout (Oncorhynchus mykiss)
G. Bullock, V. Blazer, S. Tsukuda, S. Summerfelt
2000, Aquaculture (185) 273-280
Chitosan is a deacetylation product of chitin. It is used as a flocculent for sewage and brewery wastes, and as a chelator of heavy metals. In aquaculture, chitosan has been used as an immunostimulant for protection against bacterial diseases in fish, for controlled release of vaccines, and as a diet...
NASQAN: The design and implementation of a large-river suspended sediment and trace element flux programme
A. J. Horowitz
2000, Conference Paper, IAHS-AISH Publication
In 1996 the US Geological Survey (USGS) began a national flux-based water quality monitoring programme in the Mississippi, Columbia, Colorado, and Rio Grande basins. Suspended sediment flux estimates for periods greater than a year are generally accurate within ??15%. Discharge and suspended sediment concentrations varied much more than chemical levels....
Palaeohydrology, vegetation, and climate since the late Illinois Episode (~130 ka) in south-central Illinois
B. Brandon Curry, R. G. Baker
2000, Conference Paper, Palaeogeography, Palaeoclimatology, Palaeoecology
Our interpretation of pollen and ostracode successions from four basins in south-central Illinois provides a new synthesis of palaeovegetation, palaeohydrology, and palaeoclimate for the period from the late Illinois Episode (about 130,000 years ago) to near the end of the Wisconsin Episode (about 25,000 years ago). Correlations of pollen biozones...
Leakage of active crater lake brine through the north flank at Rincon de la Vieja volcano, northwest Costa Rica, and implications for crater collapse
K.A. Kempter, G.L. Rowe
2000, Book, Journal of Volcanology and Geothermal Research
The Active Crater at Rincon de la Vieja volcano, Costa Rica, reaches an elevation of 1750 m and contains a warm, hyper-acidic crater lake that probably formed soon after the eruption of the Rio Blanco tephra deposit approximately 3500 years before present. The Active Crater is buttressed by volcanic ridges...
What is “natural”? : Yellowstone elk population - A case study
R.B. Keigley, Frederic H. Wagner
2000, Integrative Biology (1) 133-148
Ecology analyzes the structure and function of ecosystems at all points along the continuum of human disturbance, from so-called pristine forests to urban backyards. Undisturbed systems provide reference points at one end of the spectrum, and nature reserves and parks are highly valued because they can provide unique examples of...
Chemical characteristics of urban stormwater sediments and implications for environmental management, Maricopa County, Arizona
J. T. C. Parker, K. D. Fossum, T.L. Ingersoll
2000, Environmental Management (26) 99-115
Investigations of the chemical characteristics of urban stormwater sediments in the rapidly growing Phoenix metropolitan area of Maricopa County, Arizona, showed that the inorganic component of these sediments generally reflects geologic background values. Some concentrations of metals were above background values, especially cadmium, copper, lead, and zinc, indicating an anthropogenic...
Conserving inland cutthroat trout in small streams: how much stream is enough?
Robert H. Hilderbrand, Jeffrey L. Kershner
2000, North American Journal of Fisheries Management (30) 513-520
We examined the prognosis for long-term persistence of isolated populations of cutthroat troutOncorhynchus clarki and the feasibility of using barriers to protect them from nonnative salmonids. In so doing, we estimated minimum stream lengths (MSL) required by cutthroat trout populations of varying abundances and rates of population loss to emigration...
Estimating the variance and integral scale of the transmissivity field using head residual increments
Li Zheng, Stephen E. Silliman
2000, Water Resources Research (36) 1353-1358
A modification of previously published solutions regarding the spatial variation of hydraulic heads is discussed whereby the semivariogram of increments of head residuals (termed head residual increments HRIs) are related to the variance and integral scale of the transmissivity field. A first‐order solution is developed for the case of a...
Potential effects of climate change on surface-water quality in North America
Peter S. Murdoch, Jill Baron, T. L. Miller
2000, Journal of the American Water Resources Association (36) 347-366
Data from long-term ecosystem monitoring and research stations in North America and results of simulations made with interpretive models indicate that changes in climate (precipitation and temperature) can have a significant effect on the quality of surface waters. Changes in water quality during storms, snowmelt, and periods of elevated air...
Holocene environmental and climatic change in the Northern Great Plains as recorded in the geochemistry of sediments in Pickerel Lake, South Dakota
W.E. Dean, A. Schwalb
2000, Quaternary International (67) 5-20
The sediments in Pickerel Lake, northeastern South Dakota, provide a continuous record of climatic and environmental change for the last 12000 yr. Sediments deposited between 12 and 6 ka (radiocarbon) show extreme variations in composition, oxygen and carbon isotopic composition of bulk carbonate, carbon isotopic composition of organic matter, and...
Associations among fish assemblage structure and environmental variables in Willamette Basin streams, Oregon
Ian R. Waite, Kurt D. Carpenter
2000, Transactions of the American Fisheries Society (129) 754-770
As part of the U.S. Geological Survey's National Water-Quality Assessment Program, fish were collected from 24 selected stream sites in the Willamette Basin during 1993-1995 to determine the composition of the fish assemblages and their relation to the chemical and physical environment. Variance in fish relative abundance was greater among...