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Articles 16111 - 16140 of 17792
Full-Text Articles in Entire DC Network
Determination Of Thermal Maturity And Organic Matter Type By Principal Components Analysis Of The Distributions Of Polycyclic Aromatic Compounds, Michael A. Kruge
Determination Of Thermal Maturity And Organic Matter Type By Principal Components Analysis Of The Distributions Of Polycyclic Aromatic Compounds, Michael A. Kruge
Department of Earth and Environmental Studies Faculty Scholarship and Creative Works
The thermal maturity and organofacies sensitivity of polycyclic aromatic compound (PAC) distributions was explored by examination of the aromatic fractions of solvent extracts from a diverse set of 53 shales, coals and kerogen macerals which have undergone either natural or artificial maturation and which represent all three principal sedimentary organic matter (OM) types. Systematic changes with maturation were observed in the following groups of isomers: tri- and tetramethylnaphthalenes, methyl- and dimethylphenanthrenes, methyl- and dimethyldibenzothiophenes, methylpyrenes, and methylchrysenes. The maturity differences were quantified by mathematical ratios of the relative concentrations of the more thermally stable isomers to the less stable, on …
Multibeam Sonar Backscatter Lineaments And Anthropogenic Organic Components In Lacustrine Silty Clay, Evidence Of Shipping In Western Lake Ontario, C F Michael Lewis, L A. Mayer, Prasanta K. Mukhopadhyay, Michael A. Kruge, John P. Coakley, M D. Smith
Multibeam Sonar Backscatter Lineaments And Anthropogenic Organic Components In Lacustrine Silty Clay, Evidence Of Shipping In Western Lake Ontario, C F Michael Lewis, L A. Mayer, Prasanta K. Mukhopadhyay, Michael A. Kruge, John P. Coakley, M D. Smith
Department of Earth and Environmental Studies Faculty Scholarship and Creative Works
A multibeam sonar survey (95 kHz) covering more than 500 km2 of western Lake Ontario revealed anomalous lineaments of relatively high backscatter. The lineaments did not align with or parallel the most prominent structural zones beneath the lake as expected. Instead, the principal lineaments lay on lines between ports on opposite sides of the lake, especially between Toronto and Welland Canal, and Toronto and Niagara River mouth. As the lineaments underlie current and historical shipping routes used during the steamship era, they are interpreted as an acoustic response to shipping debris cumulated in the near-surface bottom sediment. An exploratory …
Iron And Manganese In The Ross Sea, Antarctica: Seasonal Iron Limitation In Antarctic Shelf Waters, Peter N. Sedwick, Giacomo R. Ditullio, Denis J. Mackey
Iron And Manganese In The Ross Sea, Antarctica: Seasonal Iron Limitation In Antarctic Shelf Waters, Peter N. Sedwick, Giacomo R. Ditullio, Denis J. Mackey
OES Faculty Publications
Dissolved iron and manganese and total dissolvable iron were measured in water column samples from the Polynya Region of the southern Ross Sea in cruises in Nov.-Dec. 1994 (spring 1994) and Dec. 1995 to Jan. 1996 (summer 1995). Iron and manganese addition bottle incubation experiments were also performed on these cruises to assess the nutritional sufficiency of ambient iron and manganese concentrations for phytoplankton growth. Generally high dissolved iron concentrations (>0.5 nM) and relatively complex iron and manganese vertical profiles were obtained in spring 1994 vs. summer 1995. Dissolved iron concentrations in the upper water column averaged 1.0 nM …
Mercury Bioaccumulation In Fish In A Region Affected By Historic Gold Mining: The South Yuba River, Deer Creek, And Bear River Watersheds, California, 1999, Jason T. May, Roger L. Hothem, Charles N. Alpers, Matthew A. Law
Mercury Bioaccumulation In Fish In A Region Affected By Historic Gold Mining: The South Yuba River, Deer Creek, And Bear River Watersheds, California, 1999, Jason T. May, Roger L. Hothem, Charles N. Alpers, Matthew A. Law
United States Geological Survey: Publications
Mercury that was used historically for gold recovery in mining areas of the Sierra Nevada continues to enter local and downstream water bodies, including the Sacramento–San Joaquin Delta and the San Francisco Bay of northern California. Methylmercury is of particular concern because it is the most prevalent form of mercury in fish and is a potent neurotoxin that bioaccumulates at successive trophic levels within food webs. In April 1999, the U.S. Geological Survey, in cooperation with several other agencies—the Forest Service (U.S. Department of Agriculture), the Bureau of Land Management, the U.S. Environmental Protection Agency, the California State Water Resources …
Mercury Contamination From Historic Gold Mining In California, Charles N. Alpers, Michael P. Hunerlach
Mercury Contamination From Historic Gold Mining In California, Charles N. Alpers, Michael P. Hunerlach
United States Geological Survey: Publications
Mercury contamination from historic gold mines represents a potential risk to human health and the environment. This fact sheet provides background information on the use of mercury in historic gold mining and processing operations in California, and describes a new USGS project that addresses the potential risks associated with mercury from these sources, with emphasis on historic hydraulic mining areas. Miners used mercury (quicksilver) to recover gold throughout the western United States at both placer (alluvial) and hardrock (lode) mines. The vast majority of mercury lost to the environment in California was from placer-gold mines, which used hydraulic, drift, and …
Metals Transport In The Sacramento River, California, 1996–1997 Volume 2: Interpretation Of Metal Loads, Charles N. Alpers, Ronald C. Antweiler, Howard E. Taylor, Peter D. Dileanis, Joseph L. Domagalski
Metals Transport In The Sacramento River, California, 1996–1997 Volume 2: Interpretation Of Metal Loads, Charles N. Alpers, Ronald C. Antweiler, Howard E. Taylor, Peter D. Dileanis, Joseph L. Domagalski
United States Geological Survey: Publications
Metals transport in the Sacramento River, northern California, from July 1996 to June 1997 was evaluated in terms of metal loads from sam-ples of water and suspended colloids that were collected on up to six occasions at 13 sites in the Sacramento River Basin. Four of the sampling periods (July, September, and November 1996; and May–June 1997) took place during relatively low-flow conditions and two sampling periods (December 1996 and January 1997) took place during high-flow and flooding conditions, respec-tively. This study focused primarily on loads of cadmium, copper, lead, and zinc, with secondary emphasis on loads of aluminum, iron, …
Ecogeochemistry Of The Subsurface Food Web At Ph 0–2.5 In Iron Mountain, California, U.S.A., Eleanora I. Robbins, Teresa M. Rodgers, Charles N. Alpers, D. Kirk Nordstrom
Ecogeochemistry Of The Subsurface Food Web At Ph 0–2.5 In Iron Mountain, California, U.S.A., Eleanora I. Robbins, Teresa M. Rodgers, Charles N. Alpers, D. Kirk Nordstrom
United States Geological Survey: Staff Publications
Pyrite oxidation in the underground mining environment of Iron Mountain, California, has created the most acidic pH values ever reported in aquatic systems. Sulfate values as high as 120 000 mg 1-1 and iron as high as 27600mg 1-1 have been measured in the mine water, which also carries abundant other dissolved metals including Al, Zn, Cu, Cd, Mn, Sb and Pb. Extreme acidity and high metal concentrations apparently do not preclude the presence of an underground acidophilic food web, which has developed with bacterial biomass at the base and heliozoans as top predators. Slimes, oil-like films, flexible …
Nutrients In Groundwaters Of The Conterminous United States, 1992-1995, Bernard Nolan, Jeffrey Stoner
Nutrients In Groundwaters Of The Conterminous United States, 1992-1995, Bernard Nolan, Jeffrey Stoner
United States Geological Survey: Staff Publications
Results of a national water quality assessment indicate that nitrate is detected in 71% of groundwater samples, more than 13 times as often as ammonia, nitrite, organic nitrogen, and orthophosphate, based on a common detection threshold of 0.2 mg/L. Shallow groundwater (typically 5 m deep or less) beneath agricultural land has the highest median nitrate concentration (3.4 mg/L), followed by shallow groundwater beneath urban land (1.6 mg/L) and deeper groundwater in major aquifers (0.48 mg/L). Nitrate exceeds the maximum contaminant level, 10 mg/L as nitrogen, in more than 15% of groundwater samples from 4 of 33 major aquifers commonly used …
Some Post-Pliocene Buried Soils Of Central United States, James Thorp, W. M. Johnson, E. C. Reed
Some Post-Pliocene Buried Soils Of Central United States, James Thorp, W. M. Johnson, E. C. Reed
Conservation and Survey Division: Faculty and Staff Publications
No abstract provided.
Disarticulation And Dissolution Of Crab Remains Across A Depth Gradient In The Bahamas: A Taphonomic Study, Rebecca A. Lincoln
Disarticulation And Dissolution Of Crab Remains Across A Depth Gradient In The Bahamas: A Taphonomic Study, Rebecca A. Lincoln
Honors Papers
The fields of Paleontology and Paleoecology would not be complete without taphonomy, the study of the processes affecting organisms between death and fossilization. Taphonomy is important because it allows us to make more complete conjectures about prehistoric organisms and environments, and makes us aware of possible holes and biases in the fossil record due to highly destructive processes or the loss of delicate, non-resistant organisms. Studies on the processes affecting modern organisms have contributed greatly to the understanding of ancient processes; however, most of these studies are nearshore and short-term. What is lacking is information on the effects of these …
Bad-Boy Bryozoan Biomarkers: Cheilostome Distribution Patterns Along A Bahamian Depth Gradient, Christopher J. Nytch
Bad-Boy Bryozoan Biomarkers: Cheilostome Distribution Patterns Along A Bahamian Depth Gradient, Christopher J. Nytch
Honors Papers
In 1993 and 1994, the Shelf and Slope Experimental Taphonomy Initiative (SSETI) deployed thirty-five samples of sea urchins along the continental shelf/slope of the Bahamas in an effort to explore the paleoecology and taphonomic potentials of shallow water carbonate environments. Samples were retrieved at 1-, 2-, and 6-year intervals for examination and comparison of epibiont accumulation. Tests and spines of the sea urchin Eucidaris were examined for encrusting cheilostome Bryozoa. Specimens were identified to the genus level. Assessment of abundance and distribution patterns with water depth shows that cheilostomes are prevalent in photic waters, and lacking at depth. Burial of …
Hypothetical Origins Of Paleozoic Fossils From The Gulf Coastal Plain Of Arkansas, Karen Arbuckle
Hypothetical Origins Of Paleozoic Fossils From The Gulf Coastal Plain Of Arkansas, Karen Arbuckle
Journal of the Arkansas Academy of Science
A fauna of reworked Paleozoic fossils has been found in chert pebbles from the Gulf Coastal Plain in eastern Columbia County, Arkansas, although the nearest mapped exposure of Mississippian and Pennsylvanian rocks are fifty-five miles northward in the southern edge of the Ouachita Mountains. The surficial rocks at the collection site have been referred to the Claiborne Group of Eocene age by the authors of the geological map of Arkansas. Additional outcrops containing similar Paleozoic fossils have been found within a 15-mile radius. The fauna includes both lacy and twig-like bryozoans, articulate brachiopods, tabulate and rugose corals, stalked echinoderms, gastropods, …
Large Pleistocene Box Turtle From Southwest Arkansas, Leo Carson Davis, John G. Scoggins, J. Alan Holman
Large Pleistocene Box Turtle From Southwest Arkansas, Leo Carson Davis, John G. Scoggins, J. Alan Holman
Journal of the Arkansas Academy of Science
No abstract provided.
Bulletin 4446 - Ord Land And Water Management Plan 2000, Agriculture Western Australia, Community Of Kununurra
Bulletin 4446 - Ord Land And Water Management Plan 2000, Agriculture Western Australia, Community Of Kununurra
Bulletins 4000 -
The wise use of the land and water of the Ord has become an imperative driven by increasing awareness of the impacts of current uses on ground water and the on the quality of the Ord River itself.
We have been lucky as a community that these resources are still in reasonable order and that we have the time to address the resource management challenges associated with our use of them. There is a wide range of land and water management issues to be addressed and all those involved have responsibilities to address some of those issues.
Detecting The Cause Of Acidification At A Seasonal Wetland On The Swan Coastal Plain, Western Australia, Through Laboratory And Field Mesocosm Experiments, Kelli O'Neill
Theses : Honours
Acidification (pH< 4.5) was detected at Lake Jandabup, a shallow, seasonal wetland on the Swan Coastal Plain. Western Australia. Concern has been raised because populations of invertebrate species have declined or disappeared since acidification, potentially compromising the status of the lake as a nature reserve. The Jake bed is underlain with pyrite (feS2), which oxidises when dry producing sulfates, hydrogen ions and ferrous iron. Being seasonal, Lake Jandabup would be expected to be naturally acidic, but the more recent trend has been a prolonged (> 1 year) and extreme acidification (pH < 4.0). This study endeavoured to explain why the Jake may have undergone an acidic change, why it may have recovered and whether it will happen again. It was hypothesised that the acidification may have been caused by prolonged drying of the lake causing excessive oxidation of pyrite which produced more acid than the wetland could neutralise through buffering. The hypothesis was tested through laboratory and field experiments. The laboratory experiment involved taking intact sediment cores from around the lake, drying them for various lengths of time, and measuring pH, sulfate, total iron, total alkalinity and total aridity upon rehydration. Dried sediment from diatomaceous earth under Fe(OH)3 precipitate gave the lowest pH of less than 4.0. High sulfates, low alkalinity and low pH were interrelated. While drying in its own right produced low pH, generally there was no significant difference between drying times for release of selected variables. The field experiment involved the establishment of small in situ mesocosms to test for the effects …
The Use Of Stable Isotopic Signatures Of Marine Biota To Map Sewage Effluent Disposed Into The Marine Environment, Adam Gartner
The Use Of Stable Isotopic Signatures Of Marine Biota To Map Sewage Effluent Disposed Into The Marine Environment, Adam Gartner
Theses : Honours
Recent work indicates that nitrogen stable isotopic signatures of aquatic biota can be used to link nutrient inputs in the marine environment to terrestrial sources. While this technique of tracing nutrients has been shown to be effective in environments that are not nutrient limited, it has not been proved that this method is effective in oligotrophic environments. This study examined whether nitrogen stable isotopic signatures of marine biota can be used to trace the distribution of sewage effluent in highly mixed, nitrogen limited waters, by examining the δ15N values of marine biota situated close to and distant from …
Characterization Of Hyporheic Zone Processes Of A Northern Prairie Stream, David B. Rush
Characterization Of Hyporheic Zone Processes Of A Northern Prairie Stream, David B. Rush
Theses and Dissertations
A hyporheic zone occurs beneath and adjacent to streams where surface water and groundwater mix. This zone is known to be a reservoir for solutes and a habitat for interstitial organisms. Hyporheic zone boundaries in the Tongue River, North Dakota, were investigated through examination of the physicochemical and biological gradients present in the stream channel and bank sediments. The effects of cattle grazing at the streamside interface of the riparian zone were also examined at two locations to determine land use impacts on the hyporheic zone.
Electrical conductivity (EC) and ammonium gradients were observed beneath the stream channel via nests …
Nutrients As A Link Between Ionic Concentration/Composition And Diatom Distributions In Saline Lakes, J. E. Saros, Sherilyn C. Fritz
Nutrients As A Link Between Ionic Concentration/Composition And Diatom Distributions In Saline Lakes, J. E. Saros, Sherilyn C. Fritz
Department of Earth and Atmospheric Sciences: Faculty Publications
Diatom profiles in closed-basin lake sediments are commonly used to reconstruct climate change based on the observed correlations between salinity (ionic concentration) and modern diatom assemblages. Diatom assemblages are strongly correlated not only with salinity but also anion composition, with certain taxa characteristic of carbonate systems and others sulfate-dominated waters. Although strong correlations exist, the actual mechanisms behind these correlations are unknown. Here we briefly review the influence of salinity and ionic composition on nutrient dynamics in saline lakes and suggest that these interactions may drive shifts in diatom species composition along gradients of ionic concentration/ composition. We discuss the …
Preliminary Results Of Bitumen And Whole-Rock Elemental Analyses Of Crp-2/2a, Victoria Land Basin, Antarctica, Richard Kettler, E. Papastavros
Preliminary Results Of Bitumen And Whole-Rock Elemental Analyses Of Crp-2/2a, Victoria Land Basin, Antarctica, Richard Kettler, E. Papastavros
Department of Earth and Atmospheric Sciences: Faculty Publications
Sediments and rocks recovered in CRP-2/2A coring operations contain relatively little organic matter (average TOC=0.28%) and very small amounts of solvent-soluble organic matter. Because Early Oligocene sediment included significant amounts of coal detritus, TOC values are higher in Early Oligocene rocks than in younger rocks. TOC values are highest in the fine-grained rocks deposited as part of the highstand systems tract (HST) and TOC values decrease from the bottom to the top of the HST. The TOC:TN ratios observed in the CRP-2/2A core typically exceed 10, and are strong evidence that the preserved organic matter comprises a mixture of detrital …
Morphology And Taxonomic Position Of The Late Cretaceous Diatom Genus Pomphodiscus Barker & Meakin, Vladimir A. Nikolaev, David M. Harwood
Morphology And Taxonomic Position Of The Late Cretaceous Diatom Genus Pomphodiscus Barker & Meakin, Vladimir A. Nikolaev, David M. Harwood
Department of Earth and Atmospheric Sciences: Faculty Publications
Results from our investigation of Upper Cretaceous diatoms from the Marca Shale Member of the Moreno Shale in California and from Ocean Drilling Program (ODP) Hole 748C on the Kerguelen Plateau ,Southern Indian Ocean enable a clarification of the taxonomic position of several diatoms. Differences in areola structure ,a primary and conservative character of the diatom valve, are used to separate diatoms recently included in the genus Benetorus. We resurrect he genus Pomphodiscusto include species with locular areolae, a central rimoportula ,and a central inflated chamber .We propose the new species Pomphodiscusk erguelensisn. sp. and new combination Pomphodiscusc …
Nest Predation On Black-Tailed Prairie Dog Colonies, Bruce Baker, Thomas R. Stanley, Glenn Plumb
Nest Predation On Black-Tailed Prairie Dog Colonies, Bruce Baker, Thomas R. Stanley, Glenn Plumb
United States Geological Survey: Staff Publications
Nest predation is the principal cause of mortality for many grassland birds. Predation rates may be higher on prairie dog colonies because they may have less available nesting cover and may increase predator abundance. We compared 14-day nest predation rates for 1,764 artificial nests on 102 black-tailed prairie dog (Cynovnys ludovicianus) colonies and their paired off-colony sites (similar habitat lacking prairie dogs) from 14 May to 26 June 1998 in South Dakota and Wyoming. Predation rates on colonies (66.2 ± 2.2%; x ± SE) were 29.5% higher than at off-colony sites (51.1 ± 2.7%). Nesting cover on colonies …
Expression Of A Dominant-Negative Mutant Of P21ras Inhibits Induction Of Nitric Oxide Synthase And Activation Of Nuclear Factor-Kb In Primary Astrocytes, Kalipada Pahan, Xiaojuan Lu, Michael J. Mckinney, Charles Wood, Faruk G. Sheikh, John R. Raymond
Expression Of A Dominant-Negative Mutant Of P21ras Inhibits Induction Of Nitric Oxide Synthase And Activation Of Nuclear Factor-Kb In Primary Astrocytes, Kalipada Pahan, Xiaojuan Lu, Michael J. Mckinney, Charles Wood, Faruk G. Sheikh, John R. Raymond
School of Biological Sciences: Faculty Publications
The present study underlines the importance of p21ras in regulating the inducible nitric oxide synthase (iNOS) in primary astrocytes. Bacterial lipopolysaccharides induced the GTP loading of p21ras, and the expression of a dominant-negative mutant of p21ras (Dp21ras) inhibited lipopolysaccharide-induced GTP loading in rat primary astrocytes. To delineate the role of p21ras in the induction of iNOS, we examined the effect of Dp21ras on the expression of iNOS and the production of nitric oxide. It is interesting that expression of Dp21ras markedly inhibited the production of nitric oxide and the expression of iNOS in lipopolysaccharide- and pro-inflammatory cytokine (tumor necrosis factor-a, …
Restoring Ecological Integrity Of Great Rivers: Historical Hydrographs Aid In Defining Reference Conditions For The Missouri River, David L. Galat, Robin Lipkin
Restoring Ecological Integrity Of Great Rivers: Historical Hydrographs Aid In Defining Reference Conditions For The Missouri River, David L. Galat, Robin Lipkin
United States Geological Survey: Staff Publications
Restoring the ecological integrity of regulated large rivers necessitates characterizing the natural flow regime. We applied ‘Indicators of Hydrologic Alteration’ to assess the natural range of variation of the Missouri River’s flow regime at 11 locations before (1929–1948) and after (1967–1996) mainstem impoundment. The 3768 km long Missouri River was divided into three sections: upper basin least-altered from flow regulation, including the lower Yellowstone River; middle basin inter-reservoir, and lower basin channelized. Flow regulation was associated with a reduction in magnitude and duration of the annual flood pulse, an increase in magnitude and duration of annual discharge minima, a reduction …
Holocene Environmental And Climatic Change In The Northern Great Plains As Recorded In The Geochemistry Of Sediments In Pickerel Lake, South Dakota, Walter E. Dean, Antje Schwalb
Holocene Environmental And Climatic Change In The Northern Great Plains As Recorded In The Geochemistry Of Sediments In Pickerel Lake, South Dakota, Walter E. Dean, Antje Schwalb
United States Geological Survey: Staff Publications
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 magnetic susceptibility. These variations reflect changes in sources of moisture, regional vegetation types, precipitation-evaporation balance, ground- and surface-water influx, water residence time, erosion, lake productivity, water level, and water temperature. The total carbonate content of late Pleistocene sediments steadily increased from <20% at the base of the core to as much as 80% in sediments deposited between 11 and 9 ka. By about 8 ka, the total carbonate content of the sediments had declined to about 40% where it remained with little variation for the past 8 kyr, suggesting relatively stable conditions. There are marked increases in values of δ13C and δ18O in bulk carbonate, …20%>
Viability Of Piping Plover Charadrius Melodus Metapopulations, Jonathan H. Plissner, Susan M. Haig
Viability Of Piping Plover Charadrius Melodus Metapopulations, Jonathan H. Plissner, Susan M. Haig
United States Geological Survey: Staff Publications
The meta-population viability analysis package, vortex, was used to examine viability and recovery objectives for piping plovers Charadrius melodus, an endangered shorebird that breeds in three distinct regions of North America. Baseline models indicate that while Atlantic Coast populations, under current management practices, are at little risk of near-term extinction, Great Plains and Great Lakes populations require 36% higher mean fecundity for a significant probability of persisting for the next 100 years. Meta-population structure (i.e. the delineation of populations within the meta-population) and inter-population dispersal rates had varying effects on model results; however, spatially-structured meta-populations exhibited lower viability than …
Single-Dilution Enzyme-Linked Immunosorbent Assay For Quantification Of Antigen-Specific Salmonid Antibody, Stewart W. Alcorn, Ronald J. Pascho
Single-Dilution Enzyme-Linked Immunosorbent Assay For Quantification Of Antigen-Specific Salmonid Antibody, Stewart W. Alcorn, Ronald J. Pascho
United States Geological Survey: Staff Publications
An enzyme-linked immunosorbent assay (ELISA) was developed on the basis of testing a single dilution of serum to quantify the level of antibody to the p57 protein of Renibacterium salmoninarum in sockeye salmon (Oncorhynchus nerka). The levels of antibody were interpolated from a standard curve constructed by relating the optical densities (OD) produced by several dilutions of a high-titer rainbow trout (O. mykiss) antiserum to the p57 protein. The ELISA OD values produced by as many as 36 test sera on each microplate were compared with the standard curve to calculate the antigen-specific antibody activity. Repeated …
Natural And Anthropogenic Influences On The Distribution Of The Threatened Neosho Madtom In A Midwestern Warmwater Stream, Mark L. Wildhaber, Vernon M. Tabor, Daniel W. Mulhern, Kenneth L. Powell, Scott P. Sowa
Natural And Anthropogenic Influences On The Distribution Of The Threatened Neosho Madtom In A Midwestern Warmwater Stream, Mark L. Wildhaber, Vernon M. Tabor, Daniel W. Mulhern, Kenneth L. Powell, Scott P. Sowa
United States Geological Survey: Staff Publications
We attempted to discern the contributions of physical habitat, water chemistry, nutrients, and contaminants from historic lead-zinc mining activities on the riffle-dwelling benthic fish community of the Spring River, a mid western warm water stream that originates in Missouri and flows into Kansas and Oklahoma. The Spring River has a fish community that includes the Neosho madtom Noturus placidus, a species federally listed as threatened. Although anthropogenic factors such as contaminants limited populations and densities of fishes, an integrated assessment of natural and anthropogenic factors was necessary to effectively estimate the influence of the latter. Fish populations in the …
Modeling The Bull Run River-Reservoir System, Scott A. Wells
Modeling The Bull Run River-Reservoir System, Scott A. Wells
Civil and Environmental Engineering Faculty Publications and Presentations
The City of Portland, Water Bureau currently operates 2 Bull Run reservoirs, Reservoir #2 and Reservoir #1 as a water supply source in the Bull Run watershed shown in Figure 1 and Figure 2. The Water Bureau wants to operate their water supply system in order to meet both water supply objectives and fish habitat objectives downstream of the Bull Run reservoirs in Bull Run River. In addition, a third Bull Run reservoir has been proposed as an additional water supply source. This reservoir also may be used to meet water supply and fish habitat objectives in Bull Run River. …
Variation Of Constitutive Model Formulation On Analytical Cake Filtration Models, Scott A. Wells
Variation Of Constitutive Model Formulation On Analytical Cake Filtration Models, Scott A. Wells
Civil and Environmental Engineering Faculty Publications and Presentations
Constitutive properties are required to model porosity, effective stress, porewater pressure, or permeability during cake filtration. By using an analytical cake filtration model based on Tiller (1975) with various constitutive property formulations, predictions of effective stress, permeability, and porosity distributions in a filter cake can be made. This analytical approach was only valid when spatially average values of porosity and pressure differential were constant over time. Several different constitutive property formulations were compared to data of effective stress and permeability as a function of porosity for kaolin clay in water. Also the spatial distribution of porosity in a filter cake …
Development, Management And Economy Of Show Caves, Arrigo A. Cigna, Ezio Burri
Development, Management And Economy Of Show Caves, Arrigo A. Cigna, Ezio Burri
International Journal of Speleology
The problems concerning the development of show caves are here considered by taking into account different aspects of the problem. A procedure to carry out an Environmental Impact Assessment (EIA) has been established in the last decade and it is now currently applied. Such an assessment starts with a pre-operational phase to obtain sufficient information on the undisturbed status of a cave to be developed into a show cave. Successively a programme for its development is established with the scope to optimise the intervention on the cave at the condition that its basic environmental parameters are not irreversibly modified. The …