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2006

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Articles 361 - 390 of 442

Full-Text Articles in Earth Sciences

Methods To Set Land Salinity Resource Condition Targets For The South West : Case Studies From Australia And New Zealand, Sharon Hu Jan 2006

Methods To Set Land Salinity Resource Condition Targets For The South West : Case Studies From Australia And New Zealand, Sharon Hu

Resource management technical reports

This Resource Management Technical Report provides background to methods to set targets on land salinity in the South West Natural Resource Management (NRM) region of Western Australia. Case studies from Australia and New Zealand have been reviewed to determine what approaches should be used. Resource Condition Targets (RCTs) are required for land salinity, soil condition and remnant vegetation.

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Ravensthorpe Area Catchment Appraisal 2006, A Massenbauer Jan 2006

Ravensthorpe Area Catchment Appraisal 2006, A Massenbauer

Resource management technical reports

The Ravensthorpe area covers 861, 000 hectares. Ninety percent of the study area covered in this report falls within the Ravensthorpe Shire, Western Australia. This document aims to give the reader a starting point from which to further assess larger scale areas of the catchment for the purpose of planning to reverse and improve land degradation and sustainable farming in Western Australia.

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Characterization And Interpretation Of The Cephalopod Marker Bed, Oakes Quarry Park, Fairborn, Ohio, Jessica Nicole Mcdonough Jan 2006

Characterization And Interpretation Of The Cephalopod Marker Bed, Oakes Quarry Park, Fairborn, Ohio, Jessica Nicole Mcdonough

Browse all Theses and Dissertations

A distinct sequence of orange-brown, fossiliferous grainstones with interbedded blue mudstones exists in the upper portion of the Silurian-aged (Llandoverian) Brassfield Formation exposure at Oakes Quarry Park, Fairborn, Ohio. The unit is locally referred to as the cephalopod marker bed as it can be easily identified and is continuous throughout the quarry. The unit varies considerably in thickness (0.3m-0.9m) and contains a variety of sedimentary structures and fossils indicative of a warm, shallow marine environment subject to wave action. Dominant fossils within the unit include echinoderms, cephalopods, bryozoans, abraded mollusks, gastropods, brachiopods, and trilobites. Less-common fossil organisms within the unit …

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Feasibility Analysis Of The Strontium Ratio Obtained From Pennsylvanian Chondricthian Dentary, Cullen John Erbacher Jan 2006

Feasibility Analysis Of The Strontium Ratio Obtained From Pennsylvanian Chondricthian Dentary, Cullen John Erbacher

Browse all Theses and Dissertations

This research was undertaken to determine the amount of time between transgressive and regressive sequences. One of the methods used to determine the amount of missing time in an unconformity is the 87Sr / 86Sr ratio. The 87Sr / 86Sr ratio will be high around brackish and freshwater environments while it will be lower in open marine conditions. Limestones and their constituent parts are susceptible to diagenetic processes that can contaminate or obliterate isotope values contained within the rocks. The purpose of this research was to discover if reliable isotope information could be pulled from Pennsylvanian aged shark teeth. Nine …

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Geostatistical Characterization Of Heterogeneity In The Aberjona River Aquifer, Woburn, Massachusetts, James Ralph Damico Jan 2006

Geostatistical Characterization Of Heterogeneity In The Aberjona River Aquifer, Woburn, Massachusetts, James Ralph Damico

Browse all Theses and Dissertations

Ground water flow and contaminant transport patterns are largely controlled by the distribution of high- and low-permeability sediments. Therefore, an accurate description of the aquifer architecture is paramount to producing a representative ground water model. Models of contaminant fate and transport in the aquifer near Woburn, Massachusetts, have previously been created by others using a deterministic approach. As a complement to these prior studies, the proportions, geometry, and juxtaposition of the different lithofacies of the aquifer were statistically characterized for developing stochastic models for the aquifer system. The descriptions of lithology from boreholes were separated into eleven categories based primarily …

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Diatom Paleolimnological Record Of Holocene Climatic And Environmental Change In The Altai Mountains, Siberia, Karlyn S. Westover, Sherilyn C. Fritz, Tatyana A. Blyakharchuk, Herbert E. Wright Jan 2006

Diatom Paleolimnological Record Of Holocene Climatic And Environmental Change In The Altai Mountains, Siberia, Karlyn S. Westover, Sherilyn C. Fritz, Tatyana A. Blyakharchuk, Herbert E. Wright

Department of Earth and Atmospheric Sciences: Faculty Publications

The sedimentary diatom records of three shallow lakes in the Altai Mountains, southern Siberia, were examined to assess the nature and timing of Holocene environmental changes. Few paleoenvironmental records, especially reconstructions not based on pollen, have been reported from this region. The lakes differ in elevation, annual precipitation, and catchment vegetation. Diatom assemblages in all lakes were dominated for the entire period of record by small benthic species of Pseudostaurosira Williams & Round, Staurosira Ehrenberg, and Staurosirella Williams & Round. Planktonic taxa only occur in very low abundances (<5%). The most diverse diatom flora was found in Dzhangyskol, which is situated at the lowest elevation within a forested catchment. A lack of detailed information on the ecological preferences of the dominant taxa and the complexity of environmental drivers make direct interpretation of the diatom record difficult. However, other proxies suggest that dramatic shifts in dominance between Staurosira elliptica and Staurosirella pinnata in Grusha Ozero reflect millennial-scale variability …

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A Miocene Palaeovalley Network In The Western Taurus (Turkey), Olivier Monod, Catherina Kuzucuoğlu, Aral İ. Okay Jan 2006

A Miocene Palaeovalley Network In The Western Taurus (Turkey), Olivier Monod, Catherina Kuzucuoğlu, Aral İ. Okay

Turkish Journal of Earth Sciences

Lower Miocene conglomerates in the Köprü and Manavgat basins contain pebbles that can be confidently traced back to their source areas, owing to their distinctive lithologies. Among others, are the green Huğlu volcanics (Late Trias), known only in allochthonous units from the Beyşehir region, or the Alanya blueschists, restricted to the Sugözü unit in the Alanya Massif. The problem is to find out how this detrital material could have travelled about eighty kilometres through the Taurus calcareous units during the Miocene. Fortunately, the present drainage system is not yet fully reorganised in the Taurus, and large areas of the chain …

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Caves And Speleogenesis At Blomstrandsøya, Kongsfjord, W. Spitsbergen, Stein-Erik Lauritzen Jan 2006

Caves And Speleogenesis At Blomstrandsøya, Kongsfjord, W. Spitsbergen, Stein-Erik Lauritzen

International Journal of Speleology

Blomstrandsøya, at Kongsfjord (78° 57’N), Spitsbergen, is within the high arctic, a completely permafrozen zone. The bedrock consists of Paleozoic marbles and has yielded a surprising amount of karst features. Early phases of hydrothermal, possibly Caledonian, speleogenesis and subsequent Devonian karstification with redbed deposits is well documented. 62 active seacaves, and more than 30 relict karst caves were found in the coastal cliffs and in escarpment faces around the island. All caves have very limited extent; they are either quite short, like most of the active sea caves, or they are soon choked by frozen sediments and ground ice after …

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The Distribution Of Diatom Flora In Ice Caves Of The Northern Yukon Territory, Canada: Relationship To Air Circulation And Freezing, Bernard Lauriol, Clément Prévost, Denis Lacelle Jan 2006

The Distribution Of Diatom Flora In Ice Caves Of The Northern Yukon Territory, Canada: Relationship To Air Circulation And Freezing, Bernard Lauriol, Clément Prévost, Denis Lacelle

International Journal of Speleology

In the late 1980’s and early 1990’s, various media in karst environments in the Northern Yukon Territory were examined for their diatom content. Cryogenic cave calcite powders, grus and various ice formations (ice plugs, ice stalagmites and floor ice) were collected from three freezing caves and one slope cave to make an inventory of the diatom content, and to explain the spatial distribution of the diatoms within the caves. The results show that approximately 20% of diatoms in the caves originate from external biotopes and habitats (e.g., river, lake, stream), with the remaining 80% of local origin (i.e., from subaerial …

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Spatial Distributions Of Perchloroethylene Reactive Transport Parameters In The Borden Aquifer, Richelle M. Allen-King, Dana Divine, Michel J. L. Robin, J. Richard Alldredge, David R. Gaylord Jan 2006

Spatial Distributions Of Perchloroethylene Reactive Transport Parameters In The Borden Aquifer, Richelle M. Allen-King, Dana Divine, Michel J. L. Robin, J. Richard Alldredge, David R. Gaylord

Conservation and Survey Division: Faculty and Staff Publications

We determined the descriptive statistical and spatial geostatistical properties of the perchloroethene ln Kd and the ln k of a 1.5 m thick by 10 m horizontal transect of the Borden aquifer near the location of the Stanford-Waterloo (SW) tracer experiment. The ln Kd distribution is not normal and is right skewed because of a few high values that occur localized in two regions of the transect. In contrast, the ln k data can be characterized by a normal distribution. A linear regression of ln Kd on ln k yields a statistically significant positive correlation, also shown …

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Alpersite (Mg,Cu)So4•7h2O, A New Mineral Of The Melanterite Group, And Cuprian Pentahydrite: Their Occurrence Within Mine Waste, Ronald C. Peterson, Jane M. Hammarstrom, Robert R. Seal Ii Jan 2006

Alpersite (Mg,Cu)So4•7h2O, A New Mineral Of The Melanterite Group, And Cuprian Pentahydrite: Their Occurrence Within Mine Waste, Ronald C. Peterson, Jane M. Hammarstrom, Robert R. Seal Ii

United States Geological Survey: Staff Publications

Alpersite, Mg0.58 Cu0.37 Zn0.02 Mn0.02 Fe0.01SO4 •7H2 O, a new mineral species with direct relevance to reactions in mine waste, occurs in a mineralogically zoned assemblage in sheltered areas at the abandoned Big Mike mine in central Nevada at a relative humidity of 65% and T = 4 °C. Blue alpersite, which is isostructural with melanterite (FeSO4 •7H2 O), is overlain by a light blue to white layer dominated by pickeringite, alunogen, and epsomite. X-ray diffraction data (MoKα radiation) from a single crystal of alpersite were refined in P21 …

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A Method For Mapping Corn Using The Us Geological Survey 1992 National Land Cover Dataset, S. K. Maxwell, J. R. Nuckols, M. H. Ward Jan 2006

A Method For Mapping Corn Using The Us Geological Survey 1992 National Land Cover Dataset, S. K. Maxwell, J. R. Nuckols, M. H. Ward

United States Geological Survey: Staff Publications

Long-term exposure to elevated nitrate levels in community drinking water supplies has been associated with an elevated risk of several cancers including non-Hodgkin’s lymphoma, colon cancer, and bladder cancer. To estimate human exposure to nitrate, specific crop type information is needed as fertilizer application rates vary widely by crop type. Corn requires the highest application of nitrogen fertilizer of crops grown in the Midwest US.We developed a method to refine the US Geological Survey National Land Cover Dataset (NLCD) (including map and original Landsat images) to distinguish corn from other crops. Overall average agreement between the resulting corn and other …

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Renewing The Conservation Commitment, Frank W. Davis, Dale D. Goble, J. Michael Scott Jan 2006

Renewing The Conservation Commitment, Frank W. Davis, Dale D. Goble, J. Michael Scott

United States Geological Survey: Staff Publications

As we write this in early 2005 there are several ESA-related pieces of legislation pending before Congress. Most of the proposed legislation is championed by Republican leaders from western states, who promise to strengthen the use of science or ensure fairer treatment of private landowners. Ir has become a perennial drama on the American political stage: "conservatives" rally to rein in a law that they believe has reached too far and "conservationists" mobilize ro defend the law that they believe offers the best ho pe for protecting biodiversity from relentless economic exploitation. There is much posturing, finger pointing, and, ultimately, …

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Breeding Biology And Success Of A Reintroduced Population Of The Critically Endangered Puaiohi (Myadestes Palmeri), Erik J. Tweed, Jeffrey T. Foster, Bethany L. Woodworth, William B. Monahan, Jherime L. Kellerman, Alan Lieberman Jan 2006

Breeding Biology And Success Of A Reintroduced Population Of The Critically Endangered Puaiohi (Myadestes Palmeri), Erik J. Tweed, Jeffrey T. Foster, Bethany L. Woodworth, William B. Monahan, Jherime L. Kellerman, Alan Lieberman

United States Geological Survey: Staff Publications

The ultimate success of reintroduction programs for endangered species depends on the ability of reintroduced animals to breed in the wild. We studied the nesting success and breeding biology of a reintroduced population of Puaiohi (Myadestes palmeri) on the island of Kaua‛i, Hawaii. Thirty-four captive-bred Puaiohi were released into the Alaka‛i Swamp in 1999–2001 and monitored using radiotelemetry. Ten females and two males paired with wild and other released birds, including one polygynous trio. From March to September, 31 nests were built. Mean clutch size was 2.0 eggs, daily nest survival was 0.97 ± 0.01 (mean ± SE) …

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Patterns Of Total Suspended Solids Concentration And The Influence Of Antecedent Conditions On Hydrograph Response To Precipitation Events On Beaver Creek, Ontario, Matthew Peter Roy Mittler Jan 2006

Patterns Of Total Suspended Solids Concentration And The Influence Of Antecedent Conditions On Hydrograph Response To Precipitation Events On Beaver Creek, Ontario, Matthew Peter Roy Mittler

Theses and Dissertations (Comprehensive)

This study explored relationships between suspended solids concentration and discharge, the influence of antecedent conditions on event hydrograhs and the state of dynamic equilibrium in a second-order stream (Beaver Creek), draining an agricultural basin in southern Ontario, near the City of Waterloo. Beaver creek was monitored for nineteen weeks from July to November of 2005. Thirteen precipitation events of various magnitude and duration were examined within the study period. Discharge and total suspended soils were sampled throughout the events. Cross sectional profiles of six transects were measured prior to and after each event. Base flow, antecedent conditions and event response …

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Ce-Qual-W2: A Two-Dimensional, Laterally Averaged, Hydrodynamic And Water Quality Model, Version 3.5, Thomas M. Cole, Scott A. Wells Jan 2006

Ce-Qual-W2: A Two-Dimensional, Laterally Averaged, Hydrodynamic And Water Quality Model, Version 3.5, Thomas M. Cole, Scott A. Wells

Civil and Environmental Engineering Faculty Publications and Presentations

This manual documents the two-dimensional, laterally averaged, hydrodynamic and water quality model CE-QUAL-W2. This manual was prepared in the Environmental Laboratory (EL), us Army Engineer Waterways Experiment Station (WES), Vicksburg, MS. Bonita Niel and Dr. William Roper, CERD-C provided funding for Version 3.1 of the manual under the Numerical Model Maintenance Program. The principal investigator for Version 3.2 of CE-QUAL-W2 and the User Manual was Mr. Thomas M. Cole of the Water Quality and Contaminant Modeling Branch (WQCMB), Environmental Processes and Effects Division (EPED), EL. This report supersedes the Version 3.2 manual. Revisions made in this V3.5 manual were made …

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Study Of Metals In Leached Soils Of A Municipal Dumpsite In Tampico, Tamaulipas, Mexico: Preliminary Results, P. F. Rodríguez-Espinosa, D. Chazaro Mendoza, J. A. Montes De Oca, G. Sánchez Torres E., Alejandro Fierro-Cabo Jan 2006

Study Of Metals In Leached Soils Of A Municipal Dumpsite In Tampico, Tamaulipas, Mexico: Preliminary Results, P. F. Rodríguez-Espinosa, D. Chazaro Mendoza, J. A. Montes De Oca, G. Sánchez Torres E., Alejandro Fierro-Cabo

School of Earth, Environmental, & Marine Sciences Faculty Publications

The Zapote dumpsite measures 420000 m 2 and is 28 years old; an estimated 2.5 millions tons of waste have accumulated on the site (household waste, clinical waste, commercial waste). The thickness of the waste is 3 to 9 meters. Since operations began, no control regulations have existed on the residues received. The Zapote dumpsite is located within a salt-marsh between a system of channels and river lagoons of brackish water, located in a tropical sedimentary environment in the urban zone of Tampico, Tamaulipas, Mexico. Recently, the Zapote has been closed and work is presently underway in its rehabilitation since …

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Brittle Compressive Failure Of Ice: Proportional Straining Vs Proportional Loading, E. M. Schulson, D. Iliescu Jan 2006

Brittle Compressive Failure Of Ice: Proportional Straining Vs Proportional Loading, E. M. Schulson, D. Iliescu

Dartmouth Scholarship

Proportional straining experiments have been performed on columnar-grained S2 fresh- water ice biaxially compressed across the columns at –108C at a strain rate of (4.5 􏰀 1.5) 􏰁 10–3 s–1. The results are compared with those obtained earlier (Iliescu and Schulson, 2004) from the same kind of material deformed to terminal failure under the same conditions, but through proportional loading. The exercise shows that the biaxial strength is practically independent of the path taken, at least under low confinement where Coulombic shear faulting limits terminal failure. First-year sea ice is expected to exhibit the same behavior.

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Exploration Of Ground Penetrating Radar And Time Domain Reflectometry Methods For The Determination Of Pavement Dielectric Constant, Baron W. Colbert Jan 2006

Exploration Of Ground Penetrating Radar And Time Domain Reflectometry Methods For The Determination Of Pavement Dielectric Constant, Baron W. Colbert

Dissertations, Master's Theses and Master's Reports - Open

Traditionally, densities of newly built roadways are checked by direct sampling (cores) or by nuclear density gauge measurements. For roadway engineers, density of asphalt pavement surfaces is essential to determine pavement quality. Unfortunately, field measurements of density by direct sampling or by nuclear measurement are slow processes. Therefore, I have explored the use of rapidly-deployed ground penetrating radar (GPR) as an alternative means of determining pavement quality. The dielectric constant of pavement surface may be a substructure parameter that correlates with pavement density, and can be used as a proxy when density of asphalt is not known from nuclear or …

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Carbon Dioxide Sequestration In Cement Kiln Dust Through Miner Carbonation, Deborah N. Huntzinger Jan 2006

Carbon Dioxide Sequestration In Cement Kiln Dust Through Miner Carbonation, Deborah N. Huntzinger

Dissertations, Master's Theses and Master's Reports - Open

The feasibility of carbon sequestration in cement kiln dust (CKD) was investigated in a series of batch and column experiments conducted under ambient temperature and pressure conditions. The significance of this work is the demonstration that alkaline wastes, such as CKD, are highly reactive with carbon dioxide (CO2). In the presence of water, CKD can sequester greater than 80% of its theoretical capacity for carbon without any amendments or modifications to the waste. Other mineral carbonation technologies for carbon sequestration rely on the use of mined mineral feedstocks as the source of oxides. The mining, pre-processing and reaction …

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Analyzing The Effects Of Vertical Acceleration And Deceleration In Multi-Phase, Debris-Flow Sediment-Column Experiments / By Christine Marie Williams., Christine Marie Williams Jan 2006

Analyzing The Effects Of Vertical Acceleration And Deceleration In Multi-Phase, Debris-Flow Sediment-Column Experiments / By Christine Marie Williams., Christine Marie Williams

Dissertations, Master's Theses and Master's Reports - Open

Water-saturated debris flows are among some of the most destructive mass movements. Their complex nature presents a challenge for quantitative description and modeling. In order to improve understanding of the dynamics of these flows, it is important to seek a simplified dynamic system underlying their behavior. Models currently in use to describe the motion of debris flows employ depth-averaged equations of motion, typically assuming negligible effects from vertical acceleration. However, in many cases debris flows experience significant vertical acceleration as they move across irregular surfaces, and it has been proposed that friction associated with vertical forces and liquefaction merit inclusion …

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Dry Creek Long Term Watershed Study: Buffer Zone Performance As Viable Amphibian Habitat, Brooke L. Talley, Thomas Crisman Jan 2006

Dry Creek Long Term Watershed Study: Buffer Zone Performance As Viable Amphibian Habitat, Brooke L. Talley, Thomas Crisman

School of Geosciences Faculty and Staff Publications

As bioindicators, amphibians typically require both terrestrial and aquatic habitats to complete their life cycles. Pre- timber-harvest monitoring (December 2002 through September 2003) of salamander and frog (Hylidae) populations was conducted in four watersheds of Decatur County, GA. Post- timber-harvest monitoring (December 2003 through September 2004) continued in the same watersheds (two reference and two treatment watersheds). Coverboards were used to monitor adult salamanders, larval salamanders were surveyed with dipnet sweeps, and frogs were monitored with vertical PVC pipes. Six salamander species (Desmognathus apalachicolae, Eurycea cirrigera, E. guttolineata, Notophthalmus viridescens, Plethodon grobmani, and Pseudotriton ruber) and five frog species (Hyla …

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Dry Creek Long Term Watershed Study: Assessment Of Immediate Response Of Aquatic Macroinvertebrates To Watershed Level Harvesting And Thinning Of Streamside Management Zones, M. W. Griswold, R. T. Winn, Thomas Crisman, W. R. White Jan 2006

Dry Creek Long Term Watershed Study: Assessment Of Immediate Response Of Aquatic Macroinvertebrates To Watershed Level Harvesting And Thinning Of Streamside Management Zones, M. W. Griswold, R. T. Winn, Thomas Crisman, W. R. White

School of Geosciences Faculty and Staff Publications

Streamside Management Zones (SMZs) are meant to protect riparian habitat and the stream ecosystem. Benthic macroinvertebrates are recognized bioindicators of water quality in streams, typically occupying multiple trophic levels in these systems and providing food for vertebrates. Thus, it is important to understand the effects of harvest within and adjacent to the SMZ on macroinvertebrate assemblages. Benthic macroinvertebrates were sampled pre- and post-harvest from four firstorder streams draining the Dry Creek watershed in southwestern Georgia. A multi-habitat sampling procedure was used. Macroinvertebrates were identified and compared using biotic indices. Comparisons were made between streams within the pre-harvest period and between …

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Service-Learning In Watershed-Based Initiatives: Keys To Education For Sustainability In Geography?, James Eflin, Amy L. Sheaffer Jan 2006

Service-Learning In Watershed-Based Initiatives: Keys To Education For Sustainability In Geography?, James Eflin, Amy L. Sheaffer

Service Learning, General

A call for combining the strengths of geographic education with environmental education to produce an 'education for sustainability' addresses local problems for sustainable development. A place-based approach encourages civic responsibility among students. Using service-learning to extend education beyond the classroom in this case study connected students with local clients in a watershed-based initiative. Theoretical underpinnings of service-learning for geographic education are discussed, and the case study is viewed from instructor, student, and client perspectives to identify successful outcomes and provide suggestions for those who might adopt service-learning for the first time.

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Thermal Variations In The Hyporheic Zone Of A Karst Stream, Toby Dogwiler, Carol Wicks Jan 2006

Thermal Variations In The Hyporheic Zone Of A Karst Stream, Toby Dogwiler, Carol Wicks

International Journal of Speleology

This investigation quantifies how temperatures in the streambed sediments of a karst stream fluctuate in relation to discharge, seasonal, and diurnal temperature variations as the stream passes through a karst window. Furthermore, the linkages between meteorological processes and temperature variation in the hyporheic zone are delineated. Examination of a high-resolution, three dimensional record of temperature variation in a karst stream substrate provides insight into thermal disturbances in the hyporheic zone. Temperatures in the upper portion of the hyporheic zone are strongly linked to air temperatures via the surface water. The variation is considerably less as depth increases. The annual temperature …

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Evaluating The Biogeochemical Cycle Of Selenium In San Francisco Bay Through Modeling, Shannon L. Meseck, Gregory A. Cutter Jan 2006

Evaluating The Biogeochemical Cycle Of Selenium In San Francisco Bay Through Modeling, Shannon L. Meseck, Gregory A. Cutter

OES Faculty Publications

A biogeochemical model was developed to simulate salinity, total suspended material, phytoplankton biomass, dissolved selenium concentrations (selenite, selenate, and organic selenide), and particulate selenium concentrations (selenite + selenate, elemental selenium, and organic selenide) in the San Francisco Bay estuary. Model-generated estuarine profiles of total dissolved selenium reproduced observed estuarine profiles at a confidence interval of 91- 99% for 8 different years under various environmental conditions. The model accurately reproduced the observed dissolved speciation at confidence intervals of 81-98% for selenite, 72-91% for selenate, and 60-96% for organic selenide. For particulate selenium, model-simulated estuarine profiles duplicated the observed behavior of total …

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Iron In Ice Cores From Law Dome: A Record Of Atmospheric Iron Deposition For Maritime East Antarctica During The Holocene And Last Glacial Maximum, Ross Edwards, Peter N. Sedwick, Vin Morgan, Claude Boutron Jan 2006

Iron In Ice Cores From Law Dome: A Record Of Atmospheric Iron Deposition For Maritime East Antarctica During The Holocene And Last Glacial Maximum, Ross Edwards, Peter N. Sedwick, Vin Morgan, Claude Boutron

OES Faculty Publications

Total dissolvable iron (TDFe) was measured in sections of ice cores recovered from Law Dome on the coast of Wilkes Land, East Antarctica. These samples include ice dating from the Last Glacial Maximum (LGM), the Last Deglaciation, and the early and mid Holocene as well as samples from the Anthropocene that have been dated with seasonal to annual resolution. Combining our TDFe concentration data with estimates of the ice accumulation rate, we estimate the atmospheric iron deposition for Law Dome and the adjacent Southern Ocean during these periods. Our results indicate that the atmospheric iron deposition flux to this region …

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Past Glacial And Interglacial Conditions In The Arctic Ocean And Marginal Seas - A Review, Dennis A. Darby, Leonid Polyak, Henning A. Bauch Jan 2006

Past Glacial And Interglacial Conditions In The Arctic Ocean And Marginal Seas - A Review, Dennis A. Darby, Leonid Polyak, Henning A. Bauch

OES Faculty Publications

Past changes in the Arctic Ocean and its marginal seas have been profound, even during the last 10,000 years. Understanding these changes, such as those occurring during the transition from glacial to interglacial climates, are important for research on modern processes, because this knowledge provides a framework and unique perspective in which to view the modern physical and biological processes. This paper discusses our current understanding of past environmental change and processes relative to those currently in progress. Special emphasis is placed on the most recent transition from a glacial state to the modern interglacial conditions.

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Nitrogen Fixation And Release Of Fixed Nitrogen By Trichodesmium Spp. In The Gulf Of Mexico, Margaret R. Mulholland, Peter W. Bernhardt, Cynthia A. Heil, Deborah A. Bronk, Judith M. O'Neil Jan 2006

Nitrogen Fixation And Release Of Fixed Nitrogen By Trichodesmium Spp. In The Gulf Of Mexico, Margaret R. Mulholland, Peter W. Bernhardt, Cynthia A. Heil, Deborah A. Bronk, Judith M. O'Neil

OES Faculty Publications

During a 3-yr study in the Gulf of Mexico, we measured dinitrogen (N2) fixation and nitrogen (N) release by Trichodesmium and compared these rates with water column N demand and the estimated N necessary to support blooms of Karenia brevis, a toxic dinoflagellate that severely affects the West Florida shelf. Net and gross N2 fixation rates were compared in simultaneous incubations using 15N2 uptake and acetylene reduction, respectively. The difference between net and gross N2 fixation is assumed to be an approximation of the rate of N release. Results demonstrate that Trichodesmium in …

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Western Caribbean Sea Surface Temperatures During The Late Quaternary, Matthew W. Schmidt, Maryline J. Vautravers, Howard J. Spero Jan 2006

Western Caribbean Sea Surface Temperatures During The Late Quaternary, Matthew W. Schmidt, Maryline J. Vautravers, Howard J. Spero

OES Faculty Publications

[1] Mg/Ca ratios in the planktonic foraminifera Globigerinoides ruber from Colombian Basin core ODP 999A suggest that Caribbean sea surface temperatures ( SSTs) were from 2.1 to 2.7°C colder than the present during the last three glacial maximums. In comparison, faunal derived SSTs ( SIMMAX method) show that August SSTs in the Caribbean varied < 2° over the past 360 kyr, whereas February SSTs varied between 21.0°C and 26.5°C. Changes in the Mg/Ca-SST record contain a strong 23 kyr periodicity, suggesting the Mg/Ca-SST record reflects a warm season weighted SST average rather than an annual mean SST. Combining several dissolution indices, we identify brief periods of decreased carbonate preservation in our record and show that MIS 11 stands out as the most intensive dissolution cycle in the Caribbean over the last 460 kyr. Comparison of Caribbean SST change with a similar estimate of tropical SST variability in the western Pacific over the past 360 kyr reveals shifts in the east-west tropical SST gradient that are coeval with glacial-interglacial climate change and consistent both with a southward migration of the glacial ITCZ and with a glacial El Niño-like mode of tropical circulation.

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