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2013

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Articles 781 - 810 of 965

Full-Text Articles in Earth Sciences

Geomorphology Of Deposits From The 2004 Indian Ocean Tsunami, Tamil Nadu, Southeastern India, Patrick Alan Johnston Jan 2013

Geomorphology Of Deposits From The 2004 Indian Ocean Tsunami, Tamil Nadu, Southeastern India, Patrick Alan Johnston

All Master's Theses

In low latitudes, geologically suitable repositories for tsunami deposits are not well defined. This project characterizes the geomorphic environments on the southeastern coast of India that preserved depositional evidence of the catastrophic tsunami created by the Mw9.0-9.3 Sumatra-Andaman earthquake on December 26, 2004. The Indian coast is particularly interesting because it is approximately 1300 km from the subduction-zone source of tsunamis across the Indian Ocean, and therefore only the largest events are capable of reaching it. The main objective of this study was to identify the settings where recognizable tsunami deposits from the 2004 event have been preferentially …


Black Carbon Measurements Of Snow And Ice Using The Single Particle Soot Photometer: Method Development And An Ad 1852-1999 Record Of Atmospheric Black Carbon From A Mount Logan Ice Core, James Andrew Menking Jan 2013

Black Carbon Measurements Of Snow And Ice Using The Single Particle Soot Photometer: Method Development And An Ad 1852-1999 Record Of Atmospheric Black Carbon From A Mount Logan Ice Core, James Andrew Menking

All Master's Theses

Black carbon (BC), produced by the combustion of fossil and biofuels, warms the climate by absorbing solar radiation when in the atmosphere and by reducing the albedo of snow and ice when deposited. Measuring BC in snow and ice is important for estimating albedo reduction and developing historical records of BC concentration. Experiments were conducted to further develop a method for measuring BC in snow and ice using the Single Particle Soot Photometer (SP2). Results suggest the optimal procedures for sample storage, treatment, and nebulization, and analysis and calibration of BC concentrations measured using the SP2 coupled to a CETAC …


Paleoseismologic Evidence For Holocene Activity On The Pinto Mountain Fault, Twentynine Palms, California, Ana Maria Cadena Jan 2013

Paleoseismologic Evidence For Holocene Activity On The Pinto Mountain Fault, Twentynine Palms, California, Ana Maria Cadena

All Master's Theses

Excavations across the Pinto Mountain fault in Twentynine Palms, California exposed faulted strata across a 32-m wide zone. Trench wall exposures revealed clear evidence for five ground-rupturing events during the Holocene, and two additional events in the late Pleistocene. Optically stimulated luminescence ages from alluvial sediments suggest that the most recent event occurred between 1.7-2.9 ka B.P. and the penultimate event between 2.7-4.2 ka B.P.. Prior to the penultimate event, there were five ground-rupturing earthquakes on the eastern Pinto Mountain fault between 3.5-13.6 ka B.P.. The average recurrence interval since 13.3-13.6 ka B.P. is 1510-1680 years, and 1200-1500 years in …


The Roles Of Humans And Climatic Variation On The Fire History Of Subalpine Meadows - Mount Rainer National Park (Washington), Michael Louis Lukens Jan 2013

The Roles Of Humans And Climatic Variation On The Fire History Of Subalpine Meadows - Mount Rainer National Park (Washington), Michael Louis Lukens

All Master's Theses

With the creation of Mount Rainier National Park (MORA) in 1899 came the active management of the park's landscapes and a heavy emphasis on fire suppression. Today managers at MORA have made returning fire to the park's landscapes a top priority. In order to achieve this goal, and to make more informed decisions in regard to the application of fire, land managers at MORA need to better understand past fire occurrences and the drivers of fire activity on the mountain. To address this problem, analysis of macroscopic charcoal preserved in lake sediments was used to reconstruct the fire history for …


Characterization Of Mass Wasting Through The Spectral Analysis Of Lidar Imagery: Owyhee River, Southeastern Oregon, Christopher Earl Markley Jan 2013

Characterization Of Mass Wasting Through The Spectral Analysis Of Lidar Imagery: Owyhee River, Southeastern Oregon, Christopher Earl Markley

All Master's Theses

Quantifying landslide character is an important aspect of understanding hillslope-channel interactions. Spectral analysis of high-resolution, LiDAR derived, DEMs was carried out following methods described by Booth et al. (2009) to determine the characteristic spectral signature inherent in different styles of landslides in the Owyhee River Canyon in southeastern Oregon. The main factor in landslide generation in this location is a lithologic contact in which a coherent basaltic caprock overlies relatively weak sediments where most of the landslide failure surfaces originated. Changes in spectral power distribution through time were quantified by comparing a sequence of adjacent rotational landslides of apparent different …


Afc-Modeler: A Microsoft® Excel© Workbook Program For Modelling Assimilation Combined With Fractional Crystallization (Afc) Process In Magmatic Systems By Using Equations Of Depaolo (1981), Mehmet Keski̇n Jan 2013

Afc-Modeler: A Microsoft® Excel© Workbook Program For Modelling Assimilation Combined With Fractional Crystallization (Afc) Process In Magmatic Systems By Using Equations Of Depaolo (1981), Mehmet Keski̇n

Turkish Journal of Earth Sciences

AFC-Modeler is a user-friendly, interactive Microsoft Excel workbook program which is specifically designed to model up to ten theoretical AFC curves (corresponding to ten different r values; r being the ratio of mass assimilation rate to fractional crystallization rate) for a set of variables that can be interactively and precisely modified by the user (i.e. D, initial element concentration and isotope ratio in magma and element concentration and isotope ratio in wallrock). Being able to model ten curves for ten different 'r' values is an important feature of the program, because results of many studies indicate that the r values …


The Upper Cretaceous Calciclastic Submarine Fan Deposits In The Eastern Pontides, Ne Turkey: Facies Architecture And Controlling Factors, Di̇lek Sofracioğlu, Rai̇f Kandemi̇r Jan 2013

The Upper Cretaceous Calciclastic Submarine Fan Deposits In The Eastern Pontides, Ne Turkey: Facies Architecture And Controlling Factors, Di̇lek Sofracioğlu, Rai̇f Kandemi̇r

Turkish Journal of Earth Sciences

The Tonya Formation, which represents the uppermost part of the Mesozoic sequence in the Eastern Pontides, consists of calciturbidites in Trabzon and its surrounding region. Two stratigraphic sections of the unit were measured in the Hacımehmet and Gürbulak areas to decipher the distribution of rock types, facies architecture, sediment textures and depositional environment. The grain size, channels, suprafan lobes and slump structures of the sediments suggest that calciclastic sequences were deposited in a submarine fan system. Calcarenites/calcirudites and hemipelagic rocks, comprising an alternation of marls and mudstones, are the two dominant lithologies described in the studied calciclastic submarine fan system. …


Carbon Farming In Wa, Department Of Agriculture And Food, Western Australia, Department Of Regional Development And Lands, Western Australia Jan 2013

Carbon Farming In Wa, Department Of Agriculture And Food, Western Australia, Department Of Regional Development And Lands, Western Australia

Natural resources published reports

Fact sheets:

1. Applying biochar to improve soil quality and crop productivity

2. Reducing methane emissions from cattle using feed additives

3. Cattle breeding for lower greenhouse gas emissions

4. Managing genetic codes to reduce methane emissions from cattle

5. Managing pastures and stocking rate to reduce methane emissions from cattle

6. Claying as a method of increasing soil carbon content

7. Green and brown manuring as part of carbon farming

8. Permanent environmental plantings to earn carbon credits

9. Nitrous oxide emissions from agricultural soils

10. Sheep genetics in methane reduction

11. Managing sheep pastures to reduce methane production …


Phosphorus Cycling In The Sargasso Sea: Investigation Using The Oxygen Isotopic Composition Of Phosphate, Enzyme-Labeled Fluorescence, And Turnover Times, Karen Mclaughlin, Jill A. Sohm, Gregory A. Cutter, Michael W. Lomas, Adina Paytan Jan 2013

Phosphorus Cycling In The Sargasso Sea: Investigation Using The Oxygen Isotopic Composition Of Phosphate, Enzyme-Labeled Fluorescence, And Turnover Times, Karen Mclaughlin, Jill A. Sohm, Gregory A. Cutter, Michael W. Lomas, Adina Paytan

OES Faculty Publications

Dissolved inorganic phosphorus (DIP) concentrations in surface water of vast areas of the ocean are extremely low (<10 nM) and phosphorus (P) availability could limit primary productivity in these regions. We explore the use of oxygen isotopic signature of dissolved phosphate (δ18OPO4) to investigate biogeochemical cycling of P in the Sargasso Sea, Atlantic Ocean. Additional techniques for studying P dynamics including 33P-based DIP turnover time estimates and percent of cells expressing alkaline phosphatase (AP) activity as measured by enzyme-labeling fluorescence are also used. In surface waters, δ18OPO4 values were lower than equilibrium by 3–6%, indicative of dissolved organic phosphorous (DOP) remineralization by extracellular enzymes. An isotope mass balance model using a variety of possible combinations of …


Evaluating Quaternary Glacial Till Sheet Volume And Duration Of Grounding Events Using Sediment Flux Calculations In The Eastern Basin Paleotroughs, Ross Sea, Anarctica, Logan Gregory Kirst Jan 2013

Evaluating Quaternary Glacial Till Sheet Volume And Duration Of Grounding Events Using Sediment Flux Calculations In The Eastern Basin Paleotroughs, Ross Sea, Anarctica, Logan Gregory Kirst

LSU Master's Theses

A sequence of three seismically-resolvable, back-stepping grounding zone wedges (GZWs) within the Glomar-Challenger Basin paleo-ice-stream trough is conventionally interpreted to have been deposited by the West Antarctic Ice Sheet (WAIS) since the end of the Last Glacial Maximum (LGM). For this to be true, there would have to have been voluminous GZW deposition via fast moving ice streams with high sediment flux during the short timeframe since the WAIS retreat began at 11 Ka 14C BP and when the WAIS moved south of Roosevelt Island at 3.2 Ka BP. In contrast to this interpretation of how the near-surface stratigraphy relates …


The Reduction And Reoxidation Of Ceria : A Natural Abundance Oxygen Isotope Approach, Justin Alan Hayles Jan 2013

The Reduction And Reoxidation Of Ceria : A Natural Abundance Oxygen Isotope Approach, Justin Alan Hayles

LSU Master's Theses

Ceria (CeO2) is a fluorite type oxide that has been used extensively as an oxygen storage media in three-way catalysts, as an oxygen partial pressure regulator, as a fuel additive for the reduction of soot and for the production of syn-gas from water and carbon dioxide. It is known that exposing ceria powders to low pO2 and/or high temperature conditions will cause ceria to partially reduce. This partial reduction leads to the formation of oxygen vacancies, which up to a limit, do not significantly influence the crystal structure. When partially reduced ceria is exposed to high pO2 environments, such as …


Metamorphic And Geochemical Signatures Of Calc-Silicate Gneisses From The Sawtooth Metamorphic Complex, Idaho, Usa : Implications For Crustal Evolution In Western North America, Isis Fukai Jan 2013

Metamorphic And Geochemical Signatures Of Calc-Silicate Gneisses From The Sawtooth Metamorphic Complex, Idaho, Usa : Implications For Crustal Evolution In Western North America, Isis Fukai

LSU Master's Theses

The Sawtooth Metamorphic Complex (SMC) of central Idaho contains exposures of metasupracrustal rocks that may provide constraints on Precambrian crustal evolution in northwestern United States. Petrographic textures, whole-rock geochemistry, and thermobarmetry of SMC calc-silicate gneisses, collected at high-resolution, record multiple stages of crustal development, including: contiguous deposition of a sandstone-to-shale sequence derived from post-Archean continental sediments, metamorphism during two medium-high-grade thermal events (M1, M2), and two distinct episodes of deformation (D1, D2). Whole-rock concentrations of Cr (23.97-76.43 ± 3.0 ppm), Ni (6.82-33.10 ± 3.5 ppm), Th (2.11-12.04 ± 1.6 ppm), Sc (3.81-11.53 ± 1.6 ppm), and Zr (322-658 ± 3.9 …


Natural Fracture Characterization In The Haynesville Shale, East Texas: A Core Study, Frank Leslie Morgan Jan 2013

Natural Fracture Characterization In The Haynesville Shale, East Texas: A Core Study, Frank Leslie Morgan

LSU Master's Theses

The Haynesville Shale in East Texas and Northwest Louisiana is one of the most studied and explored shale-gas plays in the United States. With new horizontal drilling and completion strategies, energy companies can produce hydrocarbons directly from the source rock making the Haynesville Shale an attractive resource. A key component of enhanced hydrocarbon production is the presence of natural fractures. They may serve as permeable pathways for hydrocarbon flow, especially in tight shales such as in the Haynesville Shale, where the matrix permeability is very low. In the case of the Haynesville Shale, little is known about the occurrence of …


Controls On The Composition Of Saline Formation Waters From Coastal And Offshore Louisiana, Marielle Elaine Ausburn Jan 2013

Controls On The Composition Of Saline Formation Waters From Coastal And Offshore Louisiana, Marielle Elaine Ausburn

LSU Master's Theses

Geothermal energy is a renewable energy source that can contribute to the U.S. energy mix. As such, new technologies are being explored for lower temperature systems which would open new areas for exploration in Louisiana. Unlike concepts proposed in the early 1980s, in which heat would have been extracted at the land surface from produced overpressured waters, methods currently being proposed would involve engineered down-hole heat exchangers with zero-mass-fluid withdrawal. A re-examination has been made of the controls on the composition of formation waters in south central and offshore Louisiana in the context of providing insight into water-rock reactions that …


High Resolution Tephra And U/Pb Chronology Of The 3.33 – 3.26 Ga Mendon Formation, Barberton, Greenstone Belt, South Africa, Nicholas Burns Decker Jan 2013

High Resolution Tephra And U/Pb Chronology Of The 3.33 – 3.26 Ga Mendon Formation, Barberton, Greenstone Belt, South Africa, Nicholas Burns Decker

LSU Master's Theses

The Mendon Formation in the Barberton Greenstone Belt of South Africa marks the boundary between the Onverwacht and Fig Tree Groups. These groups are characterized by mafic to ultramafic volcanism and felsic volcanism with related epiclastic sedimentation, respectively. This transition marks the end of komatiitic volcanism in the Barberton Greenstone Belt and is accompanied by numerous impact-related spherule layers. This study characterizes the upper Mendon Formation texturally and geochemically over a wide areal extent and across structure and facies change in an attempt to better understand the evolution of tectonic processes at this boundary. A suite of whole rock and …


Subsurface Stratigraphic Architecture Of Pleistocene Sediments In The Greater New Orleans Area, James Ayrer Jan 2013

Subsurface Stratigraphic Architecture Of Pleistocene Sediments In The Greater New Orleans Area, James Ayrer

LSU Master's Theses

A major environmental and economic problem currently faces the New Orleans area, in southeastern Louisiana, stemming from salinization of freshwater aquifers that are important resources for the community. Major pumping of these aquifers has altered the potentiometric flow, allowing saltier bodies of water to flow into the region. The impact of pumping wells on encroachment of saltwater and the time as well as the route for saltwater to travel from the current saltwater-freshwater interface to pumping centers is not well constrained. Water planners need additional information to make decisions about future management of groundwater resources. The most effective way to …


Spatial Variations In Salinity And Temperature Around The Bay Marchand Salt Dome, Offshore Louisiana, Laurie Richards Jan 2013

Spatial Variations In Salinity And Temperature Around The Bay Marchand Salt Dome, Offshore Louisiana, Laurie Richards

LSU Master's Theses

The Bay Marchand field is located about 60 miles south of New Orleans, Louisiana on the continental shelf. The structurally complex field has produced over 960 MMBOE as of 2012 (http://www.eplweb.com), with many of these hydrocarbons being trapped against the massive salt dome and associated faulting present in the area. A study by Bruno and Hanor (2003) documented the presence of a high salinity plume off the southeast flank of the dome that had less saline and less dense pore water below it. The purpose of this study was to investigate the spatial variations in pore water salinity and temperature …


Evaluation Of Thermal Insulation By Coal Beds In The Western Arkoma Basin, Ok And Implications For Large Scale Geothermal Resources, Matthew Freeman Jan 2013

Evaluation Of Thermal Insulation By Coal Beds In The Western Arkoma Basin, Ok And Implications For Large Scale Geothermal Resources, Matthew Freeman

LSU Master's Theses

Weighted average geothermal gradients in the Western Arkoma Basin, Oklahoma are estimated from bottom hole temperatures (BHT) from 158 oil and gas wells. The regional geothermal gradient is 28.8 °C/km. The central and north central portions of the basin have higher gradients than southern and northern portions, especially in large areas of Pittsburg and Haskell counties where geothermal gradients in excess of 36 °C/km exist. These gradients suggest that temperatures suitable for low temperature geothermal power exist at depths of 2-3 km. Coals have very low thermal conductivity (0.15 – 0.5 W/m°K) acting as thermal insulators. This study examines the …


A Clay Mineral Provenance Study Of The Northern Pandora Trough Continental Margin, Gulf Of Papua, Ashley Len Howell Jan 2013

A Clay Mineral Provenance Study Of The Northern Pandora Trough Continental Margin, Gulf Of Papua, Ashley Len Howell

LSU Master's Theses

X-ray diffraction mineralogy of western-, central-, and eastern-derived fluvial sediments within the Gulf of Papua exhibits distinct and mixed clay mineral assemblages. These mineral assemblages allow for a better understanding of how a thick muddy continental margin shelf-edge depocenter in the eastern Gulf of Papua of latest Pleistocene/early Holocene age formed, as well as connections between terrestrial sediment delivery and evolution of deep-sea deposits in this region. Modern clay mineralogy reveals a high to low gradation of illite/smectite values from the western to eastern Gulf of Papua (Slingerland et al., 2008a), which is applied to the recent past for provenance …


Short And Long Term Volcano Instability Studies At Concepción Volcano, Nicaragua, Jose Armando Saballos Jan 2013

Short And Long Term Volcano Instability Studies At Concepción Volcano, Nicaragua, Jose Armando Saballos

USF Tampa Graduate Theses and Dissertations

Concepción is the most active composite volcano in Nicaragua, and is located on Ometepe Island, within Lake Nicaragua. Moderate to small volcanic explosions with a volcanic explosivity index (VEI) of 1-2 have been characteristic of this volcano during the last four decades. Although its current activity is not violent, its volcanic deposits reveal stages of violent activity involving Plinian and sub-Plinian eruptions that deposited vast amounts of volcanic tephra in the Atlantic Ocean. These observations, together with the 31,000 people living on the island, make Concepción volcano an important target for volcanological research.

My research focuses on the investigation of …


Harmful Algal Blooms Of The West Florida Shelf And Campeche Bank: Visualization And Quantification Using Remote Sensing Methods, Inia Mariel Soto Ramos Jan 2013

Harmful Algal Blooms Of The West Florida Shelf And Campeche Bank: Visualization And Quantification Using Remote Sensing Methods, Inia Mariel Soto Ramos

USF Tampa Graduate Theses and Dissertations

Harmful Algal Blooms (HABs) in the Gulf of Mexico (GOM) are natural phenomena that can have negative impacts on marine ecosystems on which human health and the economy of some Gulf States depends. Many of the HABs in the GOM are dominated by the toxic dinoflagellate Karenia brevis. Non-toxic phytoplankton taxa such as Scrippsiella sp. also form intense blooms off the Mexican coast that result in massive fish mortality and economic losses, particularly as they may lead to anoxia.

The main objectives of this dissertation were to (1) evaluate and improve the techniques developed for detection of Karenia spp. blooms …


Modeling Potential Chemical Environments: Implications For Astrobiology, Brian Craig Szenay Jan 2013

Modeling Potential Chemical Environments: Implications For Astrobiology, Brian Craig Szenay

USF Tampa Graduate Theses and Dissertations

Modeling chemical environments is an important step to understanding the diversity of prebiotic systems that may have formed on the early earth or potentially can occur on other worlds. By using the modern Earth as a test case, these models predict scenarios with systems more conducive to the formation of the organic molecules that are important to life. Here we use the equilibrium thermodynamic modeling program HSC Chem to investigate prebiotic environments. This program uses the raw material that the user inputs into the system in order to calculate the change in amounts of chemical species forming as a function …


Morphological Changes Associated With Tropical Storm Debby In The Vicinity Of Two Tidal Inlets, John's Pass And Blind Pass, West-Central Florida, Andrew Brownell Jan 2013

Morphological Changes Associated With Tropical Storm Debby In The Vicinity Of Two Tidal Inlets, John's Pass And Blind Pass, West-Central Florida, Andrew Brownell

USF Tampa Graduate Theses and Dissertations

Tropical Storm Debby affected the Gulf coast of Florida in late June, 2012. The storm's southerly approach temporarily reversed the annual net southward longshore sediment transport. The energetic conditions associated with Tropical Storm Debby can be seen in the wind, wave and tidal measurements taken from both onshore and offshore weather stations around the dual tidal inlets system of John's Pass and Blind Pass, approximately 25 kilometers north of the mouth of Tampa Bay. The energetic and persistent southerly forcing, in addition to higher storm induced water levels and wave heights, resulted in atypical beach erosion and sediment deposition on …


Distinguishing Processes That Induce Temporal Beach Profile Changes Using Principal Component Analysis: A Case Study At Long Key, West-Central Florida, Denise Marie Davis Jan 2013

Distinguishing Processes That Induce Temporal Beach Profile Changes Using Principal Component Analysis: A Case Study At Long Key, West-Central Florida, Denise Marie Davis

USF Tampa Graduate Theses and Dissertations

The heavily developed Long Key is located in Pinellas County in west-central Florida. The structured Blind Pass at the north end of the barrier island interrupts the southward longshore sediment transport, resulting in severe and chronic beach erosion along the northern portion of the island. Frequent beach nourishments were conducted to mitigate the erosion. In this study, the performance of the most recent beach nourishment in 2010 is quantified through time-series beach profile surveys. Over the 34-month period, the nourished northern portion of the island, Upham Beach, lost up to 330 m3/m of sand, with a landward shoreline retreat of …


Hypogene Speleogenesis In The Cerna River Basin, Sw Romania: A Sedimentological, Mineralogical, And Stable Isotopic Approach, Cristina Montana Puscas Jan 2013

Hypogene Speleogenesis In The Cerna River Basin, Sw Romania: A Sedimentological, Mineralogical, And Stable Isotopic Approach, Cristina Montana Puscas

USF Tampa Graduate Theses and Dissertations

Ever since it was identified as a speleogenetic process in the Guadalupe Mountains of New Mexico, USA, hypogene speleogenesis has become the focus of numerous research projects aimed at discerning between classical epigene caves and sulfuric acid or thermal caves. The first distinguishing characteristics that were recognized for hypogene caves were passage and cave morphology. The following step was the identification of rare minerals, specific for processes associated to hypogene speleogenesis. One other important step was the recognition of the importance of stable isotopes - mainly of S - in tracing the source of S and the chemical processes affecting …


Unusual Patterns Of Seismicity During Eruptive And Non-Eruptive Periods At The Persistently Restless Telica Volcano, Nicaragua, Melanie Rodgers Jan 2013

Unusual Patterns Of Seismicity During Eruptive And Non-Eruptive Periods At The Persistently Restless Telica Volcano, Nicaragua, Melanie Rodgers

USF Tampa Graduate Theses and Dissertations

Telica Volcano, Nicaragua, is a persistently restless volcano with high rates of seismicity that can vary from less than ten events to over a thousand events per day. Low-frequency (LF) events dominate the seismic catalogue and seismicity rates at Telica show little clear correlation with periods of eruption. As such, traditional methods of forecasting of volcanic activity based on increases in seismicity and recognition of LF activity are not applicable. A single seismic station has been operating at Telica since 1993, and in 2010 we installed a broadband seismic and continuous GPS network (TESAND network) at Telica. In this study …


Stable Isotopes And Trace Elements In Tooth Enamel Bioapatite: Effects Of Diagenesis And Pretreatment On Primary Paleoecological Information, Jessica Norman Wilson Jan 2013

Stable Isotopes And Trace Elements In Tooth Enamel Bioapatite: Effects Of Diagenesis And Pretreatment On Primary Paleoecological Information, Jessica Norman Wilson

USF Tampa Graduate Theses and Dissertations

The geochemical analysis of bioapatite in vertebrate skeletal tissues is an important tool used to obtain ecological information from fossil animals. An important consideration when conducting stable isotope and trace element analyses is obtaining biogenic information that has been unaffected by diagenetic processes.

A two-step pretreatment procedure is commonly used remove diagenetically altered material by removing organic material, via an oxidation reaction with H2O2 or NaOCl, and secondary carbonate, via dissolution in dilute acetic acid, from bioapatite. While much work has been done to determine the efficacy of the pretreatment process, little research has been conducted to determine the potential …


Trace-Element And Physical Response To Melt Percolation In Summit (Greenland) Snow, Gifford J. Wong, Robert L. Hawley, Eric R. Lutz, Erich C. Osterberg Jan 2013

Trace-Element And Physical Response To Melt Percolation In Summit (Greenland) Snow, Gifford J. Wong, Robert L. Hawley, Eric R. Lutz, Erich C. Osterberg

Dartmouth Scholarship

Surface melt on a glacier can perturb the glaciochemical record beyond the natural variability. While the centre of the Greenland ice sheet is usually devoid of surface melt, many high- Arctic and alpine ice cores document frequent summertime melt events. Current hypotheses interpreting melt-affected ice-core chemistry rely on preferential elution of certain major ions. However, the precise nature of chemistry alteration is unknown because it is difficult to distinguish natural variability from melt effects in a perennially melt-affected site. We use eight trace-element snow chemistry records recovered from Summit, Greenland, to study spatial variability and melt effects on insoluble trace …


A Study Of The Impacts Of Freeze-Thaw On Cliff Recession At The Calvert Cliffs In Calvert County, Maryland, Bonnie Elizabeth Zwissler Jan 2013

A Study Of The Impacts Of Freeze-Thaw On Cliff Recession At The Calvert Cliffs In Calvert County, Maryland, Bonnie Elizabeth Zwissler

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

The Calvert Cliffs, which form much of the western coastline of the Chesapeake Bay in Calvert County, Maryland, are actively eroding and destabilizing, resulting in a critical situation for many homes in close proximity to the slope's crest. Past studies have identified that where waves directly interact with the toe of the slope, wave action controls cliff recession; however, where waves do not regularly interact with the slope toe, the past work identified that freeze-thaw controls recession. This study investigated the validity of this second claim by analyzing the recession rate and freeze-thaw behavior of six study sites along the …


Trophic State Monitoring Of Lakes And Reservoirs Using Remote Sensing, Michelle Aten Jan 2013

Trophic State Monitoring Of Lakes And Reservoirs Using Remote Sensing, Michelle Aten

Electronic Theses and Dissertations

Lakes and reservoirs are important resources that provide water for critical needs, such as drinking water, agriculture, recreation, fisheries, wildlife, and other uses. However, there is increasing concern that anthropogenic eutrophication threatens the usability of these natural resources. Therefore, this research investigates these complex hydrologic ecosystems and recommends a methodology for monitoring the trophic state of lakes and reservoirs using remote sensing data. The Mississippi Department of Environmental Quality provided in situ data for seven Mississippi lakes including, Arkabutla, Bay Springs, Enid, Grenada, Okatibbee, Ross Barnett, and Sardis lakes. This research explored the relationships between the Secchi depth (SD), chlorophyll-a …