Earth Sciences Commons^™

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 …

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.

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 …

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.

An Investigation Into The Spatial And Temporal Movement Of The Sand Dunes In The West Lake Ecosystem Of Sandbanks Provincial Park And The Implications For Management (Ontario), Jayson A. Childs

Theses and Dissertations (Comprehensive)

Sandbanks Provincial Park is located on the northern shore of eastern Lake Ontario approximately 150km east of Toronto. The park is located on the southwestern shore of Prince Edward County in Hallowell Township and the research site was located on the larger of the two baymouth barriers the park protects. The research into aeolian sediment transport was carried out over twelve months in 2003--2004 on the Wellington Baymouth barrier. Vegetated sand dunes are sensitive geomorphic systems and when the protective cover is damaged and removed, changes are inevitable. The study examined variations in the amount of sediment transport in different …

Paleocene To Early Eocene Dinoflagellate Cyst Biostratigraphy In Southeast Nigeria And The Cote D'Ivoire-Ghana Transform Margin (Odp Site 959), Hernan Antolinez-Delgado

Masters Theses

"This study represents a contribution to Early Paleogene biostratigraphy in the tropics where published studies are sparse in comparison with mid and high latitude regions. Data were derived from a comprehensive analysis of dinoflagellate cysts (dinocysts) in 45 samples from the Early Paleocene to Early Eocene interval at two localities in West Africa, namely Alo-1 well in the Anambra Basin, southeastern Nigeria, and Ocean Drilling Program Hole 959D (ODP Leg 159) in the Cote d'Ivoire-Ghana Transform Margin. Dinocyst recovery varied from very good to poor, and the specimens were commonly well preserved. The dinocyst data were calibrated with existing calcareous …

Base-Level Buffers And Buttresses: A Model For Upstream Versus Downstream Control On Fluvial Geometry And Architecture Within Sequences, John M. Holbrook, Robert W. Scott, Francisca Oboh-Ikuenobe

Geosciences and Geological and Petroleum Engineering Faculty Research & Creative Works

The effects of downstream base-level control on fluvial architecture and geometry are well explored in several broadly similar sequence-stratigraphic models. Cretaceous Dakota Group strata, U.S. Western Interior, have characteristics reflecting combined downstream and upstream base-level controls that these models cannot address. Particularly, three layers of amalgamated channel-belt sandstone within this group thicken and are continuous for distances (≤ 300 km) along dip that stretch the reasonable lengths for which these models are intended to apply. As well, architecture in up-dip reaches records repeated valley-scale cut-and-fill cycles. This contrasts with equivalent strata down dip which record channel-scale lateral migration with no …

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 …

Wellbore Stability In Water-Sensitive Shales, Qingfeng Tao

Theses and Dissertations

Wellbore instability is a widespread problem, especially when drilling in deep, low strength shale formations at high temperature and pressure. The instability can be caused by the high compressive effective stress or tensile stress due to the stress concentration and pore pressure increase while drilling. In addition to the in-situ stress and shale strength, shale instability is affected by drilling mud properties including mud weight, temperature and salinity. To assess wellbore stability in these situations, Diek and Ghassemi (2004) developed a non-linear coupled chemo-poro-thermoelasticity theory. The linearized version of the theory allows one to analytically investigate the coupled impacts of …

Salt Ingestion Caves, Charles A. Lundquist, William W. Varnedoe Jr.

International Journal of Speleology

Large vertebrate herbivores, when they find a salt-bearing layer of rock, say in a cliff face, can produce sizable voids where, over generations, they have removed and consumed salty rock. The cavities formed by this natural animal process constitute a unique class of caves that can be called salt ingestion caves. Several examples of such caves are described in various publications. An example in Mississippi U.S.A., Rock House Cave, was visited by the authors in 2000. It seems to have been formed by deer or bison. Perhaps the most spectacular example is Kitum Cave in Kenya. This cave has been …

Unconfined Versus Confined Speleogenetic Settings: Variations Of Solution Porosity, Alexander Klimchouk

International Journal of Speleology

Speleogenesis in confined settings generates cave morphologies that differ much from those formed in unconfined settings. Caves developed in unconfined settings are characterised by broadly dendritic patterns of channels due to highly competing development. In contrast, caves originated under confined conditions tend to form two- or three-dimensional mazes with densely packed conduits. This paper illustrates variations of solution (channel) porosity resulted from speleogenesis in unconfined and confined settings by the analysis of morphometric parameters of typical cave patterns. Two samples of typical cave systems formed in the respective settings are compared. The sample that represents unconfined speleogenesis consists of solely …

Tracer-Test Design For Losing Stream–Aquifer Systems, Malcolm S. Field

International Journal of Speleology

Hydrological tracer testing is an effective way for assessing the significance and extent of leakage through the bed of an influent (losing and sinking) stream. In karstic terranes, leakage from losing and sinking streams typically resurge at downstream springs, but flow may be intercepted by production wells. Although sinking streams that disappear into swallow holes and caves are relatively easy to trace, developing a tracer test design for a losing stream that allows slow percolation through its bed is complicated by the lack of basic knowledge regarding leakage rate, leakage locations along its length, and temporal variability. To overcome these …

Vashegyite From Gaura Cu Muscă Cave (Locvei Mountains, Romania): A New And Rare Phosphate Occurrence, Bogdan P. Onac, Luminiţa Zaharia, Joe Kearns, Daniel Veres

International Journal of Speleology

This study investigated the occurrence of vashegyite from a guano-rich deposit located in the Gaura cu Muscă Cave, Romania. Analytical methods used include optical microscopy, X-ray powder diffraction (XRD), scanning electron-microscopy (SEM), inductively coupled plasma-atomic emission spectrometry (ICP-AES), thermal investigations and Fourier-transform infrared (FT-IR) analyses. Vashegyite occurs as friable, chalky white, irregular nodules of up to 2.5 cm in diameter, within a 15 cm thick sequence of organic and minerogenic sediments. The chemical structural formula is: (Al_10.91Fe³⁺_0.06Na_0.1Ca_0.02Mg_0.08)_Σ=11.17[(PO₄)_8.78(SiO₄)_0.056]_Σ=8.83(OH) …

Studies Of Condensation/Evaporation Processes In The Glowworm Cave, New Zealand, C. R. De Freitas, A. Schmekal

International Journal of Speleology

The condensation/evaporation process is important in caves, especially in tourist caves where there is carbon dioxide enriched air caused by visitors. The cycle of condensation and evaporation of condensate is believed to enhance condensation corrosion. The problem is condensation is difficult to measure. This study addresses the problem and reports on a method for measuring and modelling condensation rates in a limestone cave. Electronic sensors for measuring condensation and evaporation of the condensate as part of a single continuous process of water vapour flux are tested and used to collect 12 months of data. The study site is the Glowworm …

Radio Frequency Enabled Soil Redox Potential Sensor Networks, Chris Holme

Theses : Honours

There is a need for' cost effective tools and data collection methods for field measurements; to increase both productivity and volumes of collected data in the quest for enhanced understanding and management of environmental systems. To such end, various technologies that may be combined into a cost effective soil redox sensor network were explored. Suitability of each technology, as a component of said network was evaluated. A prototype soil redox sensor network was constructed and basic laboratory and field testing was completed. Results indicate that the prototype sensor network functions correctly within bounds. Both laboratory and field testing show that …

Radon In Caves: Clinical Aspects, Stephen A. Craven, Berend J. Smit

International Journal of Speleology

Historical, experimental and clinical evidence is presented to suggest that radon constitutes a relatively small carcinogenic risk for casual visitors to caves. The risk is dependent on radon levels and the smoking of tobacco. Show cave guides, chronically exposed to radon, may be at increased risk for lung cancer due to the effects of radon, especially if they are smokers of tobacco.

Geology Of Cat Island, Bahamas: A Field Trip Guide, John E. Mylroie, H. Allen Curran, Deborah Freile, James L. Carew, Neil E. Sealey, Vincent J. Voegeli

Geosciences: Faculty Publications

See other Smith authored Field Trip Guides of Gerace Research Centre.

Modeling Groundwater Denitrification By Ferrous Iron Using Phreeqc, Tedros Tesfay

Theses and Dissertations

Nitrate is one of the most common groundwater contaminants, and ingesting it leads to potential health risks. Denitrification, the only effective process to eliminate nitrate, is limited by the abundance of biologically available electron donors. Thus, understanding the natural denitrification capacity of aquifers, through the analysis of all the major electron donors, is essential.

A better way to estimate groundwater denitrification reactions is to compute the mass balance of the redox sensitive species. The University of North Dakota (UND) denitrification team installed mesocosms (ISMs) to understand the fate of nitrate in field conditions. Accordingly, the team has shown the significant …

Evaluating Surface Area-Basin Volume Relationships For Prairie Potholes, Mike A. Davis

Theses and Dissertations

Establishing a relationship between surface area and volume of prairie potholes provides a simple method to estimate changes in water storage across the landscape. Applications include better prediction of floods and improved design for wetland restoration. Length, width, depth, surface area, and volumes were surveyed for eighty two potholes within the upper Turtle River watershed which lies sixty kilometers west of Grand Forks, ND. These data were used to determine the relationship and uncertainty between pothole surface and volume. Chi squared tests defined distributions of each variable. F and T statistical tests resolved similarities in variance and mean. The eighty …

Loss Of Nutrients From Croplands As A Result Of Soil Erosion, Munns Creek Watershed, Grundy County, Iowa, Jihyo Chong

Dissertations and Theses @ UNI

The temporal distribution of chloride, nitrate, and sulfate in the hydrologic environment were studied in Grundy County, Iowa from June to September 2004. The goal of the project was to investigate the rate of soil erosion and the subsequent loss of nutrients from the agricultural fields of the study area. Water samples were collected weekly from 6 different sites along Munns Creek in the study area near Grundy Center, Iowa. Each sample was analyzed for chloride, nitrate, and sulfate by ion chromatography. Soil core samples were collected from 22 locations in the surrounding agricultural fields. At each location, soil was …

Relationships Between Deflector Faults, Collapse Dolines And Collector Channel Formation: Some Examples From Slovenia, France Šušteršič

International Journal of Speleology

In some Slovenian caves collector channels gather sinking underground streams and redirect them for potentially long distances parallel to certain faults. The collector channels formed due to ongoing long-term collapse of cave roofs at the points where passages break through the faults, which function as a kind of screen and are termed deflector faults. The fault trends are marked by collapse within the caves, and by active collapse dolines at the surface.

Identification Of Cave Minerals By Raman Spectroscopy: New Technology For Non-Destructive Analysis, William B. White

International Journal of Speleology

The identification of minerals from caves generally requires that samples be removed from the cave for analysis in the laboratory. The usual tools are X-ray powder diffraction, the optical microscope, and the scanning electron microscope. X-ray diffraction gives a definitive fingerprint by which the mineral can be identified by comparison with a catalog of reference patterns. However, samples must be ground to powder and unstable hydrated minerals may decompose before analysis is complete. Raman spectroscopy also provides a fingerprint useful for mineral identification but with the additional advantage that some a-priori interpretation of the spectra is possible (distinguishing carbonates from …