Geological Engineering Commons^™

Separation Of Ash And Sulfur Dioxide During The 2011 Grímsvötn Eruption, E. D. Moxnes, N. I. Kristiansen, A. Stohl, L. Clarisse, A. J. Durant, K. Weber, A. Vogel

Michigan Tech Publications

Modeling the transport of volcanic ash and gases released during volcanic eruptions is crucially dependent on knowledge of the source term of the eruption, that is, the source strength as a function of altitude and time. For the first time, an inversion method is used to estimate the source terms of both volcanic sulfur dioxide (SO2) and ash. It was applied to the explosive volcanic eruption of Grímsvötn, Iceland, in May 2011. The method uses input from the particle dispersion model, FLEXPART (flexible particle dispersion model), a priori source estimates, and satellite observations of SO2 or ash total columns from …

Absorption And Fluorescence Properties Of Chromophoric Dissolved Organic Matter Of The Eastern Bering Sea In The Summer With Special Reference To The Influence Of A Cold Pool, E. J. D'Sa, J. I. Goes, H. Gomes, C. Mouw

Michigan Tech Publications

The absorption and fluorescence properties of chromophoric dissolved organic matter (CDOM) are reported for the inner shelf, slope waters and outer shelf regions of the eastern Bering Sea during the summer of 2008, when a warm, thermally stratified surface mixed layer lay over a cold pool ( < 2 °C) that occupied the entire middle shelf. CDOM absorption at 355 nm (ag355) and its spectral slope (S) in conjunction with excitation-emission matrix (EEM) fluorescence and parallel factor analysis (PARAFAC) revealed large variability in the characteristics of CDOM in different regions of the Bering Sea. PARAFAC analysis aided in the identification of three humic-like (components one, two and five) and two protein-like (a tyrosine-like component three, and a tryptophan-like component four) components. In the extensive shelf region, average absorption coefficients at 355 nm (ag355, mg-1) and DOC concentrations (μM) were highest in the inner shelf (0.342 ± 0.11 mg-1, 92.67 ± 14.60 μM) and lower in the middle (0.226 ± 0.05 mg-1, 78.38 ± 10.64 μM) and outer (0.185 ± 0.05 mg-1, 79.24 ± 18.01 μM) shelves, respectively. DOC concentrations, however were not significantly different, suggesting CDOM sources and sinks to be uncoupled from DOC. Mean spectral slopes S were elevated in the middle shelf (24.38 ± 2.25 μmg-1) especially in the surface waters (26.87 ± 2.39 μmg-1) indicating high rates of photodegradation in the highly stratified surface mixed layer, which intensified northwards in the northern middle shelf likely contributing to greater light penetration and to phytoplankton blooms at deeper depths. The fluorescent humic-like components one, two, and five were most elevated in the inner shelf most likely from riverine inputs. Along the productive "green belt" in the outer shelf/slope region, absorption and fluorescence properties indicated the presence of fresh and degraded autochthonous DOM. Near the Unimak Pass region of the Aleutian Islands, low DOC and ag355 (mean 66.99 ± 7.94 μM; 0.182 ± 0.05 mg-1) and a high S (mean 25.95 ± 1.58 μmg-1) suggested substantial photobleaching of the Alaska Coastal Water, but high intensities of humic-like and protein-like fluorescence suggested sources of fluorescent DOM from coastal runoff and glacier meltwaters during the summer. The spectral slope S vs. ag355 relationship revealed terrestrial and oceanic end members along with intermediate water masses that were modeled using nonlinear regression equations that could allow water mass differentiation based on CDOM optical properties. Spectral slope S was negatively correlated (r2 = 0.79) with apparent oxygen utilization (AOU) for waters extending from the middle shelf into the deep Bering Sea indicating increasing microbial alteration of CDOM with depth. Although our data show that the CDOM photochemical environment of the Bering Sea is complex, our current information on its optical properties will aid in better understanding of the biogeochemical role of CDOM in carbon budgets in relation to the annual sea ice and phytoplankton dynamics, and to improved algorithms of ocean color remote sensing for this region.

Seasonal Variability And Long-Term Evolution Of Tropospheric Composition In The Tropics And Southern Hemisphere, K. M. Wai, S. Wu, A. Kumar, H. Liao

Michigan Tech Publications

Impacts on tropospheric composition in the tropics and the Southern Hemisphere from biomass burning and other emission sources are studied using a global chemical transport model, surface measurements and satellite retrievals. Seasonal variations in observed CO at remote island sites are examined. Easter Island (eastern Pacific Ocean) is impacted indirectly by the hemispheric zonal transport of CO due to the burning in southern Africa/South America, via the westerlies. An increasing trend in CO by 0.33 ppb yr-1 in the past decade at Ascension Island is attributed to the combined effects of South American/southern Africa burnings and the increases in CH4 …

Effects Of Stratospheric Ozone Recovery On Photochemistry And Ozone Air Quality In The Troposphere, H. Zhang, Shiliang Wu, Y. Huang, Y. Wang

Michigan Tech Publications

There has been significant stratospheric ozone depletion since the late 1970s due to ozone-depleting substances (ODSs). With the implementation of the Montreal Protocol and its amendments and adjustments, stratospheric ozone is expected to recover towards its pre-1980 level in the coming decades. In this study, we examine the implications of stratospheric ozone recovery for the tropospheric chemistry and ozone air quality with a global chemical transport model (GEOS-Chem). With a full recovery of the stratospheric ozone, the projected increases in ozone column range from 1% over the low latitudes to more than 10% over the polar regions. The sensitivity factor …

Wetland Issues Affecting Waterfowl Conservation In North America, Heath M. Hagy, Scott C. Yaich, John W. Simpson, Eduardo Carrera, David A. Haukos, W.Carter Johnson, Charles R. Loesch, Fritz A. Reid, Scott E. Stephens, Ralph W. Tiner, Brett A. Werner, Greg S. Yarris

Natural Resource Management Faculty Publications

This paper summarises discussions by invited speakers during a special session at the 6th North American Duck Symposium on wetland issues that affect waterfowl, highlighting current ecosystem challenges and opportunities for the conservation of waterfowl in North America. Climate change, invasive species, U.S. agricultural policy (which can encourage wetland drainage and the expansion of row-crop agriculture into grasslands), cost and competition for water rights, and wetland management for non-waterfowl species were all considered to pose significant threats to waterfowl populations in the near future. Waterfowl populations were found to be faced with significant threats in several regions, including: the Central …

The Description Of An Effective Sinkhole Investigation Approach: A Case Study Of Two Sites In Greene County, Missouri, Stanley Chinedu Nwokebuihe

Masters Theses

"Karst topographies pose danger to the environment. The associated gradual subsidence or sudden collapse of the ground can lead to loss of lives and damage to property. A sinkhole is the subsidence or collapse of the overburden into subsurface cavities. Sinkholes develop in different sizes, shapes and rates all over the world especially in areas where the bedrock can be dissolved by percolating slightly acidic surface water.

Different methods have been used to investigate sinkholes. Boring is the most common of these methods. But the boring technique is quite inefficient; it only provides information of the subsurface conditions at the …

Effects Of Indentation Speed And Water Saturation Level On The Behavior Of Roubidoux Sandstone, Azupuri Ayerikujei Kaba

Masters Theses

"The experiment conducted in this research was to determine the behavior of a porous rock under an indenter. To investigate this, medium-grained sandstone was subjected to a series of indentation tests. These tests were conducted under both dry and saturated conditions using a rounded conical indenter. In addition, tests were conducted at different indentation speeds. The test results were used to calculate the mechanical specific energy (SE) and specific penetration (SP). The porewater pressure evolution in the saturated sample was also monitored.

The tests and subsequent analyses reveal that saturation did not affect the specific energy when the indentation rate …

Effects Of Grain Properties And Compaction On Single-Tool Normal Indentation Of Granular Materials, Dennis Chieze Duru

Masters Theses

"The behavior of three granular materials; filter sand, crushed garnet, and shale cutting, were investigated in an effort to evaluate the effect of grain size and shape, and material compaction under single tool load-indentation test. Force-penetration data was collected continuously through the end of each test and specific energy and specific penetration was calculated from the data.

Grain size and compaction affected the force penetration behavior. The higher the grain size, the more the fluctuation in the force of penetration. In addition, compaction reduces the force fluctuation in the fine aggregate grains, but increases the magnitude of the force fluctuations …

Performance Assessment Of Capture Zones Generated By Pv-Powered Pump And Treat Systems, Yovanna Cortes Di Lena

Doctoral Dissertations

"Pump and treat (P&T) is a technology that has been extensively used to remove and/or contain contaminated groundwater. Hydraulic containment of contaminants is accomplished by generating capture zones through pumping of groundwater. An appropriate delineation of capture zones is necessary to design an effective P&T system. P&T systems conventionally operate continuously to achieve steady-state capture zones, which require significant amounts of energy. The use of renewable energies to meet power demands of remedial systems may reduce a project's carbon dioxide emissions. The hydraulic effectiveness of a photovoltaic (PV) powered P&T system without energy storage was characterized using data collected at …

Comparison Of Core Control And Geophysical Investigations, Silica Sand Deposits, Dawmat Al Jandal, Al Jawf At Saudi Arabia, Ghassan Salem Alsulaimani

Masters Theses

"This thesis is a summary of a comprehensive geophysical investigation in southern Dawmat Al Jandal, Al Jawf in Saudi Arabia. This research demonstrates that the acquisition of both core control and geophysical data is superior to the acquisition of core control alone. Coring is expensive and is limited in subsurface coverage. Geophysical surveying, however, is a relatively rapid and cost-effective means of deriving information about the subsurface between core holes. Ground penetrating radar (GPR), Multichannel Analysis of Surface Waves (MASW), and Seismic Refraction methods were used as exploration techniques to locate surficial mineral deposits within the study area.

During the …