Physical Sciences and Mathematics Commons^™

Adsorption Of Lead On Single And Mixed Solid Systems, Soumya Das

Dissertations

Metal oxy-hydroxides and phyllosilicate minerals play a significant role in the fate and transport of heavy metals in the environment (Bertsch and Seaman, 1999). Chemical speciation of metals affects their bioavailability and chemical reactivity (Stumm and Morgan, 1996). Surface complexation models (SCMs) based on equilibrium thermodynamic principles have been successfully used to quantify adsorption of heavy metals on pure solid minerals, including phyllosilicates and oxy-hydroxides. For natural sediments with mixed mineralogy, Davis et al. (1998) suggested two different SCM approaches, namely, the component additivity and generalized composite models. In this study, adsorption of lead on pure HFO, silica and kaolinite …

Modified Fenton Oxidation Of Hydrocarbon Contaminated Soils With Cao2: Microbial Survival And Surfactant Production, Abraham Matthew Northup

Dissertations

The efficacy of CaO₂ for use in modified Fenton's (MF) reactions was investigated in this study, with the goal of developing a CaO₂-based MF oxidation technology for use in in situ chemical oxidation. Traditionally, liquid H₂O₂ (HP) is used, and is injected into the subsurface in excess to ensure a sufficient radius of influence. CaO₂ was investigated as an alternative source of H₂O₂ for MF reactions.

First, the rate of dissolution of powdered CaO₂ and the yield of HP was investigated. Our results showed that the rate of dissolution …

Laboratory Based Chemical And Isotopic Investigations On Biotic (Microbial) And Abiotic Reduction Of Iron And Oxidation Of Organic Compounds, Tsigabu Asmelash Gebrehiwet

Dissertations

Studies using chemical and isotopic techniques have been conducted to investigate experimental microbial (biotic) iron reduction and abiotic redox processes. In the microbially mediated study Fe(III) reduction and lactate oxidation at circum-neutral pH and anaerobic conditions were used to characterize the metabolic pathways followed by dissimilatory Fe⁺³ -reducing bacterium Shewanella putrefaciens strain 200R. Iron (II), Iron (III), dissolved inorganic carbon (DIC) and carbon isotope ratios were measured under bicarbonate and phosphate buffered conditions. Carbon isotope disproportionation among organic carbon substrate (lactate), biomass and respired carbon dioxide at the lag to stationary phase of the microbial growth curve showed …

Some Applications Of Gaussian Quadrature And Neural Network Modeling In Earth Flows And Other Slow-Moving Landslides In Cohesive Slope Materials, Rennie Bwalya Kaunda

Dissertations

Geometrical changes and progressive displacements in earth flows and other slow moving landslides triggered by climatic changes may be addressed by digital modeling. Gaussian quadrature, a numerical integration technique though fixed points, is employed to compute geometrical areas defined by stratigraphic (soil or rock layering) units, vertical pole projections and a slip surface, based on kinematic admissibility. An example from the Lake Michigan coast shows that the total internal geometrical area is found to be preserved during the course of the progressive deformation. Displacement monitoring of the slope shows that it became less stable over a period of eleven years …

Geophysical Monitoring Probes And Their Applications To Some Hydrogeological Problems, Laura Smart

Dissertations

Geophysical monitoring probes were constructed to monitor the vertical changes of water content and ion concentration in the subsurface. These devices contain electrodes for resistivity measurements and thermistors for temperature measurements. They are designed to monitor the resistivity and temperature of the saturated zone, the transition zone, and the vadose zone near a groundwater/surface water interface. Additional installations at the site include four monitoring wells and four Time Domain Reflectometry (TDR) access tubes, each paired with the geophysical probe installations. Pole-Pole resistivity measurements with an a-spacing of 5 cm are made using a CR1000 Campbell Scientific, Inc. datalogger. Automated data …