Thesis (M.Sc.), Memorial University of Newfoundland, 2000. / Restricted until January 2002. The CD-ROM "includes a series of .AVI files... the .AVI files are digital video captures of the 3-dimensional models used to produce the 2 dimension figures contained in this document." Bibliography: leaves 254-265. Also available online.

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The application of spectral induced polarization (SIP) to geohydrologic and geotechnical problems is considered. Some fundamental electrochemical characteristics of sulfides are reviewed. An alternate theory of the underlying cause of IP is presented. A modified field method is proposed. Two field sites are studied. Prevailing electrochemical thought is that most sulfides, especially pyrite and chalcopyrite, have passivating surface coatings. With this thought in mind, existing geophysically-oriented electrochemical measurements may be reinterpreted quite differently than has previously been done. Large impedances at low frequencies have traditionally been attributed by geophysicists to diffusional phenomena related to rapid reactions occurring at the sulfide surface. Large impedances at low frequencies with clays have traditionally been attributed to restrained ionic diffusion between zones of clay particles. Although they appear to be due to quite different mechanisms, both of these low frequency dispersions may be explained by a single rate limiting mechanism. Using fractal geometry, the large low frequency dispersions observed on sulfides may be explained by distributed high charge-transfer resistances on rough surfaces. With high surface resistances sulfides may behave like insulating clay particles and allow charge separation to occur in surface conduction current flow. Although displacement currents may flow in sulfides they are considered to be minimal in comparison to the surface conduction currents. The concept of a common polarization phenomenon allows the previous studies on rock samples containing clay particles and/or sulfides to be equated on the basis of particle size. With clay-coated sand grains it may be possible to estimate intrinsic hydraulic conductivity based on the interpreted polarizable grain size. Aquifers, and partially water saturated zones, may be IP targets if they have small amounts of polarizable clay minerals. Aquifer detection and grain size estimation are demonstrated. Theoretical work and field studies show the advantages of using a modified dipole-dipole array and data presentation methods. The large amounts of data gathered during broad-band SIP surveys are demonstrated to be very useful in layered-earth geohydrologic problems. The higher frequency data contain much earth-structure information, are easily gathered, and allow immediate qualitative structural interpretation. Lower frequency data contain information useful in aquifer characterization.

This research has been directed at the study of facilitated oxidation of aliphatic sulfides by neighboring group participation. Mesocyclic polythioether and 2-substituted 6-methylthiobicyclo[2.2.1]heptane derivatives have been examined as model compounds for biological redox reactions. The preparations, structural analogues, and oxidation studies of such compounds have been investigated. A new technique has been developed for the preparation of mesocyclic polythioethers. Conformational analysis, both gas phase and solid state, and quantum mechanical analysis of one- and two-electron oxidation of mesocyclic polythioethers have been undertaken. Crystal and molecular structures of some transition metal complexes of 1,4,7-trithiacyclononane, as well as a number of 2-substituted 6-methylthiobicyclo[2.2.1]heptane derivatives have been determined using single crystal X-ray techniques. Stereoselective oxidation of 2-endo-(hydroxymethyl)-6- endo(methylthio)bicyclo[2.2.1]heptane has been achieved leading to both corresponding diastereomeric sulfoxides.

In general, tailings dams are expected to seep. Anomalous seepage, especially when induced by internal erosion, is a major concern for owners and operators. The long established techniques for monitoring water seepage provide sparse information which may not be sufficient to detect and map the seepage path. Hence, there exists a great need for non-invasive techniques that would be sensitive to changing seepage conditions. The non-invasive nature of the techniques is particularly important because drilling and other penetrating (invasive) investigation methods are normally avoided. / Non-invasive techniques such as self-potential and high-resolution resistivity have been significantly improved in the past decade and have been successfully used for water retention dam investigation and monitoring. The main difficulty in the use of these techniques in monitoring sulfide rich tailings dams is the presence of electrochemical potentials that renders the interpretation of the acquired self-potential data difficult. / Numerical modelling is one of the latest methods in interpreting self-potential anomalies induced by liquid flow. But, in order to model streaming potentials several parameters need to be measured or estimated; (1) the hydraulic driving force and the hydraulic conductivity are required to solve for the hydraulic pressure distribution; (2) the cross-coupling conductivity distribution is needed to calculate the conduction current source parameter; and (3) the resistivity distribution is needed to determine the resulting potential distribution. / The zeta-potential and the resistivity of three pyrite rich tailings from the Abitibi region in Quebec were measured over the pH range 2 to 5 in different KCl aqueous solutions for the purpose of estimating the magnitude of electrokinetic effect induced by mine water seepage and the electrical resistivity variation induced by particle migration. The experimental and theoretical results obtained in the present study are pertinent to the interpretation of self-potential data. The zeta-potential was found to vary from -27 to -2 mV and the resistivity of the tailings was found to increase when fine particles are eroded.

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Hydrothermal discharge on the seafloor results in significant accumulation of base- and precious-metal-rich sulfide material. Technological advances as well as elevated metal prices have led to a growing interest in the direct mining of these deposits from the modern ocean floor. The research presented in this thesis details an investigation of the size, grades, distribution, and accumulation rates of these deposits on the seafloor. A three-part resource assessment, originally designed for land-based ore deposits, was used to generate a predictive framework for the global seafloor sulfide resource. Using detailed descriptions of sizes, grades and locations for 92 known deposits, a resource estimate was generated that predicts a total of ~1,000 deposits and a total global abundance of 600 Mt of sulfide within the neovolcanic zones of the modern ocean floor. A detailed study of the hydrothermal sulfide deposits along the Endeavour Segment of the Juan de Fuca Ridge was carried out to investigate the processes of sulfide accumulation at the ridge-segment scale. Results of 226Ra/Ba dating of barite within the deposits indicate that hydrothermal activity has been ongoing for ~6,000 years and venting has been continuous at the Main Endeavour and High Rise vent fields for ~2,300 and 850 years, respectively. Abundant older sulfide samples from inactive sites outside of the main vent fields indicate a complex history of venting along the ridge segment. Analysis of high-resolution bathymetry of the Endeavour Segment, generated from eight autonomous underwater vehicle surveys, revealed the location of 581 individual hydrothermal sulfide edifices along 15 km of ridge length. Using GIS-based software, the volume of each edifice was calculated, and the total amount of sulfide at Endeavour is estimated to be 1.2 Mt. This estimate is the first comprehensive resource evaluation on the seafloor at this scale. Sulfide has been accumulating within the Endeavour axial valley at a rate of ~400 tonnes per year, which is similar to estimates for the TAG deposit on the Mid-Atlantic Ridge. Using endmember hydrothermal fluid chemistry data and estimates of fluid discharge rates, the mass accumulation rate calculated for Endeavour corresponds to a sulfide depositional efficiency of 6%.

This study investigated possible reasons for the failure of the acetylene inhibition assay of denitrification in highly reducing environments and resulted in the isolation of a denitrifying Cytophaga from soil enriched by anaerobic incubation with glucose, nitrous oxide (N(,2)O), acetylene (C(,2)H(,2)), and sulfide (S('2-)). Such soil enrichments and pure cultures of the isolated Cytophaga (Is-11) reduced N(,2)O rapidly even in the presence of a normally inhibitory concentration of C(,2)H(,2) (4 kPa), providing S('2-) was present 8.0 umol (g soil)('-1) or 0.4 umol (mL culture)('-1) . The observed reaction appears to be unique to this soil Cytophaga since other organisms tested, using the same or similar experimental conditions, failed to show this response. / The isolate was characterized, after extensive comparative studies with five Cytophaga johnsonae strains, as a pigmented, Gram-negative, non-motile, gliding filamentous bacillus. Although these features established a taxonomic link with the family Cytophagaceae, the inability of Is-11 to digest chitin and DNA base composition of about 42.5 mol% (G+C) make the organism's specific affiliation uncertain.

Thesis (M.Sc.) - Carleton University, 2008. / Includes bibliographical references (p. 92-97). Also available in electronic format on the Internet.