Philosophiae Doctor - PhD / This research has been conducted by focusing on the trajectories of semiotic ensembles from various contexts that stand-up comedians exploited for aesthetic and communicative purposes. I apply the social semiotic theory of multimodality (Kress and van Leeuwen, 2001, 2006), and the notions of semiotic remediation (Bolter and Grusin, 1996, 2000) and resemiotization (Iedema, 2003) to selected audiovisual recordings performances of Trevor Noah and Loyiso Gola from South Africa; and Atunyota Akporobomeriere (Ali Baba) and Bright Okpocha (Basket Mouth) from Nigeria. I explore the trajectories of semiotic resources that the comedians used across modes, contexts and practices. I also trace the translation and interpretation of socio-cultural and political materials by South African and Nigerian stand-up comedians’ performances. The idea is also to examine the extent to which the socio-cultural and political contexts of both countries have differential effects on the choices in the semiotic resources used in the reconstruction of meanings, including cross socio-cultural taboos. The study reveals that combinations of various semiotic materials ranging from political, sociocultural, religious and personal lifestyles are remediated (repurposed) for comic and aesthetic effects. This involves translating and re-interpreting the semiotic resources across contexts and practices. In this regard, the study showed how the artists rework verbal language, images, socio-political discourses and other semiotic material for new meanings. It also reveals that although the choices of materials are similar, there is a tendency of localizing semiotic resources to particular localities and audiences, so that each artist’s performance comes out as unique to the person. The study concludes that language alone is not at the core of communication as other semiotic modes (in addition to languages) are integrated interweaving resources to make meaning. The direction of the modes or resources is multidimensional. All the spoken texts, all the non-linguistic modes: gestures, stance, movements, running on stage, postures, mimicking and others, perform vital roles to recontextualize meanings in stand-up comedy performance. Therefore, the study opens up new perspectives on social semiotic approaches to multimodality, as well as on language social semiotic and to theory and media studies. The contribution also answers the call to expand the understanding and research on the theory of ‘multimodality’ and the various concepts such as semiotic remediation and resemiotization associated with it.

Methyl Tertiary-Butyl Ether (MTBE) contamination of groundwater and surface waters has become a relevant environmental and public safety concern in recent years. This anthropogenic compound is now persistent at low concentrations in several valuable ground and surface water locations within the United States due largely to the widespread production of MTBE for use as a fuel oxygenate in conjunction with negligent underground storage practices during the 1980's and 1990's. Though there are several treatment strategies for the remediation of MTBE spill sites, the most efficient strategy may be adsorption of MTBE by a packed column of silicalite-1 adsorbent. Effective adaption of this technology requires cheap production of silicalite-1 sorbent packing particles on the order of 3 millimeters diameter. This work entails the development of a new synthesis process which results in sufficient in-situ crystallization of silicalite-1 aggregates within a 3 millimeter spherical amorphous silica gel source. The crystal aggregates sizes can be tuned from 5 to 70 µm, depending on synthesis parameters, and the finished silicalite-1 aggregate particle takes the shape of the amorphous gel source. These aggregate particles, when containing a small amorphous core, should be suitable for packed adsorption column applications. Multiple hydrothermal synthesis experiments were performed by batch methods featuring silica gel spheres as the sole silica source for the batch. Zeolite nucleation and crystal growth were demonstrated throughout the amorphous bead. Synthesis parameters were optimized both for short synthesis times, optimal mechanical properties, and cost effectiveness. The influence of product crystal size on particle hardness was also investigated. The packing production process is sufficiently ready for supporting pilot scale adsorption studies.

by Chan Sze Sze. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references (leaves 193-218). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstracts --- p.ii / 摘要 --- p.v / Contents --- p.viii / List of figures --- p.xv / List of tables --- p.xix / Abbreviations --- p.xxii / Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- The North Tsing Yi Abandoned Shipyard area --- p.1 / Chapter 1.2 --- Polycyclic aromatic hydrocarbons (PAHs) in the site --- p.3 / Chapter 1.2.1 --- Characteristics of PAHs --- p.3 / Chapter 1.2.2 --- Sources of PAHs --- p.8 / Chapter 1.2.3 --- Environmental fates of PAHs --- p.9 / Chapter 1.2.4 --- Biodegradation of PAHs --- p.10 / Chapter 1.2.5 --- Toxicity of PAHs --- p.13 / Chapter 1.2.6 --- PAHs contamination in Hong Kong --- p.14 / Chapter 1.2.7 --- Soil decontamination assessment in Hong Kong --- p.16 / Chapter 1.2.8 --- Environmental standards of PAHs --- p.18 / Chapter 1.2.9 --- Remediation technology of PAHs --- p.21 / Chapter 1.2.9.1 --- Bioremediation --- p.22 / Chapter 1.3 --- Heavy metals in the site --- p.28 / Chapter 1.3.1 --- "Characteristics of copper, lead and zinc" --- p.29 / Chapter 1.3.2 --- "Sources of copper, lead and zinc" --- p.32 / Chapter 1.3.3 --- "Environmental fates of copper, lead and zinc" --- p.34 / Chapter 1.3.4 --- "Toxicities of copper, lead and zinc" --- p.36 / Chapter 1.3.5 --- "Copper, lead and zinc contamination in Hong Kong" --- p.39 / Chapter 1.3.6 --- "Environmental standards of copper, lead and zinc" --- p.40 / Chapter 1.3.7 --- Remediation technology of heavy metal --- p.42 / Chapter 1.3.7.1 --- Chemical method --- p.42 / Chapter 1.3.7.2 --- Biological method --- p.43 / Chapter 1.3.7.3 --- Stabilization and Solidification --- p.45 / Chapter 1.4 --- Aim of study --- p.47 / Chapter 1.5 --- Objectives --- p.47 / Chapter 1.6 --- Research Strategy --- p.47 / Chapter 1.7 --- Significance of study --- p.48 / Chapter 2 --- Materials and Methods --- p.49 / Chapter 2.1 --- Soil Collection --- p.49 / Chapter 2.2 --- Characterization of soil --- p.49 / Chapter 2.2.1 --- Sample preparation --- p.49 / Chapter 2.2.2 --- "Soil pH, electrical conductivity & salinity" --- p.50 / Chapter 2.2.3 --- Total organic carbon contents --- p.51 / Chapter 2.2.4 --- Soil texture --- p.51 / Chapter 2.2.5 --- Moisture --- p.53 / Chapter 2.2.6 --- Total nitrogen and total phosphorus --- p.53 / Chapter 2.2.7 --- Available nitrogen --- p.53 / Chapter 2.2.8 --- Available phosphorus --- p.54 / Chapter 2.2.9 --- Soil bacterial and fungal population --- p.54 / Chapter 2.2.10 --- Extraction of PAHs and organic pollutants --- p.55 / Chapter 2.2.10.1 --- Extraction procedure --- p.55 / Chapter 2.2.10.2 --- GC-MS condition --- p.56 / Chapter 2.2.10.3 --- Preparation of mixed PAHs stock solution --- p.56 / Chapter 2.2.11 --- Oil and grease content --- p.57 / Chapter 2.2.12 --- Total Petroleum Hydrocarbons (TPH) --- p.57 / Chapter 2.2.13 --- Total heavy metal analysis --- p.58 / Chapter 2.2.14 --- Toxicity characteristic leaching procedure (TCLP) --- p.59 / Chapter 2.2.15 --- Extraction efficiency --- p.59 / Chapter 2.3 --- Production of mushroom compost --- p.60 / Chapter 2.4 --- Characterization of mushroom compost --- p.62 / Chapter 2.4.1 --- Enzyme assay --- p.62 / Chapter 2.4.1.1 --- Laccase assay --- p.62 / Chapter 2.4.1.2 --- Manganese peroxidase assay --- p.62 / Chapter 2.5 --- Addition of mushroom to soil on site --- p.63 / Chapter 2.5.1 --- Transportation of mushroom compost to Tsing Yi --- p.63 / Chapter 2.5.2 --- Mixing of mushroom compost and soil --- p.64 / Chapter 2.6 --- Soil Monitoring --- p.64 / Chapter 2.6.1 --- On site air and soil measurements --- p.64 / Chapter 2.6.1.1 --- Air temperature and moisture --- p.64 / Chapter 2.6.1.2 --- Light intensity --- p.64 / Chapter 2.6.1.3 --- UV intensity --- p.65 / Chapter 2.6.1.4 --- Rainfall --- p.65 / Chapter 2.6.1.5 --- Soil temperature --- p.65 / Chapter 2.6.2 --- Soil chemical characteristic --- p.65 / Chapter 2.6.3 --- Relative residue pollutant (%) --- p.65 / Chapter 2.7 --- Toxicity of treated soil --- p.66 / Chapter 2.7.1 --- Seed germination test --- p.66 / Chapter 2.7.2 --- Indigenous bacterial toxicity test --- p.67 / Chapter 2.7.3 --- Fungal toxicity test --- p.68 / Chapter 2.7.3.1 --- Preparation of ergosterol standard solution --- p.70 / Chapter 2.8 --- Soil Washing --- p.70 / Chapter 2.8.1 --- Optimization of soil washing --- p.70 / Chapter 2.8.1.1 --- Effect of hydrochloric acid concentration --- p.70 / Chapter 2.8.1.2 --- Effect of incubation time --- p.71 / Chapter 2.9 --- Phytoremediation --- p.71 / Chapter 2.10 --- Mycoextraction --- p.72 / Chapter 2.11 --- Integrated bioextraction --- p.72 / Chapter 2.12 --- Cementation --- p.73 / Chapter 2.13 --- Glass encapsulation --- p.73 / Chapter 2.14 --- Statistical analysis --- p.74 / Chapter 3 --- Results --- p.75 / Chapter 3.1 --- Characterization of soil --- p.75 / Chapter 3.2 --- Characterization of mushroom compost --- p.78 / Chapter 3.2.1 --- Enzyme activity --- p.78 / Chapter 3.2.2 --- Total nitrogen and total phosphorus contents --- p.78 / Chapter 3.3 --- Soil monitoring --- p.79 / Chapter 3.3.1 --- Initial pollutant content in biopile and fungal treatment soils --- p.79 / Chapter 3.3.2 --- On site air and soil physical characteristics --- p.81 / Chapter 3.3.2.1 --- Soil temperature and air temperature --- p.81 / Chapter 3.3.3 --- Soil chemical characteristic --- p.84 / Chapter 3.3.3.1 --- Effect of type of treatment on total petroleum hydrocarbon content --- p.85 / Chapter 3.3.3.2 --- Effect of type of treatment on oil and grease content --- p.87 / Chapter 3.3.3.3 --- Soil pH --- p.89 / Chapter 3.3.3.4 --- Moisture --- p.91 / Chapter 3.3.3.5 --- Electrical conductivity --- p.92 / Chapter 3.3.3.6 --- Salinity --- p.93 / Chapter 3.3.3.7 --- Microbial population --- p.95 / Chapter 3.3.3.8 --- Removal of organopollutant PAHs in biopile and fungal treatment --- p.98 / Chapter 3.3.3.9 --- Effect of type of treatment on residual PAHs at Day 4 --- p.104 / Chapter 3.3.3.10 --- Effect of type of treatment on residual PAHs at peak levels --- p.107 / Chapter 3.3.3.11 --- Effect of type of treatment on residual organopollutants at the end of treatments --- p.109 / Chapter 3.3.3.12 --- Effect of type of treatment on total nitrogen and phosphorus contents --- p.111 / Chapter 3.3.3.13 --- Effect of type of treatment on physical and chemical properties of soil --- p.113 / Chapter 3.4 --- Toxicity of treated soil --- p.116 / Chapter 3.4.1 --- Seed germination test --- p.116 / Chapter 3.4.2 --- Indigenous bacterial toxicity test --- p.120 / Chapter 3.4.3 --- Fungal toxicity test --- p.125 / Chapter 3.5 --- Soil washing --- p.129 / Chapter 3.5.1 --- Optimisation of soil washing --- p.129 / Chapter 3.5.1.1 --- The effect of hydrochloric acid concentration --- p.129 / Chapter 3.5.1.2 --- The effect of incubation time --- p.134 / Chapter 3.6 --- Mycoextraction --- p.139 / Chapter 3.7 --- Phytoextraction and integrated bioextraction --- p.146 / Chapter 3.8 --- Cementation --- p.153 / Chapter 3.9 --- Glass encapsulation --- p.158 / Chapter 4 --- Discussion --- p.160 / Chapter 4.1 --- Characterization of soil --- p.160 / Chapter 4.2 --- Characterization of mushroom compost --- p.162 / Chapter 4.2.1 --- Enzyme activity --- p.162 / Chapter 4.2.2 --- Total nitrogen and total phosphorus contents --- p.163 / Chapter 4.3 --- Soil monitoring --- p.163 / Chapter 4.3.1 --- Initial pollutant content in biopile and fungal treatment soil --- p.163 / Chapter 4.3.2 --- On site air and soil physical characteristics --- p.164 / Chapter 4.3.3 --- Soil chemical characteristic --- p.164 / Chapter 4.3.3.1 --- Soil pH --- p.164 / Chapter 4.3.3.2 --- Moisture --- p.165 / Chapter 4.3.3.3 --- Electrical conductivity --- p.165 / Chapter 4.3.3.4 --- Salinity --- p.166 / Chapter 4.3.3.5 --- Microbial population in biopile and fungal treatments --- p.166 / Chapter 4.3.3.6 --- Removal of organopollutant PAHs in biopile and fungal treatments --- p.168 / Chapter 4.3.3.7 --- Effect of type of treatment on residual PAHs at peak levels --- p.170 / Chapter 4.3.3.8 --- Effect of type of treatment on residual oil and grease and TPH contents --- p.171 / Chapter 4.3.3.9 --- Effect of type of treatment on total nitrogen and phosphorus contents --- p.172 / Chapter 4.3.3.10 --- Effect of type of treatment on physical and chemical properties of the soil --- p.173 / Chapter 4.4 --- Toxicity of treated soil --- p.174 / Chapter 4.5 --- Summary of Pleurotus pulmonarius mushroom compost on organopollutant remediation --- p.177 / Chapter 4.6 --- Soil washing --- p.178 / Chapter 4.7 --- Mycoextraction --- p.180 / Chapter 4.8 --- Phytoextraction and integrated bioextraction --- p.182 / Chapter 4.9 --- Cementation --- p.184 / Chapter 4.10 --- Glass encapsulation --- p.185 / Chapter 4.11 --- "Summary of physical, chemical and biological heavy metal removal treatments" --- p.186 / Chapter 4.12 --- Future studies --- p.187 / Chapter 5 --- Conclusion --- p.190 / Chapter 6 --- References --- p.193

No description available.

Sulfolane (tetrahydrothiophene 1,1-dioxide, C4H8O2S) is a highly water-soluble, non-ionizable, organic compound used along with diisopropanolamine in the SulfinolTM process to remove hydrogen sulfide from natural gas. Sulfolane has been identified in wetland vegetation near a sour gas processing facility in Alberta, Canada, and extensive uptake of sulfolane by cattails has also been demonstrated in a laboratory environment. Consequently, it has been suggested that plants could play an important role in the natural attenuation of sulfolane in contaminated wetlands. This assumes that the sulfolane is metabolized and/or sequestered in the plant and not released back into the environment during winter dieback. To address the potential release issue, individual cattails (Typha latifolia) were grown hydroponically in 500-mL glass containers containing one of three initial sulfolane concentrations (8, 40, or 200 mg/L) for a specified duration (7 to 28 days). Half the cattails were used to quantify uptake as a function of time and exposure concentration and the other half were used to evaluate the potential release of sulfolane into the hydroponic solution. Non-exposed cattails and non-planted systems containing sulfolane served as controls. The cattails used to evaluate the potential release of sulfolane were frozen directly in their individual containers at the end of the appropriate exposure period. After being frozen for a minimum of 72 hours, the containers were thawed and the amount of sulfolane released was monitored. At the end of the 28-day uptake period, sulfolane leaf tip tissue concentrations as high as 3600, 1050, and 165 mg/kg dry weight were found for the cattails initially exposed to 200, 40, and 8 mg/L sulfolane, respectively. The percentage of sulfolane subsequently released by the cattails after the freeze-thaw treatment declined as a function of the duration exposed. The percentages of sulfolane released measured in the water after 72 hours in addition to the plant tissue extractions were 71%, 54%, 27%, and 12% for the 40 mg/L concentration at 7-, 14-, 21-, and 28-day exposure periods, respectively. Other concentrations showed the same decreasing trend for increasing exposure periods. The declining release as a function of time suggests metabolism and/or sequestration of the sulfolane within the plant. The significant uptake and limited release of sulfolane from mature plants indicate that wetland plants could play an important role in its natural attenuation.

Permeable reactive barriers (PRBs) are one of the leading technologies being developed in the search for alternatives to the pump-and-treat method for the remediation of contaminated groundwater. A new optimising design methodology is proposed to aid decision-makers in finding minimum cost PRB designs for remediation problems in the presence of input uncertainty. The unique aspects of the proposed methodology are considered to be: design enhancements to improve the hydraulic performance of PRB systems; elimination of a time-consuming simulation model by determination of approximating functions relating design variables and performance measures for fully penetrating PRB systems; a versatile, spreadsheet-based optimisation model that locates minimum cost PRB designs using Excel's standard non-linear solver; and the incorporation of realistic input variability and uncertainty into the optimisation process via sensitivity analysis, scenario analysis and factorial analysis. The design methodology is developed in the context of the remediation of nitrate contamination due to current concerns with nitrate in New Zealand. Three-dimensional computer modelling identified significant variation in capture and residence time, caused by up-gradient funnels and/or a gate hydraulic conductivity that is significantly different from the surrounding aquifer. The unique design enhancements to control this variation are considered to be the customised down-gradient gate face and emplacement of funnels and side walls deeper than the gate. The use of velocity equalisation walls and manipulation of a PRB's hydraulic conductivity within certain bounds were also found to provide some control over variation in capture and residence time. Accurate functional relationships between PRB design variables and PRB performance measures were shown to be achievable for fully penetrating systems. The chosen design variables were gate length, gate width, funnel width and the reactive material proportion. The chosen performance measures were edge residence, centreline residence and capture width. A method for laboratory characterisation of reactive and non-reactive material combinations was shown to produce data points that could realistically be part of smooth polynomial interpolation functions. The use of smooth approximating functions to characterise PRB inputs and determine PRB performance enabled the creation of an efficient spreadsheet model that ran more quickly and accurately with Excel's standard non-linear solver than with the LGO global solver or Evolver genetic-algorithm based solver. The PRB optimisation model will run on a standard computer and only takes a couple of minutes per optimisation run. Significant variation is expected in inputs to PRB design, particularly in aquifer and plume characteristics. Not all of this variation is quantifiable without significant expenditure. Stochastic models that include parameter variability have historically been difficult to apply to realistic remediation design due to their size and complexity. Scenario and factorial analysis are proposed as an efficient alternative for quantifying the effects of input variability on optimal PRB design. Scenario analysis is especially recommended when high quality input information is available and variation is not expected in many input parameters. Factorial analysis is recommended for most other situations as it separates out the effects of multiple input parameters at multiple levels without an excessive number of experimental runs.

There are some 15,000 known organophosphorus chemicals. Some of these OP’s, including VX and paraoxon, demonstrate an acute neurotoxicity due to the inhibition of cholinergic enzymes. Organophosphorus chemical warfare agents and pesticide neurotoxins are subject to hydrolysis by OP degrading enzymes. To be useful as a bioremediation or anti-chemical warfare agent, the enzyme must be tailored for, and integrated into, a practical application platform. Several studies have established enzyme-based countermeasures, describing such diverse applications as decontaminating foams for surface remediation, encapsulating enzyme with liposome for in vivo therapy, enzyme attachments to surfaces for biosensors and development of a corn expression system for large-scale enzyme production. The goal of the research described here is to select, investigate and improve the operational potential of organophosphate-degrading enzymes including Organophosphorus Hydrolase (OPH, 3.1.8.1) and Organophosphorus Acid Anhydrolase (OPAA, 3.1.8.2). Using saturation kinetics, the catalytic efficiencies of these two major detoxification enzymes were characterized with substrates representing each class of OP neurotoxin, phosphotriester, phosphothioate and phosphofluoridate. OPH presents superior kinetic parameters with each OP class tested. Variants of OPH were created to increase the operational effectiveness of OP hydrolytic enzymes against phosphorothioates. An H254S/H257L mutation in the active site resulted in an improvement in the kinetics (kcat/KM) for the phosphorothioate, demeton-S. To screen potential vascular protection therapies, an in vitro protocol was developed to predict enzymatic effectiveness for protection of acetylcholinesterase from acute OP-inhibition. The protection abilities of the enzymes were directly related to their second order rate constants as inhibitory levels of OP are below the KM of the enzymes. Consideration of contaminant nature concentration and enzyme kinetic parameters, kcat and KM, is critical to understanding decontamination and effective use of enzyme technology. These technologies continue to develop and provide promising new decontamination tools for OP compounds.

More than 30,000 potential Superfund sites have been identified. Heavy metals are contaminants at many of these Superfund sites. The average cost of cleanup a single-typical Superfund site currently stands at $20 million, and it is expected that the cost may escalate to $50 million within the next decade. Problems have already been encountered during the inspection of sites, and available technologies have not been effective in treating all sites. Lack of innovative strategies for dealing with contaminated soils is a major obstacle to completing Superfund site cleanup. The characteristics of low molecular weight (LMW) organic acids (citric, oxalic, and succinic acids) can be utilized as an agent in soil washing and flushing to develop an innovative technology in the remediation of the soil contaminated with heavy metals. The objective of the work was the testing of a new remediation technology involving soil flushing and washing with LMW organic acids, designed to permanently remove heavy metals from contaminated soil at Superfund sited. Significant amounts of heavy metals (Cu, Pb, Zn) were removed and formed soluble metal-organic complexes at higher concentrations of organic ligands. At a citric concentration of 100 mM, over 70~80% of copper, lead, and zinc were mobilized and all metals extracted were complexed with citrate ions as various forms. Therefore, the use of citric acid to remove heavy metals from contaminated soils would be less costly that using EDTA. The subsequent pH elevation by hydrated lime, Ca(OH)₂, causes the decomplexation of Pb-citrate and initiates precipitation of lead hydroxide. Results showed that slightly alkaline conditions (pH 8.5), which are much lower than that used with EDTA, are needed for substantial precipitative removal of the lead. Increasing calcium nitrate concentration significantly improved the Pb(II) desorption via a cation exchange reaction, That is, the time required to recover lead from the contaminated soil during a soil column experiment was greatly reduced as the concentration of calcium nitrate in the influent was increased. Varying influent pH had little effort on the rate of lead mobilization in the soil columns due to the buffering capacity of the soil, which maintained the effluent pH at the soil pH. The effluent flow rate had no effect on mobilizing Pb(II) from the soil. A higher concentration of citric acid resulted in a much faster rate of lead mobilization from the contaminated soil. Differences in lead desorption rates between influent pHs of 4.5 and 6 were significantly high. However, lead desorption curves for citrate solution at a lower pH value (pH < 4.5) were nearly identical. The flow rate of effluent has no effect at removing lead in the range of 0.1~1.0 mL/min. Also, lead transport model was developed under the assumption of one-dimensional flow through a homogeneous porous medium. A simplified model was also developed by assuming no dispersion effect, no immobile aqueous-phase zone, and linear desorption kinetics. An analytical solution of the simplified equation was obtained by solving a partial differential equation. The computer simulations were fitted to experimental data using estimates for model parameters which were not obtainable independently in experiments. At higher concentrations and pH of the influent, this model presented here fitted well with the experimental data. / Graduation date: 2013

In order to preserve groundwater as a viable source of drinking water, remedial measures must be applied where appropriate. The application of the various remedial technologies is site and contaminant dependent. Differing geology, subsurface soil, groundwater geochemistry, type of contaminant present, cost and even accessibility to the site are all considerations when selecting an appropriate remedial system. At many sites oxygen is a limiting factor for aerobic degradation of many organic compounds like methyl tert butyl ether (MTBE) and hydrocarbons found in diesel and fuel oil, etc. (Nyer et al, 2002). Mechanisms limiting the success of getting the oxygen out of the passive release well include: · Slow chemical diffusion of oxygen in water; · Limited cross section of the groundwater flowing into the well and advecting oxygenated water back into the aquifer; and · Generally weak transverse dispersion, both horizontal and vertical, during subsequent advection of the oxygenated water in the porous media. These issues must be recognized even in the design of a passive release well remediation system. For example, a typical remedial objective is to deliver dissolved oxygen across the width and vertical extent of a contaminant zone in an aquifer. The width of the oxygen plume around the injection well defines how many oxygen-release wells are required to create a curtain of oxygen. Cost-effective design dictates fewer wells, while effective coverage may dictate more wells placed closer together. Thus, understanding the transverse width over which significant oxygen is passively released to the aquifer (the “radius of influence”) is a critical design parameter and the focus of this thesis. Due to the difficulty in getting a passively released dissolved oxygen plume to transversely encompass the total width of a contaminant plume, other more efficient means of introducing oxygen into the subsurface are required. Injecting amended water directly into a release well would increase the transverse distance in which dissolved oxygen would spread. A series of experiments were conducted at CFB Borden to assess the efficacy of an oxygen releasing technology called the iSOC™. The experiments were all conducted in the same manner, by connecting a tank of oxygen to the iSOC™ unit, which then was placed in a release well and allowed to run in experiment 1 for 103 days, experiment 2 for 132 days and experiment 3 for 29 days. iv Dissolved oxygen concentrations were measured at varying time intervals throughout each experiment using an Orion dissolved oxygen probe. Results of each of the three experiments were very similar in that dissolved oxygen was only detected in a very narrow plume (10 cm to 25 cm in width) within 1 m of the release well. The presence of BTEX, BOD and COD within the groundwater and soil at the site were investigated to assess if presented a significant enough sink for the oxygen and thereby limiting the transverse growth of the dissolved oxygen plume. Groundwater results indicated that while dissolved oxygen was utilized for BTEX degradation and to overcome the natural oxygen demand (both BOD and COD) at the site, the amount of oxygen released into the aquifer would have satisfied both of these processes. The COD of the soil at the site presented a higher oxygen demand than the groundwater and presented a greater limiting factor to the transverse growth of the oxygen plume. By releasing oxygen passively with the iSOC™ only a small transverse portion of the Borden aquifer was likely influenced. This limitation has been noted in general for passive release technologies (Wilson & Mackay, 1995). While the iSOCÔ technology develops very high oxygen levels in the groundwater in the release well, it does not overcome the hydrogeological constraint of limited transverse dispersion. Thus, a high oxygen concentration is delivered to a very narrow segment of the aquifer. Overall, transverse dispersion has a minimal impact on a passively release oxygen plume, particularly in close proximity to the release well, but once the plume has migrated a distance away from the release well the effect of transverse dispersion increases. The oxygen demand of an aquifer can also limit the effect of transverse and longitudinal dispersion. If a site has a high chemical or biological oxygen demand the released gas will be consumed before dispersion can have an effect on the plume. By injecting nutrient rich water into a release well the water will forcibly overcome any influence transverse dispersion will have in and around a release well, thereby relying on longitudinal dispersion to create a larger area for contaminant degradation to occur.

Water quality degradation is the foremost environmental issue faced by the mining industry. Negative impacts on water quality are commonly associated with unmitigated drainage emanating from sulfide-bearing mine waste deposits. These impacts stem from the liberation of acidity, sulfate, metals (e.g. Fe, Ni, Cu, Zn and Pb), and trace elements (e.g. Co, As, Cd, Sb and Tl) during the oxidation of sulfide minerals. Drainage at operational mines is commonly treated using techniques such as chemical oxidation and acid neutralization, which can succeed in achieving regulatory discharge guidelines. However, active treatment techniques are commonly burdened by high capital and operating costs. The development of passive technologies for treatment of mine drainage, which promote sulfate reduction, metal-sulfide precipitation and alkalinity production, therefore present a cost-effective alternative for managing mine drainage quality. This thesis describes laboratory and field evaluations of techniques for passive in situ treatment of acidic and neutral mine waters. Laboratory batch experiments evaluated the treatment of acid mine drainage (AMD) with mixtures of organic carbon and zero-valent iron (ZVI) for use in permeable reactive barriers (PRBs). Modest increases in sulfate-reduction rates up to 15 % were achieved by amending organic carbon mixtures with 5 to 10 % (dry wt.) ZVI. Reactive mixtures containing organic carbon supported growth of sulfate-reducing bacteria (SRB) and facilitated removal of Fe, Zn, Cd, Ni, Co and Pb. However, organic carbon was necessary to support SRB growth and sulfate reduction. Removal of Zn, Cd, Ni, Co and Pb in the absence of organic carbon is attributed to sorption and (co)precipitation reactions at the ZVI surface. Scanning electron microscopy (SEM) and X-ray absorption near-edge structure (XANES) spectroscopy confirmed the presence of secondary Fe-sulfides in mixtures containing organic carbon. The dominant reaction product in these mixtures was identified as disordered mackinawite [Fe1+xS]. The addition of ZVI to organic carbon enhanced AMD treatment over the duration of this experiment; however, long-term evaluation is required to identify optimal reactive mixtures. Field-based investigations into passive management of near-neutral pH tailings pore-water were carried out at the Greens Creek mine, located near Juneau, Alaska, USA. These studies focused on delineation of mechanisms controlling tailings pore-water chemistry, and a evaluation of the effectiveness of organic carbon amendment of tailings for passive in situ management of pore-water quality. Results demonstrate that sulfide-mineral oxidation and carbonate dissolution are the primary influences on tailings pore-water composition. Pyrite [FeS2] accounted for < 20 to > 35 wt. % of the tailings mineral assemblage, whereas dolomite [CaMg(CO3)2] and calcite [CaCO3] were present at ≤ 30 and 3 wt. %, respectively. The sulfide-mineral assemblage was dominated by pyrite; however, sphalerite [(Zn,Fe)S] and galena [PbS] were commonly observed, and tetrahedrite [(Fe,Zn,Cu,Ag)12Sb4S13], arsenopyrite [FeAsS], and chalcopyrite [CuFeS2] were present in lesser amounts. Geochemical analysis of tailings core samples generally agreed with mineralogical data. The occurrence of Cd, Cr, Co, Mo, Ni, Se, and Tl is attributed to their occurrence as impurities in primary sulfide phases. Most probable number (MPN) populations of neutrophilic sulfur-oxidizing bacteria (nSOB) and SRB were elevated at several locations within the tailings deposit. Near-neutral pH conditions dominated; however, elevated concentrations of dissolved SO4, S2O3, Fe, Zn, As, Sb, and Tl were observed within and below the oxidation zone. Field-scale experiments conducted over four years evaluated passive in situ treatment of pore-water by amending unoxidized tailings with 5 and 10 vol. % organic carbon. Field-scale cells were constructed to evaluate amendments containing differing mixtures of peat, dried spent brewing grain (SBG), and municipal biosolids (MB). Organic carbon amendment of the tailings supported the development of conditions favorable to sulfate reduction. Decreases in aqueous SO4 concentrations were observed in three cells amended with mixtures of peat, SBG, and MB. Removal of SO4 was generally accompanied by H2S production, enrichment in 34S-SO4, and increased SRB populations. Undersaturation of pore-water with respect to gypsum was observed. Sulfate reduction was sustained for the duration of the experiment in cells amended with 5 vol. % peat + SBG and 10 vol. % peat + SBG + MB. The addition of organic carbon also supported reductive dissolution of Fe(III) (oxy)hydroxides and mobilization of Fe and As. The largest increases in aqueous Fe and As concentrations were observed in cells amended with MB. Subsequent decreases in Fe and As concentrations were observed under sulfate-reducing conditions. Attenuation of Zn, Sb, and Tl accompanied SO4 removal. Mineralogical examination by SEM revealed the presence of secondary Zn-S and Fe-S precipitates on surfaces of organic carbon particles, and carbonate and aluminosilicate grains. This study demonstrates that amendment of tailings with a small and dispersed mass of organic carbon has potential to improve the quality of tailings pore water.