Mercury -contaminated sediments often act as a sink of mercury and produce methyl-mercury, an acute neurotoxin which readily bio accumulates, due to the presence of bacterial communities hosted by the sediment. One common remediation approach to manage methyl-mercury is to amend the sediment by capping or directly mixing with a sorbent. This thesis aims to assess the capabilities of some calcium-based sorbent to act in that capacity. Laboratory experiments were implemented to simulate mercury fate and behavior in geochemical conditions that capping would likely create. Well-mixed slurries showed that gypsum materials were disparate and their behavior was similar from sand to organocaly. Mercury sorption capacities of these gypsums were poor with a sorption coefficient approximately equal to 300 L/kg. Reduction of methylmercury was minimal and even increased in two of the three materials. Therefore, the three gypsums, which tend to be more cohesive when wetted, doesn’t constitute a viable material for sediment capping. / text

Literacy is a growing national concern that has resulted in federal legislation (e.g., the No Child Left Behind Act) instituting higher accountability for states and schools with regard to reading instruction and remediation. As a result, Florida's statewide measure of achievement, the reading portion of the Florida Comprehensive Assessment Test (FCAT-Reading) is now tied to retention decisions for students in the third grade as part of the pupil progression plan for the state. In its first year of implementation (2003), 23% of third-grade students failed the FCAT and over 28,000 were retained. Though failure rates are decreasing, (i.e., 6% of third grade students failed in 2006), tremendous numbers of students continue to be affected by this policy. Research has consistently shown retention to be a negative experience for children; even when academic gains are made, their subsequent achievement is equal to or lower than that of both same-grade and same-age regularly promoted students within two to three years. However, these findings cannot be generalized to the current student progression plan in Florida, which mandates remediation activities and diligent progress monitoring during and after the retention year. Therefore, holding negative beliefs about the third grade retention policy in Florida is premature as only preliminary research exists to date evaluating the outcomes of the plan. The present study examined the student progression plan in Florida as it relates to performance on the FCAT-Reading and mandated third-grade retention. More specifically, this study examined the relationship between reading performance outcomes and various student characteristics (e.g., retention status, gender, SES, race/ethnicity) as well as school-related variables (e.g., school-wide SES status, school size, Reading First status). This study also explored fifth and sixth grade performance on the FCAT-Reading of low-performing students who were promoted through good cause exemptions. Descriptive analyses revealed that of 12,685 third-grade students retained in 2003, 40% scored at Level 1 in 2006. With regard to students who were promoted due to a good cause exemption, findings indicated that a higher proportion of those who demonstrated reading proficiency through an alternative assessment procedure (67%) or through student portfolios (58%) achieved success in 2006 compared to those who did not demonstrate proficiency (13%-19%). In addition, retention status was significantly associated with scores on the 5th grade FCAT-Reading, but that association varied by student gender.

Remediation has become a compensatory way for an increasing number of students to attend college. The problem addressed in this study was whether student intellectual strengths and learning style preferences were, in part, related to placement or enrollment in remediation courses. The purpose of this quantitative study was to assess whether a particular learning style or dominant intellectual strength was characteristic of freshmen enrolled in remediation courses compared to freshmen not enrolled in remediation courses. This study filled a gap in the literature as no studies have analyzed the combination of learning style preferences with dominant intellectual strengths in an American college population. Its theoretical foundations were Gardner's multiple intelligence theory and Kolb's experiential learning theory. A total of 84 participants completed a demographics survey, the Multiple Intelligence Profiling Questionnaire III, and the Learning Styles Inventory. Results from the Spearman Rho correlation indicated a significant negative correlation between logistic/mathematical intellectual strengths and enrollment in remediation. For learning style preferences, students enrolled in remediation courses were significantly more likely to identify as Assimilating learners. Students in remediation were also significantly more likely to identify as Accommodating learners in comparison to students not enrolled in remediation courses. These results suggest that the college curriculum and how it is taught could be altered to accommodate both students' strengths and strengthen weaknesses in order to facilitate higher levels of academic success, ultimately leading to higher graduation rates and better employment opportunities; these improvements might, in turn, facilitate positive changes for communities in South Florida.

Over 110,000 known methamphetamine (meth) clandestine labs were reported in the U.S. from 1999 to 2008. The production of meth is regarded as a national epidemic, and can lead to substantial contamination of indoor materials. Due to its chemical and physical properties, meth residual can persist on indoor surfaces and in indoor air for prolonged periods. Unfortunately, most remediation techniques lack strong scientific support and cleanup standards are inconsistent across different states. A better understanding of the mechanistic interactions between meth and indoor environment can help improve remediation strategies and the development of regulations. In this study, equilibrium partitioning coefficients (Ke) between a meth surrogate and wall materials were estimated based on laboratory experiments. The resulting Ke values were then used in a screening model to predict meth decay rates from wall materials and indoor air. The effects of ventilation and indoor air mixing on meth off gassing were explored. / text

A cylindrical electrochemical reactor with a 3 in diameter copper or nickel metal foam cathode and a concentric carbon cloth anode was used to destroy aqueous phase carbon tetrachloride (CT). The results show that a high CT conversion can be achieved in regions of the cathode near the anode, but a low CT conversion is obtained in the region around the center of the cathode. This CT conversion distribution in the radial current-conducting direction suggests that a portion of the cathode worked inefficiently even though the overall CT conversion is still adequate. Further research by changing the solution pH and conductivity suggests that the radial conversion distribution is due to radial variations in cathode surface availability. The inherent difficulties that these results imply with regards to reactor scale up suggested a new approach to the design. An annular reactor, consisting of a thin (3.2 mm) nickel foam cathode wrapped around an inert Plexiglas core and separated for an external concentric anode by a semi-permeable membrane was adopted. Under compatible operating conditions, the annular reactor showed a high overall effluent CT conversion. However, experiments at low pH (2.25) yielded higher conversions than under neutral pH conditions. This result suggests that CT conversion is favored by a relatively high proton concentration. This reactor can be simulated by a one dimensional model. The annular reactor was used to destroy PCE and TCE successfully, which suggests that this technique can be employed to treat groundwater contaminated with complex mixtures of chlorinated hydrocarbons.A multi-layer reactor based on the principle of the annular reactor was developed as an option for the scale up of the system. This reactor exhibited high and uniform radial CT conversion.

This thesis examined the effect of sub-boiling temperatures on subsurface flow and mass transport, as a result of electrical resistance heating (ERH). Low temperature ERH was simulated using a newly developed two-dimensional, electro-thermal, flow and transport model (ETM). To capture the non-isothermal processes in the subsurface during low temperature ERH, the ETM included temperature dependent equations for density, viscosity, and electrical conductivity. The model was validated with laboratory experiments in which voltage distribution, instantaneous power, temperature, and tracer transport were measured. Both the tracer experiments and the simulation results indicated that flow and contaminant movement could be significantly impacted by low temperature ERH due to temperature induced buoyant flow. In the first part of the thesis, the ETM was used to study the onset of buoyant flow in the subsurface and its effect on contaminant transport. Buoyant flow was predicted to occur when the ratio between the Rayleigh and thermal Peclet numbers (buoyancy ratio), was greater than 1. The buoyancy ratio was expressed in terms of subsurface temperature, thermal expansion coefficient and hydraulic gradient, thus facilitating its application to subsurface thermal activities. The effect of buoyant flow on contaminant transport was found to be dependent on the buoyancy ratio and Rayleigh number. The second part of the thesis examined the effect of soil heterogeneity, electrical conductivity and applied groundwater flux on energy and mass transport. To examine soil heterogeneity effects, random permeability fields for two aquifers with varying levels of heterogeneity were generated. Higher soil electrical conductivity values increased the power dissipated and resulted in shorter heating times and quicker onset of buoyant flow. Consequently, electrical conductivity had a statistically significant effect on the subsurface energy distribution. The applied groundwater flux had a strong effect on heat and mass transport with lower velocities resulting in upward plume movement due to buoyancy effects. In addition, buoyant flow was observed to dominate over flow through high permeability zones. The last chapter of the thesis investigated the formation and movement of discrete gas bubbles during ERH by combining ETM with a macroscopic invasion percolation (MIP) model. The model simulated soils with different permeabilities and entry pressures at various operating temperatures and groundwater velocities. It was observed that discrete bubble formation occurred in all soils, with upward mobility being limited by lower temperatures and higher entry pressures. By including the MIP model, the resulting aqueous concentrations were significantly different from results obtained with a conventional advective-dispersive model, especially in high permeability soils. This was due to bubbles moving to cooler areas, collapsing, and contaminating previously clean zones. The results of this thesis demonstrated that sub-boiling temperatures affect subsurface flow and mass transport, especially when temperature-induced buoyant flow occurred. Although this study focused on ERH applications, the results may be applicable to other subsurface thermal activities such as geothermal heating.

This thesis examined the effect of sub-boiling temperatures on subsurface flow and mass transport, as a result of electrical resistance heating (ERH). Low temperature ERH was simulated using a newly developed two-dimensional, electro-thermal, flow and transport model (ETM). To capture the non-isothermal processes in the subsurface during low temperature ERH, the ETM included temperature dependent equations for density, viscosity, and electrical conductivity. The model was validated with laboratory experiments in which voltage distribution, instantaneous power, temperature, and tracer transport were measured. Both the tracer experiments and the simulation results indicated that flow and contaminant movement could be significantly impacted by low temperature ERH due to temperature induced buoyant flow. In the first part of the thesis, the ETM was used to study the onset of buoyant flow in the subsurface and its effect on contaminant transport. Buoyant flow was predicted to occur when the ratio between the Rayleigh and thermal Peclet numbers (buoyancy ratio), was greater than 1. The buoyancy ratio was expressed in terms of subsurface temperature, thermal expansion coefficient and hydraulic gradient, thus facilitating its application to subsurface thermal activities. The effect of buoyant flow on contaminant transport was found to be dependent on the buoyancy ratio and Rayleigh number. The second part of the thesis examined the effect of soil heterogeneity, electrical conductivity and applied groundwater flux on energy and mass transport. To examine soil heterogeneity effects, random permeability fields for two aquifers with varying levels of heterogeneity were generated. Higher soil electrical conductivity values increased the power dissipated and resulted in shorter heating times and quicker onset of buoyant flow. Consequently, electrical conductivity had a statistically significant effect on the subsurface energy distribution. The applied groundwater flux had a strong effect on heat and mass transport with lower velocities resulting in upward plume movement due to buoyancy effects. In addition, buoyant flow was observed to dominate over flow through high permeability zones. The last chapter of the thesis investigated the formation and movement of discrete gas bubbles during ERH by combining ETM with a macroscopic invasion percolation (MIP) model. The model simulated soils with different permeabilities and entry pressures at various operating temperatures and groundwater velocities. It was observed that discrete bubble formation occurred in all soils, with upward mobility being limited by lower temperatures and higher entry pressures. By including the MIP model, the resulting aqueous concentrations were significantly different from results obtained with a conventional advective-dispersive model, especially in high permeability soils. This was due to bubbles moving to cooler areas, collapsing, and contaminating previously clean zones. The results of this thesis demonstrated that sub-boiling temperatures affect subsurface flow and mass transport, especially when temperature-induced buoyant flow occurred. Although this study focused on ERH applications, the results may be applicable to other subsurface thermal activities such as geothermal heating.

This thesis explores the process of remediation and renewal in the context of decommissioned gold mining operations in Yellowknife, Northwest Territories, Canada. The work aims to demonstrate that architecture can facilitate understanding and bring awareness to the processes involved in reclaiming industrial sites by creating places for observation, interaction and refl ection. Existing mine infrastructure will be adapted and augmented to support phytoremediation processes, clean energy generation and municipal waste treatment for adjacent Yellowknife residents. These interventions are based on a series of studies involving mineral extraction processes, historic mine development and geological formations. The architectural interventions are phased and are intended to be prototypical strategies for decommissioned mine sites in general, but are specifi cally relevant to those located in sub-arctic climates.

As the Oil Sands in Northern Alberta continue to develop and new companies take up leases, they continue to fragment the region’s communities and landscape. Rather than continuing the trend of subdividing the lands and the population, through isolated workers camps, this thesis proposes a moving city that can follow industry, remediate its path and reconnect the community through its processes. Large scale canopies will cover past mining and tailings sites to create micro-climates and harvest energy through solar updraft. The elevated temperatures under the canopies will provide improved climatic conditions for human inhabitation and a bioremediation industry. Beneath the canopy, the inhabitants will be free to ‘plug-in’ to the provided infrastructure with their own version of ‘home’. A stronger attachment to the community, between people, and new clean industries that the population can find pride in, will vastly improve the reputation of the region.

As more contaminated sites are being discovered, new in situ remediation techniques need to be developed. Chemically treating soil with lime to increase soil pH is a method that may decrease the bioavailability of the contaminant. To test the usefulness of rendering metal-contaminated soils alkaline with dolomitic lime, to improve crop performance, field trials at a site in Port Colborne, ON, with soil nickel concentration (as high as 5000 mg/kg) from refinery emissions were completed. Oat and soybean yield, as well as plant uptake and bioavailabilty of nickel in soil were evaluated. Liming Ni-contaminated soils decreased soybean foliar Ni concentrations from 36.68 µg/g in unlimed fields to 19.98 µg/g in 50 t/ha limed fields in the 2007 growing season; yield of both oat and soybean in unlimed soils was the same (p>0.05) as at a reference site, suggesting that for these soils, remediation is not necessary for yield.