The biodegradation patterns of polycyclic aromatic hydrocarbon (PAH) mixtures were studied in systems with and without sediments. Naphthalene showed no change in its behaviour in the presence of any other PAH. In sediment-free systems, acenaphthene showed a diauxic pattern in the presence of naphthalene, but was unaffected with fluoranthene. Diauxy was not observed in the same mixture in sediment-containing systems. Sediment-free experiments with fluoranthene indicated it was the only PAH not degraded when present alone, and it was only degraded with naphthalene. In sediment-containing systems, fluoranthene degradation only occurred above a critical naphthalene concentration. Experiments using all three PAHs in both sediment-free and -containing systems showed results similar to those obtained using pairs. This work indicated that mixtures of PAHs do have different biodegradation patterns to single compounds. These patterns may be additive. Sediments act as a sink for PAHs, highlighting the concentration dependence of the patterns observed.

This thesis addresses the modeling of the dissolution of residually-trapped multi-component non-aqueous phase liquids (NAPLs) from a porous medium. As part of this work, a model was constructed in which the mass transfer behavior of the NAPL is characterized by a probability density function (pdf) which describes the initial distribution of residual NAPL "blob" volumes. Mass transfer from these trapped NAPL "spheres" is simulated using an empirical relationship for the Sherwood Number, a linear concentration driving force, and multi-component solubility effects. This "Distributed-Site" model is then used to match two sets of dissolution data from a laboratory column test.

Resistant desorption has been widely observed for hydrophobic organic contaminants. It is an important process that impacts sediment quality and contaminated sediment management. Conventional approaches to measure the desorption resistant fraction of sorbed contaminants are by conducting repetitive water desorption, in which the desorption resistant fraction is determined by measuring the solid phase concentration after extended desorption times. This method is time-consuming and impractical for widespread applications. In addition, the final measurement of the solid phase concentration is subject to considerable error, because there is always a fraction of water associated with the solid due to the incomplete separation of the liquid phase from the solid. In this research, a new experimental protocol was developed to rapidly and accurately measure the desorption resistant fraction based on the study of desorption of phenanthrene from Utica sediment.

The design and performance of soil vapor extraction (SVE) systems can be evaluated using mathematical models. A lack of knowledge in how to select the appropriate model and use it properly for field settings are major obstacles limiting the usage of existing codes. The predictive capabilities of many of the commercially available models have never been tested against observed performance of full-scale SVE systems. In this study, we demonstrate the applicability of a coupled, subsurface flow and vapor transport code for simulating the performance of a field-scale soil vapor extraction system. The effects of various modeling simplifications on the accuracy of model predictions, and on the computational time and effort are assessed. VENT3D, a three-dimensional multi-component, multi-phase chemical partitioning model that simulates isothermal flow and transport of organic compounds in the subsurface was selected for testing against data to demonstrate how similar codes can be used to predict the performance of a full-scale SVE system. Simulations were compared to data from pilot- and full-scale operation of an SVE system that was used to remediate a JP-4 jet-fuel contaminated site at Hill Air Force Base, Utah. The standard JP-4 composition was approximated by an equivalent mixture of 11 constituents and as a single constituent using equivalent, mole-fraction-weighted chemical properties, to determine the value of representing mixtures in a multi-component fashion. Air permeability tests data were analyzed independently to estimate vertical and horizontal permeabilities with an analytical model that simulates idealized, axisymmetric gas flow. The initial contaminant mass was the major parameter that had to be adjusted to simulate the contaminant removal using data from pilot and full-scale tests. The value of modeling field studies in a 3-dimensional mode versus 2-dimensional was evaluated. The trade-off between added accuracy in model predictions due to higher problem dimensionality, averaging flow fluctuations, and detailed representation of mixture components, and the extra computational effort and complexity was studied. The model was also used to evaluate the extent of contamination under natural conditions, to predict the effect of long-term operation on cleanup, and to demonstrate how modeling can be used to improve system design and performance.

The interaction of arsenite (As(III)) and arsenate (As(V)) with magnetite nanoparticles has been studied to evaluate the environmental impact of magnetite nanoparticles and possible beneficial use of these nanoparticles in water treatment. The effects of particle size (20--300 nm) and pH on the sorption/desorption of AS(III) and As(V) on magnetite nanoparticles were examined. On a surface area basis, it was found that large and nanometer scale magnetite particles had similar maximum As(III)/As(V) sorption capacities. However, the sorption of As(III) to magnetite showed the same Langmuir sorption slope for the nanometer scale particles as for the large particles, while the sorption of As(V) to magnetite showed a larger Langmuir sorption slope for the nanometer scale particles than for the large crystals. The particle size effect on sorption is constant over a pH range of 4.8 to 8. Sorption of As(V) was found to be greater at lower pH, while sorption of As(III) was not pH sensitive. The sorption data of both As(III) and As(V) have been modeled with the Diffuse Double Layer model. Stronger desorption hysteresis was observed for both As(III) and As(V) sorption to nanometer scale magnetite particles than that to large magnetite particles, which indicates that the decrease of particle size may increase the affinity of sorption. The experimental results showed that magnetite nanoparticles are potentially a very effective sorbent for arsenic removal in water treatment.

In Abbotsford’s Clayburn Watershed, urban rainwater runoff and agricultural land drainage generally enter surface watercourses untreated. Existing literature suggests that both inputs can potentially contribute to non-point source pollution. This study evaluates the effects of non-point source pollution on surface water quality and assesses the role of wastewater management in mitigating these effects. Based on a water quality sampling program carried out between September 2007 and August 2008 both urban rainwater runoff and agricultural land drainage were shown to significantly and negatively affect surface water quality. Subsequently, it is recommended that non-point source pollution should be included in Abbotsford’s wastewater management strategy. Mitigation measures proposed include retention treatment of rainwater in urban areas and manure recycling (waste to energy) projects for agricultural lands.

Street tree health in the City of Victoria, British Columbia has declined in the last decade. Using the health condition of six tree genera representing 72 % of the total 17,601 COV street trees inventory in 2005 this trend is likely in large part due to lack of moisture from June to October. Declining health is evident in branch die back and early leaf drop especially on species with a medium to high water requirement. The Prunus genus (cherries and plums) in particular, which comprises 29% of all COV street trees, was rated at 54% fair to dead condition which is 20% higher than all COV street trees. Current summer precipitation from June to early October totals 105 mm and evapotranspiration for the same period totals -382 mm leaving a moisture deficit of 277 mm. This deficit is projected to increase (based on extreme models) to 362 mm by 2050 and 420 mm by 2080 which will have a devastating impact on street trees which will not able to withstand the intense moisture deficit interval. Recommendations on species selection and maintenance alternatives include: regular monitoring with site specific information, changing the list of trees used for selection and planting, increase watering, and increased maintenance. The results and recommendations of this study may be of value to other jurisdictions that will be affected by the impacts of moisture deficit related to climate change.

This research investigates the nature of the influences children have on their parents' environmental behaviour following involvement in a week long environmental education experience. Using the grounded theory method, children and their mothers were interviewed about their ideas about the ways they felt the children influenced their parents. Four of the five children interviewed reported that they influenced their parents, citing examples of environmental action in the home as an area of influence. Similarly, the majority of parents felt their environmental knowledge and behavior was influenced by their children. What appear to be barriers to effective child-to-parent influence communication are explored, including aspects of program enjoyment and relationships between family members. The theme of child confidence and its relationship to child-to-adult influence is also considered. Areas for future research are identified, including a recommendation for research into the child-to-father influence relationship.

This study explores the organizational culture of the Vancouver Airport Authority as it relates to environmental values and practices. The intent of this research was to investigate the effects of a particular work climate and culture on decision-making related to pro-environmental behaviours. A mixed-methods approach was taken, including a multiple regression survey of employees exploring connectivity with nature, environmental values, and environmental behaviours, and a series of grounded theory interviews probing the obstacles and opportunities to effective environmental management. The results indicate that while age and connectivity with nature were the most significant predictors of general environmental values and behaviours, work-related behaviours were best predicted by human-resource factors such as top management support, training, empowerment, teamwork, and reward programs. Obstacles and opportunities to successful environmental management, garnered from employee interviews, fit into these human resource categories. Recommendations are made both for future research and for the Vancouver Airport Authority.

No description available.