The four papers of this dissertation explore themes related to waste prevention, the system boundaries, functional units and scale of life cycle assessments (LCAs) of municipal solid waste (MSW) management, as well as the transparency and consistency of the application of LCA methods. The first paper is a comparative analysis of the methodological choices and transparency of 20 LCAs of MSW that were recently published in peer-reviewed journals, and includes a comparison of their midpoint level impact values using statistical indicators. The second paper proposes a conceptual model, designated WasteMAP (Waste Management And Prevention), for evaluating LCAs of MSW which incorporate waste prevention. In WasteMAP, waste prevention through dematerialization is viewed as analogous to waste treatments so long as it does not affect the functional output (product services) of MSW-generating product systems. Papers 3 and 4 comprise the WasteMAP LCA case study. Paper 3 depicts product LCAs of wine and spirit packaging (conventional, lightweight and refillable, each type generating different quantities of waste) at the scale of the individual package and the municipality. At the municipal scale, the LCAs address impacts from the wine and spirit packaging supplied in the City of Toronto, Canada in 2008, and a waste prevention scenario which substitutes lighter weight and reusable containers. The lowest endpoint level impacts out of the five container types studied were associated with refillable containers and aseptic cartons. Paper 4 addresses the Toronto MSW management system and applies the WasteMAP model to allow for the comparison, on a functionally equivalent basis, of the LCA results of a reference scenario, based on 2008 data, with a scenario incorporating six types of waste prevention activities (prevention of unaddressed advertising mail, disposable plastic bags, newspapers, lightweight and refillable wine and spirit packaging, and yard waste). The findings highlight the benefits of waste prevention, and the relative significance of the decision to account for recycled content when modelling waste prevention. The endpoint level impact assessment results using the ReCiPe and Impact 2002+ evaluation methods are in keeping with the assumption in the waste hierarchy that waste prevention has a superior environmental performance.

Soil fungi play an important role in regulating plant communities as well as above and below ground ecosystem-level processes; conversely, plant communities may also affect the structure and functionality of these root-associating fungi. Alteration of these fungal communities due to non-native plant invasion has the potential to disrupt biogeochemical cycling, soil structure, and plant growth. Both beneficial symbionts such as arbuscular mycorrhizal fungi (AMF) as well as the total fungal community are potentially altered by aggressive invasive plant species in such a way as to disrupt existing native endophytic fungal communities in the soil post invasion. This disruption could provide a pathway for invasion and suggests the importance of investigating plant-fungal associations in invaded ranges. I used molecular techniques to characterize the fungal communities colonizing Vincetoxicum rossicum or Dog-strangling vine (DSV) and Alliaria petiolata or garlic mustard, both European natives that are currently well established in Eastern North America, as well as native plants that are commonly found persisting in the presence of dense colonies of DSV, as well as those same natives growing separately from DSV. Fungi colonizing different plant groups were analyzed using primers that target the internal transcribed spacer region of the ribosomal operon in order to amplify total fungal species (TF), as well as primers designed to exclusively amplify AMF using small subunit rRNA sequences. Significant differences were observed in the diversity of both the TF and the AMF communities colonizing native plants in the invaded sites relative to the uninvaded sites. Sequencing work indicated that DSV forms associations with a broad array of fungal partners relative to proximal native plants, suggesting the likelihood of it being a fungal generalist. As well, DSV was found to associate with described opportunistic AMF such as Glomus intraradices, G. caledonium, G. fasciculatum and G. mosseae, while natives growing within DSV patches were not. Finally, garlic mustard was found to have the dominant effect where DSV and garlic mustard were co-occurring. These findings support the ongoing investigations into plant invasion processes, and therefore contribute to the development of effective strategies for invasive species management as well as site restoration techniques.

This dissertation reports a study exploring adult engagement with sustainability learning practices in EcoSchools-certified secondary schools in Canada, Lithuania and Sweden as a means towards shaping a liveable future. The study is situated in the area of education for sustainable development. The study design was initially based on an interest in revealing specific practices of sustainability education as a means of improving the relationship between environmental impact and wealth. While echoing findings in the existing literature, this research contributes to the development of the field through insight into the perspectives that adults bring to sustainability education. Primary data collected in the spring of 2006 were recorded (mostly single) semistructured interviews with 30 individuals (national coordinators, caretakers, teachers and administrators), including 10 Canadians from four schools, 14 Lithuanians from four schools, and six Swedes from two schools. Four phases of qualitative analysis were used on the data: initial transcript coding and trends; précis document trends; a six-stage model of interview responses allowing vertical (between question) and horizontal (between stage) comparisons; word maps of subthemes as a scaffold to detail participants’ four primary views (long, wide, deep, dynamic) regarding sustainability. Ultimately, the results of this study point less than expected to revealing specific transferable practices regarding success and challenge in EcoSchools. Rather, these findings provide some insight into a means of shaping a sustainable future through an individual’s sustainability perspective: a living responsiveness based on a sense of connection, supported by improved sustainability cognition, and realized through sustainability practice and considered engagement.

Open and throughfall precipitation samples were collected at Haliburton Forest for a total of nine events from July – November of 2009. The following species were analyzed quantitatively: NO3-, SO42-, Cl-, HCOO-, C2O42-, NH4+, Na+, K+, Ca2+, and Mg2+. Wet deposition inputs to the system were quantified and the sources of wet-deposited species were probed. The throughfall method was employed to quantify inputs to the forest floor and probe canopy-precipitation interactions. Leaf wash samples at three heights aided in the interpretation of throughfall data and allowed for an examination of vertical profiles of dry deposition to the canopy. Results suggest possible nitrate foliar leaching during the growing season, although this appears to cease during senescence. This finding supports previous evidence that Haliburton Forest has shifted from nitrogen-limitation toward nitrogen-saturation and estimated total atmospheric N inputs to the system are close to the proposed critical load of 10 kg N ha-1 yr-1.

I studied how geology, land use and rainfall, correlated with peak flow responses in 110 headwater stream sites during a drought year. Highest discharges were observed in the most developed catchments and in the most poorly drained soils, but specific responses were variable depending on both geology and land disturbance. Redundancy analysis indicated that both surficial geology and land disturbance were important predictors of discharge and that rainfall was in general a poor predictor of discharge. I conclude that responses of headwater streams to individual storms are unpredictable from data generated using GIS, but increased peak flows occur associated with human development, mitigated by surficial geology. The headwater streams that are most vulnerable to flow alterations occur on poorly drained soils, and where urbanization tends to concentrate. Much greater attention to managing water is required if further degradation of stream ecosystems is to be prevented from our future land use.

Doctor of Philosophy / Department of Agronomy / Ganga M. Hettiarachchi / Constructed wetland treatment systems (CWTSs) are an alternative adaptation for flue-gas desulfurization (FGD) wastewater purification. A series of laboratory-based soil column studies mimicking a pilot-scale CWTS was carried out to evaluate the performance of the treatment system in detail. The main objectives of studies were to (1) understand the transport characteristics, retention capacity and transformation of selenium and other FGD constituents in the CWTS, (2) evaluate the effectiveness of soil treatments and influent flow rate on the performance of the CWTS, and (3) develop a mechanistic understanding of the CWTS performance through monitoring interrelationships of selenium (Se), arsenic (As), iron (Fe), and sulfur (S). Ferrihydrite (1% w/w), and labile organic carbon (OC) were used as soil treatments. Different influent flow rates, X (1.42 mL/hour), 2X, or 1/2X were used depending on the objectives of each study. Deoxygenated 1:1 mixture of FGD: raw water was the influent. It was delivered to the saturated columns with an upward flow. Effluent samples were collected continuously, and analyzed for constituents of concern. End of these experiments, soil from sectioned columns were used for total elemental analysis, sequential extraction procedure (SEP) for Se, and synchrotron-based X-ray spectroscopy analyses. Results indicated a complete Se retention by the columns. Boron, and fluorine partially retained whereas sodium, sulfur, and chlorine retention was weak, agreeing with field observations. Some of the initially-retained Se (~ 4 to 5%) was mobilized by changing redox conditions in the soil. Selenium fed with the wastewater accumulated in the bottom 1/3 (inlet) of the soil columns and was mainly sequestrated as stable forms revealed by SEP. Bulk-, and micro-XANES analyses suggested the retention mechanism of Se from the FGD wastewater was via the transformation of Se into reduced/stable forms [Se(IV), organic Se, and Se(0)]. Under wetland conditions, native soil As was mobilized by reductive dissolution of As associated minerals. However, the ferrihydrite amendment suppressed the native soil As mobility. Micro-XRF mapping integrated with As, and Fe-XANES suggested that the mechanism of native soil As retention was the sequestration of released As with newly precipitated secondary Fe minerals. A long-term study carried out with X, 1/2X flow rates, and OC source indicated enhanced S retention by the slow flow rate (1/2X), most likely due to the time dependency of biogenic S reduction. Further, bulk S-, As-, and Fe-XANES revealed that long submergence period and the slow flow rate increased the formation of reduced and/or biogenic S, realgar-like, and greigite-like species. These observations indicated that modified flow rates could have a significant impact on the long-term trace element (such as As) sequestration in the CWTS. Our studies provide useful information to improve the performance, and longevity of a full-scale CWTS for FGD wastewaters.

Master of Science / Department of Chemical Engineering / Larry A. Glasgow / Feedlots, animal production facilities, and agricultural lands are point and non-point sources for nutrient enrichment of surrounding waterways and result in human enhanced eutrophication. Artificial elevation and increased enrichment from animal wastes, fertilizer, and runoff greatly increase the speed of this natural process and leads to degraded water quality, algae blooms, and fish kills. Phosphorous is typically the limiting nutrient for plant growth, and thus is the main focus of this paper. Phosphates enable excessive and choking plant growth that lead to depleted dissolved oxygen and excessive decaying plant matter, subsequently damaging the aquatic ecosystem. In order to provide an inexpensive and feasible solution to minimize phosphate eutrophication, a passive, vortex generating flume has been proposed to provide the necessary mixing for the removal of phosphorus from waste waters. Preliminary tests with dye tracers and electrolyte pulse injections have been conducted to model the flow characteristics and determine the residence time under a variety of flow conditions, angle of inclination and flow rate. The flume was modeled by two methods: four continuously stirred tank reactors (CSTRs) in series and as four CSTRs in series operating in parallel with a plug flow reactor (PFR). The hydraulic model fit a total of five parameters to the experimental data: Residence time, the inlet concentrations of the electrolyte pulse tracer, and the injection times of the tracer to both types of reactors. The kinetic model was built based on data collected from a different study of swine lagoons using magnesium chloride to precipitate phosphorus as the mineral struvite. The precipitation kinetics were modeled using first order and irreversible reaction and incorporated into the hydraulic model. The vortex generating flume provided an operating space that sufficiently removed phosphorus from the waste stream. Future work will include pilot scale testing of the model using waste streams and the investigation of a scour to minimize solid formation in the flume.

Master of Science / Department of Biology / John M. Blair / Anthropogenic activities impact ecosystems in numerous direct and indirect ways, affecting the cycling of carbon (C) and nitrogen (N) on local, regional and global scales. North America tallgrass prairie is an ecosystem profoundly altered by anthropogenic activities, with most native prairie converted to alternate land uses or heavily impacted by other environmental changes. While aboveground responses to anthropogenic drivers have received much attention, the responses of belowground biota, ecological processes, and nutrient allocation to land management and environmental change are poorly documented, especially over long timeframes. This research builds upon a long-term experiment (the Belowground Plot Experiment) initiated in 1986 at Konza Prairie Biological Station (Manhattan, KS). I utilized a subset of treatments to address the effects of annual burning vs. fire suppression and/or chronic N additions on soil C and N dynamics and microbial communities in tallgrass prairie. I measured a suite of soil variables related to C and N cycling during the 2012 growing season, including total soil C and N, microbial biomass C and N, in situ net N mineralization, potential N mineralization, in situ CO2 efflux, and potentially mineralizable soil C. I also assessed changes in microbial community composition using microbial phospholipid fatty acids (PLFA) profiles. Annual burning significantly (p≤0.05) increased the soil C:N ratio and in situ CO2 efflux, while decreasing potential ammonification and nitrification rates. Annual burning also increased total PLFA mass and relative abundance of fungi. Chronic N addition (100 kg N ha-1 year-1) significantly reduced the soil C:N ratio, while increasing total soil N and potential nitrification and ammonification rates. Chronic N addition reduced potential C mineralization, microbial biomass C and N, and altered microbial community composition by increasing abundance of bacterial PLFAs and reducing fungal PLFAs. Sampling date also significantly affected many variables. These results indicate that different fire regimes and chronic N enrichment over decades affects soil C and N pools and transformations, as well as microbial biomass and composition. In total, this study highlights the importance of long-term ecological research and identifies likely changes in tallgrass prairie nutrient dynamics and soil microbial communities under increased N and frequent burning.

Doctor of Philosophy / Department of Biology / Keith B. Gido / Many native freshwater animals are imperiled as a result of habitat alteration, species introductions and climate-moderated changes in disturbance regimes. Native conservation and nonnative species management could benefit from greater understanding of critical factors promoting or inhibiting native and nonnative success in the absence of human-caused ecosystem change. The objectives of this dissertation were to (1) explain spatiotemporal patterns of native and nonnative success, (2) describe native and nonnative response to uncharacteristic wildfire disturbance, and (3) test the hypothesis that wildfire disturbance has differential effects on native and nonnative species. This research was conducted across six sites in three reaches (tributary, canyon, and valley) of the unfragmented and largely-unmodified upper Gila River Basin of southwestern New Mexico. Secondary production was measured to quantify success of native and nonnative fishes prior to wildfires during 2008-2011. Native fish production was greater than nonnatives across a range of environmental conditions, although nonnative fish, tadpole, and crayfish production could approach or exceed that of native macroinvertebrates and fishes in canyon habitats, a warmwater tributary, or in valley sites, respectively. The second objective was accomplished by measuring biomass changes of a warmwater native and nonnative community during 2010-2013 before and after consecutive, uncharacteristic wildfires. Several native insect and fish taxa decreased after both wildfires, whereas nonnative decreases were most pronounced for salmonids and more limited for other taxa. Finally, effects of uncharacteristic wildfires followed by extreme flooding on metapopulations of native and nonnative fishes were contrasted during 2008-2013. Wildfire and flood disturbances increased extinction probabilities of all native fishes while leaving many nonnative fishes unaffected. These findings revealed a swinging pendulum of native and nonnative success, wherein wildfire disturbance resulted in a pendulum swing in favor of nonnatives. Ensuring the pendulum swings back in favor of natives will be facilitated by management activities that decrease wildfire size and intensity and maintain inherent ecosystem resilience.

Master of Science / Department of Civil Engineering / Natalie Mladenov / The Colorado Front Range of the Rocky Mountains contains undeveloped, barren soils, yet in this environment there is strong evidence for a microbial role in increased nitrogen (N) export. Barren soils in alpine environments are severely carbon-limited, and organic carbon (OC) is the main energy source for heterotrophic microbial activity and sustenance of life. Atmospheric deposition can contain high amounts of OC. Atmospheric pollutants, dust events, and biological aerosols, such as bacteria, may be important contributors to the atmospheric OC load. In this stage of the research we evaluated seasonal trends and annual loadings in the chemical composition and optical spectroscopic (fluorescence and UV-vis absorbance) signatures of wet deposition and dry deposition in an alpine environment, at Niwot Ridge in the Rocky Mountains of Colorado to better understand the sources and chemical characteristics of atmospheric deposition. Dry deposition was found to be an important source of OC to the alpine. Wet deposition contributed substantially greater amounts of dissolved ammonium, nitrate, and sulfate. There were also positive relationships between dissolved organic carbon (DOC) concentrations and ammonium, nitrate and sulfate concentrations in wet deposition, which may be derived from such sources as dust and urban air pollution. We also observed the presence of seasonally-variable fluorescent components in atmospheric samples that are different from aquatic dissolved organic matter (DOM). Finally, the quality of atmospheric organic compounds reflects photodegradation during transport through the atmosphere. These results are relevant because atmospheric inputs of carbon and other nutrients may influence nitrification in barren, alpine soils and, ultimately, the export of nitrate from alpine watersheds.