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Low Emission Vehicles (LEVs) represent a car classification which utilizes advancements in automotive technology to address policy objectives associated with energy security and greenhouse gas emissions. The effectiveness of LEVs at addressing these objectives will not only depend on their technical performance but also on their levels of adoption by consumers. With LEVs encompassing cars which are significantly different compared to conventional market options, the understanding of consumer response to these vehicles remains limited. This thesis addresses this limitation in existing knowledge by providing a detailed examination of consumer demand for LEVs in the UK. Through the application of psychometric methods, this thesis assesses the influence of socio-psychological constructs over LEV preference. A bespoke conceptual framework has been developed to provide insights regarding the influence of attitudes, emotions and values. This framework was applied to the design of a self completion household questionnaire distributed over the cities of Newcastle upon Tyne and Dundee. The meanings placed on car ownership are measured alongside the concept of innovativeness to determine if these traits are likely to hinder or advance LEV adoption. Additionally, past research has tended to consider consumer demand for LEVs at a market level perspective with little attention given to social stratification. This thesis advances knowledge in this area by producing a structural analysis of the emerging market for LEVs. Noteworthy consumer segments are identified, described and compared according to their socio-psychological profiles, socio-economic characteristics and LEV preferences. Principle results of the thesis are that socio-psychological constructs account for a greater degree of variance compared to socio-economic characteristics when explaining evaluations of LEVs. The propensity to consider cars through symbolic, emotive and functional meanings tends to decrease assessments made concerning the functional capabilities of LEVs. The concept of innovativeness displays a positive influence over preferences towards LEVs indicating that these vehicles are being considered as innovations. Moreover, heterogeneous consumer segments with unique socio-psychological and demographic profiles are emerging in the LEV market. These segments display a range of LEV preference structures from those which hold high preferences and are likely to characterize early adopters to those which exhibit low preferences and are likely to represent non-adopters.

The purpose of a greenhouse is to maintain desirable growing conditions for plants during the different seasons of the year. The glass-covered greenhouse has been found to be suitable for this purpose through many yeara of use and improvement. It has been very popular for providing a controlled environment in which out-of-season crops can be grown and also as a research house for the study of plant growth. The sturdy construction required to support the weight of glass involves a high initial cost. With the development of plastic sheeting suitable for use as a glazing material, a new type of greenhouse has evolved. Greenhouses covered with plastic do not require the sturdy structure necessary to support glass, although a permanent construction may be used. To date the plastic greenhouse has found its greatest use as a temporary low cost structure. The possibility of growing crops intolerant of frost during the winter months in the southwestern United States where mild winters keep heating costs low, has increased interest in plastic greenhouses. Since high temperatures occur during the summer months in the Southwest, cooling as well as heating have to be provided if the greenhouse is to be operated through the entire year. This study was designed to measure the modification of the environment within a plastic greenhouse and to evaluate the growth response of tomatoes under these conditions. Studies were conducted to determine the temperatures which could be maintained in a plastic greenhouse during the summer, winter and spring seasons. The growth response of tomatoes under plastic was studied using winter and spring variety trials.

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The goal of this study was to prove that aquaponic systems can produce lettuce of equal growth and quality compared to hydroponic lettuce production and to determine the stocking density of fish required for plant growth. Aquaponics is the integration of recirculating aquaculture and hydroponic plant production. The project had four objectives. The first objective was to determine the biomass of fish required for plant growth to develop a fish to plant density ratio. The second objective was to compare lettuce grown with aquaponic water and a hydroponic solution under the same environmental conditions. The third objective was to compare the quality of lettuce grown with aquaponics water plus nutrient supplementation with a hydroponic solution. The fourth objective was to determine the nitrogen dynamics in the aquaponic system and to compare the nutrient composition of lettuce grown with aquaponics water with nutrient supplementation and hydroponic solution. It was determined that under the specified environmental conditions 5 kg m⁻³ of Nile tilapia (O. niloticus) fed 2% of their body weight daily yields on average 4.7 kg m⁻² of lettuce (L. sativa cv. Rex) in 35 days. There was no significant difference (p ≤ 0.05) in biomass or chlorophyll concentration index in lettuce (L. sativa cv. Rex) grown with aquaponics water and nutrient supplements versus a hydroponic solution. The aquaponics solution generated equal biomass and chlorophyll concentration indexes compared to the hydroponic solution. Aquaponics water plus supplementation can yield L. sativa cv. Rex with equal biomass accumulation and chlorophyll concentration indexes compared to hydroponics lettuce. Nutrients added to the aquaponics system consisted of iron, manganese, and zinc. These nutrient concentrations became depleted in the aquaponics water over time and were not replenished via the fish feed. Dolomite was added to the aquaponics system every two weeks to increase the buffering capacity of the water and maintain optimal pH levels. Aquaponics lettuce had similar nutrient composition to hydroponic lettuce. One head of L. sativa cv. Rex (176.75 ± 31.03) will assimilate approximately 5.96 grams of nitrogen (3.38% per dry gram lettuce). One kilogram of fish will yield 6.4 lettuce heads (1,128 grams) and fixate 38.13 grams of nitrogen.

Biochar incorporation in soils has the potential to remove carbon from the atmosphere and to improve soil quality. This research focused on evaluation of the benefit of biochar incorporation in an Arizona soil. Different concentrations of biochar (charcoal from mesquite biomass-derived black carbon) were added to soil in greenhouse experiments. Seven common or potential Southern Arizona crops (alfalfa, wheat, cotton, grain and sweet sorghum, barley and switch grass) were evaluated in the greenhouse experiment. In this experiment; increased biochar concentration treatments produced greater height and biomass production in alfalfa. Sorghum biomass production also increased with biochar concentration. There were no significant differences in biomass production in wheat and barley with increased biochar concentration. Switch grass biomass production had a significant negative correlation with increased biochar concentration. Sweet sorghum biomass production was evaluated in a field experiment conducted at the University of Arizona Red Rock Agricultural Center. A relatively small amount of biochar was incorporated in the top 20 cm of soil in one treatment and soil only was the other treatment: there were no significant differences in yield.Water characteristic curves and bulk densities were measured for biochar/soil mixes. The FASE model was used to simulate evapotranspiration and crop yield for the field sorghum experiment and for several crops grown in the Valsequillo Irrigation District, Puebla, Mexico with measured soil parameters. The model predicted no significant increase in sorghum yield for the level of biochar incorporated in the soil. An increase in yield was predicted for Valsequillo crops.

The Argentine Pampa is a global producer of maize (Zea mays L.) and soybean [Glycine max L. (Merr.), however agricultural practices have caused severe soil degradation and amplified greenhouse gas (GHG) production rates. This study presents the effects of maize-legume intercrops compared with maize and soybean sole crops on GHG production rates and soil physical properties over two field seasons. It also presents the results from a laboratory study in which GHGs were quantified from soils amended with maize and soybean crop residues. In the field study, soil organic carbon (SOC) concentrations were significantly greater (p<0.05) in the maize sole crop and intercrops, whereas soil bulk density was significantly lower in the intercrops and as a consequence soil infiltration was higher. Soil total nitrogen (TN) concentrations were not significantly different between treatments. Soil CO2 production rates were significantly greater in the maize sole crop but did not differ significantly for N2O. However, over the two field seasons both trace gases showed a general trend of greater production rates in the maize sole crop followed by the soybean sole crop. Linear regression between soil GHGs and soil temperature or volumetric soil moisture accounted for up to 51% of the variability in soil CO2 production rates and 60% of the soil N2O production rates. In the laboratory study, soil GHG production rates varied between treatments and between residue addition for both CO2 and N2O but varied only narrowly between treatments and experiments for CH4. Results from this study provided further insight into the effect of agroecosystem management practices on GHG production rates and soil physical and chemical characteristics, and contributed to improving our understanding of optimal agroecosystem design.

Degradation of permafrost in peatlands can convert forested peat plateaus to inundated collapse bogs. Due to increased unfrozen soil carbon stocks and more saturated conditions, collapse bogs can potentially be large emitters of methane. Using a network of bubble traps permanently installed in peat, I tested several hypotheses about controls on ebullition in collapse bogs with varying time since thaw in interior Alaska. Ebullition increased during the growing season, likely due to increased substrate availability and warmer soils. Bubbles were found primarily in shallow peat layers, and were dominated by modern carbon. Ebullition hot spots were associated with high sedge density throughout the collapse sites. Episodic ebullition occurred during atmospheric pressure changes. Overall, my study demonstrated that permafrost thaw in peatlands will result in methane emissions through ebullition that include both young and old carbon, contradictory to the generally accepted paradigm; that ebullition in peatlands is solely a surface process.

Greenhouse tomatoes are the most widely grown greenhouse vegetable in Ontario, with southwestern Ontario having the largest concentration of greenhouse tomato operations in North America. However, there is little data concerning the environmental impacts of producing greenhouse tomatoes in Ontario. This study was conducted to evaluate the potential environmental impacts of greenhouse tomato production in southwestern Ontario by using a life cycle assessment (LCA). Data were collected from greenhouse tomato growers in Leamington, Ontario via a survey, with additional data from documents and databases. The major source of environmental impact came from the energy and source (i.e. fossil fuels) required for heating the greenhouse, followed by fertilization, electricity use, and if included, liquid CO2. Different modelling scenarios proved effective in revealing the benefits and detriments of using various heating sources. This study revealed that energy saving methods should be investigated to mitigate the environmental burdens caused by heating the greenhouse.

Livestock agriculture is a source of methane (CH4), nitrous oxide (N2O) and ammonia (NH3) emissions. A comprehensive approach aimed at mitigating these emissions is needed to reduce the environmental footprint of agriculture. This thesis examined three aspects of a comprehensive mitigation strategy which included: evaluating a management consideration, improving flux measurement techniques, and modeling emissions. The relationships between total solids (TS), gas emissions and surface crust dynamics were assessed. Diurnal and long–term CH4 and N2O flux variations were examined in the context of improving discrete sampling protocols. Finally, a mechanistic model that predicts CH4 emissions from manure slurries was evaluated. Over long–term storage, the crusts were not effective in mitigating total gas emissions because the slurries remained open to the atmosphere for a significant portion of the time. Total CH4 and NH3 emissions were related linearly to TS, while N2O exhibited a sigmoid response. The linear response to TS observed for CH4 and NH3 occurred despite varying crust conditions suggesting that the availability of substrates in slurries is the more important regulator of emissions over long–term storage. Diurnal CH4 and N2O flux variations were linked with the diurnal surface temperature (T0) cycle, with the strength of the relationship depending on surface crust conditions. An assessment of discrete sampling protocols revealed that sampling intervals should be ≤7 d. In terms of the timing, it is best to sample these gases when the T0 is closest to the daily mean, which would typically be before 0900 h or after 1700 h. A mechanistic model of CH4 emissions from slurries was evaluated. The model was most accurate during the first 47 d of storage, after which the accuracy decreased. However, total emissions estimated over 145 d were within –21.1 to 6.0% of measured emissions for slurries with TS 3.2%, 5.8% and 8.2%. Emissions were also modeled using the USEPA inventory method. There was relatively good agreement between the USEPA and mechanistic models, with relative percent differences ranging from 19.9 to 37.3%, which is encouraging from the standpoint of advancing greenhouse gas inventory methods. / Ontario Graduate Scholarship