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All roadway agencies monitor and maintain their infrastructure as it deteriorates over time. Agencies allocate the money that they have for maintenance, rehabilitation and reconstruction operations across their entire network. Regular and timely maintenance and rehabilitation treatments can postpone the need for reconstruction on a roadway. The need for infrastructure sustainability has been brought to the forefront of society and has become an important part of any public agency’s decision making processes. To achieve sustainable roadways social, economic and environmental benefits must be achieved while maintaining technically sound solutions. By considering the amount of energy that is consumed and the amount of greenhouse gas (GHG) emissions generated through various roadway treatments, sustainability can be brought into the decision making process. The objective of this research was to develop a probabilistic model that quantifies the amount of energy that is consumed and carbon dioxide equivalents (CO2e) generated for typical roadway construction, maintenance, rehabilitation and reconstruction projects in Saskatchewan and Alberta. The model constructed within this work was divided into three sub-models: 1) material production, 2) equipment usage and 3) material transport. For every variable that was required to be entered into each sub-model, a low, average or most likely and high value was determined. By using a range of input values the uncertainty of the values entered was incorporated and sensitive parameters were identified. A base case study of a one lane-kilometer (lane-km), 3,700 m2, section of rural roadway was analyzed. For the initial construction of a lane-km of traditional flexible pavement roadway it was determined that 1,870 GJ (giga joules) of energy is required. Based on an annual average amount of energy used per home in Saskatchewan, 126 GJ/year, 1,870 GJ would power approximately 15 homes for one year. Similarly it was determined that 152.4 tonnes (t) CO2e are emitted for the construction of a lane-km of traditional flexible pavement roadway. Based on an average CO2e generation value of 5.1 t per passenger vehicle per year the GHG emissions generated from the construction of a lane-km of roadway is equivalent to the GHG emissions released by approximately 30 passenger vehicles over one year. It was also determined that the volume of CO2e generated for initial construction compared to the volume of material in the roadway was a ratio of 30 to 1. The base case study also reviewed various maintenance, rehabilitation and reconstruction treatments for the amount of energy consumed and GHG emissions generated for one lane-km. From the modeled values it was found that the order of energy consumed and CO2e generated from least to greatest for maintenance treatments is: fog seal, slurry seal, micro surfacing, single, double and triple chip seal and ultra thin overlay. For rehabilitation and reconstruction treatments the order of energy consumed and CO2e generation from least to greatest is: cold in-place recycling, mill and fill, full depth reclamation, remove and replace with recycled materials and remove and replace with virgin materials. Through a sensitivity analysis of the input parameters, it was observed that for maintenance treatments the sensitive parameters were the equipment efficiency (EFE) value, the placement rate of the treatment, the aggregate application rate and the amount of asphalt binder included in the treatment. For rehabilitation and reconstruction treatments, the two most sensitive parameters were the asphalt concrete plant energy and the application rate of the Portland cement. Further investigation into how each sub-model contributed to the overall amount of energy consumed and CO2e generated found the production of materials contributed the greatest to the overall values. When examining the production of each layer in a traditional flexible pavement roadway structure, the asphalt layers contributed the greatest to the energy consumed at 72.1 percent of all materials produced. The asphalt layers also contributed the greatest to the GHG emissions generated from the production of materials at 42.7 percent. Further breaking down the production of the asphalt layers, the energy requirements at the hot mix asphalt concrete plant account for 75.9 percent of the energy consumed and 52.0 percent of the CO2e generated for the production of the materials of the asphalt layers. The cost of each treatment was reviewed based on the cost of diesel at $1.21/litre and the amount of energy consumed. The costs of energy for the maintenance treatments ranged from $174/lane-km for fog seal to $5,488/lane-km of the ultra thin overlay. The cold in-place recycling and mill and fill rehabilitation treatments had energy costs of $13,545 and $21,440/lane-km respectively. The costs of the energy consumed for the reconstruction treatments ranged from $21,710/lane-km for full depth reclamation and $71,164/lane-km for remove and replace with virgin materials. Based on a review of the City of Saskatoon’s 2012 proposed treatment plan for its roadway network the cost of energy was estimated at $1,232,000 for work on 93 lane-km of roadway. The costs of GHG emissions were also determined based on the amount of CO2e generated and the value of one tonne of carbon on the voluntary carbon credit market at $6/tonne. The costs of carbon for the maintenance treatments ranged from $3/lane-km for fog seal to $64/lane-km for the ultra thin overlay. For the rehabilitation treatments the cost of carbon for the cold in-place recycling was $224/lane-km and $266/lane-km for the mill and fill treatment. The reconstruction treatments ranged from $524/lane-km for full depth reclamation and $1,062 for remove and replace with virgin materials. Finally four field case studies were reviewed to determine the amount of energy consumed and GHG emissions generated through construction. The first was the reconstruction of Range Road 232, a rural roadway with virgin materials. The second was the reconstruction of Kenderdine Road with recycled materials. The energy consumed and GHG emissions generated for these construction projects are 1,917 and 1,146 GJ/lane-km, and 150.3 and 92.6 t CO2e/lane-km, respectively. The third case study further reviewed the use of warm mix asphalt concrete (WMAC) and the use of recycled asphalt pavement (RAP) in the Kenderdine Road pavement structure. This research determined that with the incorporation of WMAC and 10 percent RAP in the asphalt layers and with the use of recycled materials in the base layers the amount of energy consumed would be reduced by 31.8 percent and the GHG emissions reduced by 34.8 percent compared to a traditional virgin pavement structure. The final case study reviewed the City of Saskatoon’s 2012 proposed roadway restoration and reconstruction plan. From the model it was found that 38,281 GJ of energy was consumed and 2,617 t CO2e was generated. This work shows that the probabilistic model developed in this research may be applied to a variety of roadway treatments from maintenance to reconstruction in urban and rural applications. With the use of the model, roadway project managers can make informed decisions for roadway treatments based on energy consumption and GHG emission generation values. By incorporating the amount of energy that is consumed and GHG emissions generated into the decision making process of roadway infrastructure management, more sustainable infrastructure management can be achieved.

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The aim of this thesis was to investigate soil and environmental factors which influence the adsorption of DOC in upland, moorland soils. In Chapter 1 climate change, the greenhouse effect and the global carbon cycle are discussed briefly. A more detailed discussion of carbon cycling in the plant-soil-water system focuses on DOC retention in podzols and the review concludes with a summary of the aims of this thesis. A peaty podzol has greater potential to retain DOC than the other major soil types within the Glen Dye catchment, N.E. Scotland. Retention of DOC by physico-chemical surface interactions occurred in the mineral horizons of the soil where locally high concentrations of amorphous Fe and Al were present. Laboratory experiments using potassium hydrogen phthalate as a source of DOC showed that DOC retention is favoured by longer contact times between soil and solution. Net retention of DOC in the podzol profile is decreased by increasing the solution pH and by repeated wetting/drying and freezing/thawing cycles. As temperature and reaction time increased, respiration becomes more important as a mechanism for depleting solution phthalate DOC concentrations. Annual fluxes of DOC in precipitation, podzolic O, E and Bs soil horizon solution and stream water were estimated for the Burn of Waterhead catchment to be 35, 121, 83, 37 and 48 kg C ha-1yr-1 respectively. The DOC fluxes and the concentrations of related elements varied seasonally, with the largest DOC fluxes produced in the autumn and lowest in the summer. The annual DOC flux from the Burn of Waterhead was lower than fluxes from other catchments at Glen Dye. Results from the field site supported laboratory experimental results which suggested that climate change will result in an increase in the DOC flux from results which suggested that climate change will result in an increase in the DOC flux from peaty podzolic soil.

This thesis investigates the potential of improved control to reduce greenhouse gas (GHG) emissions resulting from existing wastewater treatment plants (WWTPs), and demonstrates that significant reductions can be achieved without the need for extensive redesign of treatment processes and without increasing operational costs. An emissions model is developed for use in this study, informed by an in-depth analysis of existing state-of-the-art methods and models for estimating GHG emissions, taking into account their suitability for dynamic modelling and WWTP control strategy optimisation. Through the use of local and global sensitivity analysis tools, sources of uncertainty in the modelling of GHG emissions from wastewater treatment are investigated, revealing critical parameters and parameter interactions; these interaction effects have not been considered in previous studies and thus provide a better understanding of WWTP model characterisation. A key finding is that uncertainty in modelled nitrous oxide (N2O) emissions is the primary contributor to uncertainty in total GHG emissions, due largely to the interaction effects of nitrogen conversion modelling parameters. Further local and global sensitivity analysis is used to investigate the effects of adjusting control handle values on GHG emissions, revealing critical control handles and sensitive emission sources for control. This knowledge assists with the following control strategy development and aids an efficient design and optimisation process. Sources with the greatest variance in emissions, and therefore the greatest need to monitor, are also identified. It is found that variance in total emissions is predominantly due to changes in direct N2O emissions and selection of suitable values for wastage flow rate and aeration intensity in the final activated sludge reactor is of key importance. Sets of Pareto optimal operational and control parameter values are derived using a multi-objective genetic algorithm, NSGA-II, with objectives including minimisation of GHG emissions, operational costs and effluent pollutant concentrations, subject to legislative compliance. It is found that multi-objective optimisation can facilitate a significant reduction in GHG emissions without the need for plant redesign or modification of the control strategy layout, but there are trade-offs to consider: most importantly, if operational costs are not to be increased, reduction of GHG emissions is likely to incur an increase in effluent ammonia and total nitrogen concentrations. Alternative control strategies are also investigated and it is concluded that independent control of dissolved oxygen in each aerated activated sludge reactor is beneficial. Optimised solutions are also assessed with respect to their reliability, robustness and resilience, taking into account the effects of influent perturbations and sensor failures on effluent quality and GHG emissions. This reveals that solutions predicted to achieve the most significant reductions in GHG emissions and operational costs under existing design conditions may perform poorly in reality when subject to threats. Dissolved oxygen setpoints which correspond with unacceptable effluent quality reliability and decision variables which should not be considered in future optimisation due to their negative impacts on reliability, robustness and resilience are also identified. Lastly, guidelines for the development of control strategies to reduce GHG emissions are presented. These address GHG emission sources, key control handles and decision variables, choice of control strategy, optimisation and detailed design, and model limitations and uncertainties.

Soil is the largest terrestrial carbon (C) store, containing an estimated ~1500 Gt C in the upper 1 m of soil. The long term storage of soil organic C (SOC) requires that it is somehow protected from microbial decomposition – or ‘stabilised’ – in the soil matrix. Three mechanisms are commonly identified as factors controlling the stability of SOM: chemical recalcitrance, physical protection in aggregates and adsorption to soil mineral surfaces. The stability of SOC in the soil matrix can be influenced by management practices and changes in soil structure can lead to loss of SOC and increases in greenhouse gas (GHG) emissions. It is, therefore, important to understand the impact that management practices have on SOC stability and to manage soils in such a way as to optimise the volume of SOC which is locked away for climatically significant periods of time. Two methods are generally used to estimate SOC stability: indirectly by measuring CO2 fluxes as a proxy for SOC microbial decomposition, or directly through physical fractionation of soil in to pools with different levels of physical and chemical protection. Both methods were employed in this thesis. Arable and grassland soils which represent the range of soil textures and climatic conditions of the main agricultural areas in the UK were incubated at two different moisture contents and with or without inorganic fertiliser application and GHG fluxes from them were monitored. Soil texture, mineral N concentration and soil C concentration were found to be the most important measured variables controlling GHG fluxes of the UK agricultural soils in this study. The results were generally in support of those found in the literature for a wide range of soils, conditions and locations; however, N2O emissions from the two Scottish soils appeared to be more sensitive to inorganic N fertilisation at the higher moisture content than the other soils, with the N2O emissions being exceptionally high in comparison. Although incubations of whole soils are useful in measuring the impacts of soil management practices on GHG emissions under controlled conditions they do not identify the mechanisms controlling the stability of SOC. Dividing SOM into functional pools may identify different C stabilising mechanisms and improves soil C models. A large number of operationally defined separation methods have been used to fractionate SOM into biologically meaningful pools of different stability. Direct comparisons of different fractionation methods using radiocarbon (14C) dating and spectroscopic analyses has not previously been undertaken. Average 14C ages and chemical composition of SOM fractions isolated from a grassland soil using three published and frequently applied fractionation methods were compared. (1) a density separation technique isolating three fractions (2) a combined physical and chemical separation isolating five fractions (3) a hot-water extraction method isolating two fractions. The fractions from Method 1 had the most distinct average 14C ages, the fractions from Method 2 fell into two age groups, and both Method 3 fractions were dominated by modern C. The average 14C ages of the labile fractions from Method 1 and 2 were higher than the mineral bound fractions, although they made up a relatively small proportion of the total SOC. This was a surprising result, and spectroscopic analysis confirmed that these fractions had greater relative contents of aliphatic and aromatic characteristics than the mineral bound fractions. The presence of black C in a whole soil sample and one of the labile fractions from Method 2 was confirmed by hydrogen pyrolysis. The availability of archived soils from an abandoned long term tillage treatment experiment and the ability to relocate the plots provided a unique opportunity to assess the resilience of SOC stocks to land management practices several years after the conversion from arable to grassland. SOC stability was assessed by soil fractionation of archived (1975) and freshly collected (2014) soil samples. The mass corrected SOC stocks from the four different treatments (deep plough, shallow plough, chisel plough and direct drill) were higher in 2014 than 1975 across the whole profile (0 – 36 cm). Reductions were observed at some depths for some treatments but the overall effect was an evening out of SOC stocks across all plots. The fractionations (using Method 2), revealed that there was a relative increase in the mass of the sand and aggregate fraction but a decrease in the relative proportion of SOC stored in this fraction (physically protected). There was also a significant increase in the C:N ratio of the silt and clay fraction (chemical adsorption). This suggests that reduced disturbance of agricultural soils leads to preferential physical stabilisation of fresh SOM but also increased adsorption of older material to mineral surfaces. The labile fractions were sensitive to land-use change in all tillage treatment plots, but were more sensitive in the low impact tillage plots (chisel plough and direct drill) than the inversion tillage plots (deep plough and shallow plough). It is well established that tillage disrupts aggregation. However, a direct measurement of the level of SOM physical protection in the soil matrix due to aggregation has not previously been undertaken. The soil was fractionated using Method 1 (fractions with distinctly different 14C ages) and isolated soil fractions were incubated separately, recombined and mixed in to whole soil at three different temperatures. The C respiration rate of the isolated intra-aggregate fraction was generally consistently as high as the whole soil. This supports the theory that there is a labile component of soil which is protected from decomposition by physical protection within aggregates. Therefore, the lack of any priming effect with the addition of labile fractions to the whole soil, and indeed the suppression of emissions relative to the whole soil, was unusual. Fractions and whole soils incubated at 25 and 35 °C had a wider range of Q10 (temperature sensitivity) values than those incubated at 15 and 25 °C, however, median values were surprisingly similar (range from 0.7 to 1.9). Overall, the results from this thesis highlight the importance of the soil structure in stabilising C. Disrupting aggregates leaves a proportion of otherwise stable C susceptible to loss through microbial decomposition, particularly when the entire soil matrix is disrupted. It also provided some unexpected results which warrant future investigation; in particular, further direct measurement of physical stabilisation of SOM in soils of different type, from different climates and different land uses would be useful.

The OSU global coupled atmosphere/ocean general circulation model (A/O GCM) has been used to simulate the present (lxCO₂) climate and to investigate a CO₂-induced (2xCO₂) climate change. Previous analysis of the lxCO₂ simulation showed distinct errors in the simulated sea surface temperature (SST) and sea ice which were attributed primarily to the atmospheric GM (AGCM). Analysis of the 2xCO₂ simulation showed that the CO₂-induced warming penetrated into the ocean; this caused a delay in the equilibration of the climate system with an estimated e-folding time of 50-75 years. The present study has two objectives. The principal objective is to answer the question: By what pathways and through which physical processes does the simulated ocean general circulation produce the penetration of the CO₂-induced warming into the ocean? The secondary objective is to evaluate the performance of the oceanic GCM (OGCM) in the lxCO₂ simulation. The comparison of the simulated lxCO₂ internal oceanic fields with the corresponding observations shows that although they are basically similar, there are distinct errors. Further analysis shows that these errors were generated by the OGCM during its spin-up integration prior to its coupling with the AGCM. This study thus shows that it is not sufficient to compare the simulated SST with the observed SST to evaluate the performance of the OGCM. It is also necessary to compare the simulated internal oceanic quantities with the corresponding observed quantities. The global mean analysis of the CO₂-induced climate changes shows that the ocean gains heat at a rate of 3 W/m² due to the CO₂ doubling. This heat penetrates downward into the ocean predominantly through the reduction in the convective overturning. The zonal mean analysis shows that the surface warming increased from the tropics toward the mid-latitudes of both hemispheres and penetrated gradually to the deeper ocean. The oceanic warming penetrated to a greater depth in the subtropics and mid-latitudes than in the equatorial region. A zonal mean heat budget analysis shows that the CO₂-induced warming of the ocean occurs predominantly through the downward transport of heat, with the meridional heat flux being only of secondary importance. In the tropics the penetration of the CO₂-induced heating is minimized by the upwelling of cold water. In the subtropics the heating is transported downward more readily by the downwelling existing there. In the high latitudes the suppressed convection plays the dominant role in the downward penetration of the CO₂-induced heating. / Graduation date: 1987

This paper argues that a key mechanism through which greenhouse gas affects growth is via total factor productivity (TFP). We first estimate TFP based on a production function and then estimate the determinants of TFP, paying particular attention to four variables: greenhouse gas, openness of trade, inflation, saving rate ¡@¡@We major results are as follows: 1.In the fixed effect¡GThe impact of greenhouse gas and inflation on TFP to be negative, significant. The impact of openness of trade on TFP to be positive, significant. The impact of saving rate on TFP to be insignificant. 2.The relations between CO2 and TFP have in the degree change, the degree of interplay decreases progressively along with time. 3.The relationship between CO2 and TFP with the countries of OECD is lager than with the countries of Non-OECD. The impact of saving rate on TFP is significant in the countries of OECD, but insignificant in the countries of Non-OECD.

The objective of this study was to optimize the cultural and environmental conditions necessary to produce high quality basil in a semi-arid climate during summer. Basil grown in a retractable roof greenhouse (RRGH) and full sun over two years using production systems including rockwool, containers, raised beds, vertical towers, and soil was evaluated based on biomass accumulation, morphological characteristics and quality. Photosynthetic response of basil to temperature and light was tested in a growth chamber to determine the optimum conditions that enhance photosynthesis and increase productivity. Biomass accumulation and quality of basil were affected by environment and cultural practices, with the largest quantities of highest quality basil produced in rockwool or raised beds in the RRGH. The response of basil to light and temperature indicated that highest photosynthesis during summer occurred between temperatures of 25 to 35 °C at a light intensity of 1500 μmol m⁻¹ s⁻¹.