Gas hydrate can precipitate in pore space of marine sediment when gas concentrations exceed solubility conditions within a gas hydrate stability zone (GHSZ). Here we present analytical expressions that relate the top of the GHSZ and the amount of gas hydrate within the GHSZ to the depth of the sulfate-methane transition (SMT). The expressions are strictly valid for steady-state systems in which (1) all gas is methane, (2) all methane enters the GHSZ from the base, and (3) no methane escapes the top through seafloor venting. These constraints mean that anaerobic oxidation of methane (AOM) is the only sink of gas, allowing a direct coupling of SMT depth to net methane flux. We also show that a basic gas hydrate saturation profile can be determined from the SMT depth via analytical expressions if site-specific parameters such as sedimentation rate, methane solubility and porosity are known. We evaluate our analytical model at gas hydrate bearing sites along the Cascadia margin where methane is mostly sourced from depth. The analytical expressions provide a fast and convenient method to calculate gas hydrate saturation for a given geologic setting.

This study employs a novel approach in order to satisfy the need in industry for a computationally inexpensive means to modelling soot formation in engines fuelled by natural gas. The complex geometries found in practical combustion devices along with the requirement to solve turbulent, chemically reacting, and multi-phase flows necessitates this goal. A two-equation model, which tracks soot mass and soot number density, is employed. The goal is to apply this model in engine simulations at Westport Innovations, an industry partner. Experimental data is used to validate the model in various operating conditions. Numerical data obtained from a detailed sectional soot model is also used to augment available validation data, especially with respect to soot formation/oxidation mechanisms. The developed model shows good agreement compared to experimental data and the detailed sectional soot model among all cases considered and will be further tested and applied in Westport’s natural gas engine simulations.

The aim of this study was to investigate the importance of winter season for the production of carbon dioxide (CO2) and methane (CH4) in humic and clear-water boreal aquatic systems. The study was conducted in 16 experimental ponds in northern Sweden during the winter of 2013. Half of the ponds had a higher concentration of dissolved organic carbon (DOC). CO2, CH4, DOC and dissolved inorganic carbon (DIC) were measured repeatedly under the ice from January to April. The results show that CO2 was accumulated continually during winter. No difference in winter accumulation were found between humic and clear ponds. CH4 was rarely accumulated in neither humic nor clear ponds, and was not an important part of the gas flux at spring ice melt. At ice melt, the flux from humic ponds accounted for 1.6 g C m-2 and 1.7 g C m-2 from clear ponds, which was equivalent for 15.6% respective 100% of the annual gas emissions. On a whole-year basis humic ponds acted as a source of 10.3 g C m-2, while clear ponds acted as a sink of 14.7 g C m-2. 76 mg m-2 d-1 DOC was consumed in humic and 59 mg m-2 d-1 DOC in clear ponds while the DIC accumulation was 125 mg m-2 d-1 in humic and 118 mg m-2 d-1 in clear ponds. This study stresses the importance of ice-covered boreal aquatic systems as a significant parts of the global carbon cycling.

This study employs a novel approach in order to satisfy the need in industry for a computationally inexpensive means to modelling soot formation in engines fuelled by natural gas. The complex geometries found in practical combustion devices along with the requirement to solve turbulent, chemically reacting, and multi-phase flows necessitates this goal. A two-equation model, which tracks soot mass and soot number density, is employed. The goal is to apply this model in engine simulations at Westport Innovations, an industry partner. Experimental data is used to validate the model in various operating conditions. Numerical data obtained from a detailed sectional soot model is also used to augment available validation data, especially with respect to soot formation/oxidation mechanisms. The developed model shows good agreement compared to experimental data and the detailed sectional soot model among all cases considered and will be further tested and applied in Westport’s natural gas engine simulations.

Freshwater ecosystems have long been neglected as an important part of the global carbon cycle. However, research shows that most of the world’s lakes are net-heterotrophic and consequently emitters of greenhouse gases to the atmosphere. In many boreal and north-temperate lakes, most of the yearly emissions usually occur in spring, shortly after ice-thaw. The aim of this study was to quantify the flux of carbon dioxide (CO2) and methane (CH4) in three boreal lakes, during this annual event. In order to do this, water samples were collected before and after ice-thaw, and the flux was estimated as the difference in mass of carbon between the two sampling occasions. The results showed that the lakes had accumulated high amounts of carbon over the winter, with higher concentrations generally at higher depths. The fluxes during ice-thaw ranged from 234–380 (mean: 302) and -1.15–15.12 (mean: 8.64) mmol m-2 y-1 for CO2 and CH4, respectively. Given their small sizes, the lakes emitted less carbon, per unit area, than expected. This was assumed to be due to the lakes’ rather isolated locations and since the heating of the water rapidly caused them to become highly stratified, thus preventing the wind from releasing deeper stored carbon. Presumably, this holds true for other similar boreal lakes as well, which suggests that attention – in such ecosystems – also needs to be brought to other mixing periods.

The demand for meat and other animal products over the past couple decades has led to a changeover from small family operated farms, into large commercial facilities. The increase in animal density and population has created new issues related to waste management and pollution. Aerial pollutants, such as carbon dioxide, methane, ammonia, nitrous oxide and particulate matter, are all byproducts of agricultural processes. This study examines the concentrations, emission rates, and emission factors of ammonia, methane, and particulate matter that are emitted from a commercial dairy barn. The commercial dairy facility was located near New Hamburg in Ontario, Canada. It has the capacity to house 501 animals total, split between lactating cows, dry cows, heifers, bulls and calves. Lactating cows are confined in tie stalls while the rest of the herd used free stall pens. The barn is mechanically ventilated and uses a set of 14 fans with diameters of 1.22 m to ventilate the barn. Concentration data were measured over two sampling periods; the first took place in January – March 2013 and the second from May – July 2013. The pollutant concentrations, ventilation rates, and animal weights were used to generate emission factors based on an animal unit (AU – equivalent to 500 kg live mass) basis. The emission factors for ammonia, methane, PM10 and PM2.5 averaged over the two campaigns were 1.12 g hr-1 AU-1, 25.08 g hr-1 AU-1, 9.33 mg hr-1 AU-1 and 4.96 mg hr-1 AU-1, respectively and agree well with reported values in the literature. The time of year had an impact on the emission levels as all of the pollutants, except methane, were higher in the second sampling campaign compared to the first. A large increase was seen in the ammonia and particulate matter, while a more moderate change was seen in the methane. Peaks in ammonia emissions correlated well with feed times, and are highly influenced by animal activity. Methane emissions were dominated by the digestive process in the rumen, and have a lag period after feeding before the emissions spike. Although particulate matter increased, it was not correlated to a specific event in the barn. / Agriculture and Agri-Food Canada, Ontario Ministry of Agriculture Food, Ontario Ministry of Rural Affairs, Dairy Farmers of Canada, Dairy Farmers of Ontario

Northern peatlands are large repositories of carbon and little is known about the effect the microbial community has on carbon mineralization rates, and there is concern that a loss of microbial diversity due to environmental change may lead to reduced ecosystem functioning. Microbial communities vary among peatland types and abiotic variables such as temperature and pH have a large influence on carbon dioxide production, but distinguishing between abiotic controls and the role of microbial community structure has proved challenging. Microbial activity and community composition was characterized in three peatlands within the James Bay Lowlands, Ontario. Similar dominant microbial taxa were observed at all three peatlands despite differences in nutrient content and substrate quality and geographic location. In contrast, microbial activity differed among the sites, indicating that it is influenced by the quality of the peat substrate and the presence of microbial inhibitors. A series of reciprocal field and laboratory transplant experiments were conducted at a rich and poor fen near White River, Ontario to more explicitly distinguish between the abiotic and microbial controls on carbon mineralization. The effect of transplantation differed between the laboratory and field studies and when viewed individually could lead to different interpretations of the effect of substrate change. Surprisingly, intensive sampling within both fens was unable to reveal a difference between the rich and poor fen microbial community due to high within site temporal and spatial variation. Thus studies with small sampling effort will have a very incomplete understanding of microbial community structure and thus microbial ecology. A reciprocal sterilization transplant experiment was also conducted to examine how different microbial communities adapted to various peat substrates influenced C-mineralization patterns. Post-inoculation/incubation bacterial communities across peatlands converged towards a similar community structure, suggesting that abiotic variables are the dominant control on peatland microbial activity and community composition. The studies presented in this thesis collectively show that across a broad range of temperate and sub-arctic peatland types dominant members of the microbial community are generally similar, and decomposition rates can be predicted by broader controlling environmental factors rather than temporal niche or distributional constraints of the microbial community.

Condensed tannins (CT) are polyphenolic compounds that have demonstrated biological activities in ruminants including suppression of enteric methane (CH4) production, protein binding and suppression of gastrointestinal nematode (GIN) infections. Some forage CT have been reported to be biologically active, whereas others have demonstrated no biological activity at all. While the chemical structure of CT has been postulated to be a key contributing factor affecting biological activity, the specific factors that determine whether or not CT from a specific forage have bioactive properties remain unknown. Results from previous studies have shown that as molecular weight of CT increases, CT biological activity also increases. Others have reported no effect of CT molecular weight on biological activity. The relationship between molecular weight of CT and CT biological activity remains inconclusive. The effect of molecular weight of CT from a variety of warm-season perennial legumes commonly consumed by ruminants on biological activity has not been adequately explored. The objectives of this study were to determine if molecular weight of CT from warm-season perennial legumes could predict the biological activity of CT relative to suppression of enteric CH4 production, protein-binding ability (PB) and anthelmintic activity, and to compare the biological activity of CT from native warm-season perennial legumes to that of the introduced species Lespedeza cuneata, a plant that has gained attention in recent years due its anthelmintic properties. All or a combination of the following warm-season perennial legume species were evaluated for in vitro gas production, protein-precipitable phenolics (PPP) and PB, and percent larval migration inhibition (LMI). Eight North American native warm-season perennial legumes: Leucaena retusa Benth. (littleleaf leadtree), Desmanthus illinoensis (Michx.) MacMill. Ex B.L. Rob. & Fernald (Illinois bundleflower), Lespedeza stuevei Nutt. (tall lespedeza), Mimosa strigillosa Torr. & A. Gray (powderpuff), Neptunia lutea (Leavenworth) Benth. (yellow puff), two ecotypes of Acacia angustissima var. hirta (Nutt.) B.L. Rob (prairie acacia), Desmodium paniculatum (L.) DC. var. paniculatum (panicledleaf ticktrefoil), and two introduced legumes: Arachis glabrata Benth. (rhizoma peanut) and Lespedeza cuneata (Dum. Cours.) G. Don (sericea lespedeza) were included. In vitro CH4 production regressed on CT MW resulted in a R2 of 0.0009 (P = 0.80). There was no correlation between PPP or PB and MW of CT (R^2 0.11; P = 0.17 and R^2 0.02; P = 0.54, respectively). There was a weak correlation between CT MW and percent LMI (R^2 0.34; P = 0.05). The results of our study strongly suggested that CT MW does not explain the biological activities of enteric methane suppression or protein-binding ability. Condensed tannin MW may be involved in anthelmintic activity of CT from the forage legumes surveyed. North American native legumes containing biologically active CT, as compared to introduced species, were identified as having promise for use in ruminant diets.

Methylosinus trichosporium OB3b is a wild type, obligate methanotroph that grows only on one-carbon compounds and, in the absence of copper, produces high levels of soluble methane monooxygenase (sMMO) to metabolize methane to methanol. SMMO has gained a great deal of attention in the bioremediation and chemical industries because of its low substrate specificity and its ability to oxidize chlorinated hydrocarbons. Much literature exists on cultivating this organism on methane, however no one has achieved dry cell weight densities exceeding 18 g/L. Biomass growth is limited due to mass transfer of methane to cells. This study investigated the growth of M. trichosporium on the water soluble carbon source, methanol while retaining sMMO activity. Methanol was found to completely inhibit growth at 40 g/L. For online methanol measurements during fed-batch cultivation, an in situ probe was constructed from autoclavable materials and equipped with a Figaro TGS822 vapor sensor. The probe was designed to prevent the sensor coming in contact with water aerosols which affect its performance. The probe was an essential component of a feedback methanol control system. The cumulative CO2 production (CCP) strategy was used to feed methanol in fed-batch experiments. In an initial bioreactor study, growth nutrients were fed in excess. The yields of biomass to nutrients were determined and the growth medium modified accordingly. A biomass density of 19 g/L (growth rate of 0.013-0.065 h-1) was achieved with sMMO activity of 300 to 500 [µmol naphthol][g of biomass]-1[h]-1. The subsequent bioreactor study involved feeding of nutrients based on their yields in relation to methanol, a biomass density of 62 g/L (growth rate of 0.034- 0.08 h-1) was achieved. The inoculum cultures utilized in the bioreactor studies were maintained on Noble agar plates containing nitrogen minimal salts medium and methane. After 6 months of subsequent plate transfers, M. trichosporium lost the ability to produce high levels of sMMO. The enzyme activity in methanol grown cells was recovered by subculturing in liquid NMS medium with methane as the sole carbon source, the activity increased from 8 to 600 [µmol naphthol][g of biomass]-1[h]-1. It is recommended that further studies be carried out on stimulating sMMO activity during cultivation on methanol. / Thesis (Master, Chemical Engineering) -- Queen's University, 2008-08-21 15:14:42.475

The performance characteristics of a diesel fuel piloted syngas compression ignition engine are presented in this thesis. A stock Hatz 1D81 engine was converted to operate in dual fuel mode through the elimination of the governor system and addition of an in-cylinder pressure transducer and custom intake system to facilitate the mixing of the gaseous fuel and combustion air. The engine was run on a Superflow water brake dynamometer and benchmarked with diesel to compare against manufacturer specifications. This was followed by dual fuel operation on methane and syngas, with the results being compared through performance characteristics. When operated on methane, the engine attained higher peak in-cylinder pressures along with higher torque, power, and thermal efficiency values for equal equivalence ratios. It was necessary to use greater amounts of syngas to reach comparable results with methane due to the lower energy content of syngas. The ignition delay was greater for syngas, and the onset of knock occurred earlier with syngas in comparison to methane. The heat release, Q, was comparable for both fuels and the exhaust gas emissions were significantly lower for operation with syngas. With emphasis on clean engine operation, syngas operation proved to be viable due to its renewable nature, significantly lower exhaust gas emissions, equal heat release characteristics, and larger useable operating range when compared to methane. / Thesis (Master, Mechanical and Materials Engineering) -- Queen's University, 2012-05-28 15:02:49.227