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

While most micrometeorological measurement techniques are only suitable for windy conditions, the Nocturnal Boundary Layer Technique can be used to measure trace gas flux during calm, clear nights as the nighttime stability enables gas emitted at the ground to accumulate. The difference between two measurements over the whole depth of this layer is believed to integrate emissions from a large area representative of, in this study, an agricultural farm. A tethersonde and infrared gas analyzer attached to a blimp carrying a bag sampling system monitored atmospheric variables for each ascent during two summer field campaigns. A mini-SODAR was installed in the field to obtain the wind flowfield. Strong accumulation was observed under low level jets suggesting that this feature acts as a good lid for trace gases. An average background vertical motion different from zero seemed to have more influence on gas propagation than did intermittent turbulence. On at least one night, a density current created by the nearby St-Lawrence River was observed to influence measurements.

No description available.

No description available.

Human development owes a great debt to cheap plentiful energy. Historically, abundant and energy dense materials such as coal, oil and more recently natural gas, have played an important role in powering our economies. To this day, any study analysing the short-term costs and benefits of energy system expansion, will continue to favour fossil fuels. At the same time, there is increasing concern about the levels of human made greenhouse gasses such as CO2 (the major by product of burning fossil fuels) and their forecasted effects on the global climate. This thesis investigates the consequences of using political intervention to internalize the cost of future negative effects of anthropogenic CO2 emissions. More specifically, this thesis investigates the effects of regulatory and market based instruments for curbing CO2 emissions from electric power systems in terms of both cost and efficacy. A model is developed to approximate the yearly changes in generation capacity and electricity supply mixture of a power system subject to the constraints of carbon abatement policies. The model proposes a novel approach for incorporating investment in non-dispatchable, intermittent wind generation capacity as a decision variable in the planning process. The model also investigates the effects of the stochastic nature of input parameters through the use of Monte Carlo simulation. To explore many features of this model, the Ontario power system is chosen for a case study because of its diverse portfolio of both generation technologies and political objectives. Five policies are simulated and compared with a ‘business-as-usual’ base case in which no carbon abatement policy is imposed. No single policy can meet all of the political objectives being investigated; however, some policies are clear winners in terms of specific objectives. Due to the broad scope of this work, the study finds many conclusions, such as: - Aggressive policies do not always promote heavy investment in intermittent wind generation sources. - On a $/tCO2 avoided basis, aggressive policies are expensive. Modest policies (very small penalties for CO2 emissions) are very sensitive to the uncertainties in future fuel prices and load profiles. - Investment in nuclear capacity is very responsive to the severity of CO2 penalty. The study also concludes that the most aggressive policies produce the greatest overall reductions in CO2 emissions. / Graduate

Thesis (PhD)--University of South Australia, 2002

Thesis (PhD)--University of South Australia, 1997

Thesis (PhD(Agricultural Economics, Extension and Rural Development))--University of Pretoria, 2005. / Abstract in English. Includes bibliographical references.

Thesis (LL.M.)--University of Calgary (Canada), 2004. / Adviser: Alastair Lucas. Includes bibliographical references.

Thesis (M.E.S.)--Evergreen State College, 2009. / "June, 2009." Title from title screen (viewed 4/8/2010). Includes bibliographical references.