Quantifying Sources of Methane in the Alberta Oil Sands

Abstract:

In the summer of 2013, an aircraft measurement campaign led by Environment Canada with participation from university researchers took place to investigate the sources and transformations of gas pollutants in the Alberta oil sands region close to Fort McMurray, Alberta. Apart from its ability to change the radiative forcing of the atmosphere, methane is also a significant precursor to the formation of formaldehyde, an important radical source. Thus, emissions of methane from facilities need to be understood since they can have air quality implications through alteration of the radical budget and hence, the oxidation capacity of the air mass. Methane was measured, along with other gases, via a cavity ring-down spectroscopy instrument installed on the Convair-580 aircraft. In total, there were 22 flights with 82 hours of measurements in the vicinity of oil sands facilities between August 13 and September 7, 2013. Various tools have been used to visualize the spatial and temporal variation in mixing ratios of methane and other trace gases in order to identify possible sources of methane. Enhancements of methane from background levels of 1.9 ppm up to ~4 ppm were observed close to energy mining facilities in the oil sands region. Sources of methane identified include open pit mining, tailings ponds, upgrader stacks and in-situ mining operations. Quantification of the emission rates of methane from distinct sources has been accomplished from box flights and downwind screen flights by identifying the ratios of trace gases emitted and through use of the Top-down Emission Rate Retrieval Algorithm (TERRA). Methane emission rates for some of these sources will be presented.