Quantifying fugitive gas emissions from an oil sands tailings pond with open-path Fourier transform infrared measurements

Fugitive emissions from tailings ponds contribute significantly to facility emissions in the Alberta oil sands, but details on chemical emission profiles and the temporal and spatial variability of emissions to the atmosphere are sparse, since flux measurement techniques applied for compliance monitoring have their limitations. In this study, open-path Fourier transform infrared spectroscopy was evaluated as a potential alternative method for quantifying spatially representative fluxes for various pollutants (methane, ammonia, and alkanes) from a particular pond, using vertical-fluxgradient and inverse-dispersion methods. Gradient fluxes of methane averaged 4.3 g m(-2) d(-1) but were 44 % lower than nearby eddy covariance measurements, while inverse-dispersion fluxes agreed to within 30 %. With the gradient fluxes method, significant NH3 emission fluxes were observed (0.05 g m(-2) d(-1), 42 t yr(-1)), and total alkane fluxes were estimated to be 1.05 g m(-2) d(-1) (881 t yr(-1)), representing 9.6 % of the facility emissions.