Abstract. Aircraft-based measurements of methane (CH4) and other air pollutants in
the Athabasca Oil Sands Region (AOSR) were made during a summer intensive
field campaign between 13 August and 7 September 2013 in support of the
Joint Canada–Alberta Implementation Plan for Oil Sands Monitoring. Chemical
signatures were used to identify CH4 sources from tailings ponds (BTEX
VOCs), open pit surface mines (NOy and rBC) and elevated plumes from
bitumen upgrading facilities (SO2 and NOy). Emission rates of
CH4 were determined for the five primary surface mining facilities in
the region using two mass-balance methods. Emission rates from source
categories within each facility were estimated when plumes from the sources
were spatially separable. Tailings ponds accounted for 45 % of total
CH4 emissions measured from the major surface mining facilities in the
region, while emissions from operations in the open pit mines accounted for
∼ 50 %. The average open pit surface mining emission rates
ranged from 1.2 to 2.8 t of CH4 h−1 for different facilities
in the AOSR. Amongst the 19 tailings ponds, Mildred Lake Settling Basin, the
oldest pond in the region, was found to be responsible for the majority of
tailings ponds emissions of CH4 (> 70 %). The sum of
measured emission rates of CH4 from the five major facilities,
19.2 ± 1.1 t CH4 h−1, was similar to a single mass-balance
determination of CH4 from all major sources in the AOSR determined from
a single flight downwind of the facilities, 23.7 ± 3.7 t CH4 h−1.
The measured hourly CH4 emission rate from all facilities in
the AOSR is 48 ± 8 % higher than that extracted for 2013 from the
Canadian Greenhouse Gas Reporting Program, a legislated facility-reported
emissions inventory, converted to hourly units. The measured emissions
correspond to an emissions rate of 0.17 ± 0.01 Tg CH4 yr−1 if
the emissions are assumed as temporally constant, which is an uncertain assumption. The
emission rates reported here are relevant for the summer season. In the future,
effort should be devoted to measurements in different seasons to further our
understanding of the seasonal parameters impacting fugitive emissions of CH4
and to allow for better estimates of annual emissions and year-to-year
variability.
The role of snow processes and hillslopes on runoff generation in present and future climates in a recently constructed watershed in the Athabasca oil sands region
