Nitrogen Dioxide & Sulfur Dioxide Over Canadian oil sands

Data from the Ozone Monitoring Instrument (OMI) show distinct enhancements in nitrogen dioxide (NO₂) and sulfur dioxide (SO₂) over a region of surface mining in the Canadian oil sands.

The oil sands are located in the north-east corner of the province of Alberta, Canada and contain the second largest reserve (after Saudi Arabia) of oil globally.

Shown along the top are maps over a portion of the oil sands where extensive surface mining occurs: a NASA LandSat image from 2009 indicating vegetation removal in the region of surface mining (left), OMI mean NO₂ (middle), and OMI mean SO₂ (right). OMI data were averaged over the period 2005-2010. White values indicate background levels, increasing through yellow-orange, with brown-black the largest. Maximum values clearly correspond to the location of the industrial activity.

The time graph shows that NO₂ has been increasing at a rate of 10% per year over this period. SO₂ trends have not yet been assessed. Maximum NO₂ and SO₂ values are comparable to those seen over large North American power plants.

It is expected that oil production will double and annual capital investments will reach $20B by 2020 further highlighting the need for monitoring pollution in this area. These results make use of improved mapping techniques able to resolve detail down to 10 km. These are the first satellite-based results of pollution over the oil sands.

Earth Observatory Feature : Emissions from Oil Sands Mining

Technical Description of Figure:

• Upper left: NASA LandSat image showing land changes (white color indicates deforestation) in the region of mining operations.
• Upper middle: OMI annual mean tropospheric NO₂ vertical column density (VCD) in units of 1015 molec/cm2, averaged over 2005-2010, shown on a 1x1 km2 grid and calculated using an averaging radius of 8 km. Large NO₂ emission sources are Syncrude (left black dot) and Suncor (right black dot).
• Upper left: OMI summertime mean tropospheric SO₂ VCD in units of 1015 molec/cm2, averaged over 2005-2010 shown on a 2x2 km2 grid and calculated using an averaging radius of 24 km. Large SO₂ emission sources are Syncrude (left black dot) and Suncor (right black dot).
• Lower right: Time series of seasonal OMI NO₂ total mass of the NO₂ enhancement in tonnes. Also shown is the fit to the time series using a trend model with constant, linear, and annual harmonic terms and the calculated linear trend and trend uncertainties. The rate of emission throughout the year is roughly constant. The seasonality of the NO₂ is due to its changing chemical lifetime.

Significance: This is a first study of the abundance of NO₂ and SO₂ over the Canadian oil sands, based on UV/visible nadir-viewing satellite instruments. A trend in the mass of the NO₂ enhancement-the quantity most representative of NO₂ emissions-of 10.4±3.5%/yr (2005-2010) was found to result from increases in both the maximum pollution levels and the total area of the enhancement. SO₂ pollution values over the oil sands are similar as those of large power plants. This highlights the importance of satellite observations in providing a macroscopic or comprehensive view.

Relevance for future science: Aura OMI will continue monitoring anthropogenic NO₂ and SO₂ pollution sources from space to detect trends in aerosol and ozone precursors to provide an overlap with ESA Sentinel-5 precursor mission (TropOMI) planned to launch in 2015. The Decadal Survey recommended the Geostationary Coastal and Air Pollution Events (GEO-CAPE) tier 2 mission, which is planned to launch after 2020. It will allow more frequent monitoring of anthropogenic NO₂ and SO₂ pollution over N. America, including the oil sands region.

A next generation, OMI-like sensor is being considered by the Canadian Space Agency for inclusion on the Polar Communication and Weather (PCW) mission scheduled for launch in 2018. It would monitor SO₂ pollution over the Arctic and sub-Arctic regions.

Data Source:

• Operational PBL SO₂ data from the Dutch/Finnish Ozone Monitoring Instrument (OMI) on board the NASA Aura satellite.
• NASA LandSat image obtained from Earth Observatory.

Reference: McLinden, C.A., V. Fioletov, K. F. Boersma, N. Krotkov, C. E. Sioris, J. P.Veefkind, and K. Yang, Air quality over the Canadian oil sands: A first assessment using satellite observations (2011), Geophysical Research Letters, in press, 2011GL050273R. Boersma, K. F., et al. (2011), An improved tropospheric NO2 column retrieval algorithm for the Ozone Monitoring Instrument, Atmos. Meas. Tech., 4, 1905- 1928, doi:10.5194/amt-4-1905-2011. Krotkov, N.A., S. A. Carn, A. J. Krueger, P. K. Bhartia, and K. Yang (2006), Band residual difference algorithm for retrieval of SO2 from the Aura Ozone Monitoring Instrument (OMI), IEEE Trans. Geosci. Remote Sens., 44, 1259-1266.

McLinden, C., et al., (2012), Geophysical Research Letters, in press

02.07.2012