Over the last decade, there has been a significant increase in the number of operating and proposed bitumen recovery and upgrading activities in the Athabasca Oil Sands region. These activities include surface mining, in-situ recovery, extraction, and upgrading operations that release nitrogen oxides (NOx) to the atmosphere. The NOx emissions are produced by the high temperature combustion of solid fuels (e.g., coke), liquid fuels (e.g., diesel oil), and gaseous fuels (e.g., natural gas). During the 1980 to 1995 period, regional NOx emissions were in the 36 to 60 t/d range. Future (~2010 to 2015 and beyond) NOx emissions are expected to increase to approximately 355 t/d, which represents an increase by a factor in the 6 to 10 range. These future NOx projections do not account for potential reductions in NOx from the introduction of Type IV standards for non-road diesel engines.

NOx is emitted into the atmosphere primarily as nitric oxide (NO), which subsequently reacts with other atmospheric compounds to produce nitrogen dioxide (NO2), nitric acid (HNO3) and particulate nitrate (NO3-). While there are a number of potential adverse environmental responses to these compounds, the primary focus for this assessment is potential eutrophication changes due to deposition of these nitrogen (N) compounds. Given the proposed increase in NOx emissions, the NOxSOx Management Working Group (NSMWG) of the Cumulative Environmental Management Association (CEMA) commissioned this study to assess the performance and suitability of the CALMET-CALPUFF model system in estimating N deposition in the region.

The evaluation approach and report organization is comprised of the following components: 1. A review of the regional setting that summarizes the emission sources, the ambient concentration measurements, the regional deposition calculations, and regional meteorology. The focus provides a summary in the context of NOx parameters for the 1998 to 2002 period. Where appropriate, this information has been complemented with data from prior periods. This information is provided in Part A of the report. 2. A critical review of the CALPUFF model assumptions and available options to determine the best practical science application of the model to the oil sands region. The review considers source geometry (Section 5), transport and dispersion (Section 6), plume chemistry (Section 7) and plume deposition (Section 8). These sections are provided in Part B. 3. The application of the CALPUFF model based on the critical review conclusions to predict concentrations and deposition that can be compared to the measurements presented in regional setting review. The comparison in Part C (Section 9) provides an indication of the dispersion model performance.

The application of the CALPUFF model to predict regional concentration and deposition fields for the nitrogen compounds considered by the model (e.g., NO, NO2, HNO3 and NO3-) and to predict the mass transport of nitrogen compounds out of the study area. These results are provided in Part D (Section 10).