Sensitivity of Ambient NO2 Concentration to Upstream Oil and Gas and Transportation Emissions in Alberta
Creators: Hajiparvaneh, Erfan
Publisher: name: University of Alberta Library
Year: 2023

<p>Ambient exposure to nitrogen dioxide (NO2) and ozone (O3) is associated with severe health problems and health-related economic burdens. The levels of NO2 concentration in the province of Alberta show that they will exceed the updated Canadian Ambient Air Quality Standards (CAAQS) in Edmonton and Calgary. This research aims to identify the sensitivity of NO2 concentration to changes in emissions from two primary sources of transportation and upstream oil and gas for populated areas in Alberta. It also investigates the O3 concentration differences in the summer and winter due to variations of NO2. Understanding primary sources of criteria air contaminants (CACs), including NO2 and O3 in Alberta, using a detailed atmospheric air pollution model is the focus of this work.</p>

<p>Meteorological parameters of temperature and wind were captured using the open-source Weather Forecasting and Research (WRF) model. The most recent comprehensive Alberta emission inventory data for 2013 was used as the base year emission input. The emission data were processed using the US EPA Sparse Matrix Object Kernel (SMOKE) to generate gridded outputs of temporal, spatial, and chemical profiles of emission sources. WRF and SMOKE outputs were combined with the Community Multiscale Air Quality (CMAQ) chemical transport model. A nested domain with the finest spatial resolution of 4 km x 4 km was used in the model domain of the province of Alberta.</p>

<p>The air pollution model output was validated using data from 40 air quality ground observation stations provided by the National Air Pollution Surveillance (NAPS) program. Validation was performed using two periods: January 2019 (10th-20th) and July 2019 (15th-25th). Hourly averaged simulation results were compared to ground station measurements. The model performance adequately replicated the spatiotemporal profiles of hourly averages of NO2 and O3 measurements. The effect of winter and summer temperatures on both temporal and spatial emission concentration was evaluated. Analyzing the diurnal simulation data shows that the average daily NO2 concentration in winter is 18 &lt;= NO2 &lt;= 24 ppb in Calgary and Edmonton, the major cities of Alberta, which is approximately three times higher than the average of 6&lt;= NO2&lt;=8 ppb for summer. Industries and oilsands areas also experience the same trend from 3&lt;= NO2&lt;=5 ppb in summer to 9&lt;= NO2&lt;=13 ppb in winter. </p>

<p>A sensitivity analysis was carried out to determine the effect of primary anthropogenic emission sources, namely mobile sources and upstream oil and gas (UOG), on the concentration of NO2. Approximately  48% and 15% of NOx emissions in Alberta come from UOG and mobile sources, respectively. The sensitivity analysis results at monitoring stations located in the cities of Edmonton and Calgary showed that mobile sources contributed to significantly higher fractions of 54% and 46% of NO2 in cold and warm modeling periods, respectively. In these stations, the impact of UOG sources was found to be less than 10% for each modeling period. The UOG sources effect is more pronounced at a regional background station and outside urban areas. Analyzing O3 concentration variation due to perturbed emission reveals that the cities of Edmonton and Calgary, are NOx-saturated regimes. Furthermore, sensitivity analysis showed that the NO2 concentration almost linearly responded to emission changes. The linear response of NO2 to emission perturbation indicates in Alberta&#39;s two large cities, emissions from mobile sources should be reduced by 20% to meet 2025 CAAQS limits.</p>

<p>The research air pollution simulation tool developed in this thesis has been validated with ground-level concentration measurements. It can be used to examine scenarios to analyze the interactions of CACs concentrations with weather-related incidents, climate change, and technologies and policy changes.</p>