Journal cover Journal topic
Atmospheric Chemistry and Physics An interactive open-access journal of the European Geosciences Union
Atmos. Chem. Phys., 18, 3457-3467, 2018
https://doi.org/10.5194/acp-18-3457-2018
© Author(s) 2018. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
08 Mar 2018
Emissions databases for polycyclic aromatic compounds in the Canadian Athabasca oil sands region – development using current knowledge and evaluation with passive sampling and air dispersion modelling data
Xin Qiu1, Irene Cheng2, Fuquan Yang1, Erin Horb3, Leiming Zhang2, and Tom Harner2 1Novus Environmental Inc., Guelph, Ontario, N1G 4T2, Canada
2Air Quality Research Division, Science and Technology Branch, Environment and Climate Change Canada, Toronto, Ontario, M3H 5T4, Canada
3Novus Environmental Inc., Calgary, Alberta, T2R 1K7, Canada
Abstract. Two speciated and spatially resolved emissions databases for polycyclic aromatic compounds (PACs) in the Athabasca oil sands region (AOSR) were developed. The first database was derived from volatile organic compound (VOC) emissions data provided by the Cumulative Environmental Management Association (CEMA) and the second database was derived from additional data collected within the Joint Canada–Alberta Oil Sands Monitoring (JOSM) program. CALPUFF modelling results for atmospheric polycyclic aromatic hydrocarbons (PAHs), alkylated PAHs, and dibenzothiophenes (DBTs), obtained using each of the emissions databases, are presented and compared with measurements from a passive air monitoring network. The JOSM-derived emissions resulted in better model–measurement agreement in the total PAH concentrations and for most PAH species concentrations compared to results using CEMA-derived emissions. At local sites near oil sands mines, the percent error of the model compared to observations decreased from 30 % using the CEMA-derived emissions to 17 % using the JOSM-derived emissions. The improvement at local sites was likely attributed to the inclusion of updated tailings pond emissions estimated from JOSM activities. In either the CEMA-derived or JOSM-derived emissions scenario, the model underestimated PAH concentrations by a factor of 3 at remote locations. Potential reasons for the disagreement include forest fire emissions, re-emissions of previously deposited PAHs, and long-range transport not considered in the model. Alkylated PAH and DBT concentrations were also significantly underestimated. The CALPUFF model is expected to predict higher concentrations because of the limited chemistry and deposition modelling. Thus the model underestimation of PACs is likely due to gaps in the emissions database for these compounds and uncertainties in the methodology for estimating the emissions. Future work is required that focuses on improving the PAC emissions estimation and speciation methodologies and reducing the uncertainties in VOC emissions which are subsequently used in PAC emissions estimation.
Citation: Qiu, X., Cheng, I., Yang, F., Horb, E., Zhang, L., and Harner, T.: Emissions databases for polycyclic aromatic compounds in the Canadian Athabasca oil sands region – development using current knowledge and evaluation with passive sampling and air dispersion modelling data, Atmos. Chem. Phys., 18, 3457-3467, https://doi.org/10.5194/acp-18-3457-2018, 2018.
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Short summary
We developed emissions databases for polycyclic aromatic compounds (PACs) in the Athabasca oil sands region and evaluated the emissions databases by comparing CALPUFF-modelled concentrations with monitored data. Model–measurement agreement improved near oil sands mines due to updated PAC emissions from tailings ponds. Modelled concentrations were underestimated at remote sites and for alkylated PACs suggesting that the emissions of PACs particularly alkylated compounds are underestimated.
We developed emissions databases for polycyclic aromatic compounds (PACs) in the Athabasca oil...
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