Trends in Passively-Measured Ozone, Nitrogen Dioxide and Sulfur Dioxide Concentrations in the Athabasca Oil Sands Region of Alberta, Canada

Abstract

The Athabasca Oil Sands Region (AOSR) in northeastern Alberta, Canada has attracted much international attention in recent years due to the increased level of oil sands operations. A passive sampling program was initiated in 1999 to monitor ozone (O 3 ), nitrogen dioxide (NO 2 ) and sulfur dioxide (SO 2 ) in the AOSR for the estimation of the exposure of the forest monitoring sites and the characterization of temporal trends. Since 1999, highest concentrations of O 3 and NO 2 occurred in April and winter, respectively. The observed spring O 3 maximum is common in the northern hemisphere. The higher winter-time NO 2 concentrations were due to low atmospheric mixing height, stable atmosphere, and higher emissions during winter.Sen-Theil trend analysis, a non-parametric analysis for temporal trending, determined that O 3 concentrations from 2000 to 2009 did not change. NO 2 concentrations increased slightly at three sites, and significantly increased at two sites closer to stationary and mobile sources. SO 2 concentration was increasing at JP107 and was decreasing at JP101. SO 2 concentrations did not increase at 4 other sites close to the major emissions. This suggests that SO 2 emissions were likely stable.Spatial analysis was conducted to characterize the concentration distribution in the region. The O 3 concentrations were low near the emission sources (9.4 km) likely due to local O 3 titration. Highest NO 2 and SO 2 concentrations were measured near the main source area. Generally, passively measured monthly average concentrations of O 3 , NO 2 and SO 2 stabilized at 20, 48 and 48 km from the main source area suggesting NO 2 and SO 2 emission influences were limited to < 50 km away from the major sources. However, one site (JP107) located near the Athabasca River Valley, 94 km north of the main source area, had higher SO 2 and NO 2 concentrations. This could be attributed to influence of valley flow, and/or to additional sources added in the region since 2007.

Field performance evaluation of Maxxam passive samplers for regional monitoring of ambient SO2, NO2 and O3 concentrations in Alberta, Canada

“…This may have been due to the lower temperatures coupled with a greater frequency of high atmospheric stability and mixing height conditions during winter resulting in higher concentrations (Atkins and Lee, 1995). In rural Alberta the use of wood combustion and fossil fuel combustion for residential heating, and industrial emissions during winter can cause higher NO 2 and SO 2 concentrations compared to summer (Hsu, 2013;WBK, 2007). O 3 concentrations were particularly dominant in the spring and early summer (March through June) period, where maximum concentrations ranged from 35 to 56 ppb.…”

“…Historical field studies of these passive samplers (EPCM, 2000;Brassard, 2001;WBK, 2007;RWDI, 2008;Hsu et al, 2010;Hsu, 2013) are limited either by small sample size or by being qualitative rather than quantitative. Therefore, a robust estimate of the field measurement errors (expressed by precision and accuracy) of the passive samplers was sought to aid in the interpretation of time-weighted average ambient concentrations of SO 2 , NO 2 , and O 3 .…”

“…These samplers can be used to determine time-weighted average concentrations that are useful for comparing to regulatory criteria and informing the public. In Canada, several types of passive samplers have been used to measure SO 2 , NO 2 and O 3 concentrations for studying indoor and ambient air quality (Alberta Health and Wellness, 2000;Kindzierski and Sembaluk, 2001;Kindzierski and Ranganathan, 2006;Wheeler et al, 2011;Gibson et al, 2013;Hsu, 2013) and forest and vegetation exposures (Krupa and Legge, 2000;Cox, 2003).…”

Measurement of nitrogen dioxide and sulfur dioxide by satellite and passive monitors in Northeastern British Columbia, Canada.

“…However, continuous and passive measurement techniques have different purposes and uses, therefore it is suggested that the data from these two methods can be suitably compared for general trends rather than compared on an absolute basis (Hsu, 2013).…”

“…Ambient concentrations o f these species were measured using passive diffusive samplers, which have been widely used across America and Europe for the assessment o f atmospheric NO2 and SO2 concentrations (e.g. Bytnerowicz et al, 2010;Campos et al, 2010;Cape et al, 2004;Cox, 2003;Hafkenscheid et al, 2009;Hagenbjork-Gustafsson et al, 1999;Hsu, 2013;Kirchner et al, 2005;Legge et al, 1996;Tang et al, 1997;Tang et al, 1999;Tang et al, 2001;Van Reeuwijk et al, 1998;Vardoulakis et al, 2009;Zbieranowski and Aheme, 2012a) and for filling gaps in monitoring networks (Zbieranowski and Aheme, 2012a). To the best of our knowledge, there are no published articles available that describe the ambient air concentrations o f Northeastern B.C.…”