To evaluate the effectiveness of emission control regulations designed for reducing air pollution, chemically resolved PM_(2.5) data have been collected across Canada through the National Air Pollution Surveillance ne...To evaluate the effectiveness of emission control regulations designed for reducing air pollution, chemically resolved PM_(2.5) data have been collected across Canada through the National Air Pollution Surveillance network in the past decade. 24-hr time integrated PM_(2.5) collected at seven urban and two rural sites during 2010-2016 were analyzed to characterize geographical and seasonal patterns and associated potential causes. Site-specific seven-year mean gravimetric PM_(2.5) mass concentrations ranged from 5.7 to 9.6 μg/m^(3). Seven-year mean concentrations of SO_(4)^(2-), NO_(3)^(-), NH_(4)^(+), organic carbon(OC), and elemental carbon(EC) were in the range of 0.68 to 1.6, 0.21 to 1.5, 0.27 to 0.71, 1.1 to 1.9, and 0.37 to 0.71 μg/m^(3), accounting for 10.8%-18.1%, 3.7%-16.7%, 4.7%-7.4%, 18.4%-21.0%, and 6.4%-10.6%, respectively, of gravimetric PM_(2.5) mass. PM_(2.5) and its five major chemical components showed higher concentrations in southeastern Canada and lower values in Atlantic Canada, with the seven-year mean ratios between the two regions being on the order of 1.7 for PM_(2.5) and 1.8-7.1 for its chemical components. When comparing the concentrations between urban and rural sites within the same region, those of SO_(4)^(2-) and NH_(4)^(+) were comparable, while those of NO_(3)^(-), OC, and EC were around 20%, 40%-50%, and 70%-80%, respectively, higher at urban than rural sites, indicating the regional scale impacts of SO_(4)^(2-) and NH_(4)^(+) and effects of local sources on OC and EC. Monthly variations generally showed summertime peaks for SO_(4)^(2-) and wintertime peaks for NO_(3)^(-), but those of NH_(4)^(+), OC, and EC exhibited different seasonality at different locations.展开更多
基金supported by the China Scholarship Council for one year as a visiting fellow at Environment and Climate Change Canada。
文摘To evaluate the effectiveness of emission control regulations designed for reducing air pollution, chemically resolved PM_(2.5) data have been collected across Canada through the National Air Pollution Surveillance network in the past decade. 24-hr time integrated PM_(2.5) collected at seven urban and two rural sites during 2010-2016 were analyzed to characterize geographical and seasonal patterns and associated potential causes. Site-specific seven-year mean gravimetric PM_(2.5) mass concentrations ranged from 5.7 to 9.6 μg/m^(3). Seven-year mean concentrations of SO_(4)^(2-), NO_(3)^(-), NH_(4)^(+), organic carbon(OC), and elemental carbon(EC) were in the range of 0.68 to 1.6, 0.21 to 1.5, 0.27 to 0.71, 1.1 to 1.9, and 0.37 to 0.71 μg/m^(3), accounting for 10.8%-18.1%, 3.7%-16.7%, 4.7%-7.4%, 18.4%-21.0%, and 6.4%-10.6%, respectively, of gravimetric PM_(2.5) mass. PM_(2.5) and its five major chemical components showed higher concentrations in southeastern Canada and lower values in Atlantic Canada, with the seven-year mean ratios between the two regions being on the order of 1.7 for PM_(2.5) and 1.8-7.1 for its chemical components. When comparing the concentrations between urban and rural sites within the same region, those of SO_(4)^(2-) and NH_(4)^(+) were comparable, while those of NO_(3)^(-), OC, and EC were around 20%, 40%-50%, and 70%-80%, respectively, higher at urban than rural sites, indicating the regional scale impacts of SO_(4)^(2-) and NH_(4)^(+) and effects of local sources on OC and EC. Monthly variations generally showed summertime peaks for SO_(4)^(2-) and wintertime peaks for NO_(3)^(-), but those of NH_(4)^(+), OC, and EC exhibited different seasonality at different locations.
