Time-series of weekly total carbon （TC） concentrations of fine aerosol particles （PM2.5） in Beijing and Toronto were compared to investigate their respective levels and temporal patterns over two years from August...Time-series of weekly total carbon （TC） concentrations of fine aerosol particles （PM2.5） in Beijing and Toronto were compared to investigate their respective levels and temporal patterns over two years from August 2001 through July 2003. In addition to this comparison, differences in the factors contributing to the observed concentrations and their temporal variations are discussed. Based upon past knowledge about the two megacities with highly contrasting air pollutant levels, it is not surprising that the average TC concentration in Belling （31.5 μg C m^-3） was greater than that in Toronto by a factor of 8.3. Despite their large concentration differences, in both cities TC comprised a similarly large component of PM2.5. TC concentrations exhibited very different seasonal patterns between the two cities. In Beijing, TC experienced higher levels and greater weekly fluctuations in winter whereas in Toronto this behavior was seen in summer. As a result, the greatest gap in TC concentrations between Beijing and Toronto （by a factor of 12.7） occurred in winter, while the smallest gap （a factor of 4.6） was in summer. In Beijing, seasonal variations in the emissions probably played a greater role than meteorology in influencing the TC seasonality, while in Toronto during the warm months more than 80% of the hourly winds were recorded from the south, along with many potential anthropogenic sources for the days with high TC concentrations. This comparison of the differences provides insight into the major factors affecting carbonaceous aerosol in each city.展开更多
采集了忻州市4个监测点位采暖季和非采暖季环境空气PM10样品,利用Elementar Analysensysteme GmbH vario EL cube测定有机碳(organic carbon,OC)和元素碳(elemental carbon,EC)的质量浓度,通过OC和EC的时空分布、比值以及相关性分析揭...采集了忻州市4个监测点位采暖季和非采暖季环境空气PM10样品,利用Elementar Analysensysteme GmbH vario EL cube测定有机碳(organic carbon,OC)和元素碳(elemental carbon,EC)的质量浓度,通过OC和EC的时空分布、比值以及相关性分析揭示忻州市的碳组分污染特征.结果表明,忻州市PM10中OC和EC的平均质量浓度分别为(18.5±4.5)μg·m-3和(16.1±4.3)μg·m-3,采暖季和非采暖季TCA占PM10的比例分别为70.7%和43.8%;4个监测点位采暖季OC的质量浓度均高于非采暖季,XT、DC和KQ监测点采暖季EC的质量浓度高于非采暖季,SQ监测点则相反,采暖季燃煤是OC和EC的主要来源;监测点XT的OC质量浓度最高,为24.1μg·m-3,DC的EC质量浓度最高,为22.0μg·m-3,SQ的OC和EC质量浓度最低,分别为17.2μg·m-3和14.5μg·m-3,区域性污染特征存在差异;OC/EC均值小于2,一次污染严重;非采暖季OC与EC浓度相关性较好(R2=0.55),二者排放源单一,主要来源为机动车尾气排放,采暖季相关性不显著(R2=0.13),二者排放源复杂.忻州市主要通过控制燃煤、机动车尾气、生物质燃烧、工业源等的一次排放来减轻碳组分污染,进而提高环境空气质量.展开更多
基金funded by National Natural Science Foundation of China(NSFC)projects(Grant Nos.20322203 and 40675079)the National Science Fund for Distinguished Young Scholars of NSFC(Grant No.20625722)
文摘Time-series of weekly total carbon （TC） concentrations of fine aerosol particles （PM2.5） in Beijing and Toronto were compared to investigate their respective levels and temporal patterns over two years from August 2001 through July 2003. In addition to this comparison, differences in the factors contributing to the observed concentrations and their temporal variations are discussed. Based upon past knowledge about the two megacities with highly contrasting air pollutant levels, it is not surprising that the average TC concentration in Belling （31.5 μg C m^-3） was greater than that in Toronto by a factor of 8.3. Despite their large concentration differences, in both cities TC comprised a similarly large component of PM2.5. TC concentrations exhibited very different seasonal patterns between the two cities. In Beijing, TC experienced higher levels and greater weekly fluctuations in winter whereas in Toronto this behavior was seen in summer. As a result, the greatest gap in TC concentrations between Beijing and Toronto （by a factor of 12.7） occurred in winter, while the smallest gap （a factor of 4.6） was in summer. In Beijing, seasonal variations in the emissions probably played a greater role than meteorology in influencing the TC seasonality, while in Toronto during the warm months more than 80% of the hourly winds were recorded from the south, along with many potential anthropogenic sources for the days with high TC concentrations. This comparison of the differences provides insight into the major factors affecting carbonaceous aerosol in each city.
文摘采集了忻州市4个监测点位采暖季和非采暖季环境空气PM10样品,利用Elementar Analysensysteme GmbH vario EL cube测定有机碳(organic carbon,OC)和元素碳(elemental carbon,EC)的质量浓度,通过OC和EC的时空分布、比值以及相关性分析揭示忻州市的碳组分污染特征.结果表明,忻州市PM10中OC和EC的平均质量浓度分别为(18.5±4.5)μg·m-3和(16.1±4.3)μg·m-3,采暖季和非采暖季TCA占PM10的比例分别为70.7%和43.8%;4个监测点位采暖季OC的质量浓度均高于非采暖季,XT、DC和KQ监测点采暖季EC的质量浓度高于非采暖季,SQ监测点则相反,采暖季燃煤是OC和EC的主要来源;监测点XT的OC质量浓度最高,为24.1μg·m-3,DC的EC质量浓度最高,为22.0μg·m-3,SQ的OC和EC质量浓度最低,分别为17.2μg·m-3和14.5μg·m-3,区域性污染特征存在差异;OC/EC均值小于2,一次污染严重;非采暖季OC与EC浓度相关性较好(R2=0.55),二者排放源单一,主要来源为机动车尾气排放,采暖季相关性不显著(R2=0.13),二者排放源复杂.忻州市主要通过控制燃煤、机动车尾气、生物质燃烧、工业源等的一次排放来减轻碳组分污染,进而提高环境空气质量.
