Temporal variations of elemental carbon in Tokyo
Temporal variations of elemental carbon in Tokyo
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DOI：
10.1029/2005jd006257
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发表时间：
2006-06-17
影响因子：
4.4
通讯作者：
Ehara, K.
中科院分区：
文献类型：
--
作者：
Kondo, Y.;Komazaki, Y.;Ehara, K.
[1]2003-2005年，对东京大学东京校区不同季节的细元素碳(EC)质量浓度和一氧化碳(CO)混合比进行了测量。用半连续热光分析仪测量了EC。非挥发性气溶胶质量浓度的测量结果表明，非挥发性气溶胶的质量浓度很好地代表了EC的质量浓度，系统误差约为4%。大部分非挥发性气溶胶和EC质量浓度的体积当量直径在50-200 nm之间，在130 nm左右达到峰值。由于来源的相似性，EC和CO在整个测量期间的相关性总体上是紧密的。因此，EC-CO相关斜率(Delta EC/Delta CO)在验证EC排放清单方面是一个有用的参数。EC浓度和Delta EC/Delta CO具有明显的日变化特征。在工作日，EC和Delta EC/Delta CO在清晨(当地时间0400-0800)达到最大值，分别约为3微克m(-3)和9 ng m(-3)/百万分之，这是柴油发动机重型卡车的交通密度最高的时候。此外，在星期日，这些数值低了两倍。重型卡车交通表现出类似的日变化和工作日/周末的变化，表明柴油发动机排放的废气是EC的重要来源。月平均Delta EC/Delta CO表现出季节性变化，在美国马里兰州观察到的温度季节变化之后，在春秋达到最大值，在仲冬达到最小值(Chen等人，2001年)。这种温度依赖性很可能是由于柴油机排放的EC对进气温度的温度依赖性。2003年10月，东京都开始对柴油车颗粒物排放进行更严格的监管。然而，Delta EC/Delta CO值没有变化，在考虑到温度依赖性的情况下，在新法规开始实施一年后超过了自然变异性(10%)。这表明，东京都的颗粒物排放法规在1年后对降低EC浓度没有效果。
[1] Mass concentrations of elemental carbon (EC) in fine mode and mixing ratios of carbon monoxide ( CO) were measured at the University of Tokyo campus in Tokyo in different seasons in 2003 - 2005. Measurements of EC were made using a semicontinuous thermal-optical analyzer. The mass concentrations of nonvolatile aerosol measured by the calibrated scanning mobility particle sizer combined with a heated inlet agreed with the independent EC measurements with a systematic difference of about 4%, demonstrating that the mass concentrations of nonvolatile aerosol well represent those for EC. A majority of the nonvolatile aerosol and therefore EC mass concentration was in volume equivalent diameters between 50 and 200 nm, peaking at around 130 nm. The correlation of EC and CO was generally compact throughout the measurement period because of the similarity in sources. The slope of the EC-CO correlation (Delta EC/Delta CO) is therefore a useful parameter in validating EC emission inventories. The EC concentration and Delta EC/Delta CO showed distinct diurnal variation. On weekdays, EC and Delta EC/Delta CO reached maximum values of about 3 mu g m(-3) and 9 ng m(-3)/parts per billion by volume, respectively, in the early morning ( 0400 - 0800 local time), when the traffic density of heavy-duty trucks with diesel engines was highest. In addition, these values were lower by a factor of 2 on Sundays. The heavy truck traffic showed similar diurnal and weekday/weekend variations, indicating that exhaust from diesel engines is an important source of EC. Monthly mean Delta EC/Delta CO showed a seasonal variation, reaching broad maximum values in spring- autumn and reaching minimum values in midwinter, following the seasonal variation in temperature, as observed in Maryland, United States ( Chen et al., 2001). This temperature dependence is likely due to the temperature dependence of EC emissions from diesel engines on intake air temperature. More stringent regulation of emissions of particles from diesel cars started in the Tokyo Metropolitan Area in October 2003. The Delta EC/Delta CO values did not change, however, exceeding the natural variability (10%) after 1 year from the start of the new regulations, when the temperature dependence is taken into account. This indicates that the regulation of particle emissions in the Tokyo Metropolitan Area was not effective in reducing the EC concentrations after 1 year.