School of Automobile and Traffic Engineering, Jiangsu University, Zhenjiang, 212013, People's Republic of China.
College of Energy, Soochow University, Suzhou, 215006, People's Republic of China.
Environ Sci Pollut Res Int. 2019 May;26(14):14014-14023. doi: 10.1007/s11356-019-04783-1. Epub 2019 Mar 9.
External morphology and internal carbonaceous compositions are important characteristics for the source recognition of atmospheric particulate matter (PM). The fractal dimension of morphology and carbon components of diesel PM with different sizes both at high and low load were studied through fractal theory and thermal optical reflection method. It is revealed that small-size PM absorbs more soluble organic fractions and correspondingly has greater box dimension. Due to heavy aggregation, PM collected at low load has greater box dimension than that at high load because of heavy aggregation. OC1, which is the most volatile among organic carbons, is remarkably increased at low load or for small-size PM, absorbing more unburned hydrocarbons. At low load, a large amount of EC1 (char-EC) is generated and the ratio of OC/EC is more than 10, while, at high load, the EC is mainly composed of EC2 (soot-EC) and the ratio of OC/EC is less than 1. Apparently, the box dimension from the morphology of diesel PM presents a positive correlation with the ratio of OC/EC. Via above external and internal characteristics, particulates exhausted from motor vehicles in the atmosphere can be beneficially identified.
外部形态和内部含碳成分是大气颗粒物（PM）源识别的重要特征。采用分形理论和热光反射法研究了不同负荷下柴油机 PM 大小的形态和碳成分的分维数。结果表明，小粒径 PM 吸收更多的可溶性有机部分，因此具有更大的盒维数。由于严重的聚集，低负荷下收集的 PM 比高负荷下的 PM 具有更大的盒维数，因为低负荷下的 PM 比高负荷下的 PM 更易聚集。OC1 是有机碳中挥发性最大的，在低负荷或小粒径 PM 中明显增加，吸收了更多未燃烧的碳氢化合物。在低负荷下，大量的 EC1（炭黑-EC）生成，OC/EC 比值大于 10，而在高负荷下，EC 主要由 EC2（ soot-EC）组成，OC/EC 比值小于 1。显然，柴油机 PM 形态的盒维数与 OC/EC 比值呈正相关。通过上述外部和内部特征，可以有效地识别大气中机动车排放的颗粒物。
