Modification of soot by volatile species in an urban atmosphere.
Modification of soot by volatile species in an urban atmosphere.
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DOI：
10.1016/j.scitotenv.2007.08.016
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发表时间：
2008-01
期刊：
影响因子：
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通讯作者：
Zongbo Shi;Daizhou Zhang;Hezhe Ji;S. Hasegawa;M. Hayashi
中科院分区：
文献类型：
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作者：
Zongbo Shi;Daizhou Zhang;Hezhe Ji;S. Hasegawa;M. Hayashi
对日本西南部熊本市（32°48′n, 134°45′e）市区大气中的气溶胶样本进行了铝箔纸取样。部分样品在纯氦气和氧气(2%)-氦气（98%）混合气体中加热至550℃。利用扫描电子显微镜和能量色散x射线能谱仪分别对未加热和加热部位的颗粒进行了形貌和元素组成表征。从形态上看，含烟颗粒主要有链状和亚圆形两种类型。链状颗粒可能是年轻的煤烟颗粒，因为这些颗粒在加热后的样品中表现出与未加热样品相似的形态。相比之下，亚圆形颗粒是由煤灰包裹的挥发性物质组成的。加热使这些颗粒部分蒸发，只有加热后才能识别出烟炱夹杂物。挥发分中含硫化合物较多，但残留物中未检出硫，说明挥发分主要产生于大气中的烟尘颗粒上。次圆形含烟颗粒的直径约为夹杂物的3倍。这些结果表明，烟尘颗粒的大小和组成可能会受到城市大气中挥发性物质的实质性改变。
Aerosol samples in the urban atmosphere of Kumamoto (32°48′N, 134°45′E) in southwestern Japan were collected onto aluminum foil strips. Parts of the samples were heated to 550 °C in pure helium gas, and oxygen (2%)–helium (98%) mixture gas. Particles in unheated and heated parts were characterized individually by their morphology and elemental composition using a scanning electron microscope equipped with an energy dispersive X-ray spectrometer. There were mainly two types of soot-containing particles according to the morphology: chain-like and sub-round. Chain-like particles were likely young soot particles because such particles in heated specimens showed similar morphology to those in unheated specimen. In contrast, the sub-round particles were composed of volatile species encapsulated with soot. The heating caused partial evaporation of such particles, and the soot inclusions could be identified only after the heating. The volatile species frequently contained sulfur compounds, but sulfur was not detected in the residues, suggesting that the volatile species were mainly produced on soot particles in the atmosphere. The sub-round soot-containing particles were approximately 3 times larger in diameter than the inclusions. These results suggest that soot particles could be substantially modified in size and composition by volatile species in the urban atmosphere.