Leaves of 9 landscaping tree species, includes Koelreuteria paniculata, were collected from roadside of the West-3-Ring Road in Beijing and studied for their micro-morphological (stoma, epidermal hair, etc.,) features with Environmental Scanning Electron Microscope (ESEM) as well as associated particulate matters (PMs) using Energy Spectrometer (EDS). The result showed that leaves of plants were one of the main means/ways/channels to retain airborne PMs and the retention abilities were various due to differences of their epidermal micro structures. Higher PM retention rate was associated with higher density of leaf surface microgroove structures, cells and stoma. The leaf epidermal hair also played a role in catching PMs, whilst the liquid exudation on it had an adhesive effect. It was observed that different sizes of PMs embedded in the leaf microgroove structures, the spaces between cells and stoma. For all the plant species (except Robinia pseudoacacia), particle retention rate was in the order for various PM sizes as 0.1~0.5 mm>0.5~1 mm > over 1 mm. Under ESEM, elements C and O were identified on leaves broadly with Si, Fe and Mn also found on most plant leaves, which basically indicated that apart from their general function of PM collection, plant leaves could clean up air pollutions arose from oil burning, coal burning and industrial production in the West-3-Ring Road area.%以栾树(Koelreuteria paniculata)等9种常见于北京市区主干道旁的园林植物的叶片为研究对象,采用环境扫描电镜(Environmental Scanning Electron Microscope,ESEM)对这些植物叶片的气孔、表皮毛等微形态特征及其对颗粒物的滞留作用进行观察和描述,并对在叶片上滞留的颗粒物进行能谱分析.结果表明,植物叶片是滞留大气颗粒物的主要器官之一,叶片上下表皮的微结构差异影响其对颗粒物的滞留潜力.叶片上的细纹结构、细胞之间的间隔、气孔等部位镶嵌着不同粒径的颗粒物.叶片表皮的细纹结构越密集、细胞之间的间隔越小、气孔密度越大,对颗粒物的阻滞作用越明显.另外,叶片表皮毛能够对颗粒物起到一定的滞留作用.植物分泌的液态状物质能够粘滞颗粒物.除刺槐(Robinia pseudoacacia)外,其他8种植物叶片表面滞留的粒径介于0.1~0.5 mm之间的颗粒物最多,介于0.5~1 mm之间的次之,粒径>1 mm以上的颗粒物数量最少.通过能谱分析发现,C和O在植物叶片滞留的颗粒物中广泛存在;Si、Fe、Mn等在大多数植物叶片上也有发现.以北京西三环这一市区主干道为例,根据不同元素在植物叶片上的积累,基本可以判断,植物借助叶表皮微形态学结构特征,在富集颗粒物的同时,对以燃油型、燃煤型和工业生产排放的颗粒为主的大气污染物具有净化作用.
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