空气凤梨叶表鳞片对大气颗粒物滞留与吸收的影响研究

It has quite been realized that particulate pollution is a very real and serious problem. Some previous studies have shown that plants are effective in trapping and adsorbing many pollutant particles, and they can act as biological absorbers or filters of pollutants. Plant species differ significantly in their abilities to mitigate particulate pollution due to differences in their leaf surface characteristics, especially foliar trichomes, specialized structures getting in touch with atmospheric particles firstly. However, effect of foliar trichomes on particulate retention and uptake has not been investigated until now. So epiphytic Tillandsia species with typical trichomes, are chosen to assess the function of foliar trichomes in trapping and adsorbing airborne particles. Particulate components and contents on the leave surface and in the internal leave will be analyzed after trichomes are removed with adhesive tapes. Transport pathways of particles in the leave will be determined with scanning electron microscopy (SEM), transmission electron microscope (TEM) and energy dispersive spectrometer (EDS). At the same time, resuspension ratio of particles on the leave surface will be analyzed to discover the function of trichomes is reflected mainly in the process of particles deposition, resuspension or adsorption.

雾霾问题是人们关注的焦点，而植物能够减轻大气颗粒物污染已成为人们的共识。叶表附属物是植物与大气颗粒物最先接触的特殊结构。但是，现在还罕有研究表明这些特殊结构是如何影响大气颗粒物的滞留和吸收的。因此，本项目拟选择具有典型叶表鳞片的植物类群空气凤梨为研究对象，通过人工鳞片去除技术，将具有鳞片和已无鳞片的空气凤梨分别暴露于大气颗粒物污染环境中，比较分析空气凤梨叶片表面和叶片内部的颗粒物成分与含量，阐明叶表覆盖鳞片的空气凤梨是否能够快速有效地滞留颗粒物。通过扫描电镜、透射电镜、能谱分析等手段，探究颗粒物在植物体内的转运途径。通过分析大气颗粒物再悬浮的比例，阐明鳞片的作用主要体现在大气颗粒物的沉积、再悬浮还是吸收过程中。从多个角度深入探讨叶表附属物在大气颗粒物滞留与吸收过程中发挥的功能，为人们选择更有效的净化大气污染植物种类提供理论依据。

本项目选择具有典型叶表鳞片的植物类群-空气凤梨为研究对象，深入探讨了叶表附属物这一特殊结构在大气颗粒物滞留方面的效果和机制。结果表明，无论是对最大滞尘量还是自然滞尘量，与去除鳞片的植株相比，具有鳞片的空气凤梨总是能滞留更多的颗粒物。颗粒物沉降于空气凤梨叶片后，无鳞片的叶片上超过80%的颗粒物能在风力作用下再悬浮起来，而此比例远大于拥有鳞片的空气凤梨。与之相比，虽然空气凤梨也能有效吸收大气颗粒物中的重金属和有机成分，但鳞片在此过程中的作用不明显。相关性分析表明，空气凤梨叶内无机元素主要来源于大气颗粒物，重金属进入植物叶片后主要累积在细胞壁和细胞器中，而以颗粒物为载体进入空气凤梨叶内的有机成分很少。另外，受外界环境胁迫后，空气凤梨遭受到了一定的生理损伤，但人工去除鳞片实验表明，鳞片的存在能在一定程度上增强其抗性。因此，空气凤梨叶表鳞片在大气颗粒物滞留过程中起着重要作用，既有一般附属物所具有的防护功能，还能有效降低沉降于叶表面颗粒物的再悬浮，起着促进颗粒物滞留的作用。