城市绿化植物叶片表面特征对滞尘能力的影响

Relationships between leaf surface characteristics and dust-capturing capability of urban greening plant species

以西安市21种常见绿化植物为对象,采用人工降尘方法测定植物叶片的最大滞尘量,研究植物叶片表面绒毛、润湿性、表面自由能及其分量对滞尘能力的影响.结果表明:21种供试植物叶片的最大滞尘量在0.8～38.6g·m-2,不同树种最大滞尘量差异显著,物种间相差40倍以上.叶片表面绒毛数量及其形态、分布特征对滞尘能力具有重要影响,可能与绒毛和颗粒物间的作用方式有关.除叶片表面着生绒毛的悬铃木、国槐、榆叶梅和毛梾4个物种外,其他植物叶片接触角与最大滞尘量均呈显著负相关.接触角较小、易润湿的植物叶片最大滞尘量在2.0～8.0g·m-2,而接触角较大的银杏、三叶草、紫叶小檗和鸡爪槭的最大滞尘量均<2.0g·m-2.叶片表面自由能主要表现分子间色散力的作用,而极性分量对表面自由能的贡献低于20%,可能与叶片表面含有的非极性或弱极性物质有关.最大滞尘量与叶片表面自由能及其色散分量呈显著正相关,而与极性分量的相关关系不显著.

Taking 21 representative urban greening species in Xi’an as test objects,their leaf dustcapturing capability was determined by artificial dust-deposition method,and the relationships between the dust-capturing capability and leaf surface features,e. g. ,trichomes,wettability,surface free energy and its polar and dispersive components on dust-capturing capability were studied. For the tested 21 species,their maximum leaf dust-capturing capability was 0. 8 - 38. 6 g·m -2,and there was a significant difference among them,with the greatest variation up to forty times. The amount,distribution,and morphology of trichomes had great influence on the leaf dust-capturing capability,possibly due to the different action patterns between trichomes and particulate matters. There was a significant negative relationship between leaf contact angle and maximum leaf dust-cap- turing capability （ r = - 0. 523） ,except for four species whose leaf surface has trichomes. For wet- table leaves,their maximum dust-capturing capacity ranged from 2. 0 to 8. 0 g·m -2,but for nonwettable leaves,their maximum dust-capturing capacity was below 2. 0 g·m -2. The leaf surface free energy was mainly manifested in the action of dispersive component,while the contribution of polar free energy was lower than 20% ,which could be related to the existence of non-polar or weakly polar substances on leaf surface. The leaf surface free energy and its dispersive component had a significant positive correlation （ r = 0. 500,0. 572） with the maximum leaf dust-capturing ca- pability,but the positive correlation between polar free energy and maximum dust-capturing capability was not significant （ r = 0. 244） .