武汉市15种阔叶乔木滞尘能力与叶表微形态特征

Dust- retention capability and leaf surface micromorphology of 15 broad-leaved tree species in Wuhan

以武汉市15种常见的阔叶乔木为研究对象,通过3级滤膜过滤法测定了各乔木单位叶面积滞留不同粒径颗粒物(TSP、PM>10、PM10、PM2.5)的质量,并通过扫描电镜观察比较了15种乔木的叶表面微形态结构,分析了微形态对植物滞尘能力的影响。结果表明:15种乔木单位叶面积的滞尘量存在显著差异(P<0.05),综合滞尘能力最强的植物为二球悬铃木、桂花和石楠,除以上3者外,女贞和广玉兰分别具有较强的滞留PM10和PM2.5的能力;加杨滞留TSP和PM>10的能力最弱,玉兰滞留PM10和PM2.5的能力最弱。各乔木单位叶面积滞留PM2.5和PM10的质量分别占总粉尘量的0.7%—8.9%和3.6%—33.9%。叶表面微结构观察表明,叶表面粗糙、褶皱较多,或被有蜡质层的植物有利于粉尘颗粒物的附着。相关性分析表明,植物单位叶面积的滞尘量与叶表面沟槽的宽度呈显著相关,上下表面沟槽宽度越小,越有利于细微颗粒物(PM2.5)的滞留,下表面沟槽宽度增加,有利于粉尘总颗粒物(TSP)的滞留。由此可见,叶表面粗糙度、蜡质含量和沟槽宽度等微形态结构是调控绿化树种叶片滞尘能力的重要因素,在武汉以治理大气粉尘污染为目标进行城市绿化时,可考虑选择二球悬铃木、桂花和石楠等滞尘能力强的树种。

We selected 15 common broad⁃leaved tree species in Wuhan and quantified particles of different sizes(TSP,PM>10,PM10,PM2.5)per unit leaf area using a 3⁃layer membrane filtration method.To explore the influence of leaf surface micromorphology on dust⁃retention ability,the leaf surface micromorphology of the 15 tree species was observed by scanning electron microscopy(SEM).The results showed that there were significant differences in dust retention per unit leaf area among the 15 tree species(P<0.05).The plants with the strongest dust⁃retention ability were Platanus acerifolia,Osmanthus fragrans,and Photinia magnolia.In addition to,Ligustrum lucidum and Magnolia grandiflora had a strong ability to retain PM10 and PM2.5 on their leaves,respectively.Populus×canadensis had the weakest ability to retain TSP and PM>10,and Magnolia denudata had the weakest ability to retain PM10 and PM2.5.The ratio of PM2.5 and PM10 mass per unit leaf area to total dust content ranged from 0.7%to 8.9%and from 3.6%to 33.9%,respectively.Micromorphological observations of the leaf surfaces showed that rough,wrinkled leaves or a waxy layer on the leaves were conducive to the attachment of dust particles.The correlation analyses indicated that the amount of dust per unit leaf area was significantly correlated with the width of the grooves on the leaf surface.The smaller the width of grooves on the upper and lower surfaces,the more favorable the retention of fine particles(PM2.5).The larger the width of grooves on the lower surface,the more favorable the retention of total particles(TSP).Therefore,the micromorphological structure of the leaf surface(roughness,wax content,and groove width)are important factors in the dust⁃retention capability of greening tree species.When urban greening is carried out in Wuhan to control atmospheric dust pollution,we suggest to choose tree species with a strong dust⁃retention capability,such as P.acerifolia,O.fragrans,and P.magnolia.