城市园林树木叶面微结构特征对大气颗粒物滞留能力的影响

Effects of leaf microstructure characteristics of urban trees on atmospheric particulates retention capacity

园林植物叶面微结构会影响其截留大气颗粒物的能力。选取乌鲁木齐市主干道10种常见落叶阔叶树种,采用水洗滤膜法测定不同树种单位叶面积对空气总悬浮颗粒物(TSP)、大颗粒物(PM_(>10))、粗颗粒物(PM_(3—10))和细颗粒物(PM_(1—3))的滞纳量,探究不同粒级颗粒物含量及其占总颗粒物含量的百分比;用高倍电子显微镜观察叶表面微形态特征(绒毛长度、气孔半径、凹槽宽度等),分析叶表面在微观结构下各形态特征与其不同粒级颗粒物吸附能力间的相关性。结果表明:不同树种单位叶面积颗粒物滞纳量表现出较大差异,其中榆树总颗粒物滞纳量最高(53.38±0.71)μg,是红瑞木总颗粒物滞纳量(4.90±0.64)μg的10倍;PM_(>10)颗粒物平均含量占TSP约80%。榆树的PM_(3—10)、PM_(1—3)滞纳量最高,达(9.14±1.08)μg和(7.75±0.05)μg,是其他树种的3—5倍。气孔数量与TSP、PM_(>10)颗粒物含量呈显著正相关性,相关系数均为0.51(P<0.05);绒毛长度与PM_(1—3)含量具有显著负相关关系,相关系数为-0.57(P<0.05)。试验树种滞尘主要以大颗粒物为主,且叶面微结构与大颗粒物滞尘量关系密切;叶面凹槽与TSP、PM_(>10)、PM_(1—3)颗粒物含量呈负相关关系,其中叶背面凹槽宽度与PM_(>10)含量呈显著负相关(P<0.05)。通过测定10种树木叶片滞纳颗粒物含量发现,榆树、山楂等树木的叶面微结构特征具有较强的颗粒物滞纳能力,在乌鲁木齐市街道绿化工作中可作为优选物种应用。

The leaf micro⁃structure of gaden plants can affect their ability to intercept atmospheric particulate matters.In this study,10 common deciduous broad⁃leaved tree species were selected from the main roads in Urumqi,Northwestern China.The retention of total suspended particulate matter(TSP),large particulate matter(PM_(>10)),coarse particulate matter(PM_(3-10)),and fine particulate matter(PM_(1-3))of different tree species per unit leaf area were determined by using water⁃washed membrane method.The content of particulate matter in different particle classes and its percentage of the total particulate matter content was further investigated.The micro⁃morphological characteristics of the leaf surface(villi length,stomata radius,and groove width,etc.)were observed with an electron microscope.The correlation between the morphological characteristics of the leaf surface under the micro⁃structure and the adsorption capacity of different particle sizes was analyzed.The results showed that there were significant differences in the amount of particulate matter per unit leaf area among the 10 tree species,and the amount of total particulate matter in Ulmus densa was the highest(53.38±0.71)μg.It is 10 times of the total amount of Swida alba(4.90±0.64)μg;The average content of PM_(>10) particles accounted for about 80%of the TSP.Ulmus densa has the highest amount of PM_(3-10) and PM_(1-3),which were(9.141±1.08)μg and(7.75±0.05)μg.It is 3-5 times of other tree species.There was a significantly positive correlation between the number of stoma and the content of TSP,PM_(>10),and the correlation coefficients were both 0.51(P<0.05);There was a significantly negative correlation between villus length and PM_(1-3) content,the coefficients-0.57(P<0.05);The foliar dusts tested in this study were mainly dominated by large particles,and the foliar micro⁃structure was closely related to the amount of large particles;Leaf surface grooves were negatively correlated with TSP,PM_(>10),and PM_(1-3) content;Among them,leaf abaxial epidermis groove width and PM_(>10) content are correlated negatively,coefficients-0.32(P<0.05).It is found that the leaf microstructure characteristics of Ulmus densa and Crataegus pinnatifida lead to their strong dust retention ability,which could be used as preferred species in street greening work in Urumqi.