乔木滞留大气颗粒物能力及其与叶表面微结构关系

Atmospheric Particle Retention Capacity of Trees and Its Relationship with Leaf Surface Microstructure

植物在净化城市大气颗粒物方面发挥着重要作用,为了明晰不同植物滞留大气颗粒物的能力差异及其与叶表面微观结构的关系,文章以杭州地区10种常见乔木为研究对象,采用重量分析法,结合SEM/EDS技术和ImageJ软件,观测叶表面微观结构,量化植物滞留大气颗粒物能力,并分析颗粒物的来源。结果表明:10种乔木单位叶面积滞留颗粒物质量存在显著差异,其中二球悬铃木、榔榆和桂花滞留各粒径颗粒物的能力均较强,水杉和无患子滞留TSP和PM_(10)的能力较强,玉兰和木荷滞留各粒径颗粒物的能力均较弱;叶表面存在皱褶、密集深沟槽、蜡质和突起等结构的乔木,有利于颗粒物的滞留,而叶表面平坦、沟槽较宽的乔木滞留颗粒物的能力较弱;叶片表面的沟槽宽度与叶片滞留PM_(2.5)质量呈显著负相关关系;C和O元素存在于所有被测颗粒物中,且含量较高;大多数乔木叶片上存在N、Mg、Al、Si和K元素;叶片上滞留的颗粒物主要来自汽车尾气和土壤扬尘。因此,在城市绿化建设中应结合对滞留颗粒物有利的叶表面微观结构特征选择并推广相应树种。

Plants play an important role in purifying urban atmospheric particulate matter(PM).To clarify the difference in the atmospheric particle retention capacity of different trees species and its relationship with leaf surface microstructure,this study selects ten common tree species in Hangzhou to observe the microstructure of leaf surface,evaluate the PM retention capacity and analyze the sources of particulate matter using the rinse and weigh method combined with SEM/EDS technology and ImageJ software.The results show that there are significant differences in the mass of retained particulate matter per unit leaf area among the ten species.Platanus acerifolia,Ulmus parvifolia and Osmanthus fragrans present a high retention capacity of the PM of all sizes.Metasequoia glyptostroboides and Sapindus mukorossi have higher capacity to retain TSP and PM_(10),while Magnolia denudata and Schima superba have a low capacity to retain particles of all sizes.The species whose leaf surfaces have a large number of wrinkles,dense deep grooves,wax,protrusions,etc.are good for particle retention,while those with flat and wide-groove leaf surface has a low capacity to retain particles.The adaxial groove width of leaf surface has a significant negative correlation with the retained PM_(25)mass.C and O elements are found in all the particles determined,whose content is high,and N,Mg,Al,Si,and K elements are present on the leaves of most trees.The main sources of particulate matter retained on the leaves are automobile exhaust and soil dust.Therefore,tree species with leaf surface microstructure beneficial to PM retention should be selected and extended in urban landscaping.