园林植物滞留不同粒径大气颗粒物的特征及规律

为研究常用园林植物滞留大气颗粒物的能力，本文以北京市常用园林植物为例，应用直接采样、电镜分析和统计分析的方法，对选定园林植物滞留不同粒径大气颗粒物的特征及规律进行了系统分析。结果表明：（1）园林植物滞留的颗粒物形状为不规则块体、球体和聚合体，通过对比分析得出，滞留大气颗粒物能力由高到低的微形态结构依次是蜡质结构〉绒毛〉沟槽〉条状突起，并且这些微形态结构越密集、深浅差别越大，越有利于滞留大气颗粒物。（2）以园林植物叶片滞留颗粒物的数量进行统计时，得出园林植物叶片表面大部分为PM10（Dp≤10μm），均在98%以上，而PM2.5（Dp≤2.5μm）均在90%以上，粗颗粒物（Dp〉10μm）的数量对总体数量的贡献非常小，均在2%以下；以体积进行统计时，得出PM10的体积在总体积中的比例在50%以上，对颗粒物总体积贡献最大，滞留的PM2.5体积占总体积8.5%-17.6%，粗颗粒物（Dp〉10μm）体积占总体积20%以上。（3）对园林植物滞留颗粒物累积规律分析得出：在相同观测叶面积下，园林植物滞尘10 d的叶表面颗粒物数量较滞尘5 d的叶表面颗粒物数量均有所增加，增幅最大的是小叶黄杨（Buxus microphylla），增幅最小的是月季（Rosa chinensis），通过方差分析得出绦柳（Salix matsudana f.pendula）叶表面颗粒物数量显著低于除银杏（Ginkgo biloba）之外的其它7种树种，大叶黄杨（Euonymus japonicus）、小叶黄杨和国槐（ Sophora japonica）叶表面滞留颗粒物的数量较多，并且显著高于月季、银杏和绦柳叶表面滞留的颗粒物数量；滞尘10 d后园林植物叶表面滞留的颗粒物的总面积均未超过观测叶面积的25%，至于叶片持续滞留颗粒物多少天后达到饱和状态仍需进一步研究。

The Characteristics of deposition of airborne particulate matters with different size on certain plants

In order to research retention capacity of airborne particulate matters （PM） by common plants, some representative plants in Beijing were chosen to systematically analyze the characteristics of deposition of PM with different size on them by using direct sampling, electron microscope analysis and statistical analysis methods. The results showed that：1） PM retained by plants had shapes of irregular block, ball and polymer. Plants which had more waxy leaf surface, or had more glandular hairs and wrinkles on leaves could retain PM more easily. 2） Over 98% of PM deposition on plants’ leaf surface were PM10（Dp≤10 μm）, PM2.5（Dp≤2.5 μm） accounted for over 90%, whereas, coarse particles accounted for less than 2%;The volume percentage of PM10 was over 50%, that of PM2.5 was 8.5%-17.6%, and the volume percentage of coarse particulate was over 20%. 3） With the same study area, leaves which retained PM for 10 days had more PM deposition than those retained PM for 5 days, Buxus microphylla had the largest increase, while Rosa chinensis had the smallest. Analysis of variance indicated that PM deposition on Salix matsudana f.pendula leaf surface was significantly less than other plants except for Ginkgo biloba, and the deposition of PM on leaf surface of Euonymus japonicus, Buxus microphylla and Sophora japonica were remarkably more than Rosa chinensis, Ginkgo biloba and Salix matsudana f.pendula. Moreover, The area of PM deposition was less than 25%of research leaf surface area. The time which it takes to get saturation state for PM deposition on leave surface will be studied in further research.