北京市常用园林植物滞留PM_(2.5)能力的研究

Capability of Common Garden Plants in Beijing to Retain PM_(2.5)

为了研究常用园林植物滞留颗粒物的能力,选择北京市常用的园林植物种类作为研究对象,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颗粒物尤其是细颗粒物PM2.5的能力进行系统分析。结果表明:1)9种园林植物叶表面PM2.5的数量比占90%以上,体积比占20%以下。2)5种乔木单位叶面积滞留PM2.5的体积比较:国槐(Sophora japonica)>钻石海棠(Malus yunnanensis cv.sparkler)>银杏(Ginkgo biloba)>杂交马褂木(Liriodendron chinense×L.tulipifera)>绦柳(Salix matsudana f.pendula);4种灌木比较:大叶黄杨(Euonymus japonicus)>小叶黄杨(Buxus microphylla)>金叶女贞(Ligustrum×vicaryi)>月季(Rosa chinensis)。通过方差分析发现,绦柳单位叶面积滞留PM2.5的体积显著低于其他8种树种,小叶黄杨、大叶黄杨、金叶女贞和国槐单位叶面积滞留PM2.5的体积显著高于其他几种树种。3)比较园林植物在不同高度单位叶面积滞留颗粒物的体积时,除绦柳以外,其余8种园林树种均呈现出下层叶片单位叶面积滞留颗粒物的体积要高于顶层叶片。4)与滞尘5d相比,滞留10d后9种园林植物单位叶面积滞留PM2.5的体积和数量均呈增加状态,增幅最大的是小叶黄杨,大叶黄杨次之,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。5)结合植物滞留细颗粒物能力大小分析得出,植物叶表面不论是通过细胞之间的排列形成的沟槽还是通过各种条状突起、波状突起和脊状突起形成的沟槽,只要沟槽越密集、深浅差别越大,越有利于滞留细颗粒物,且叶表面有蜡质、腺毛等结构也有利于细颗粒物的滞留。

Several commonly used species of landscape plants in Beijing were chosen to study their capacities of catching airborne particles.Direct sampling,electron microscope analysis and statistical analysis methods were employed to systematically analyze the characteristics of the deposition of particles in different sizes on different plants.The results showed that 1)over 98% of PM deposition on plants' leaf surface were PM10(DP≤10μm)in quantity,PM2.5(DP≤2.5μm)accounted for over 90%,while coarse particles accounted for less than 2%.The volume percentage of PM10 was over 50%,that of PM2.5and coarse particulate were 8.5%-17.6%and over 20%,respectively.2)The volume of PM2.5retained by 5kinds of trees per unit leaf area was in the order of Sophora japonica> Malus yunnanensis cv.sparkler > Ginkgo biloba >Liriodendron chinense ×L.tulipifera > Salix matsudanaf.pendula,while the volume of PM2.5retainedby 4kinds of shrubs per unit leaf area was in the order of Euonymus japonicus> Buxus microphylla >Ligustrum ×vicaryi> Rosa chinensis.Analysis of variance showed that the volume of PM deposition on Salix matsudanaf.pendulaleaf surface was significantly less than other plants species,and the deposition volume of PM on leaf surface of Euonymus japonicus,Buxus microphylla,Ligustrum × vicaryi and Sophora japonica were remarkably more than other plants.3)Except for Salix matsudana f.pendula,the volume of particles retained by lower leaves of 8plants species per unit leaf area was much more than top ones.4)Compared to the volume of PM2.5retained for 5days,that retained for 10 days increased for 9species of plants per unit leaf area.The greatest increase was 45.9% occurred in Buxus microphylla,while Euonymus japonicus was the second one.The quantity of PM2.5retained by 9species of plants per unit leaf area increased as well.The time which it takes to get saturation state for PM deposition on leave surface needs further study.5)Whether the groove on the plant leaf surface formed by arranged cells or through a variety of strip protuberance,wave protrusions and ridges,as long as the groove is more intense and of greater depth difference,the plant could detain more fine particulate matters.What's more,the plants whose leaf surfaces had wax and more glandular hairs could also more easily detain fine particles.