乔木对不同粒径颗粒物吸滞作用研究

Retention of Atmospheric Dust of Varied Particle Sizes by Landscape Tree Leaves

【目的】研究青岛市城阳区道路绿地8种乔木对不同粒径颗粒物的滞尘能力,为城市园林绿化提供科学依据。【方法】用洗脱法并通过微孔滤膜过滤测定8种乔木对不同粒径颗粒物的滞尘能力。计算8种植株的单株叶面积和单株滞尘量,对比8种乔木单株滞尘量的大小,用JEOL7500F电子显微镜观测叶表面,分析叶表面结构与不同粒径颗粒物滞尘量之间的关系。【结果】不同树种滞尘能力存在差异,国槐和紫叶李对PM 10吸附能力较强,毛白杨和悬铃木较弱,总体表现为:国槐>紫叶李>女贞>洋白蜡>栾树>绦柳>毛白杨>悬铃木;紫叶李对PM 5滞尘能力最强,栾树最弱,紫叶李对PM 5单位叶面积滞尘量是栾树的约2.4倍;对PM 2.5吸附能力表现为国槐最强,栾树次之,绦柳最弱。对单株滞尘量的研究表明,悬铃木对不同粒径颗粒物单株滞尘量最大,栾树和紫叶李较低。进一步研究表明,具有叶表面粗糙、绒毛密集,气孔开口较大、沟壑明显等特征的植物滞尘能力较强。【结论】国槐和紫叶李对PM 10吸附能力较强,毛白杨和悬铃木较弱;紫叶李对PM 5滞尘能力最强,栾树最弱;对PM 2.5吸附能力表现为国槐最强,栾树次之,绦柳最弱。悬铃木对不同粒径颗粒物单株滞尘量最大,栾树和紫叶李较低;具有叶表面粗糙、绒毛密集,气孔开口较大、沟壑明显等特征的植物滞尘能力较强。

【Objective】Effects of atmospheric dust particle size and landscape tree type on urban air quality improvement through dust retention of the plants were investigated.【Methods】Dust retention of 8 varieties of landscape trees in Chengyang District of Qingdao City was studied according to the particle sizes determined by eluting the retained dust on leaves with water followed by microporous filtration membrane filtration.The leaf surface morphology was examined under a JEOL7500F electron microscope.The average total leaf area and dust retention rates on varied particle sizes per plant of each variety were obtained for analysis.【Results】Among the tested species,Sophora japonica and Prunus cerasifera collected the highest,while Populus tomentosa and Platanus orientalis the lowest,amounts of PM 10 particles.The overall dust retention rates of the 8 varieties ranked as:S.japonica>P.cerasifera>Ligustrum lucidum>Fraxinus pennsylvanica>Koelreuteria paniculata>Salix matsudana>P.tomentosa>P.orientalis.PM 5 adhered more to the leaves of P.cerasifera but less to those of K.paniculata.The dust retention per unit leaf area of P.cerasifera was approximately 2.4 times higher than that of K.paniculata.The greatest retention on PM 2.5 was found with S.japonica followed by K.paniculata,and lowest with S.matsudana.On dust retention of all particle sizes,P.orientalis was the highest,whereas,K.paniculata and P.cerasifera the lowest.It appeared that the rougher the surface,the denser the villi,the larger the stomatal openings,and the more apparent the gully of the leaves were,the greater ability of the plants to retain dust fallen from the atmosphere.【Conclusion】S.japonica and P.cerasifera demonstrated a superior capacity to adsorb PM 10 on their leaves,but not P.tomentosa or P.orientalis;P.cerasifera to PM 5,but not K.paniculata;and,S.japonica to PM 2.5 followed by K.paniculata,but not S.matsudana.Including all varied particle sizes,the overall dust retention amount per plant of P.orientalis was the highest,while K.paniculata and P.cerasifera the lowest of the 8 tree varieties tested.And,trees of leaves with rough surface,dense villi,large stomatal openings,and obvious gully tended to collect more atmospheric dust that benefits air quality improvement for the vicinity.The information would aid the tree selection in urban landscape planning.