大叶女贞叶面结构对滞留颗粒物粒径的影响
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摘要
为分析叶面微结构对滞留颗粒物粒径的影响,以分布较广的常绿植物——大叶女贞为研究对象,用激光粒度分析仪(湿法)测定叶面尘的粒径分布,用扫描电子显微镜和原子力显微镜观察叶面微结构;并用图像处理软件(图像法)分析叶面颗粒物的粒径特征,探讨不同测定方法对叶面颗粒物粒径分布的可能影响。结果表明,大叶女贞叶面滞留颗粒物粒径呈双峰分布,湿法测定的颗粒物粒径范围为0.4~52.6μm,粒径峰值为18.9μm、36.2μm,粒径均值为8.8μm;图像法测定的颗粒物粒径范围为0.4~27.8μm,粒径峰值为17.5μm、27.8μm,粒径均值为7.2μm。叶表面分布有大量的突起和凹陷,凹陷直径介于0.6~30μm,直径小于2.5μm和10μm的凹陷约占到总量的50%和80%。可吸入颗粒物(PM10)和细颗粒物(PM2.5)主要滞留在叶表的凹陷结构中,有少量粒径大于10μm的颗粒物滞留在突起之上。PM2.5和PM10的体积分数仅占滞尘总量的17.9%和50.4%(湿法)、16.8%和45.9%(图像法),但数量多于大粒径颗粒物,这与小粒径的颗粒在个数上占优势、但大粒径的颗粒则对叶面滞留颗粒物的质量(或体积)贡献较大有关。叶背面颗粒物附着密度较正面小,PM2.5等颗粒物多分布在气孔周围,有少量颗粒物沉积在气孔上,从而堵塞气孔。
This paper is inclined to make an exploration of the particle size distribution and its relation to the surface microstructures by using the foliar samples of Ligustrum lucidum collected from Xi'an University of Architecture and Technology. The particle size distribution of the collected samples can be determined with a laser particle size analyzer. The microstructure of leaf surfaces can be observed using an electronic scanning microscopy(SEM) and the atomic force microscopy(AFM). The particle size distribution can also be compared between the laser scattering method and the microscopic method,which helps to make clear the two peak values existing in the size distribution of the foliar dust. However,the particle size range,the peak and mean values of the particles can be found different if analyzed via the two methods. For example,the laser scattering method tends to show higher values than the microscopic method does,with the particle size ranging between 0. 4-52. 6 μm and 0. 4-27. 8 μm,with the peak values being 18. 9 μm and 36. 2 μm,or17. 5 μm and 27. 8 μm,and with their mean values being 8. 8 μm and 7. 2 μm,respectively. What is more,there can be found many papillae and hollows on the surfaces of the leaves,with the diameters of the hollows ranging from 0. 6 μm to 30 μm. The ratio of the hollows with diameters less than 2. 5 μm and 10 μm accounts for 50%and 80% of the total,respectively. Furthermore,the fine particles(particulate matter with an aerodynamic diameter less than 2. 5 μm,PM2. 5) and PM10(particulate matter with an aerodynamic diameter less than 10 μm) tend to settle down in the hollow structures,with only few of them with diameters over 10 μm scattering on the papillae. The ratio of PM2. 5and PM10 particles turns to account for only17. 9% and 50. 4%,according to the laser scattering method whereas they account for 16. 8% and 45. 9% of the total particulates on the leaves in accordance with the calculations gained by using the microscopic method,respectively. However,the number of such particles still accounts for most parts of the particles. This may be due to the fact that the small particles(< 10 μm) dominate the numbers while the large ones dominate the mass or the volume. As to the density of the particles on the abaxial surface,much less proves to be than that on the adaxial surface,with lots of them distributed around the stomata. At the same time,the particles with a diameter of 5 μm scattering on the stomatal pores can occlude the stomata. Thus,it can be inferred from the study results that the plant species examined in our study can effectively capture PM2. 5and PM10,hence the recommendation to plant trees along the two road sides or trees to be used as road curbs.
This paper is inclined to make an exploration of the particle size distribution and its relation to the surface microstructures by using the foliar samples of Ligustrum lucidum collected from Xi'an University of Architecture and Technology. The particle size distribution of the collected samples can be determined with a laser particle size analyzer. The microstructure of leaf surfaces can be observed using an electronic scanning microscopy(SEM) and the atomic force microscopy(AFM). The particle size distribution can also be compared between the laser scattering method and the microscopic method,which helps to make clear the two peak values existing in the size distribution of the foliar dust. However,the particle size range,the peak and mean values of the particles can be found different if analyzed via the two methods. For example,the laser scattering method tends to show higher values than the microscopic method does,with the particle size ranging between 0. 4-52. 6 μm and 0. 4-27. 8 μm,with the peak values being 18. 9 μm and 36. 2 μm,or17. 5 μm and 27. 8 μm,and with their mean values being 8. 8 μm and 7. 2 μm,respectively. What is more,there can be found many papillae and hollows on the surfaces of the leaves,with the diameters of the hollows ranging from 0. 6 μm to 30 μm. The ratio of the hollows with diameters less than 2. 5 μm and 10 μm accounts for 50%and 80% of the total,respectively. Furthermore,the fine particles(particulate matter with an aerodynamic diameter less than 2. 5 μm,PM2. 5) and PM10(particulate matter with an aerodynamic diameter less than 10 μm) tend to settle down in the hollow structures,with only few of them with diameters over 10 μm scattering on the papillae. The ratio of PM2. 5and PM10 particles turns to account for only17. 9% and 50. 4%,according to the laser scattering method whereas they account for 16. 8% and 45. 9% of the total particulates on the leaves in accordance with the calculations gained by using the microscopic method,respectively. However,the number of such particles still accounts for most parts of the particles. This may be due to the fact that the small particles(< 10 μm) dominate the numbers while the large ones dominate the mass or the volume. As to the density of the particles on the abaxial surface,much less proves to be than that on the adaxial surface,with lots of them distributed around the stomata. At the same time,the particles with a diameter of 5 μm scattering on the stomatal pores can occlude the stomata. Thus,it can be inferred from the study results that the plant species examined in our study can effectively capture PM2. 5and PM10,hence the recommendation to plant trees along the two road sides or trees to be used as road curbs.
引文
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[10]PERKINS M C,ROBERTS C J,BRIGGS D,et al.Surface morphology and chemistry of Prunus laurocerasus L.leaves:a study using X-ray photoelectron spectroscopy,time-of-flight secondary-ion mass spectrometry,atomic-force microscopy and scanning-electron microscopy[J].Planta,2005,221(1):123-134.
[11]KOCH K,NEINHUIS C,ENSIKAT H J,et al.Self assembly of epicuticular waxes on living plant surfaces imaged by atomic force microscopy(AFM)[J].Journal of Experimental Botany,2004,55(397):711-718.
[12]SHI Hui(石辉),WANG Huixia(王会霞),LI Yangyang(李秧秧),et al.Leaf surface microstructure of Ligustrum lucidum and Viburnum odoratissimum observed by atomic force microscopy[J].Acta Ecologica Sinica(生态学报),2011,31(5):1471-1477.
[13]CHEN Shaoxiong(陈少雄),CHEN Jianan(陈家楠),CAI Jiye(蔡继业).Morphological observation on stomata of cabbage mustard by atomic force microscope[J].Journal of Hunan Agricultural University:Natural Sciences(湖南农业大学学报:自然科学版),2010,36(1):9-11.
[14]CARRERAS H A,CA珘NAS M S,PIGNATA M L.Differences in responses to urban air pollutants by Ligustrum lucidum Ait.and Ligustrum lucidum Ait.f.tricolor(Rehd.)Rehd[J].Environmental Pollution,1996,93(2):211-218.
[15]WANG Huixia(王会霞),SHI Hui(石辉),LI Yangyang(李秧秧).Relationships between leaf surface characteristics and dust-capturing capability of urban greening plant species[J].Chinese Journal of Applied Ecology(应用生态学报),2010,21(12):3077-3082.
[16]LI Fenfen(李芬芬),ZHANG Benshan(张本山).Comparison of different starch granule diameter measurement methods of starch granule diameter[J].Food and Fermentation Industries(食品与发酵工业),2010,36(4):171-174.
[17]RUIJGROK W,TIEBEN H,EISINGA P.The dry deposition of particles to a forest canopy:a comparison of model and experimental results[J].Atmospheric Environment,1997,31(3):399-415.
[18]LI Jingsheng(李敬生),SHEN Qin(沈琴),CHANG Qing(昌庆),et al.Intensifing action of supersonic sound on the processes of chemical engineering[J].Journal of Xi’an University of Architecture and Technology:Natural Science Edition(西安建筑科技大学学报:自然科学版),2007,39(4):563-568.
[19]YU Qingjie(于庆杰),WANG Xiangbin(王祥彬).Applications of ultrasound in superfine powder dispersal[J].Polyester Industry(聚酯工业),2004,17(3):30-31.
[20]JIN Yan(金焱),BI Xuegong(毕学工),ZHANG Jing(张晶).Study of coagulation mechanism of particles in liquid under ultrasonic treatment[J].The Chinese Journal of Process Engineering(过程工程学报),2011,11(4):620-626.
[21]LU S G,ZHENG Y W,BAI S Q.A HRTEM/EDX approach to identification of the source of dust particles on urban tree leaves[J].Atmospheric Environment,2008,42(26):6431-6441.
[22]WANG Lei(王蕾),GAO Shangyu(高尚玉),LIU Lianyou(刘连友),et al.Atmospheric particle-retaining capability of eleven garden plant species in Beijing[J].Chinese Journal of Applied Ecology(应用生态学报),2006,17(4):597-601.
[23]GRANTZ D A,GARNER J H B,JOHNSON D W.Ecological effects of particulate matter[J].Environment International,2003,29(2):213-239.
[24]WILD E,DENT J,THOMAS G O,et al.Visualizing the air-to-leaf transfer and within-leaf movement and distribution of phenanthrene:further studies utilizing two photon excitation microscopy[J].Environmental Science and Technology,2006,40(3):907-916.
[25]SMITH K E C,JONES K C.Particles and vegetation:implications for the transfer of particle-bound organic contaminants to vegetation[J].Science of the Total Environment,2000,246(2/3):207-236.
[26]YU Man(余曼),WANG Zhengxiang(汪正祥),LEI Yun(雷耘),et al.Study on dust detaining effect of major species of greening trees in Wuhan[J].Chinese Journal of Environmental Engineering(环境工程学报),2009,3(7):1333-1339.
[27]BURKHARDT J.Hygroscopic particles on leaves:nutrients or desiccants[J].Ecological Monographs,2010,80(3):369-399.
[2]WANG Zhijuan(王志娟),HAN Lihui(韩力慧),CHEN Xufeng(陈旭峰),et al.Characteristics and sources of PM2.5in typical atmospheric pollution episodes in Beijing[J].Journal of Safety and Environment(安全与环境学报),2012,12(5):122-126.
[3]TOMAˇSEVIC’M,VUKMIROVIC’Z,RAJˇSIC’S,et al.Characterization of trace metal particles deposited on some deciduous tree leaves in an urban area[J].Chemosphere,2005,61(6):753-760.
[4]RASANEN J V,HOLOPAINEN T,JOUTSENSAARI J,et al.Effects of species-specific leaf characteristics and reduced water availability on fine particle capture efficiency of trees[J].Environmental Pollution,2013,183:64-70.
[5]JIA Yan(贾彦),WU Chao(吴超),DONG Chunfang(董春芳),et al.Measurement on ability of dust removal of seven green plants at microconditions[J].Journal of Central South University:Science and Technology(中南大学学报:自然科学版),2012,43(11):4547-4553.
[6]ZU Yuangang(祖元刚),ZHANG Yuliang(张宇亮),LIU Zhiguo(刘志国),et al.Application of atomic force microscope in plant biology research[J].Chinese Bulletin of Botany(植物学通报),2006,23(6):708-717.
[7]MECHABER W L,MARSHALL D B,MECHABER R A,et al.Mapping leaf surface landscapes[J].Proceedings of the National Academy of Sciences,1996,93(10):4600-4603.
[8]WAGNER P,FURSTNER R,BARTHLOTT W,et al.Quantitative assessment to the structural basis of water repellency in natural and technical surfaces[J].Journal of Experimental Botany,2003,54(385):1295-1303.
[9]BURTON Z,BHUSHAN B.Surface characterization and adhesion and friction properties of hydrophobic leaf surfaces[J].Ultramicroscopy,2006,106(8/9):709-719.
[10]PERKINS M C,ROBERTS C J,BRIGGS D,et al.Surface morphology and chemistry of Prunus laurocerasus L.leaves:a study using X-ray photoelectron spectroscopy,time-of-flight secondary-ion mass spectrometry,atomic-force microscopy and scanning-electron microscopy[J].Planta,2005,221(1):123-134.
[11]KOCH K,NEINHUIS C,ENSIKAT H J,et al.Self assembly of epicuticular waxes on living plant surfaces imaged by atomic force microscopy(AFM)[J].Journal of Experimental Botany,2004,55(397):711-718.
[12]SHI Hui(石辉),WANG Huixia(王会霞),LI Yangyang(李秧秧),et al.Leaf surface microstructure of Ligustrum lucidum and Viburnum odoratissimum observed by atomic force microscopy[J].Acta Ecologica Sinica(生态学报),2011,31(5):1471-1477.
[13]CHEN Shaoxiong(陈少雄),CHEN Jianan(陈家楠),CAI Jiye(蔡继业).Morphological observation on stomata of cabbage mustard by atomic force microscope[J].Journal of Hunan Agricultural University:Natural Sciences(湖南农业大学学报:自然科学版),2010,36(1):9-11.
[14]CARRERAS H A,CA珘NAS M S,PIGNATA M L.Differences in responses to urban air pollutants by Ligustrum lucidum Ait.and Ligustrum lucidum Ait.f.tricolor(Rehd.)Rehd[J].Environmental Pollution,1996,93(2):211-218.
[15]WANG Huixia(王会霞),SHI Hui(石辉),LI Yangyang(李秧秧).Relationships between leaf surface characteristics and dust-capturing capability of urban greening plant species[J].Chinese Journal of Applied Ecology(应用生态学报),2010,21(12):3077-3082.
[16]LI Fenfen(李芬芬),ZHANG Benshan(张本山).Comparison of different starch granule diameter measurement methods of starch granule diameter[J].Food and Fermentation Industries(食品与发酵工业),2010,36(4):171-174.
[17]RUIJGROK W,TIEBEN H,EISINGA P.The dry deposition of particles to a forest canopy:a comparison of model and experimental results[J].Atmospheric Environment,1997,31(3):399-415.
[18]LI Jingsheng(李敬生),SHEN Qin(沈琴),CHANG Qing(昌庆),et al.Intensifing action of supersonic sound on the processes of chemical engineering[J].Journal of Xi’an University of Architecture and Technology:Natural Science Edition(西安建筑科技大学学报:自然科学版),2007,39(4):563-568.
[19]YU Qingjie(于庆杰),WANG Xiangbin(王祥彬).Applications of ultrasound in superfine powder dispersal[J].Polyester Industry(聚酯工业),2004,17(3):30-31.
[20]JIN Yan(金焱),BI Xuegong(毕学工),ZHANG Jing(张晶).Study of coagulation mechanism of particles in liquid under ultrasonic treatment[J].The Chinese Journal of Process Engineering(过程工程学报),2011,11(4):620-626.
[21]LU S G,ZHENG Y W,BAI S Q.A HRTEM/EDX approach to identification of the source of dust particles on urban tree leaves[J].Atmospheric Environment,2008,42(26):6431-6441.
[22]WANG Lei(王蕾),GAO Shangyu(高尚玉),LIU Lianyou(刘连友),et al.Atmospheric particle-retaining capability of eleven garden plant species in Beijing[J].Chinese Journal of Applied Ecology(应用生态学报),2006,17(4):597-601.
[23]GRANTZ D A,GARNER J H B,JOHNSON D W.Ecological effects of particulate matter[J].Environment International,2003,29(2):213-239.
[24]WILD E,DENT J,THOMAS G O,et al.Visualizing the air-to-leaf transfer and within-leaf movement and distribution of phenanthrene:further studies utilizing two photon excitation microscopy[J].Environmental Science and Technology,2006,40(3):907-916.
[25]SMITH K E C,JONES K C.Particles and vegetation:implications for the transfer of particle-bound organic contaminants to vegetation[J].Science of the Total Environment,2000,246(2/3):207-236.
[26]YU Man(余曼),WANG Zhengxiang(汪正祥),LEI Yun(雷耘),et al.Study on dust detaining effect of major species of greening trees in Wuhan[J].Chinese Journal of Environmental Engineering(环境工程学报),2009,3(7):1333-1339.
[27]BURKHARDT J.Hygroscopic particles on leaves:nutrients or desiccants[J].Ecological Monographs,2010,80(3):369-399.