【作者】 阮氏清草（NGUYEN THI THANH THAO）；

【导师】 余新晓；

【作者基本信息】 北京林业大学 ， 水土保持与荒漠化防治， 2014， 博士

【摘要】 以PM2.5(粒径2.5μg的颗粒物)为代表的颗粒物会对人体健康造成直接的危害。怎样利用城市森林植被或者城市森林系统来控制和阻滞大气颗粒物?一方面,应该控制PM的排放源头从而减少大气污染；另一方面,应该制定用于减少可造成空气中PM累计的合理而高效的方法。为优化利用城市植被阻滞PM的效果,本研究于2013年在北京奥林匹克公园选择5种常见的城市森林种类进行了研究。研究结果表明城市森林系统能够调控和吸收空气中的颗粒物。五种森林类型中,灌木林和阔叶林在叶片生长成熟后吸收空气中PM的效果最好。在冬季,常绿植被(针叶系统)和混交植被系统阻滞空气中的颗粒物效果最突出,并且与其他森林系统差异显著。在各类城市森林类型叶片的四个生长阶段研究发现,叶片通常在早上对空气中的PM2.5吸收量最高,下午和晚上相对较低。PM2.5的浓度在叶片萌芽阶段最高,在叶片成熟阶段下降,在落叶之前又有回升。PM浓度在夏、秋、冬三个季节之间差异显著。四种粒径类型的PM的浓度均为夏季最低。TSP和PM1o在9月份和11月份的浓度值明显高于其他月份,并且在三个季节之间没有显著差异。PM2.5和PM1的浓度在秋季最高,夏季最低,其中8月份达到最低,在冬季其浓度值介于夏秋两季之间,并且与夏季没有显著差别。5种城市植被类型和对照点的年均PM浓度悬浮效率排序是：阔叶林>混交林>灌木林>针叶林>对照>草地(TSP)；阔叶林>针叶林>灌木林>混交林>对照>草地(PM1o)和针叶林>混交林>阔叶林>灌木林>对照>草地(PM2.s和PM1)。5种城市植被类型和对照点在叶片的4个生长阶段PM2.5吸收效率排序为：针叶林>阔叶林>灌木林>混交林>草地和对照.PM浓度日变化是早晚较高,白天较低。早晨和夜晚对比而言,PM浓度通常在夜晚偏低。早晚浓度较高的原因在于空气湿度较高。在不同时期,空气中PM浓度和城市森林类型之间的时间变化差异显著。草地不能阻滞悬浮在空气中的颗粒物,但是草地生长茂盛,能够降低由于风力扬起地面上的尘土造成的空气粉尘污染。因此,应该在其他森林系统中培育草地覆盖地面,从而提高防尘效果,降低空气污染。VOC, OC和EC在叶片不同生长阶段和不同的森林类型中有显著变化。在叶片生长成熟的阶段EC/TC值及OC/EC值相对于其他阶段更高。针叶林的VOC浓度比其他类型高,但是OC/EC比其他的低。OC和EC浓度在灌木林和草地中最高,在混交植被林和对照组中最低。通常,4种水溶性无机粒子贡献了1/3的PM2.5,NH4+, SO42-,NO3和口CV在落叶前阶段比其余阶段相对高一些。针叶林具有最高的PM25浓度,然而这4种水溶性无机粒子的浓度在PM2,5中并不高,混交植被林可以相对有效的阻滞SO42-和NO3-。阔叶林CV浓度比其他城市植被类型高。SO42-和C1-在植被萌芽阶段和叶片生长成熟阶段较高,NO3-在叶片生长阶段最高,在叶片发芽阶段最低。NH4+在落叶之前的阶段比其他时段显著高。OC指数总是高出EC指数水平的2-4.5倍。EC/OC值随地点变化而变化,反映出引起颗粒物污染的源头是变化的。所有树种吸附的颗粒物(PM)按照粒径分为：大的(10-100,μm),较粗的(3.0-10μm),细小的(0.4-3.0μm)三种类型。分别运用重量分析法来量化叶片表面积累和吸附的蜡层PM颗粒。研究发现不同的树种间存在显著差异。不同粒径的颗粒在不同的树种和不同的叶片表面存在差异,这一差异同样存在于不同的叶腊层。叶腊层PM的数量是由不同的物种及颗粒物粒径而决定的。在秋季,降雨量较小,叶片表明三种粒径类型的颗粒物都比夏季显著高研究发现,所选9种植物种捕获吸收颗粒物的能力显著不同。其中,Sophora japonica和Platycladus orientalis能力最强Iris lactea和Amygdalus persica能力最差。针叶科(Platycladusorientalis和Pinustabuliformis)表现出比其他树木,灌木和草地更强的吸收PM(所有三种粒径)的能力。Platycladusorientalis表现出比Pinustabuliformis混合植被更高的单位叶面积颗粒物量级,这表明Pinus tabuliformis混合植被的PM含量比针叶类高。PM在叶面和叶腊层的沉积过程取决于多种因素：沉积时间,降雨,风力。城市森林植被类型也对这种沉积过程有影响。在灌木林和阔叶林的研究中,PM25浓度与LAI之间呈中等程度的负相关。混交林中同样有类似的显著负相关关系,但是相关性弱于阔叶林和灌木林。针叶林中PM25浓度与LAI的相关关系最低。雾霾天后,混交林和灌木林的TSP-PM10的累积量高于其它森林类型。但是PM25和PM1在针叶林是最高的,其次是阔叶和灌木类型。草地和对照有良好条件,TSP和PM10的浓度表现出低于其它的森林类型。更多还原

【Abstract】 Particulate matter (PM), especially, PM2.5causes harm directly to the health of people. How to use urban tree species or urban forest systems to control and prevent from atmospheric PM. On one hand, controlling the source emitting PM in order to minimize air pollution caused by PM is necessary. On the other hand, reasonable and highly effective methods for reduce available "in-the-air" PM accumulation must be defined. In order to optimise the effectiveness of particulate matter by reducing urban tree planting design, five commonly cultivated kinds of urban forest types were studied in Olympic park of Beijing city in2013year. Weighing method was used to collect PM2.5for PM2.5concentration and chemical composition analysis. TSP, PM10, PM2.5and PM1were measured by Air Dust-mate monitor. Chemical compositions of analyzed individual particles included carbonaceous and water-soluble inorganic ions. Particles on leaf surface and in-wax were used in water wash-off and chloroform wash-off methods.Results show that the urban forest systems are capable of storing and capturing dust from the air. The types of Shrub and Broadleaf tree have the ability to control particulate matter in the air most effectively at the stage when leaves are fully developed. During the leafless season, evergreen systems (for example coniferous types) and mixed tree systems (broad leaves and coniferous) are likely to be the most effective for preventing high aerosol PM2.5concentrations and have significant differences from other forest systems.The ability of year-PM concentration, absorption between no-tree system and with-tree systems shows Broadleaf treetype is highest (66.15%for TSP;35.32%for PM10), Conifertypeuptake is highest PM2.5(19.71%) and PM1(20.88%) compared to Control (no-tree). Grassland is mostly lower Control. And the ability of PM2.5concentration at four leaves growth stages shows high uptake for Conifer type up to:66.6%, followed closely by the Shrub and the Mixed tree type; with the Grassland lowest at33.6%. The concentration of PM2.5absorption between the models of urban forest at four leaves growth stages show Conifer are higher than the Control, and there is a significant difference with the remainder models.The PM concentrations suspend efficency of six urban forest types in year variation in descending order is Broadleaf tree> Mixed tree> Shrub> Conifer> Control> Grassland (with TSP); Broadleaf tree> Conifer> Shrub> Mixed tree> Control> Grassland (with PM10) and Conifer> Mixed tree> Broadleaf tree> Shrub> Control> Grassland (PM2.5and PM1). And the PM2.5capture efficency of six urban forest types at four growth stages of leaves is Conifer>Broadleaf tree>Shrub>Mixed tree> Grassland and Control.The year variation of the aerosol PM concentrations shows that PM concentrationsare highest in late spring, autumn and winter, and low in summer. The average for all urban forest types at the four stages of leaf growth and the different times of year studied, TSP, PM10, PM2.5and PM1capture in the morning and night air are high and low in the afternoon and evening.The experiment of this research does not show correlation of VOC, Cations, Anions and PM2.5concentration in the air clearly. Correlation analysis between VOC, OC, EC and PM2.5-mass showed:weak correlation between VOC and EC with increasing PM2.5-mass (R2=0.4364and R2=0.4422), and no significant correlation between OC, TC, NH4+, NO3-and PM2.5mass (R2=0.0646). There are correlation between the concentration of PM2.5and SO42-(R2=0.3181)/and Cl-(R2=0.3512), but no strong regression.Needle leaves and hairy-waxy leaves show their ability to deposit and capture PM content on the surface as well as in waxed layer. This project only focuses on the variation of PMs content at different seasons of a year. Necessary to replicate the experiment in subsequent studies or in further studies to be able to prove the result.Coniferous trees at different seasons show that PM content is highest in winter. Due to its long deposition process from previous months of the year, especially after rainy season. Small and rough needle leaves showan ability to capture large and coarst particles, but for fine particles, long and smooth needle leaves are more effective.Mixed tree urban forest type shows its effectiveness in capture PM concentration in comparison to monoculture forest type.The concentration of PM in air showed high correlation with humidity. In the morning, night or high humidity day, the aerosol PM concentration increases and varies in the same direction relative to humidity fluctuations.With haze pollution afterwards, the accumulation of TSP and PM10showed in Mixed tree and Shrub showed10is higher than in other models. But with PM2.5and PM1, Conifer showed the highest, followed by Broadleaf and Shrub systems. In Grassland and Control with favorable conditions, concentration of TSP, and PM10showed lower than remain forest types.更多还原