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题名: 北京城市街道峡谷空气颗粒物污染及绿化带优化配置的模拟研究
作者: 周姝雯1
学位类别: 硕士
答辩日期: 2017-05
授予单位: 中国科学院大学
授予地点: 北京
导师: 马克明
关键词: 街道峡谷,绿地设置,颗粒物,数值模拟,优化配置 ; street canyons, greening arragement, particulate matters, numerical simulation, optimal configuration
其他题名: Simulation study on atmospheric particulate matters pollution and the optimal settings of green beltsin urban street canyons in Beijing
学位专业: 生态学
中文摘要: 城市街道是城市居民重要的活动场所,其空气质量与居民健康密切相关。合理规划街道绿化带能改变街道空气流场进而高效改善空气质量。本研究基于风洞试验分别测试了风向垂直和平行于街道走向时15种绿化带设置方式和对照组街道峡谷中的风速分布规律;实地调查了北京市13条典型街道峡谷的几何特征、气象因素、植物特征、及机动车通行情况,分析了这些因素与空气颗粒物浓度之间的相关关系;基于数值模型法分析了绿化带位置和树种选择对行人污染暴露风险的影响。得出如下主要结论: (1) 街道峡谷树种选择及行道树排列方式与街道峡谷中的空气流通有密切联系,植物类型、孔隙度、树冠形状、树木高度、树木排列连续性及绿化带位置的差异将引起植物冠层周围气体流动细节的差异。为了改善街道峡谷行人所处的风环境,应尽量选择灌木植物或低矮、冠幅小、孔隙度较大的球形阔叶树木作为街道峡谷行道树,并且应将灌木或阔叶树木连续排列在街道峡谷中央以改变街道峡谷中的涡流结构,从而使街道峡谷背风面行人高度的风速大幅增加。所测试的案例中最利于街道峡谷通风的是:两列灌木、一列灌木、一列连续排列的阔叶树及一列间隔排列的阔叶树,最不利于街道峡谷通风的是:两列分段排列的阔叶树。 (2) 绿化带、污染源强度、气象因子和道路结构影响街道峡谷中的颗粒物浓度,粒径大的颗粒物受这些因素的影响程度往往更强。绿化带对颗粒物具有一定的削弱作用,对总颗粒物(TPM)的削减作用达到7.2%,但对小粒径颗粒物的削减作用不明显。机动车产生的PM10是街道峡谷中重要的颗粒物污染源,街道峡谷中每小时PM10污染源排放强度与颗粒物浓度的日变化曲线保持一致。街道峡谷颗粒物浓度与气象因素有密切联系,空气温度与PM2.5和PM10浓度之间存在极显著负相关关系,相对湿度与PM2.5和PM10浓度之间存在极显著正相关关系,颗粒物平均浓度与街道峡谷内平均风速之间呈负相关关系。 (3) 采用ENVI-met模型模拟植物对街道峡谷污染物扩散及沉降影响的研究表明,街道峡谷中的绿化带因高度、树冠形状、孔隙度等植物个体特征和种植位置、种植宽度、种植间隔、排列方式等植物配置特征各不相同,从而对颗粒物的影响也不一样,加之受到污染物排放强度、街道几何结构及气象条件等因素影响,街道峡谷绿化带优化配置方案需要具体案例具体分析。绿化带位置和树种选择对于降低街道峡谷行人污染暴露风险有重要作用,在“最大浓度距离(DMC)”以内的位置种植冠层高度与行人高度一致的绿化带,选择树干高度(枝下高)低、冠幅大的植物作为行道树能够有效降低行人的污染暴露风险。 本研究揭示了城市街道峡谷空气颗粒物的污染分布及其影响因素,特别是街道绿地的作用,探讨了街道峡谷绿地优化配置方案,其结果可为城市街道大气环境改善和绿地建设提供科学依据。
英文摘要: City streets are important places for urban residents, and the air quality in streets is closely related to residents’ health. Reasonable planning of street green belts may change the air flow field and thus effectively improve the air quality. In this study, the wind tunnel was used to test the wind speed distribution in street canyons with 15 kinds of green belts settings and the control group when the wind is perpendicular and parallel to the street. Then, the geometric characteristics, meteorological factors, plant characteristics and motor vehicle traffic of 13 typical street canyons in Beijing were investigated, and the correlation between these factors and the particles concentrations were analyzed. Finally, the influence of the location of green belts and the selection of tree species on the pollution exposure risk of pedestrians were analyzed based on numerical model.The main conclusions are as follows: (1) The selection of tree species and the location of green belts in street canyon are closely related to the air circulation in the street canyon. Differences of plant species, porosity, crown profile, tree height, tree planting continuity, and green belt location will cause differences of the gas flow around the plant canopy in the details. In order to improve the wind environment of pedestrianss in street canyons, shrubs should be selected as far as possible, or low broad-leafed trees with narrow crown breadth, large porosity and spherical canopy. Besides, shrubs or broad-leafed trees should be arranged in the central street canyon to change the vortex structure of the street canyon, so that the leeward pedestrians height of the wind speed increased significantly. Among the cases tested, the most favorable cases of street canyon ventilation are: two sidewise shrub barriers, a central shrub barrier, a row of continuous broad-leaved trees and a row of spaced broad-leaved trees, but the most unfavorable cases to the street canyon ventilation is: two sectionalized sidewise broad-leaved trees. (2) Green belts, pollution source intensity, meteorological factors and street geomety affect the concentration of particulate matters in street canyons, and particles with large size are often affected by these factors intensively.The green belts have a certain effect on weakening the particulate matter, and the reduction of total particulate matters (TPM) concentration is 7.2%, but the effect on the reduction of small particle size is not obvious. The PM10 generated by the motor vehicle is an important particulates source in the street canyon. The daily emission intensity of the PM10 pollution source in the street canyon is consistent with the diurnal variation of particulate matter concentration. Street canyon particle concentration and meteorological factors are closely linked. There is a significant negative correlation between air temperature and PM2.5/PM10 concentrations, but a significant positive correlation between relative humidity and PM2.5/PM10 concentrations. The average concentrations of particulate matters were negatively correlated with the average wind speed in the street canyons. (3) The ENVI-met model was used to simulate the effects of plants on the diffusion and sedimentation of pollutants in street canyons. The results showed that the green belts in street canyons have different individual characteristics, e.g. height, crown profile, porosity and configuration characteristics, e.g. geening location, planting width, planting interval, arrangement and, so that the impact on the particles is not the same. Coupled with the influence of pollutant emission intensity, street geometry, weather conditions and other factors, street canyon green belt optimization program requires specific analysis of specific cases. The location of the green belts and the selection of tree species play important roles in reducing the pollution exposure risk of pedestrians in street canyons. Setting plants with the canopy height consistent with pedestrians height within the "maximum concentration distance (DMC)", and selecting trees with low trunk height (branch high) and large crown can effectively reduce the pollution exposure risk of pedestrians in street canyons. This study reveals the distribution of airborne particulate matters in urban street canyons and its influencing factors, especially the role of the green belts. And this study discusses the optimization scheme of plant setting in street canyons. The result can provide scientific basis for the improvement of urban street atmospheric environment and greening construction.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/38761
Appears in Collections:城市与区域生态国家重点实验室_学位论文

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作者单位: 1.中国科学院生态环境研究中心

Recommended Citation:
周姝雯. 北京城市街道峡谷空气颗粒物污染及绿化带优化配置的模拟研究[D]. 北京. 中国科学院大学. 2017.
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