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题名: 北京城区国槐叶面尘的空间分布及重金属污染特征
作者: 戴斯迪
学位类别: 硕士
答辩日期: 2012
授予单位: 中国科学院研究生院
授予地点: 北京
导师: 马克明
关键词: 叶面尘 ; foliar dust ; 滞尘量 ; dust retention ; 重金属 ; particle size ; 粒径分析 ; heavy metal ; 源解析 ; pollution source
其他题名: Distribution of particle matters and characteristics of heavy metals in the foliar dust of Sophora japonica in Beijing
中文摘要:     叶面尘是空气颗粒物污染情况的良好指示物,研究叶面尘的分布和污染特征对于识别城市空气颗粒污染源具有重要意义。由于北京市机动车保有量的迅猛增加,交通排放对城市空气颗粒污染物的贡献逐年提高,交通排放的颗粒物不止污染路域环境,还会随气流迁移,影响整个城市的空气质量,逐渐成为相关领域的关注热点。国槐(Sophora japonica)是北京市行道树的主要物种,本研究通过分析不同类型道路上国槐叶面尘的分布和重金属污染特征来探讨交通源颗粒污染物的排放特征,通过对比公园及其邻近道路叶面尘的滞尘量、粒径分布、重金属污染情况及其可能来源,探讨交通排放对于城市颗粒污染的影响程度,以期为颗粒物污染治理提供参考。研究结果表明: 1.交通排放使行道树国槐的滞尘量显著高于城区背景值,快速路、主干路、次干路、支路的滞尘量比值为100:84:75:75,主要受车流量影响。叶面尘重金属浓度基本表现为主干路>次干路和支路>快速路,主要受路况和交通拥挤程度的影响。道路叶面尘中的重金属主要来自交通排放,其中机动车排放(轮胎磨损、车体磨损、尾气排放等)占60%左右,路面磨损及路面灰尘的二次扬尘产生的重金属污染接近30%。机动车排放主要产生Cu、Pb、Zn,污染程度都达到中度以上,Cr、Ni有轻度污染。 2.公园国槐的滞尘量显著低于其邻近道路,二者的重金属污染情况相似,污染水平均表现为Cu>Pb>Zn>Cr>Ni,但公园叶面尘的重金属浓度一般高于道路。道路叶面尘重金属主要来自交通排放,相比之下公园叶面尘重金属的来源较复杂,交通排放是最重要的来源,贡献率超过总量的1/3,其次来自土壤母质,小部分来自工业排放和化石燃料燃烧排放等。 3.道路叶面尘中PM2.5/PM10的比值大于公园,说明交通排放是PM2.5的重要来源。公园国槐0~3μm粒径范围的叶面尘附着密度明显大于邻近的道路,这既为公园叶面尘中较高的重金属浓度提供了合理解释,也说明公园植物对小粒径颗粒物的净化能力优于道路植物,对改善PM2.5污染具有潜在价值。
英文摘要:     Foliar dust is a good indicator for airborne particle pollution. The study on distribution and pollution characteristics of foliar dust is important for identifying the airborne particle source. With the rapid increase of traffic flow in Beijing, emissions from transportation have been increasing year by year, leading to decrease of air quality in urban area. However, characteristics of road-based particle emissions and their effects on urban air quality have not been well studied. Sophora japonica is the main species of roadside trees in Beijing urban area. In this study, 91 sites of Sophora japonica along different types of roads were investigated to reveal the feature of road-based particle emission; twelve parks and their neighboring roads in Beijing were investigated to compare the particle pollution between parks and roadside environments. The dust retention, particle size distribution, and heavy metal concentration of foliar dusts were measured, and possible pollution sources of heavy metals were identified. The results show that: 1. Foliar dust retention of the roadside trees (0.68 g/m2) was significantly higher (with P=0.054) than the background value of Beijing urban area (0.51g/m2). Foliar dust retention on different types of roads, which were mostly determined by traffic volume, was the highest for roadside trees of freeways, followed by those of major arterial, minor arterial, and collector roads, with a ratio of 100:84:75:75. The concentrations of heavy metals in foliar dust decreased in the order of major arterial>freeway>minor arterial and collector roads. This is mainly affected by traffic condition. The heavy metals were originated from traffic emission; where about 60% of the heavy metals in foliar dust were derived from vehicle emissions (such as tyro abrasion, brake wear abrasion, vent-pipe emission, etc.) and nearly 30% contributed by road surface abrasion and secondary fugitive dust. Vehicle emissions mainly produced Cu, Pb and Zn and caused moderate level of pollution for these metals, while the pollution of Cr and Ni were less significan. 2. Foliar dust retention of park trees was significantly lower than that of its neighboring roadside trees (P=0.041). Heavy metal contamination in foliar dust on park trees and roadside trees was similar. The levels of heavy metal pollution in foliar dusts decreased in the order of Cu>Pb>Zn>Cr>Ni>Mn. The concentrations of heavy metals in foliar dust on park trees were generally higher than that of roadside trees. The major source of foliar heavy metals on roadside trees were traffic emissions, while possible sources of heavy metals on park trees were more complicated. Traffic emissions were the most important source, which contributed more than one-third of heavy metals, with soil parent materials following as the second source, and a minor source was related to industrial emission and fuel combustion. 3. The value of PM2.5/PM10 in foliar dust on roadside trees was greater than that of park trees, which means traffic emissions was an important source of PM2.5. The density of foliar dust with size of 0~3μm was much greater for leaves of park trees, which explaines the higher heavy metal concentration of foliar dust on park trees. It also indicates that park trees serves a better performance on purifying fine particle, and have a potential effect on controlling PM2.5 pollution.
内容类型: 学位论文
URI标识: http://ir.rcees.ac.cn/handle/311016/35095
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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Recommended Citation:
戴斯迪. 北京城区国槐叶面尘的空间分布及重金属污染特征[D]. 北京. 中国科学院研究生院. 2012.
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