呼和浩特市道路沿线土壤重金属的积累及影响因素

发布时间：2018-04-27 10:05

  本文选题：呼和浩特市 + 道路　； 参考：《内蒙古师范大学》2015年硕士论文

【摘要】：作为城市生态系统重要组成部分之一的城市土壤,不但能够对污染物质进行容纳缓冲和净化,还可能经过生态系统将污染物尤其是重金属污染物作用于人类自身。随着城市人口的增加,工业的发展,机动车辆也会随之增加,重金属对人体危害的强度也在增加。所以,在城市化进程中深入研究城市道路土壤重金属元素积累情况并对其进行评价是非常必要的。本文对呼和浩特市城市发展进程中道路土壤的重金属积累问题进行研究,采用多因素综合评定法,综合分析影响呼和浩特市道路土壤环境质量。首先,按照道路等级不同对城市土壤进行分区采样,测定土壤p H值、有机质含量、重金属F e、P b、Cu、Mn、Cr的含量,共计130个样品。测定表明,通车时间越长、车流量越大,道路表层重金属含量累积量越大,道路重金属含量高速路国道省道乡间路,除乡间路Cu、Mn、Cr元素外,其余道路土壤重金属元素平均含量均超过内蒙古自治区土壤背景值,道路表层土壤重金属F e、P b、Cu、Mn、Cr含量分别为内蒙古自治区土壤背景值的1.49倍、2.74倍、1.39倍、1.22倍和1.43倍;研究表明道路土壤表层重金属含量在道路边含量达到最大,然后随距离的增加下降,在3 0~50m附近达到第二个峰值,后又逐步下降接近土壤背景值。路旁土壤重金属含量的峰值出现在离开路基一定距离处的原因,可能是由于车辆快速行驶导致路基附近出现湍流所致。而离开路基一段距离后,湍流消失利于颗粒物沉降,从而造成路旁土壤重金属在道路旁呈偏态分布;其次,对高速路上风、下风侧土壤进行配对样品均值和T检验,统计表明:峰值浓度出现的位置相较于下风向更接近道路。另外,车辆类型、运载货物的不同也会影响道路土壤中重金属元素P b、C u累积量的差异。通过相关分析,重金属元素F e、P b、Mn、Cr之间存在较强的相关性,可能具有相同的来源。Cu与其他元素之间的相关系数小于0.6,为中等程度相关。经过聚类分析和主成分分析,识别道路沉积物中重金属的来源,将5种重金属元素辨识为2个主成分,第一主成分(贡献率7 0%以上)主要为交通活动产生的污染源,包括F e、P b、Cr、Mn元素,第二主成分Cu元素为“自然源因子”;最后,根据国家土壤环境质量标准二级标准(GB1561 8-199 5)计算了呼和浩特市道路两侧土壤重金属累积程度(高速路国道省道乡间路),潜在生态危害综合数:RI=∑Er i=1.77,表明呼和浩特市道路周边表层土壤重金属Cu、Cr、P b环境整体良好,五种重金属元素的累积程度明显低于东京、广州等发达城市,这可能与近几年呼和浩特市道路周边加强生态建设以及城市发展历史较短密切相关。
[Abstract]:As one of the important parts of urban ecosystem, urban soil can not only absorb and purify the pollutants, but also affect the pollutants, especially heavy metal pollutants, through the ecosystem. With the increase of urban population and the development of industry, motor vehicles will also increase, and the intensity of heavy metal harm to human body will also increase. Therefore, it is necessary to study and evaluate the accumulation of heavy metals in urban road soil in the process of urbanization. In this paper, the accumulation of heavy metals in the road soil in the course of urban development in Hohhot was studied. The comprehensive evaluation method was used to analyze comprehensively the environmental quality of the road soil in Hohhot. Firstly, according to the different road grade, the soil pH value, the content of organic matter and the content of heavy metal, Fe, Pb, Cu, mn, Cr in urban soil were measured, and a total of 130 samples were collected. The results show that the longer the opening time, the greater the traffic flow, the greater the accumulation of heavy metals in the surface layer of the road, the higher the heavy metal content of the road, the higher the heavy metal content of the road, the higher the content of heavy metal in the highway, the more the provincial road, the rural road, except for the element of Cufen Mn@@ The average content of heavy metal elements in other road soils was higher than the soil background values of Inner Mongolia Autonomous region, and the content of heavy metals in the surface soils was 1.49 times, 2.74 times, 1.39 times, 1.22 times and 1.43 times of the soil background values of Inner Mongolia, respectively. The results showed that the content of heavy metals in the surface layer of road soil reached the maximum at the edge of the road, then decreased with the increase of the distance, reached the second peak value at the distance of 30 ~ 50m, and then gradually decreased to the soil background value. The peak value of heavy metal content in the roadside soil appears at a certain distance from the roadbed, which may be due to the turbulence near the roadbed caused by the rapid driving of the vehicle. After a distance away from the roadbed, the turbulence disappear is beneficial to the settling of particulate matter, which results in the distribution of heavy metals in the roadside soil. Secondly, the mean value and T test of the matched samples are carried out on the wind and downwind side of the highway. Statistics show that the location of peak concentration is closer to the road than the downwind direction. In addition, the type of vehicle and the different cargoes can also affect the accumulation of heavy metals in road soil. According to the correlation analysis, there is a strong correlation between heavy metal element, Fe, P, B, mn, Cr, and the correlation coefficient between the same source, Cu and other elements is less than 0.6, which is moderate. Through cluster analysis and principal component analysis, the sources of heavy metals in road sediments were identified. The five heavy metals were identified as two principal components. The first principal component (contribution rate of more than 70%) was mainly the source of pollution caused by traffic activities. The second principal component Cu is "natural source factor". According to the second grade standard of national soil environmental quality standard (GB1561 8-1995), the accumulation degree of heavy metals on both sides of the road in Hohhot city is calculated (the comprehensive number of potential ecological hazards is: Ri = 鈭，

本文编号：1810288