【作者】 徐欣；

【导师】 马建华；

【作者基本信息】 河南大学 ， 环境科学， 2010， 硕士

【摘要】 本文选择郑州市、中牟县、韩寺镇和郭辛庄作为研究对象,在野外调查采样、室内分析的基础上,对不同等级城镇地面灰尘中Cr、Ni、Zn、Pb和Cu的含量水平、空间分布、富集特征、污染状况、潜在生态风险等开展了对比研究。全文共分为六个部分:第一部分:主要介绍了城镇地面灰尘重金属污染的研究现状和发展趋势,以及本研究的内容和意义。第二部分:全面介绍了郑州市、中牟县和韩寺镇的概况,包括它们的自然地理状况和社会经济状况。第三部分:主要介绍本研究城镇地面灰尘的采样点布设、样品采集、样品预处理、试验项目和方法。第四部分:主要介绍了郑州市、中牟县和韩寺镇地面灰尘中重金属的含量和空间分布情况,以及分析了地面灰尘中重金属含量与粒径的关系。第五部分:主要采用富集指数法对郑州市、中牟县和韩寺镇地面灰尘中重金属的来源进行初步分析。第六部分:主要采用地积累指数法和潜在生态风险指数法对郑州市、中牟县和韩寺镇地面灰尘中重金属污染情况进行评价。通过以上研究,得出以下主要结论:(1)郑州市、中牟县和韩寺镇地面灰尘中各个重金属均有不同程度的积累。郑州市地面灰尘Cr、Ni、Zn、Pb和Cu的平均含量分别为84.59、37.60、317.00、227.01和22.66 mg/kg,分别为对照区(郭辛庄)重金属平均值的2.3、1.9、7.3、4.9和7.0倍;中牟县城地面灰尘Cr、Ni、Zn、Pb和Cu的平均含量分别为47.36、21.37、179.05、80.57和12.40 mg/kg,分别为对照区重金属平均值的1.31、1.05、4.14、1.76、3.84倍;韩寺镇地面灰尘中Cr、Ni、Zn、Pb和Cu的平均含量分别为41.57、15.50、67.89、46.91和2.11 mg/kg,分别为对照区重金属平均值的1.15、0.76、1.57、1.02和0.65倍。地面灰尘重金属含量随城镇规模的减小而下降,即郑州市>中牟县>韩寺镇>郭辛庄。(2)郑州市地面灰尘各个重金属含量的空间分布差异较大,局部污染严重。郑州市三环以内区域的地面灰尘中的Zn、Pb和Cu含量较高,其高值中心位于西三环和南三环附近等工业区和交通要道。地面灰尘中Cr和Ni的含量相对较低,但局部含量较高,也存在多个高值中心。Cr的高值中心分布在郑州西绕城公路、以及西三环的北端到南端区域;Ni的高值中心分布在郑州西绕城公路和北三环附近区域。郑州市东北部地区的地面灰尘中的重金属含量最低。中牟县城和韩寺镇,面积较小,功能分区不甚明显,故地面灰尘重金属含量空间变异也很明显,但没有规律可循。(3)地面灰尘颗粒大小相差悬殊。但以细颗粒(<0.15 mm)部分为主,粗颗粒(>0.25 mm)部分所占比例最少。除了灰尘中的铜以外,其他4种重金属(Pb、Zn、Ni、Cr)在不同粒级组中的分布均表现为细颗粒>粗颗粒>中颗粒的特征。其原因除了细颗粒比表面大,对重金属吸附能力强以外,可能还与中、粗颗粒的矿物组成有关,尚需进一步研究。(4)以对照区地面灰尘重金属含量作为背景含量,计算得到不同等级城镇地表灰尘中各个重金属的富集系数也随城镇规模的减小而下降。郑州市地面灰尘中重金属的平均富集系数的大小为:Pb(6.05)>Cu(4.32)>Zn(4.08)>Cr(1.49)>Ni(1.32),其中Pb属于显著富集,Cu和Zn属于中度富集,Cr和Ni属于轻度富集。中牟县地面灰尘中重金属富集系数的大小为:Zn(3.47)>Cu(3.01)> Pb(1.97) >Cr(1.40)> Ni(1.08),其中Zn和Cu中度富集,其他重金属属于轻度富集。韩寺镇地面灰尘中重金属富集系数的大小为:Cr(1.47)> Pb(1.46)> Zn(1.43)> Ni(0.95)> Cu(0.78),其中Cr、Pb和Zn属于轻度富集,其他重金属没有发生富集。总体上来说,地面灰尘中的Cr和Ni主要来自城镇周围土壤母质或自然沉积物,是自然源重金属;而Pb、Cu和Zn主要与城市人类活动有关(汽车尾气排放、汽车轮胎和刹车里衬磨损、燃煤和工业生产等),是人为源重金属。(5)从地面灰尘中重金属地积累情况来看,郑州市地面灰尘重金属污染>中牟县城>韩寺镇>郭辛庄,随着城镇规模的扩大、人口增加和工业积聚增强,地面灰尘重金属污染有增强的趋势。郑州市地面灰尘中的Cu属于较重污染,Zn和Pb属于中度污染,Cr属于轻度污染,Ni属于无污染。中牟县地面灰尘中的Cu属于轻度污染,Zn属于中度污染,Cr和Ni属于无污染状态。而韩寺镇地面灰尘中Pb、Cu、Cr和Ni的地积累指数(除了Zn)都小于0,属于无污染,但是Zn处于轻污染状态。(6)郑州市、中牟县和韩寺镇地面灰尘中重金属潜在生态危害均为轻微危害。其中Cr、Ni和Zn的污染指数较低,Pb和Cu的指数较高些。虽然如此,地面灰尘中重金属的潜在生态风险指数仍表现出郑州市>中牟县城>韩寺镇>郭辛庄的趋势。更多还原

【Abstract】 Based on 145 samples of surface dust collecting in different-scale-cities, Zhengzhou, Zhongmou, Hansi and Guoxin, the concentrations, distribution and pollution assessment of heavy metals in the samples were studied, the sources of heavy metals on surface dust were also discussed in this paper.There are six main parts of this dissertation:PartⅠ:In this part, the current situation and development tendency of the research about the urban surface dust were generally introduced. Then the author summarized the present situation of the study abroad on the urban surface dust.PartⅡ:Background of study areas such as the history of different-scale-cities, the natural situations and the economies were also introduced.PartⅢ: Mainly introduce the principles, methods, sample processing and preparation of urban surface dust, and the steps of experimental methods.PartⅣ:Mainly introduce the concentrations and their space distribution of heavy metals, and the relationship of the concentrations between the particle fractions.PartⅤ:Mainly introduce the EF index, with this method to analyse the sources of the heavy metals.PartⅥ:Mainly introduce two ways of the pollution assessment methods, to analyse the conditions of pollution in different-scale-citiesThe main conclusions of this study can be summed up as follows:(1) There are different levels of accumulation on the content of heavy metals in different-scale-cities. The average content of Cr, Ni, Zn, Pb and Cu on surface dust of the city in Zhengzhou area is 84.59, 37.60, 317.00, 227.01 and 22.66 mg/kg respectively, which is 2.3, 1.9, 7.3, 4.9 and 7.0 times of the dust background value. The average content of Cr, Ni, Zn, Pb and Cu on surface dust of the town in Zhongmou area is 47.36, 21.37, 179.05, 80.57 and 12.40 mg/kg respectively, which is 1.31, 1.05, 4.14, 1.76 and 3.84 times of the dust background value. The average content of Cr, Ni, Zn, Pb and Cu on surface dust of the town in Hansi area is 41.57, 15.50, 67.89, 46.91 and 2.11 mg/kg respectively, which is 1.15, 0.76, 1.57, 1.02 and 0.65 times of the dust background value. The order of the heavy metal content on surface dust is Zhengzhou > Zhongmou > Hansi > Guoxin.(2) There are differences between the spatial distributions of each heavy metal on urban surface dust in Zhengzhou. And the partial pollution is serious. Heavy metal pollution of Cu and Pb and Zn are serious in the urban areas especially within the industry districts and the heavy traffic areas of the South and West; the heavy metal pollution of Cr and Ni are relatively less serious, the Cr of the pollution centers situated mainly at the outer circle of the west and somewhere from south to north; the Ni of the pollution centers situated at the outer circle of the north and west. The lowest level content of the heavy metals situated at the northeast of Zhengzhou. Because that area is limited and not functional, the spatial distribution of each heavy metals on surface dust in Zhongmou and Hansi is obvious but without orderliness.(3)There are differences between the size of particles on urban surface dust of the different-scale-cities. The most of the particles is the small particles, and the least is the coarse particles. The different sizes of the surface dust of the contribution rate for heavy metals are: small particles> coarse particles > medium particles, except Cu. The reason is that the bigger specific surface area it is, the stronger absorbability it has. Some intensive study will be carried on.(4) With the concentration of heavy metals in the contrast areas as the background, we found that the EF index in the big scale city is higher than the small ones. The order of the average index of EF in Zhengzhou is: Pb>Cu>Zn>Cr>Ni. The highest EF index of the heavy metals is Pb which reaches high pollution level; the EF index of Cu and Zn reach middle level; and the index of Cr and Ni reach light. The order of the index of EF in Zhongmou is: Zn >Cu> Pb >Cr > Ni. The highest EF index of the heavy metals is Zn. The index of Zn and Cu reach middle pollution level; the others reach light pollution level. The order of the index of EF in Hansi is: Cr > Pb > Zn > Ni> Cu. The index of Cr, Pb and Zn reach the light pollution level and others reach the clean level. As result, The heavy metals of Cr and Ni on surface dust mainly originate from the erosion and weathering of the rock and soil, they are the lithopogenic heavy metals; the heavy metals of Zn, Cu and Pb mostly come from the sources of traffic-related and industrial, and they are the anthropogenic heavy metals.(5) By using the method of geoaccumulation index to assess the heavy metal pollution on surface dust of Zhengzhou, Zhongmou and Hansi, the order of the geoaccumulation index in different-scale-cities is: Zhengzhou > Zhongmou > Hansi > Guoxin, owing to the scale expansion, population explosion and intensive industries, there is a strong tendency on the pollution of the heavy metals. Pollution of Cu in dust is the most serious, then that of Zn and Pb, Cr is the lightest, and that of Ni is clean. The geoaccumulation index of five heavy metals in Hansi is below 0, which means that they are all at clean level.(6) By using the method of potential ecological risk index to assess the heavy metal pollutions on surface dust, the results show that: they are all at light pollution level. The order of potential ecological risk index in different-scale-cities is Zhengzhou >Zhongmou >Hansi> Guoxin.更多还原