电厂周边表土重金属污染研究与来源分析

发布时间：2018-05-31 17:52

本文选题：土壤 + 重金属污染　；参考：《华北电力大学》2017年硕士论文

【摘要】：化石燃料燃烧的废弃物排放通过大气沉降作用进入土壤是土壤重金属污染主要来源之一,为全面对比研究土壤重金属污染情况,本文对地处不同环境的三座电厂周边表层土壤中重金属污染进行研究。测定采集土壤样品的pH值,阳离子交换量以及Zn,Cu,Pb,Hg,Ni,Cr,Cd,As等八种重金属元素含量。绘制电厂周边表层土壤中八种重金属元素含量二维空间分布图。对照当地土壤环境背景值与国家土壤环境质量标准值对污染程度进行评价,并对重金属污染源进行分析与预测。3号电厂As元素平均含量小于当地土壤环境背景值,约为其0.9倍,三电厂其余元素平均含量均超过背景值。1号电厂Hg元素平均含量为背景值25.4倍,属三电厂八种重金属元素中最大。单样本K-S检验显示1号电厂的Cu,Hg,2号电厂的Zn,Cd,3号电厂的Hg服从常用对数正态分布,其余元素服从标准正态分布。地积累指数法单元素污染程度评价显示Hg为三电厂普遍污染最严重元素,均在不同程度上达到重度污染。内梅罗污染指数法与污染负荷指数法综合污染程度评价结果显示1号电厂周边土壤八种重金属元素综合污染程度相对较重,2号电厂次之,3号电厂最低。1号电厂区域污染负荷指数为2.8,达到强污染水平,2号与3号电厂分别为1.8,1.7,属中污染水平。潜在生态危害指数法评价显示Hg与Cd属三电厂普遍生态危害最严重元素,Ni与Zn为最轻。Hg是八种重金属元素中生态危害程度最大元素。1号电厂八种重金属元素潜在生态危害指数为1152.92,具有很强生态危害性,2号电厂为187.46,3号电厂为190.03,为中等生态危害程度。运用改进评价模型,参比土壤质量标准值与环境背景值,考虑元素含量与毒性系数,参考主流综合污染指数法思想通过加权平均以双重途径最终求得电厂重金属综合污染系数。1号电厂地处城区,综合污染系数最大,达1.85,3号电厂地处乡村,综合污染系数次之,为0.91,2号电厂地处郊区,污染程度最小,为0.69。1号与3号电厂八种重金属元素间普遍显著性相关,2号电厂重金属元素间相关性较差。1号与3号电厂八种元素均被分为四类,2号电厂被分为五类。农业生产,工业废弃物排放,路面交通,居民日常生活活动等均是土壤重金属污染主要来源,一些元素受单一污染源影响较大,一些则受到多种污染源联合影响。
[Abstract]:Waste emissions from fossil fuel combustion are one of the main sources of heavy metal pollution in soil through atmospheric deposition. The pollution of heavy metals in the surface soil of three power plants in different environments was studied in this paper. The pH value, cation exchange capacity and the contents of eight heavy metals, such as Zn ~ (2 +) Cu ~ (2 +) ~ (2 +) ~ (2 +) ~ (2 +) and Zn ~ (2 +) Cu ~ (2 +) ~ (2 +) ~ ( The spatial distribution of eight heavy metal elements in the surface soil around the power plant was plotted. Compared with the local soil environment background value and the national soil environmental quality standard value, the pollution degree was evaluated, and the heavy metal pollution sources were analyzed and forecasted. The average content of as element in No. 3 power plant was less than the local soil environmental background value, which was about 0.9 times of the local soil environmental background value. The average content of Hg in No. 1 power plant is 25.4 times the background value, which is the largest among the eight heavy metal elements in three power plants. The single sample K-S test shows that the Cu Hg of No. 1 Power Plant, ZnCU CD of No. 2 Power Plant, Hg service of No. 3 Power Plant follow the usual logarithmic normal distribution, and the rest of the elements are distributed according to the standard normal distribution. The evaluation of pollution degree of single element by the method of land accumulation index shows that Hg is the most serious pollution element in three power plants, and all of them reach serious pollution in varying degrees. The comprehensive pollution degree evaluation of Nemero pollution index method and pollution load index method shows that the comprehensive pollution degree of eight heavy metal elements in the surrounding soil of No.1 Power Plant is relatively heavy, followed by No.2 Power Plant, No. 3 Power Plant, and the lowest in No.1 Power Plant area. The pollution load index was 2.8, which reached the level of strong pollution, and that of No.2 and No.3 power plants was 1.8 ~ 1.7, respectively, which belonged to the medium pollution level. The evaluation of potential ecological hazard index shows that Ni and Zn are the lightest of the eight heavy metal elements, and the potential of eight heavy metal elements in No. 1 Power Plant. The index of ecological hazard is 1152.92, which has strong ecological hazard. The number 2 of power plant is 187.46, and the number of power plant No. 3 is 190.03, which is the middle degree of ecological hazard. The improved evaluation model was used to compare the standard value of soil quality and environmental background value, and to consider the content of elements and toxicity coefficient. The comprehensive pollution coefficient of heavy metals in power plant is obtained by means of weighted average method with reference to the mainstream comprehensive pollution index method. Power plant No. 1 is located in the urban area, the comprehensive pollution coefficient is the largest, and power plant No. 3 is located in the countryside, and the comprehensive pollution coefficient is the second. The No. 2 Power Plant is located in the suburb and has the least pollution. The results showed that there were significant correlations between the eight heavy metal elements in 0.69.1 and No.3 power plants, but poor correlations among the eight heavy metals elements in No. 2 power plant, and the eight elements in No. 1 and No. 3 power plants were divided into four categories and the second power plants were divided into five categories. Agricultural production, industrial waste discharge, road traffic, daily life activities of residents are the main sources of soil heavy metal pollution, some elements are affected by a single source of pollution, others by a combination of multiple sources of pollution.
【学位授予单位】：华北电力大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X53

【参考文献】