某铀尾矿库周边土壤中核素U与重金属元素空间分布与污染评价研究

发布时间：2018-06-12 04:47

本文选题：土壤 + 重金属　；参考：《西南科技大学》2017年硕士论文

【摘要】：某铀尾矿库自上世纪投入运营以来,共服役30多年,库中堆积了两百多万吨的铀尾矿砂。因此查明某铀尾矿库周边土壤中的核素U与重金属元素Mn、As、Pb、Cr的空间分布与污染状况,研究铀尾矿库对周边土壤影响具有重要意义。本文在野外采样、检测的基础上,利用SPSS软件对各元素进行描述性统计;通过GS+软件的半变异函数计算拟合出各元素最优模型,在此基础上运用ArcGIS中普通克里格法的进行空间插值,制作出各元素的空间分布图;比较单因子污染指数法与地质累积污染指数法评结果,使得评价结果更准确,采用内梅罗综合污染指数法对研究区土壤中的5种元素进行综合污染评价。主要研究内容和结论如下:1、研究区土壤中5种元素含量范围较广,变异系数较大,都不符合正态分布,通过与中国土壤背景值与湖南省土壤背景值,发现5种元素都存在较大比例的土壤样品元素含量大于背景值;2、GS+软件对5种元素的半变异函数计算结果显示,U元素的最优拟合模型为高斯模型,Mn元素、Pb元素和Cr元素的最优模型为指数模型;C0+C/C0比值表明U、As元素表现为中等相关性,Mn、Pb元素和Cr元素均表现为强烈的空间相关性;利用ArcGIS制作5种元素的空间分布图;3、单因子污染指数法评价结果显示研究区土壤中U元素污染较重的土壤主要集中在铀尾矿库周围200m区域;Mn元素和As元素重度超标的土壤主要分布在研究区东南部向;Pb元素轻微超标土壤分布广;Cr轻微超标土壤主要分布围绕在铀尾矿库的南、东、北侧,以及研究区的东南向。地质累积污染指数法结果显示除了 U元素、As元素外,其余三个元素为无污染。内梅罗综合污染指数法结果显示研究区土壤污染较重的区域主要分布在尾矿库周围以及研究区的东南部地区。
[Abstract]:A uranium tailings reservoir has been in service for more than 30 years since it was put into operation in the last century, and more than 2 million tons of uranium tailings have been accumulated in the reservoir. Therefore, it is of great significance to find out the spatial distribution and pollution of the nuclide U and the heavy metal element MnAsAsPbCr in the soil around a uranium tailings reservoir, and to study the influence of the uranium tailing reservoir on the surrounding soil. In this paper, on the basis of field sampling and detection, we use SPSS software to describe each element, calculate and fit the optimal model of each element by the semi-variable function of GS software. On this basis, the spatial interpolation of common Kriging method in ArcGIS is used to make the spatial distribution map of each element, and the evaluation results of single factor pollution index method and geological cumulative pollution index method are compared to make the evaluation results more accurate. The comprehensive pollution assessment of five elements in the soil of the study area was carried out by using the Nemero comprehensive pollution index method. The main contents and conclusions are as follows: 1. The content of five elements in the soil of the study area is relatively wide, and the coefficient of variation is large, all of them do not accord with the normal distribution. By comparing with the soil background value of China and the soil background value of Hunan Province, It is found that there is a larger proportion of elements in soil samples than in the background value. The results of semi-variogram calculation of the five elements show that the optimal fitting model of U element is Gao Si model, mn element, Pb element and Cr element. The optimal model of the elements is the exponential model C _ 0 C / C _ 0 ratio, which indicates that the elements of UMNO _ as show a strong spatial correlation between Mn-Pb element and Cr element. The spatial distribution map of five elements was made by ArcGIS. The results of single factor pollution index method showed that the soil with heavy U element pollution was mainly concentrated in the 200 m area around uranium tailings reservoir, mn element and as element were super heavy. The labeled soils are mainly distributed in the southeastern part of the study area. To the east and north, and to the southeast of the research area. The results of the geological accumulative pollution index method show that the other three elements are non-polluted except for the elements of U and as. The results of Nemero comprehensive pollution index method showed that the regions with heavy soil pollution in the study area were mainly distributed around the tailings reservoir and in the southeast of the study area.
【学位授予单位】：西南科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X751;X825

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