美国Okeechobee湖流域土壤重金属的空间分布特征与污染评价

发布时间：2018-05-03 06:10

本文选题：Okeechobee湖流域 + 土壤重金属　；参考：《上海师范大学》2015年硕士论文

【摘要】：土壤是环境的重要组成部分,它是水、空气和岩石之间进行生态循环的媒介。随着经济的飞速发展、工农业现代化水平的提高,很多地区土壤受到重金属污染。对土壤重金属的空间分布及污染状况的研究,对于土壤环境保护与治理具有十分重要的意义。本文运用地统计学与GIS相结合的方法对美国Okeechobee湖流域土壤Cu、Zn、Pb、Cr、Cd、Co、Ni、Mn、Fe9种重金属的空间分布特征及污染状况进行分析,得到以下结论：1、研究区土壤重金属数据统计特征分析结果表明：土壤表层Cu、Zn、Pb,亚表层Cu、Zn、Pb、Fe,均属于强变异性,表层Fe、Cd、Co、Cr、Mn、Ni,亚表层Cd、Co、Cr、Mn、Ni的均属于中等变异,表层Cu、Zn、Pb、Cd、Co,亚表层Cu、Zn、Pb、Fe、Cd、Co、Cr都不符合正态分布,而表层Fe、Cr、Mn、Ni,亚表层Mn、Ni均符合正态分布。2、半方差函数拟合结果表明：在各项同性条件下,土壤表层Cu、亚表层Cu分别符合球状模型和指数模型,表层Zn和亚表层Zn均符合指数模型,表层Pb和亚表层Pb分别符合指数模型和球状模型,表层Fe亚表层Fe符合球状模型,表层Mn和亚表层Mn分别符合指数模型和高斯模型,表层Cd和亚表层Cd符合线性模型,表层Co、亚表层Co分别符合线性模型和高斯模型,表层Cr、亚表层Cr符合高斯模型,表层Fe、亚表层Fe符合球状模型,表层Ni、亚表层Ni符合高斯模型。3、在各项异性条件下,各重金属在不同方向上的变异函数差异较为明显,除土壤表层Co、Fe,亚表层Co、Fe、Mn表现出较为明显的各项同性特征外,其余均表现出明显的方向性特点。土壤表层、亚表层Cd和表层、亚表层Cr在各个方向上变异程度均较大。表层Cu在2km范围以外变化趋势逐渐拉大,亚表层Cu在8km范围之外,变化趋势较为明显。表层Mn在南北方向和西北-东南方向空间变化趋势较大,表层、亚表层Ni在各个方向上变异程度均较大。表层Pb在7km之外变化趋势较大,亚表层Pb在8km之外变化趋势较大。表层Zn在各个方向上虽有变化,但是趋势较为缓和。亚表层Zn在10km之外,西北-东南方向变化较大。4、交叉验证结果显示,表层土壤Cu以普通克里格插值效果最好,表层土壤Cu呈岛状与条带状分布相结合的特征,亚表层Cu采用泛克里格法插值效果最好,亚表层Cu的分布状况与表层基本一致。表层Zn以普通克里格插值效果最好,表层土壤Zn呈岛状分布,亚表层Zn采用简单克里格法插值误差最小,呈岛状与块状结合分布。表层Pb以普通克里格插值效果最好,呈岛状分布,亚表层Pb以简单克里格插值效果最好,亚表层Pb分布情况和表层类似,但含量明显低于表层。表层Cd最适合析取克里格插值方法,呈块状分布,亚表层Cd采用普通克里格和泛克里格法插值精度最高,分布情况与表层类似。表层Co采用普通克里格和泛克里格插值误差最小,呈块状分布,亚表层Co最适宜简单克里格法,呈岛状和面状分布相结合。表层Mn采用简单克里格插值误差最小,主要呈岛状分布,亚表层Mn采用简单克里格法插值误差最小,分布状况与表层类似。表层Cr最适合的是析取克里格法,呈岛状与带状分布,亚表层Cr采用简单克里格法插值误差最小,分布状况与表层相似。表层Fe也最适合普通克里格插值,呈现明显的岛状与块状分布,亚表层Fe采用简单克里格法插值,分布与表层相类似。表层Ni用简单克里格法插值,亚表层Ni采用简单克里格法,插值误差较小,呈岛状分布。5、采用地累积指数法对重金属污染状况进行评价,结果显示,研究区域土壤表层Cd污染比较严重,约70%的研究区域受Cd污染,污染区主要集中在研究区西北部和Okeechobee湖以南地区。近半数采样点土壤Cu污染也较为严重,Cu污染较严重区域主要是在Okeechobee湖西北部和东南部,其分布受人为干扰的影响较大。根据潜在生态风险指数法评价结果,七种重金属的生态风险由大到小分别为Cd、Cu、Pb、Ni、Zn、Mn、Cr,潜在生态危害指数RI=166.55,表明研究区域土壤表层重金属污染存在中等生态危害。
[Abstract]:Soil is an important part of the environment. It is the medium of ecological circulation between water, air and rock. With the rapid development of the economy and the improvement of the modernization level of industry and agriculture, the soil is polluted by heavy metals in many areas. The study on the spatial distribution and pollution of heavy metals in the soil has ten. In this paper, the spatial distribution characteristics and pollution status of soil Cu, Zn, Pb, Cr, Cd, Co, Ni, Mn and Fe9 heavy metals in the soil of the Okeechobee Lake Basin in the United States were analyzed by using the method of geostatistics and GIS, and the following conclusions were obtained: 1, the statistical analysis of the data of the soil heavy gold in the study area showed that the soil surface layer Cu Surface Cu, Zn, Pb, Fe, all belong to strong variability, surface Fe, Cd, Co, Cr, Mn, Ni, subsurface Cd are medium variation. Under the condition, the soil surface Cu and subsurface Cu conforms to the spherical model and the exponential model respectively. The surface Zn and subsurface Zn conforms to the exponential model. The surface Pb and subsurface Pb conforms to the exponential model and the spherical model respectively. The subsurface Fe of the surface is conformed to the spherical model, and the surface Mn and the subsurface Mn conforms to the exponential model and the Gauss model respectively, and the surface Cd and subsurface are subsurface. Layer Cd conforms to linear model, surface Co, subsurface Co conforms to linear model and Gauss model respectively, surface Cr, subsurface Cr conforms to Gauss model, surface Fe, subsurface Fe conforms to spherical model, surface Ni, subsurface Ni conforms to Gauss model.3, under the various heterosexual conditions, the variation function of each heavy metal in different directions is more obvious, except soil The surface layer Co, Fe, subsurface Co, Fe, Mn showed obvious homosexual characteristics, and the rest showed obvious directional characteristics. The soil surface, subsurface layer Cd and surface layer, subsurface Cr in each direction have greater variation degree. The surface Cu is gradually widening from the 2km range, and the subsurface Cu is outside the 8km range. It is obvious that the surface Mn changes in the north and south direction and northwest to Southeast, and the surface layer and subsurface Ni have greater variation in each direction. The surface Pb changes outside the 7km, and the subsurface Pb has a larger trend outside the 8km. The surface Zn is changed in all directions, but the trend is relatively mild. Subsurface Zn Outside the 10km, the Northwest - southeast direction has a larger change of.4. The cross validation results show that the surface soil Cu is best with the common Kriging interpolation, the surface soil Cu is characterized by the combination of island and strip distribution, and the subsurface Cu is best interpolated by Pan Kriging, and the distribution of subsurface layer Cu is basically the same as the surface layer. The surface Zn is universal. The surface soil Zn has the best effect, the surface soil is distributed in the form of island, and the subsurface Zn adopts the simple Kriging method to interpolate the smallest error. The surface Pb is the best with the common Kriging interpolation. The subsurface Pb is best with simple Kriging interpolation, and the subsurface Pb distribution is similar to the surface layer, but the surface layer is similar to the surface layer, but the surface layer is similar to the surface layer. The content of the surface Cd is better than the surface layer. The surface Cd is the most suitable for the disjunctive method. The subsurface Cd has the highest interpolation accuracy with the ordinary Craig and the pan Craig method, and the distribution is similar to the surface layer. The surface Co uses the ordinary Craig and the pan Craig interpolation error to be the smallest, and the subsurface Co is the most suitable for the simple Craig. The surface Mn uses simple Kriging interpolation to minimize the error of simple Kriging interpolation. The subsurface Mn uses simple Kriging interpolation to minimize the error, and the distribution is similar to the surface layer. The surface Cr is most suitable for the precipitation Kriging method, the island and the banded distribution, the subsurface Cr is interpolated by simple Kriging method The error is the smallest and the distribution is similar to the surface layer. The surface Fe is also most suitable for ordinary Craig interpolation, showing obvious island and massive distribution. Subsurface Fe is interpolated by simple Craig method, and the distribution is similar to the surface layer. The surface Ni is interpolated by simple Craig method, and the subsurface Ni is simple monkrige method, the interpolation error is smaller,.5 distribution in the island shape is obtained. The method of land accumulation index is used to evaluate the pollution of heavy metals. The results show that the soil surface Cd pollution in the study area is more serious, about 70% of the research area is polluted by Cd. The polluted areas are mainly concentrated in the northwest of the research area and the south of the Okeechobee Lake. The soil Cu pollution is more serious in nearly half of the sampling points, and the most serious area of Cu pollution is the main area. According to the potential ecological risk index method, the ecological risk of seven kinds of heavy metals is Cd, Cu, Pb, Ni, Zn, Mn, Cr, and the potential ecological hazard index RI=166.55, according to the evaluation result of the potential ecological risk index method, which indicates that the soil surface heavy metal pollution in the study area has medium ecological danger. Harm.

【学位授予单位】：上海师范大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X53;X825

【参考文献】