基于GIS和多元变量模型的洞庭湖沉积物中重金属的空间风险评价和来源解析

发布时间：2018-06-04 04:42

本文选题：重金属污染 + 污染特征　；参考：《湖南大学》2013年硕士论文

【摘要】：城市河流时刻接纳来自于城市的大量人为污染。在众多污染中,重金属由于其在环境中的持久性、循环性以及生态危害性而倍受关注。沉积物既是重金属的汇,又是潜在的次生污染源。评价沉积物中重金属的污染有助于了解人类以及不同生物暴露在水生环境中可能受到的潜在风险以及所处空间的环境质量,进行沉积物中重金属的来源解析则可以帮助人们从根本上有效控制和减少污染源的排放。本文以洞庭湖沉积物为研究对象,设置10个具有代表性的采样点位,采用箱式采泥器进行沉积物采样,用电感耦合等离子体质谱法和原子荧光法分别测定了样品中Cd、Pb、Cr、As、Cu和Hg、Zn的含量,通过分析得出：七种重金属的平均含量均高于洞庭湖水系沉积物背景值,重金属平均含量由高到低依次是：ZnCrPbCuAsCdHg。随后运用反距离权重插值法进行空间插值,结果表明Pb、Cd、As、Zn和Cu的空间分布图相似,Hg和Cr的分布图各异,重金属的高值区主要集中洞庭湖的中下游地区。综合运用地累积指数、潜在生态风险指数法并结合GIS的空间可视化分析确定了洞庭湖沉积物重要污染的重金属和污染区域,分析认为：洞庭湖沉积物中重金属重点污染因子为Cd、Hg、Cr和As,重点污染区域为洞庭湖出口及其附近区域及各大支流汇入洞庭湖的河口三角洲。基于模型不确定性的考虑,运用相关分析法、主成分分析法、正矩阵因子分解法、傅立叶和谱分析法分别解析了洞庭湖沉积中重金属的污染源,综合四种解析方法的结果得到三类污染源。第一类因子上的主要污染物为Pb、Cd、As、Zn和Cu,主要来源为人为活动中的工业废水排放和采矿业废水的排放所带来的污染；第二类因子主要污染物为Hg,主要来源于自然风化；第三类因子主要污染物为Cr,主要来源于人类活动中的生活污水和农业生产。经过各个模型之间的交叉验证与对比得出结论：在数据量及数据代表性不足情况下的,主成分分析结合傅立叶和谱分析将会得到更加准确可靠的解析结果。
[Abstract]:Urban rivers always accept a large amount of man-made pollution from the city. Among all kinds of pollution, heavy metals have attracted much attention because of their persistence, recycling and ecological harmfulness in the environment. Sediment is not only a sink of heavy metals, but also a potential secondary pollution source. Assessing the contamination of heavy metals in sediments contributes to an understanding of the potential risks to which humans and different organisms are exposed to the aquatic environment and the environmental quality of the space in which they are exposed, The analysis of the source of heavy metals in sediments can help people to effectively control and reduce the emission of pollution sources. In this paper, taking Dongting Lake sediment as the research object, 10 representative sampling sites are set up, and the sediment sampling is carried out with box mud collector. The contents of Cu and Hgzn in the samples were determined by inductively coupled plasma mass spectrometry (ICP-MS) and atomic fluorescence spectrometry (AFS), respectively. The results show that the average contents of seven heavy metals are higher than the background values of sediments in Dongting Lake. The average content of heavy metals from high to low is: ZnCrPbCuAsCdHg. Then the inverse distance weight interpolation method is used to carry out spatial interpolation. The results show that the spatial distribution maps of Zn and Cu are similar to those of Hg and Cr, and the high value regions of heavy metals are mainly concentrated in the middle and lower reaches of Dongting Lake. Combined with land accumulation index, potential ecological risk index method and spatial visualization analysis of GIS, the heavy metals and polluted areas of sediments in Dongting Lake were determined. It is concluded that the major pollution factors of heavy metals in the sediments of Dongting Lake are CD HgN Cr and As.The main polluted areas are the outlet of Dongting Lake and its adjacent area and the estuarine deltas where the major tributaries converge into Dongting Lake. Based on the uncertainty of the model, correlation analysis, principal component analysis, positive matrix factorization, Fourier and spectral analysis were used to analyze the pollution sources of heavy metals in Dongting Lake sediments. Three kinds of pollution sources are obtained by synthesizing the results of four analytical methods. The main pollutants in the first type of factors are Pb, CD, C, Zn and Cu, which mainly come from the discharge of industrial wastewater from human activities and from the discharge of mining wastewater, and the second type of major pollutants are Hg, mainly from natural weathering. The third factor is Cr, which mainly comes from domestic sewage and agricultural production in human activities. After the cross-validation and comparison among the models, it is concluded that the principal component analysis (PCA) combined with Fourier and spectral analysis will obtain more accurate and reliable analytical results under the condition of the data volume and data representation is insufficient.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：P208;X824;X524

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