大渡河流域石棉段沉积物重金属污染及生态风险评价

发布时间：2018-01-04 10:08

本文关键词：大渡河流域石棉段沉积物重金属污染及生态风险评价　出处：《成都理工大学》2015年硕士论文　论文类型：学位论文

【摘要】：以大渡河流域石棉段水系沉积物中的重金属为研究对象,在通过水系沉积物1:5万区域地球化学调查,重点分析了大渡河流域石棉段水系沉积物中重金属元素As、Cd、Cr、Cu、Hg、Ni、Pb、Zn的总量和富集分异特征,并通过相关性分析和聚类分析方法来研究水系沉积物中8种重金属元素的相互关系,初步应用两种常用地积累指数法和潜在生态危害指数法两种污染评价方法对研究区沉积物中的重金属污染进行了评价,取得结论如下:选取中国沉积物综合平均值、中国水系沉积物背景值、长江沉积物背景值、中国土壤背景值和四川A层土壤背景值5种指标作为参考背景值,研究大渡河流域石棉段水系沉积物重金属元素总量特征,除了As元素平均含量低于长江沉积物背景值外,各元素平均含量均高于参考背景值;8种元素最小值都小于5项参考背景值,以中国水系沉积物背景值为例,8种元素的最大值是背景值的几十倍到上千倍,如Cd的最大值是背景值的192倍、Pb的最大值是背景值的1044倍等,说明大渡河流域石棉段沉积物受到相当程度的重金属污染。与长江沉积物重金属含量背景值相比,大渡河流域石棉段沉积物中重金属含量富集程度和分异程度较高。从富集系数来看,重金属元素富集程度依次为PbCdHgNiCrZnAsCu。从变异系数来看,大渡河流域石棉段沉积物重金属含量有较大的变异。其中As、Cd、Cu、Hg、Pb的变异系数都在2以上,属于极强分异型。相关性分析结果显示,在水系沉积物中As、Cd、Cu、Pb和Zn元素间具有良好的相关性;Cr与Ni之间有显著的正相关;Hg与其他元素相关性都比较差。聚类分析结果显示沉积物中8种重金属元素可以分为As-Cu-Pb、Cd-Zn、Hg和Cr-Ni四类组合关系。这两种分析方法表明研究区重金属污染是人为作用和自然作用共同导致的结果。研究区重金属污染进行的潜在生态风险评价主要运用地积累指数法和潜在生态危害指数法,两种方法评价结果具有高度的一致性。Cd属于中度-严重污染,强-极强生态危害,中度及以上污染点75处,强及以上生态危害点257处,是潜在生态危害指数最主要的贡献者。Pb、Hg次之,Pb属于中度-严重污染和中等-强生态危害,Hg属于中度-偏重污染和中等-很强生态危害。As、Cu属于中等-偏重污染和中等-强生态危害,Cr、Ni、Zn属于中度-偏重污染和轻度生态危害。大渡河流域石棉段水系沉积物总体上属于中等生态危害,污染程度属于中度-偏重度污染,其中Cd、Pb和Hg尤其值得关注。
[Abstract]:The section of the Dadu River Valley asbestos heavy metals in sediments as the research object, through sediment 1:5 000 regional geochemical survey, focuses on the analysis of heavy metals in the Dadu River section of asbestos in sediments As, Cd, Cr, Cu, Hg, Ni, Pb, Zn and the total concentration distribution, the relationship between and through the correlation analysis and cluster analysis method to study the 8 kinds of heavy metal elements in the sediments, preliminary application of two kinds of commonly used heavy metals accumulation index and potential ecological risk index method of two kinds of evaluation methods for pollution in the study area in sediment pollution was evaluated. The conclusions are as follows: the selection of Chinese sediment average, Chinese river sediments of Yangtze River Sediment background value, the background value, the background value of soil Chinese and Sichuan A layer soil background values of 5 indicators as reference background value, on the Dadu River section of water flow domain asbestos sink The accumulation of heavy metals in addition to total characteristics, the average content of As is lower than the background value of elements of Yangtze River sediment, the average content of each element were higher than the reference background value; 8 elements are less than the minimum value of 5 reference background value, to China sediment background values of 8 elements for example, the value is the background value of several times thousands of times, such as the maximum value of Cd is 192 times higher than the background value, the maximum value of Pb is 1044 times higher than the background value, that the sediment in the Dadu River section of asbestos by the heavy metal pollution degree. Compared with the background value of heavy metal content in the sediments of Yangtze River, the enrichment of heavy metals in sediments of the Dadu River valley section and asbestos a higher degree of differentiation. The enrichment coefficient, the enrichment of heavy metal elements in PbCdHgNiCrZnAsCu. from the aspect of variation coefficient, variation in the Dadu River section of asbestos heavy metals in the sediments of the As, Cd, Cu, Hg, the coefficient of variation of Pb in more than 2, which belongs to the strong differentiation. The results of correlation analysis showed that in sediments As, Cd, Cu, Pb and Zn have a good correlation between the elements; there was a significant positive correlation between Cr and Ni; the correlation between Hg and other elements are relatively poor clustering analysis results showed that the 8 kinds of heavy metals in the sediments can be divided into As-Cu-Pb, Cd-Zn, Hg and Cr-Ni four kinds of combination. The two methods show that the heavy metal pollution in the study area is artificial and natural effect due to the heavy metal pollution in the area. Potential ecological risk in the evaluation mainly uses the method of index of geo accumulation and the potential ecological risk index method, evaluation results of the two methods is consistent with the height of the.Cd belongs to moderate pollution, strong extremely strong ecological harm, moderate pollution and over 75, and more than 257 points of ecological risk, potential ecological risk The main contribution of damage index of.Pb, Hg, Pb belongs to moderate pollution and medium strong ecological harm, Hg belongs to moderate - and medium - strong emphasis on pollution ecological risk.As, Cu belong to the middle - and medium - strong emphasis on pollution and ecological damage, Cr, Ni, Zn belongs to moderate pollution stress and mild ecological hazard. The Dadu River valley section of river sediment asbestos is generally moderate ecological risk, the degree of pollution belongs to moderate emphasis of pollution, including Cd, Pb and Hg of particular concern.

【学位授予单位】：成都理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X52;X826

【参考文献】