Geochemical Study On Heavy Metal Elements In Sediments In Panzhihua Downtown Area

This thesis starts with sediments in Panzhihua downtown area, and focuses not only on the physical chemistry characteristics of Jinsha River and its branches within a range of about 40km in Panzhihua City, which is from Jinjiang Station on the east and to Geliping on the west, but also on the geochemical characteristics of heavy metals in sediments. In the thesis, the author uses geochemical methods to study heavy metals in sediments in Panzhihua downtown area from the angle of environment and gets some creative achievements. They are:(1) Using X-ray diffraction and scanning electrical mirror to analyze the grain size and components of sediments. The mineral in sediments consists mainly of quartz, second to which is clay mineral. The sediment exists in the form of mineral aggregate and looks irregular, having obvious edges and corners; the sediment is constituted mainly of naturally weathered and eroded material, together with artificial products caused by industrial activities.(2) Study the space distribution characteristics of heavy metals in sediment. Heavy metals' contents are the highest in the middle reaches of the river; their contents in branch are generally higher than in the trunk stream; branches have great influence on the trunk stream; on the profile, most heavy metals have higher contents on upper levels than at the bottom.(3) Study the heavy metals' distribution characteristics in different granularity samples. It is found that, except V, all elements have higher contents in fine grain samples than in coarse grain samples; heavy metals in the two samples have strong correlation.(4) Analyze the correlation between heavy metals. It is found that there is a comparatively obvious positive correlation between elements, except Pb and Zn. Clustering analysis shows that the type of heavy metals is Ti-V-As-Cu-Co-Cr-Mn, Pb-Zn Type; while factor analysis shows that the source of heavy metals is related to rock backgrounds such as basic-superbasic rock.(5) Using continually extraction to analyze the speciation characteristics of heavy metals. It is found that heavy metals mainly exist in residua, while the content of ion exchange is very low; all elements' speciations are different. In space distribution, all speciations change greatly in the middle reaches of the river, which might be influenced by industrial activities.(6) Using three advanced methods and two standards to evaluate the pollution caused by heavy metals in sediments in Panzhihua downtown area. It is found that the evaluated results for Jinshajiang standard are a little higher that those for global shale standard; from the results of three different evaluating methods, it can be found that the general evaluated results are identical, that is, the pollution caused by heavy metals in sediments in Panzhihua downtown area is lighter, belonging to light-medium pollution.(7) Analyze the source of heavy metals that cause pollution. The author thinks that the heavy metals in sediments are mainly caused by waste water discharged from factories along the river. Meanwhile, high geological background of Panzhihua City is another reason for high content of heavy metals in sediments. At the end of the thesis, the author also puts forward some countermeasures and suggestions for protecting water environment.