Investigation And Pollution Assessment Of Heavy Metals In Surface Sediments From Typical Regions In Upstream Of Yellow River

With the rapid development of the economy and society, the expansion of the urbanpopulation, and more and more pollutants are discharged into the yellow river, the problem ofthe water pollution in yellow river is more serious in recent years. Therefore, the study ofpollution condition of water quality and sediment has an important practical significance forthe ecological environment protection.Taking the method of field sampling and laboratory analysis. This thesis took the surfacesediments of122sample points of typical regions in four provinces (including Qinghai,Gansu, Ningxia and Inner Mongolia) in upstream of Yellow Rivers the research object,collected and analysed the surface sediments and control samples in0~5cm, investigated andresearched systematically the characteristic of content and spatial distribution pattern of eightheavy metals (Cu, Fe, Mn, Ni, Zn, Cr, Pb and Cd) in surface sediments. We can understandthe sources of each heavy metal element through the relevant research and principalcomponent analysis, and the evaluating pollution level in surface sediments from typicalregions in four provinces in upstream of Yellow river by the method of Geo-accumulationIndex, Sediment Enrichment Factors and Pollution Load Index. The following conclusionsare:(1) The mean values of the heavy metal contents of the surface sediments from the fourtypical provinces in upstream of Yellow River are arranged in the decreasing order: Fe>Mn>Cr>Zn>Ni>Cu>Pb>Cd. According to the multiples between the average value and thebackground value of the heavy meatals, the pollution of Cr is the most serious, and Zn is thelightest. Standard deviation and variation coefficient between the heavy metal elements havelarge difference. The result indicates that pollution levels between each sample point have bigdifference, it may be related to some factors, such as heavy metal sources，the influence andmanners of human activities.(2)There is a significantly positive correlation relationship between Cu, Fe, Mn and Znin surface sediments from the four typical provinces in upstream of Yellow river. These heavymetals which are controlled by the first factor, well-distributed in sediments, mainly in naturalsedimentation, and less affected by human disturbance are belong to the “natural sourceelements”. So they have similar geochemical behavior in sources, transportation andenrichment factors. The correlation between Cd and Cr is significantly positive, they belongto the “artificial source element” with the control of the second factor, and the source anddistribution of them are similar. The main sources are from several kinds of industrialprocesses such as machinery manufacturing, smelting metal mines, electric power, chemical raw materials and the burning of fossil fuels, plastics, semiconductor, and superconducting etc.The source and distribution of Ni and Pb may be affected by natural geological backgroundand human activity.(3)The pollution of the Fe, Mn and Zn is from no pollution to weak pollution, theseelements may come from natural sources such as natural sedimentation and crustal movement.The pollution of Cu, Ni, Pb and Cd is weak, these elements come from stone fragments andother factors. Heavy metal Cr which belong to moderate pollution may be caused by humanactivities, such as industrial wastewater, vehicle emissions, chemical manufacturing, and thesevere loss of element Cr from coal mine going into rivers through surface water and so on.Generally speaking, the pollution level of four provinces in upstream of Yellow River is fromunpolluted to moderately polluted degree.