Sedimentary Records And Source Analysis Of Metal Elements Contamination In Chaohu Lake

With the rapid development of urbanization and industrialization,environment was getting more heavily polluted by heavy metals.In order to reflect pollution status of heavy metals in soil and sediment and to grasp the spatial variation characteristics,Chaohu Lake was selected as study area,then to analyse REEs from 47 surface sediments,heavy metals from four sediment cores in main estuaries,and most metal elements from 22 surface soil samples in agricultural areas.To determine the potential sources by Cluster analysis and other data analysis techniques.Furthermore to estimate the correlation between soil erosion in agricultural surface soils with heavy metal enrichment in lake sediments.Then results are shown as follows:(1)The mean concentration of ?REE were found higher in the Chaohu Lake than background value,and showed right-tilting mode,?LREE was heavily enriched.?REE was found higher concentration in the eastern Lake,however,a higher level of REEs fraction was found in the western Chaohu Lake,which means extensively anthropogenic activities.(2)Metal elements including Zn,Pb,Co,Cr,Cd,Mn,As and Cu in sediment cores collected from Chaohu Lake showed significant distribution.Analysis show that all sampling areas were extremely contaminated by Cd,and Mn was not enriched.Cluster analysis indicates the residual elements in sediment cores were generally from natural materials for Mn,and from urban origins for Cu,Zn and Pb,then the remaining elements was proved from agricultural activities.(3)Rice soil samples along two main tributaries of Chaohu Lake were collected to determine 30 metal elements.Results implied that elements were depleted because of soil erosion and weathering and enriched in sediments of the lake.The depletion of elements(Sn,Ti,Zr,V,Hf,Mn,Nb,Sr,Zn,Cd,Ga,U,Se,Th)in soils were predominately due to that these metals existed with a large mobile fraction.While As,Th and Se moderately accumulated in the soils due to their insusceptibility of transport potentials.Therefore,our study implied agricultural soils could play a important role in the input of heavy metals into sediments via soil erosion and weathering.