Study On Control Factors Of Bioavailability Of Heavy Metals In Sediment

Pollution in the Taihu lake basin has been the key environmental issues of governance,extensive research against the pollution of Taihu lake basin's research focuses on the study of distributions of nitrogen and phosphorus in the sediments of Taihu lake basin and on the study of distribution of heavy metals study area of Taihu lake basin.Firstly the large,multiple-site sampling study and evaluation of potential risks in Taihu lake basin are carried out and,it also summizes of the pollution of Taihu lake basin according to the results of study.Because there are many factors affecting bioavailability of heavy metals in the sediments,the study on sediment properties and effects of cyanobacteria on the bioavailability of heavy metals in the sediments is carried out.Experiments are divided into three parts,as follows:contents of heavy metals in surface sediment of Taihu lake basin water distribution decreases from North to South,and from East to West.With the ananlysis of the risk assessment of heavy metals in the Taihu basin,Taihu Lake watershed heavy metals in the surface sediments,Cu,Zn,and Pb,Ni,Cr,Fe and Mn pollution situation is not serious,and the high risk level of heavy metals Hg,Cd,is the main factor causing ecological risk in surface sediments in Taihu lake basin.the end of different nature of the effects of sediment on bioavailability of heavy metals are as follows:the experiment measured heavy metals Pb,Cd cover water changes in content as the time goes on and Fe,and Mn and the As and Cr contents decreased with time for change.Sulfides in sediment organic matter content is higher than that in sandy sediments,Content for SEM,in most cases in the sand is higher than that in the organic matter content.SEM-AVS content differs in the sediments of different nature,the toxicity of heavy metals in organic matter is less than sandy sediment toxicity.Different forms of heavy metals in sediments of content there is a big difference.Overall,the sedium cinterct in oxidizable organic matter in the sediments of the heavy metal content is higher than that in sandy sediments.The weak state of heavy metal influenced by bioturbation,and reducible concentrations of heavy metals in addition to sediment type influence and biological disturbances,and also influenced by heavy metal kind.Bioturbation effects DGT metal fluxes and relates to the combination of depth and heavy metals in the sediments.the phytoplankton algae on sediment heavy metal Cr,Mn,As,Cd concentrations is significantly higher than that of blue-green algae sediment.Reoxygenation period,increasing the number of blue-green algae,that joined after oxygen blue-green algae numbers increases again.Gathered in the blue-green algae during the sediment surface,no sediment toxicity to aquatic organisms containing blue-green algae is less than the presence of blue-green algae sediment.Deaths in blue-green algae,blue-green algae deposits increased toxicity to aquatic organisms.Reoxygenation in cyanobacteria,blue-green algae-free sediment toxicity on aquatic organisms.A great influence on the bioavailability of heavy metals,with or without algae in sediment,heavy metals acid configuration,oxidation States,reducible concentrations show a certain rule.Description of blue-green algae phytoplankton accumulation,death and reaeration process has an impact on forms of heavy metals in the sediments.PEEPER measured results shows the Fe content is less than in the overlying water content of sediments,blue-green algae in sediment of Fe content is less than no algae sediment content.DGT test indicates that the presence of blue-green algae sediment accumulation stage of heavy metal Cr on the content,As,Pb,Cd,Mn,Fe,etc have little effect,in death,effects of cyanobacteria on concentrations of heavy metals Pb,Mn.In blue-green algae aeration,cyanobacteria existes on the effects of heavy metals Mn,Pb.