Distribution And Ecological Risk Evaluation Of Heavy Metals In Sediments Of The River Of The Downstream Of The Smelter

After more than half a century, Chinese industry has developed rapidly. However, the water pollution has been more serious. Heavy metals pollution in sediment has increasingly became a outstanding environmental problem with its huge harm and deep impact and difficult management. Compared with other pollution, there were series of characteristics of heavy metals pollution, such as long-term, cumulative, concealed, latent and irreversible, what also brought a lot of difficulty to the ecological risk assessment of heavy metals pollution.In this topic, a polluted river by smelter wastewater and waste gas haved been made as research object, heavy metal pollution in river, which is on the downstream of the smelter,of six sections of sediment(surface, middle and deep)were used as samples, analysised the geometrical shape of sediment heavy metals,the damage degree of the ecological risk of harm for the environment.In this study, we analysised major heavy metal residues such as Pb,Cd,Cr,Cu,Zn. The results indicate that Pb,Cr and Cu in the tested samples existed mainly as stable state, oppositely, Cd and Zn existed mainly as unstable state. Pb,Cd,Cr,Cu,Zn Its biological effective state content of roughly:73%,98%,67%,78%and52%respectively. From the point of biological effective state content of heavy metals,Cd,Pb and Cu are the highest elements,and these three factors in the river sediment content is big, and have high ecological risk impact to the environment.In order to study the river’s ecological risk assessment reference values closer to the real situation, but also in order to ensure the accuracy of the evaluation results, in accordance with the "The Technical Specification for soil Environmental monitoring", the research area near the river where the soil background values were determined to be done. And the measured soil background value were used as follow-up evaluation of the reference value. widely used evaluation methods were compared to determine the use of the accumulation index and potential ecological risk assessment method for the two methods studied comparative evaluation. Detection of heavy metals in sediment study reach full capacity of the underlying data were evaluated respectively using the above two methods. Accumulation index in the evaluation results showed that five factor the level of potential ecological risk of heavy metals from high to low in turn is: Cd>Pb>Cu>Zn>Cr, six sections of the overall pollution level from high to low in turn is:6#>1#>3#>2#>5#>4#, and pollution levels in the vertical level, its turn is surface> middle> deep. Method of potential ecological risk assessment results showed that five factor the level of potential ecological risk of heavy metals from high to low in turn is:Cd>Pb=Cu>Zn=Cr, six sections of the overall pollution level from high to low in turn is:6#>1#>3#>2#>5#=4#, and pollution levels in the vertical level, its turn is:surface> middle> deep.Analysis of two kinds of evaluation results and comparison, evaluation of heavy metal pollution and its impact on the ecological environment of risk are the same. I analysed and compared the differences of two methods of ecological risk assessment, and give the analysis on two kinds of evaluation results and speculation. And pointed out the advantages and disadvantages of the two methods respectively, In the ecological risk assessment, we should adopt the method of combination of two methods to avoid large deviation of evaluation results.