Risk Assessment Of Heavy Metals In Basin Based On Ssd Source

With the rapid development of China's social economy,the increasing demand of metal products leads to an increase in the discharge of heavy metal pollutants.Heavy metal is a kind of persistent pollutants,which could be difficult to degrade.It will enter the human body through food chain and threaten human health.Water is one of the important resources that people need to survive.If the water is polluted by heavy metals,the living creatures in water will be directly affected,which could further threaten the human health.The tolerance of water species to pollutants in particular region depends on,the climate,geographical position,and species.Deriving watershed water quality criteria of heavy metals,adjusting measures to local conditions of river basin ecological risk assessment of heavy metals in water body is important.Taking drinking water conservation district of Biliuhe River Basin as an example,this study aimed to improve the water ecological risk assessment method of heavy metals.Mercury,zinc,and copper were selected as typical pollutants to conduct the ecological risk assessment of heavy metals in water,which was on the basis of Species sensitivity distribution.The main results are as follows:?1?Derive the benchmark of heavy metal water quality in Biliuhe River Basin with species sensitivity distribution model.19 acute toxicity data of Cu,21 acute toxicity data of Hg and 24 acute toxicity data of Zn were collected from the CNKI network and ECOTOX database.According to the methods provided by Technical Guideline for Deriving Water Quality Criteria for the Protection of Freshwater Aquatic Organisms,The most suitable model were selected and HC₅?Hazardous concentration for 5%of species?of Biliuhe River Basin were 1.03?g L^-1,87.10?g L^-11 and 10.72?g L^-1.In the end,the acute water quality standard of Biliuhe River Basin on mercury,zinc and copper were 0.52?g L^-1,43.55?g L^-11 and 5.36?g L^-1.?2?The ecological risk assessment of heavy metal in Biliuhe River Basin were carried out by safety threshold method,single factor index method and nemerrow index method.The safety threshold method was applied to evaluate the risk of heavy metals Hg,Zn and Cu in the drinking water source of Biliuhe River Basin on the basis of the SSD that all the evaluations were less than 1.There was less risk of heavy metals Hg,Zn and Cu in short term.The single factor index method for heavy metals Hg,Zn and Cu in the Biliuhe River Basin were evaluated using the water quality benchmarks deduced in this paper as evaluation criteria.The results showed that there were less risk of Hg,Cu in short term.The single factor index of Zn was more than 1 which needed to strengthen management.Compared with the results which were based on the first level standard restriction of Environmental Quality Standards of Surface Water as the evaluation criteria showed?GB3838-2002?had a problem of excessive protection of Hg.The evaluation results of Zn and Cu were similar to those of the original standard.Using Nemerow index method to assess the risk of the Biliuhe River Basin,The evaluation results which were based on the water quality criterias deduced in this paper were lower than the results which were based on the first level standard restriction of Environmental Quality Standards of Surface Water?GB3838-2002?as the evaluation criteria.All the sampling sites of heavy metals Hg,Zn and Cu were less than 1.There was less risk of heavy metal Hg,Zn and Cu in the short term.It can be seen from our study,the original standard has the problem of over-protection of water body in the drinking water source area of Biliuhe River Basin.This study showed that original standard had excessive protection problems.The water quality benchmark of heavy metals Hg,Zn and Cu in Biliuhe River Basin with species sensitivity distribution model provided scientific support and effective protection.