Study On The Sediment Quality Guidelines For Heavy Metals In Poyang Lake,China

Lakes provide abundant freshwater for humans and ecosystems.However,in the past decades,the rapid industrialization and urbanization have seriously threatened the ecological security of lakes.Heavy metals pollution in environmental water bodies such as lakes has been widely concerned by the world and has become a serious global environmental and public health problem.Rapidly growing human activities have made the hazard of heavy metals in aquatic environment a universal and long-term problem.The sediments can accumulate dissolved and particulate pollutants such as heavy metals in the aquatic environment,which is one of the main sinks of many pollutants.At the same time,it can also be a potential source of pollutants in overlying water under certain conditions.Sediments pollution can be toxic to benthic organisms and may be transmitted to higher level organisms through bioaccumulation,threatening ecosystems and even human health.This is already a worldwide problem,therefore,it is urgent to develop an appropriate sediment quality guidelines(SQG).As the largest freshwater lake in China,Poyang Lake is of great significance for maintaining ecological security of regions and countries.Therefore,in this study,the preliminary research on SQG of Cu,Pb,Zn and Cd in Poyang Lake was conducted through Equilibrium Partitioning Approach(EqPA)and Species Sensitivity Distributions(SSD).After analysis and comparison,the best SQG of Poyang Lake was selected.And then,several key and sensitive species of poyang lake ecosystem were selected to verify the derived SQG of Poyang Lake,and ecological risk index method and terrestrial accumulation index method were used to evaluate the ecological risk of heavy metals pollution in sediments of Poyang Lake,in order to lay a technical foundation for sediment quality standards of Poyang Lake,and to provide reference for sediment quality assessment of other lakes.The results of this study are as follows:(1)The toxicity of four heavy metals in the sediments was tested using three benthic organisms(M.anguillicaudatus,B.aeruginosa and C.fluminea),and the LC50 and EC50 values of the toxicity of four heavy metals to three benthic organisms were obtained.And the sensitivity rankings of 3 species to 4 heavy metals were obtained,the results were M.anguillicaudatus:Cd>Cu>Pb>Zn,B.aeruginosa:Cd>Pb>Cu>Zn,C.fluminea:Cd>Cu>Pb>Zn.(2)The Equilibrium Partitioning Approach(EqPA)and the Species Sensitivity Distributions(SSD)were used to derive the sediment quality guidelines(SQG)of heavy metals in Poyang Lake.The results derived by EqPA were single values,and the SQG of Cu,Pb,Zn,and Cd were 59.93,76.13,109.32,and 3.50 mg/kg,respectively.The results derived by SSD were double values,and the chronic guidelines(SQGchronic)of Cu,Pb,Zn,and Cd were 56.08,46.70,96.06 and 1.45 mg/kg,respectively,and the acute guidelines(SQGacute)were 153.4,237.7,467.7 and 30.18 mg/kg,respectively.The results derived by the two methods were generally closer to others SQG at home and abroad,although some of them had differences in some degree,they were within the same order of magnitude.In this study,after considering many factors,the results derived by SSD were recommended as the SQG of heavy metals in Poyang Lake.(3)Two benthic organisms(M.anguillicaudatus and B.aeruginosa)were selected,and the SQG of Poyang Lake derived in this study was verified by the method of spiked sediment toxicity verification.From the results of biological tests,the SQG for Cu,Pb,Zn,and Cd in Poyang Lake derived by SSD in this study basically accords with the meanings it represents,that is,when the sediment was lower than SQG-L,the sediment was not toxic and when it was higher than SQG-H,the sediment was obviously toxic,when it was between the SQG-L and SQG-H,the sediment was toxic but the toxicity was uncertain,and the sediment benchmark was verified.(4)The potential ecological risk index method and geoaccumulation index method were used to evaluate the pollution status of heavy metals in sediments of Poyang Lake.The evaluation results of the potential ecological risk index method showed that the pollution of four heavy metals in the sediments were generally low-risk.And the results of geoaccumulation index method showed that Cu,Pb,and Zn were generally pollution-free,while Cd was medium to high pollution.Besides,a four-level standard recommended value for protecting 95%,85%,70%,and 50%of aquatic organisms from heavy metals in sediments was derived using the species sensitivity distribution method,which can provide a scientific basis for the protection and management of aquatic ecosystems.