Quality Assessment Technology Of Sediment Polluted By SQCs Of Heavy Metals Of The Taihu Lake

Our country own a lot of lakes and reservoirs,which total storage capacity is 6.38 × 10118)3.50% of the country's urban drinking water was provided to the lake.Therefore,the safety of freshwater lakes affects human health.In the past twenty years,a lot of research has been made on the water quality criteria about the water environment.According to research result,our government formulated the “Environment Quality Standard for Surface Water ”(GB3838-2002).However,the study of lake sediment quality criteria has hardly made.In this paper,Taihu Lake was used as an example to the sediment criteria(SQC)of heavy metals and organic pollutants.the pollution degree of heavy metals and organic matter were evaluated basing on the SQC,meanwhile,the ecological effects of them are assessed according to the evaluation methods.The objective of this paper is to construct freshwater lake sediment quality evaluation system,so as to provide scientific basis for lake management in our country,at the same time has some reference value for other freshwater lake sediment quality evaluation.In this paper,the method of establishing the Sediment Quality Criteria of freshwater lake at home and abroad is summarized by reviewing the literature.In this study,Equilibrium Partitioning Approach was used to calculate the sediment quality guidelines of Taihu Lake.SQC was calculated and derived by Equilibrium Partitioning Approach based on the measured data.According to SQC,the pollution degree of heavy metals in sediments was evaluated by Geo-accumulation index method,meanwhile,the ecological toxicity of polycyclic aromatic hydrocarbon(PAHs)and organochlorine pesticides(OCPs)in sediments was evaluated by probable effect concentration quotients.The corresponding results are as follows:(1)The calculated SQCs of Cr,Ni,Zn,Cd,Pb and Cu were 26.86,48.44,34.59,0.81,70.99 and 13.96 mg/kg in Taihu Lake,respectively.Compared with other SQCs,SQCs of Cr and Zn in Taihu Lake are lower than them in Dianchi Lake and North America,but SQC of Pb are higher than it in Dianchi Lake and North America;SQCs of Cu and Cd are closer to them in North America.(2)The SQC values of DDD,DDE,DDT,?-BHC,?-HCH,?-HCH and ?-HCH were 1.51,1.94,2.44,2.15,3.98,217,and 6.22 ug/g in Taihu Lake,respectively.The calculated SQCs of acenaphthene,fluorene,phenanthrene,anthracene,fluoranthene,pyrene,benzene [a] and anthracene,chrysene,benzene [b] and fluoranthene,benzene [k] and fluoranthene,indene [1,2,3-cd] pyrene,dibenzo [a,h] anthracene and benzene [g,h,i] and pyrene were 8.03 × 103,8.61 × 103,9.60 × 103,1.05 × 104,1.06 x 104,1.26 x 104,1.24 x 104,1.50 x 104,1.51 x 104,1.74 x 104,1.71 x 104,1,70 x 104,2.02 x 104,1.97 x 104,1.95 x 104 ug/g.(3)Based on the heavy metal SQC value,the heavy metal risk of sediments is divided into six evaluation standard grades by the accumulation index method.The evaluation results of heavy metal are that Meiliang Bay,Gonghu Bay,Zhushan Bay and East Taihu belong to three-stages pollution and that Xu Lake,lake area and coastal areas are the class ? pollution.Therefore,to strengthen heavy metal monitor in Meiliang Bay,Gonghu Bay and East Taihu Lake,if necessary,the need for dredging sediment.Judging from pollution degree of heavy metal,the degree of heavy metals followed an order of Zn> Ni> Cu> Cr> Cd> Pb.Cd and Pb have an no effect on water in Taihu Lake,and other heavy metals belonged to mild pollution.(4)Fifteen kinds of preferential control polycyclic aromatic hydrocarbons(PAHs)were monitored in the sediment from Taihu Lake,and the range of PAHs was 209-3843 ng/g,with the mean concentrations of 584 ng/g.Six kinds of organochlorine pesticides(OCPs)were detected,and the concentration range of OCPs was 8.0-32.5 ng/g,with the average concentration of 17.8 ng/g.The values of MPEC-Q were calculated based on the SQC of PAHs and OCPs.The results of calculation were 2.67 × 10-6 and 1.4 × 10-3,respectively,which were much smaller than 0.1,and it was deduced that PAHs and OCPs will not be toxic to benthic organisms,which its toxicity of the possibility of occurrence relatively is relatively small.