| Objective:1.To investigate the distribution characteristics of PBDEs and heavy metals in drinking water sources in the Chongqing section of the Three Gorges reservoir.2.Using PBDEs and heavy metals as characteristic pollutants in the electronics manufacturing industry,and analyzing their spatial correlation with electronic manufacturing.3.Conduct ecological risk assessment and health risk assessment of PBDEs and heavy metals,and make reasonable suggestions.Methods:1.Taking the area along the Yangtze River in the Chongqing section of the Three Gorges reservoir as the study area,to conduct an interview questionnaire survey of electronics manufacturing companies in the study area.The questionnaire includes:the number of electronic manufacturing enterprises,product types,investment amount and development trends2.Divide the surface water basins of the study area into upper,middle and lower reaches.21 centralized drinking water units for drinking water are selected to investigate the basic situation of the water supply unit and the protection measures for the water source.3.According to the Standard Test Method for Drinking Water(GB/T 5750-2006),source water,factory water and sediment are collected.PBDEs are detected by gas chromatography-mass spectrometry(GC-MS)and heavy metal are detected by inductively coupled plasma-mass spectrometry(ICP-MS),such as Hg,Cr,Cd,Pb,Ni,As,Zn,Cu,Mn and Fe.4.Use EpiData3.1 to build the database,use ArcGisl0.3 to map and spatial analysis and use Excle and SPSS21.0 for statistical description and statistical analysis,the test level is 0.05.The US Environmental Protection Agency’s health risk assessment model is used to evaluate the health risks of heavy metals in the drinking water pathway.The quotient method is used to assessed the ecological risk assessment of PBDEs in sediments.The ecological risk assessment of heavy metals in sediments is carried out by using the land accumulation index method and the potential ecological risk index method.Results:1.The total number of electronic manufacturing in this study area is 65,of which the electronics manufacturing enterprises in the upstream areas are concentrated,with the largest number and investment,accounting for 81.54%and 93.02%respectively.Among the 26 typical electronic manufacturing enterprises,the quantity of waste residue,water and gas is 17,5 and 14 respectively.2.Each of the 21 water supply units has a hygiene permit,and the water treatment process mainly includes pretreatment,flocculation,sedimentation,filtration and disinfection.There are pollution problems in some water sources.3.In 21 centralized water supply units,31 kinds of PBDEs are not detected in the source water and the factory water.The concentration of PBDEs in sediments ranges from ND to 15.66 ng/g.The detection rate of PBDEs in sediments is 45%,and the main dominant pollutants are BDE-62,BDE-66 and BDE-209.4.In 21 centralized water supply units,the over-standard rates of Ni and Fe in the source water are 4.76%and 19.05%,respectively,and the other heavy metals do not exceed the standard.10 kinds of heavy metals in the factory water are not exceeded.The average contents of Hg,Cr,Cd,Pb and Ni in sediments are 0.09,65.77,0.83,34.31 and 29.51 mg/kg,respectively,and the over-standard rates are 14.29%,14.29%,80.95%,33.33%and 23.81%,respectively.In space,the pollution degree of the five heavy metals generally decreases from upstream to downstream.5.The heavy metals Hg,Cr,Cd,Pb and Ni are significantly correlated with each other at the 0.01 level.There is no significant correlation between PBDEs and five heavy metals.Hg,Cr,Cd,Pb,and Ni have higher loads on the first principal component,and PBDEs have higher loads on the second principal component.6.The health risks of PBDEs in the factory water are low.The total cancer risk value of heavy metals in the factory water is 2.26x 10-6～3.28×10-5/year,and the average value is 1.10×10-5/year.The total risk value of non-carcinogenic substances is 1.10×10-2／1.44×10-1,and the average value is 3.47×10-2.7.The total risk quotient(Q)of PBDEs is less than 1 in sediments from water sources and the risk quotient of Penta-BDEs is much higher than Octa-BDEs and Deca-BDEs8.The ecological risk of heavy metals in sediments is generally at a moderate ecological hazard level.The assessment by the geoaccumulation index shows that the pollution degree of heavy metals is:Cd>Ni>Pb>Cr>Hg,and the assessment by potential ecological risk index indicates that the potential ecological risk of heavy metal is:Cd>Hg>Pb>Ni>Cr.Cd and Hg have the highest contribution to total ecological risk.In space,the ecological risk level of heavy metals gradually decreases from upstream to downstream.Conclusion:1.The pollution level of PBDEs in the source water and the factory water is low in the Chongqing section of the Three Gorges reservoir area,while the sediments in the water source are polluted by PBDEs.The main dominant pollutants are BDE-62,BDE-66 and BDE-209.The health risks of PBDEs through drinking water pathways are relatively low,and the total ecological risk of PBDEs in sediments is relatively low.However,since the ecological risk quotient of Penta-BDEs is close to 0.1,the monitoring of Penta-BDEs should be strengthened in this region.2.The pollution of heavy metals in the factory water is relatively low,while the pollution of heavy metals in source water and sediment is relatively high in the Chongqing section of the Three Gorges reservoir area.The health risks of the carcinogens such as Cr,Cd,As and non-carcinogens such as Hg,Pb,Ni,Zn,Cu,Mn and Fe are acceptable in generally in the factory water,but the monitoring of As and Pb should be strengthened.The total ecological risk of heavy metals in sediments is at a medium level,and Cd and Hg are the pollutants in the sediment that need to be preferentially controlled.3.In spatial distribution,the pollution degree of PBDEs and heavy metals in the sediments of water source is consistent with that of electronic manufacturing,and the dense areas of the electronics manufacturing industry are relatively polluted. |
