| Scince the first dectection from the environmental samples in Sweden,polybrominated diphenyl ethers(PBDEs)have drawn great attention due to their wide occurrence,potential source and environmental influence.In 2009,Stockholm convention restricted the production of tera-,penta-and hexa-BDEs while deca-BDE was the only permitted commercial PBDEs prodcuts for production and use.In the meantime,with the increasing number of population,emmissions of domestic waste,especially electronic waste were also continuely increasing.Thus,the PBDEs source was increased,which lead to the potential risk to the health of human beings.In this study,PBDEs and hydroxylated polybrominated diphenyl ethers(OH-PBDEs)were target pollutants and the sediments collecting from the rivers in Jiading District,Shanghai was the target samples for analysis.The concentration level,compostition constitution of PBDE congeners,potential source and risk assessment were systematically investigated.In addition,human serum samples were also collected from Jiading District,Shanghai and the concentration of PBDEs and OH-PBDEs in serum was studied.The metabiltic pathway was explored by analysis of correlation among differernt PBDE congeners.Besides,photodegradation effect for OH-PBDEs under UV irradiation was investigated and the preferable conditions were picked out during the photolysis.And the degradation production was identitfied.The results are shown as follows:(1)PBDEs and OH-PBDEs could be detected in all the sediment samples and their total concentrations were 755-7715 pg g-1 and 60-101 pg g-1,respectively.And their mean concentrations were 6568 and 80 pg g-1,respectively.Compared with the contamination level in other areas,the concentration of BDE-209 was comparatively low in shanghai,which was lower that of the cities with heavy industy.(2)BDE-209 constituded more than 75%of total PBDEs after analysis,which indicates that BDE-209 was the main PBDE in sediment and deca-BDE was the main commercial product of PBDEs.In addition,the composition of PBDE congeners was different between the sampes of N1,N2 and N3,N4,N5,which suggests that point source of PBDEs was existed in the study area.Besides,in the analysis of OH-PBDEs,6-OH-BDE 47,2’-OH-BDE 68 and 6’-OH-BDE 99 accounted for 23.8%-69.7%,0-46.2%and 0-35.3%of total OH-PBDEs concentration,respectively,which means that they are the main congeners of OH-PBDEs in sediment.(3)According to the analysis by Spearman test,the BDE-209 and ∑14-PBDEs were significant correlated(r = 0.943,p<0.01).In addition,no significant correlation were observed among OH-PBDE congeners except for 6-OH-BDE 47 and 6-OH-BDE 137,which suggests that the transformation among OH-PBDEs may not occur in sediment.(4)PBDEs were no risk to the aqutic creatures based on the risk assessment.While when high concentration of BDE-209 occurred in the aqutic environment,it may transfer to penta-BDE which is high toxic to algae and therefore it will cause potential ecological risk.(5)The concentration of PBDEs in human serum ranged from 0.280 to 12.330 ng g-1 w,with the mean value of 2.162 ng g-1 lw.The concentration level was comparatively low which was similar to the conditions in Hangzhou and Wenzhou city,which were all less than 10ng g-1 lw.The concentration of OH-PBDEs was 0.045-0.363 ng g-1 lw and the mean value was 0.187 ng g-1 Iw.The concentration level of OH-PBDEs is human serum from this study was similar with the values in other creatures,which rang from 0.02 to 3 ng g-1 lw.(6)BDE-47 was the main PBDE congener in human serum,which accounted for 70%-100%of total concentration.This might be attributed to half-life of deca-BDE in human blood.In addition,among six OH-PBDE congeners,6-OH-BDE-47 constituted the majority part than others,which has the concentration ranging from 0.081-0.1176 ng g-1 lw.(7)Based on the result of Spearman test,significant correlation was observed between BDE-47 and BDE-28(p<0.05).Same relationship was also occurred between BDE-47 and other PBDE congeners(BDE-100,-85 and-154).In addition,significant correlations were also observed bwteen 3-OH-BDE-47 and 6-OH-BDE-47,and bewteen 3-OH-BDE-47 and 6’-OH-BDE-99(p<0.01).Such results indicates that these PBDE or OH-PBDE congeners share the similar metabolic sources.However,no significant correlation between total PBDEs and total OH-PBDEs,which suggests that OH-PBDEs was not metabolized from PBDEs directly in human serum.The reason may be that PBDEs transfer into another mid-product and then turn to OH-PBDEs indirectly.Or this may be attrited to the limit categories of PBDE/OH-PBDE congeners we investigated.Another reason may be the fact that OH-PBDEs are directly generated by dietary intake.(8)2’-HO-BDE-68(500 μg L-1)was photodegraded under UV irradiation and its rate constant was 0.24 min-1.The degradation efficacy of UV system was better than that of visble light and electron beam irradiation.(9)When the intial concentration was comparatively low,it has little influence on the degradation efficacy under UV light system.While when the intial concentaitn increased to 1000 μg L-1,it has significant negative effect on the degradation efficacy.In addition,alkaline condition was preferable for the U V degradation and the additive of H2O2 also could promote the efficacy of photolysis.(10)The main photodegradation products were 1,3,8-TBDD,2,4-DBP,di-HO-DBB and di-HO-TBDE. |
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