| Shanghai is a provincial-level administrative region,municipality directly under the central government of the People's Republic of China.It's also China's international economic,financial,trade,shipping,technological innovation center.While the large population in cities is driving the continuous economic growth,the environmental pollution of dioxins and dioxin-like compounds,emitted from the incineration of domestic waste,automobile exhaust,and the production,use and disposal of industrial chemicals,cannot be ignored.Dioxins and dioxin-like compounds are a type of persistent organic pollutants containing halogen elements,that normally act as degradation-resistant,strong lipophilic and long-range transport characteristics.They also have biological toxicity,endocrine disrupting and"three causes"effects.Throughout the country,there are relatively few studies on dioxins and dioxin-like compounds in Shanghai,and even fewer studies on brominated dioxins.This study established the pre-treatment,purification and separation methods for three categories of dioxins and dioxin-like compounds(PCDD/Fs,dl-PCBs and PBDD/Fs)and PBDEs,a category of the important precursor compound for PBDD/Fs.Two domestic waste incinerators in downtown Shanghai were selected as the research area of typical pollution source surrounding area in urban and 44 municipal environmental atmospheric monitoring points in the 16 administrative regions of Shanghai were selected as the urban background research area.The concentrations of PCDD/Fs,dl-PCBs,PBDD/Fs and PBDEs in ambient atmosphere and soil samples from contaminated and background areas in Shanghai,as well as the distribution characteristics of congeners,qualitative and quantitative pollution sources identification,were studied in this research.Finally,based on the contaminated levels of these four compounds in the environmental medias,the health risks of Shanghai urban residents due to environmental exposure of these four compounds are evaluated.The main conclusions of the research are as follows:1)In this study,silica gel column containing silver nitrate silica gel and florisil column were applied to separate and purify PCDD/Fs,dl-PCBs,PBDD/Fs and PBDEs effectively and completely at the same time.2)For soils from typical pollution source surrounding area in Shanghai:the TEQ concentrations of PCDD/Fs ranged from 0.362 to 31.4 ng·WHO-TEQ·kg-1(average:2.72 ng·WHO-TEQ·kg-1);the TEQ concentrations of dl-PCBs ranged from 0.0111 to3.79 ng·WHO-TEQ·kg-1(average:0.363 ng·WHO-TEQ·kg-1);the TEQ concentrations of PBDD/Fs ranged from 0.561 to 15.9 ng·WHO-TEQ·kg-1(average:3.66 ng·WHO-TEQ·kg-1);the concentrations of PBDEs ranged from 0.819 to 89.6ng·g-1(average:30.9 ng·g-1).3)For the ambient atmosphere from typical pollution source surrounding area in Shanghai:the TEQ concentrations of PCDD/Fs ranged from 0.0309 to 0.507pg·WHO-TEQ·m-3(average:0.168pg·WHO-TEQ·m-3);the TEQ concentrations of dl-PCBs ranged from 0.00641 to 0.104 pg·WHO-TEQ·m-3(average:0.0377pg·WHO-TEQ·m-3);the TEQ concentrations of PBDD/Fs ranged from 0.0138 to0.115 pg·TEQ·m-3(average:0.0443 pg·TEQ·m-3);the concentrations of PBDEs ranged from 41.9 to 982 pg·m-3(average:175 pg·m-3).The seasonal variation of PCDD/Fs,dl-PCBs,PBDD/Fs and PBDEs in ambient atmosphere samples from Shanghai contaminated areas was different,which indicated that the concentrations of PCDD/Fs,dl-PCBs,PBDD/Fs and PBDEs in ambient atmosphere samples from Shanghai contaminated areas was mainly affected by pollution sources rather than climate.4)The average concentrations of PCDD/Fs,PCBs,and PBDEs in the ambient atmosphere samples from Shanghai background areas were 0.0426 pg·WHO-TEQ·m-3,0.00659 pg·WHO-TEQ·m-3,and 119 pg·m-3,respectively.The concentrations of PCDD/Fs,PCBs and PBDEs in the ambient atmosphere from Shanghai background areas were significantly lower than those from the contaminated areas.5)Active sampling and passive sampling techniques were applied to study PCDD/Fs,PCBs,PBDD/Fs and PBDEs in the ambient atmosphere of Shanghai.For PCDD/Fs,PCBs and PBDEs,the contaminated levels,congener characteristics,and seasonal characteristics obtained by these two sampling techniques were consistent,indicating that the passive sampling technique can be well applied to the researches of PCDD/Fs,PCBs and PBDEs.The monitoring and research of PBDD/Fs by passive sampling technology needs further confirmation.6)Qualitative and quantitative source apportionment results showed that the main sources of PCDD/Fs in Shanghai's urban environment were traffic pollution,steel industry and waste incineration;the main sources of dl-PCBs were commercial PCB product disposal,waste incineration,and industrial production;the main sources of PBDEs were commercial PBDEs use and disposal;PBDD/Fs may be mainly affected by commercial deca-BDE products and brominated flame retardants in electronic waste.PBDD/Fs in urban environmental soil has obvious sources other than atmospheric dry-wet deposition PBDD/Fs.As brominated flame retardants are still mass-produced and used in China,the impact of brominated organic pollution in urban polluted areas needs further attention.7)The environmental exposure health risks of dioxin compounds(PCDD/Fs,dl-PCBs and PBDD/Fs)for adults and children in Shanghai urban area were within the acceptable range.However,in contaminated areas,the environmental exposure carcinogenic health risk of dioxin compounds for children had reached 10E-5,which required further attention.The environmental exposure health risk value of BDE-209for the residents in Shanghai urban areas was at the level of 10E-11,and the health risk caused by environmental exposure of BDE-209 can be ignored.But it needs to be concerned that massive amount of BDE-209 in environment may be converted into more toxic compounds,such as PBDD/Fs,which pose environmental exposure risks. |
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