Distribution And Risk Assessment Of New Organic Pollutants In Sediments From The Intertidal Zone Of The New River Estuary

The production,usage,existing forms in environment and mechanism of toxicity of new organic pollutants have attracted the attention of environmentalists.Tris-2,3-dibromopropyl isocyanurate（TBC）and hexabromocyclododecane（HBCDs）are alternative brominated flame retardants for PBDEs.Polyhalogen substitution and mixed halogen substitution of polyhalogenated carbazoles（PCZs）are organic pollutants having received attention in recent years.They are widely used in the production of dyes,pigments,photoconductors,and photosensitive materials.The relevant studies have shown that they has persistent organic pollutants（POPs）and toxicity of dioxins,and they are widely distributed in the environment.The coastal areas of Beidaihe once was extremely rich in wetland resources.The seabeach resources and marshes resources are especially abundant near the estuary of the New River.However,the vegetation of the wetland and ecological diversity were seriously damaged since the incident of 19-3 oil spill in Bohai Sea.The important regulatory function of wetland in ecosystem degenerates obviously,which is especially serious near the estuary of New River.Therefore,this article studied the content levels and component characteristics of TBC,HBCDs and PHCs in the intertidal zone sediments at the estuary of New River in Beidaihe wetland.The correlation analysis,reserve estimation and the ecological risk assessment of these three types of new organic pollutants were carried out.In this study,the sediment samples were pretreated（freeze-drying,Soxhlet extraction,column chromatography purification,rotary evaporation,and nitrogen blowing enrichment）.The sediment samples were analyzed by the way of UPLC-MS-MS（TBC,HBCDs）and GC-MS（PHCs）.The research results showed that the detection rates were100%for TBC,HBCDs,PHCs and these three diastereomers（α-,β-andγ-HBCD）of HBCDs.The concentration ranges of TBC,HBCDs and PHCs are 2.8-35.1,10.3-43.5,and 2.2-60.9 ng·g^-11 respectively.The mean concentrations of them were 13.4,18.2 and7.8 ng·g^-11 respectively.According to the correlation analysis between varieties of organic pollutants,and between the organic pollutants and TOC,there was a weak correlation between TBC andα-HBCD（r=0.759,p<0.01）,and betweenβ-HBCD（r=0.807,p<0.01）andγ-HBCD（r=0.839,p<0.01）.The correlation betweenγ-HBCD（r=0.999,p<0.01）and∑HBCDs was more remarkable than the correlation betweenα-HBCD（r=0.921,p<0.01）and∑HBCDs,and betweenβ-HBCD（r=0.942,p<0.01）and∑HBCDs.The correlation between TOC and TBC,and between TOC and HBCDs is weak.36-BCZ,36-CCZ,36-ICZ,and 1368–BCZ are positively correlated withΣPHCs.However,there is no correlation between the TOC and CZ,and between PHCs andΣPHCs.The reserve estimation and ecological risk assessment of new organic pollutants in the sampling area were also carried out.The storage volume of TBC、∑HBCDs、and∑PHCs is estimated to be 200.8,272.2 and 123.9 ng·cm^-22 respectively.The research results showed that the storage volume of new organic pollutants in the sampling area is relatively large.The risk quotient（HQ）of HBCDs ranged from 0.06 to 0.25,which indicated that there may exist low or moderate ecological risks in this region.The TEQ value of toxicity equivalent evaluation for PHCs was as high as 17.66 pg TEQ·g^-1.It was lower than the TEQ value of safe sediment,which was 20 pg TEQ·g^-1.It indicated that the risks to the environment are relatively low.It compared the sampling area with the various regions of the world in this research,which was in order to study the pollution levels of TBC,HBCDs and PHCs in the intertidal zone sediments at the estuary of the New River further.The research results showed that the concentrations of TBC and HBCDs in the sampling area were at the higher level around the world,while the concentration of PHCs in the sampling was at the medium level around the world according to the previous research.