Surface Soil Pbde Profiles,Sources,Health Risk Assessment Of PBDEs And The Relationship To Economic Factors Along The Yangtze River Urban Agglomeration Belts In China

Polybrominated diphenyl ether（PBDEs）is a common brominated flame retardant.It is widely used in the production and polymer materials to reduce its flammability,casualties and economic losses.However,due to its persistence,bioaccumulation and toxicity,it has gradually attracted human attention.The industry in the Yangtze River Delta region（YRD）is well developed,so a large number of PBDEs flame retardant products are used.Current research indicates that PBDEs already exist in various environmental media in YRD.The soil medium not only receives PBDEs from other media as a“sink”through atmospheric sedimentation,but also acts as a“source”to diffuse PBDEs to other environmental media through soil erosion and surface runoff.PBDEs can be harmful for human health due to biological amplification.Therefore,the environmental quality of PBDEs in soils is closely linked to the economic development of the region and human health.Although the YRD is a densely populated area in China,there are a few related studies on PBDEs in urban soils there,and these study areas are mainly scattered in typical cities such as Shanghai,Suzhou,Nantong and Hangzhou.And most of the researches focus on monitoring of PBDEs in the soil environment.This paper focuses on the two urban agglomeration belts of Shanghai-Nanjing（SNUB）and Shanghai-Hangzhou（SHUB）and investigating the PBDEs pollution level,homologue profiles,spatial distribution and source analysis in soils of different land use in this region,using a health risk model assess the human health risk of PBDEs,and constructing coupling coordination model to explore the degree of the coupling and coordination between PBDEs and urban economic development.The study provided a reliable scientific basis for the PBDEs environment of urban topsoil,sustainable development of urban economy and the maintenance of residents’health in the Yangtze River Delta urban agglomeration belts（YRUBs）.The main conclusions are as following:（1）The concentration ofΣ₁₉PBDEs in the soil of the YRUBs was in the range 0.17to 218.55 ng/g dw,and the average value was 13.40±33.50 ng/g dw.The concentration level of the SNUB was higher than that of the SHUB.The spatial distribution differentiation in the cities showed Suzhou>Changzhou>Shanghai>Wuxi>Jiaxing>Zhenjiang>Nanjing>Hangzhou.Spatial distribution differentiation of PBDEs average concentrations in terms of land use showed industrial land>residential land>commercial land>agricultural and forest land>green park.（2）The PBDE homologue profile in the surface soil displayed that BDE-209accounted for the largest proportion among 19 PBDE congeners,with an average content of 75%,followed by BDE-206（5.43%）,BDE-207（4.26%）and BDE-99（4.16%）.Deca-BDE dominated and contributed 74.92%among the 8 PBDE homologues（74.92%）,followed by nona-BDE（13.83%）and penta-BDE（5.25%）.Among the cities,deca-BDE accounted for the highest proportion in Changzhou（86.74%）and the lowest proportion in Hangzhou（45.57%）.In contrast,penta-BDE was the lowest proportion in Changzhou（0.39%）and the highest proportion in Hangzhou（20.03%）.The proportion of nona-BDE among cities remained at 11%-17%.（3）There was no significant correlation between PBDEs concentrations and the total organic carbon（TOC）of the soils in the YRUBs.However,theΣ₁₉PBDEs in the soil of agricultural and forestry land and green park showed a significant positive correlation with soil TOC,the correlation coefficients were 0.77 and 0.85（p<0.05）.There were positive correlations between low-PBDEs and TOC in soils of industrial and commercial land.There was also a significant positive correlation between octa-BDE and soil TOC in residential land soils.（4）The results showed that the Deca-BDEs and its substitution were the main source of PBDEs in the soil of the YRUBs by principal component analysis and multiple linear regression model.Deca-BDEs dominated the contribution of the three commercial PBDEs production（87.25%±1.53 p<0.001）using the method of least squares.The contribution rates of Deca-BDEs in Suzhou and Changzhou exceeded 95%,the contribution rate of Penta-BDEs in Hangzhou reached 27.62%.It proved that after Penta-BDEs and Octa-BDEs were banned in 2009,Octa-BDEs has become the main PBDEs flame retardant which were used in industrial production.（5）Risks evaluations were conducted by the incremental lifetime cancer risk model（ILCR）.It was used to evaluate the non-cancer risks and cancer risks of PBDEs in the soil of the YRUBs.The non-cancer health index（HI）in all cities were less than1 and the values of cancer risk（CR）were more than 10^-6.The values of HI and CR all showed the trends in infants>children>baby>adolescents>adults,that indicated the young children and infants have more potential health risks from soil PBDEs in the YRUBs.The cancer risk of BDE-209 in Suzhou,Changzhou and Shanghai were higher than other cities,which should draw enough attention.（6）Based on the coupling coordination degree model,the degree of coupling and coordination between the PBDEs pollution and the social economic development was in the range 0.38 to 0.63.The YRUBs were divided into two groups according to their degrees of coupling coordination between PBDE concentration system and socioeconomic system.One group was PBDEs-Economy resistant areas including Wuxi,Nanjing,Hangzhou and Zhenjiang.The other was PBDEs-Economy mutual promotion areas,including Shanghai,Suzhou,Changzhou and Jiaxing.