| With the improvement of urbanization level in China,the problem of urban pollution has become increasingly prominent.Shanghai,an international metropolis and China’s economic and industrial center,is facing the increasingly severe environmental pollution situation.Therefore,it is of great theoretical and practical significance to study the pollution status of Shanghai.Hexabromocyclododecane（HBCDD）is a widely used additive brominated flame retardant,which has been listed in Annex A of Persistent Organic Pollutants of Stockholm Convention in 2013 due to its high toxicity,environmental persistence,bioaccumulation and long distance migration.However,limited research was conducted on the pollution status of HBCDD in Shanghai.In this paper,the soil,road dust and bark in the typical areas of Shanghai were taken as the target medium.The levels,distributions,diastereoisomer profiles,correlations between different environmental media and correlations between different functional areas of HBCDD in the target medium were studied.At the same time,the evaluation for the potential human exposure risk of HBCDD in different populations in Shanghai was conducted,and it will be helpful to fulfill the"Stockholm Convention on Persistent Organic Pollutants"for China and provide basic data and theoretical support for the development of various types of control strategies.The main results and conclusions of this paper were listed below:1.The levels,spatial distributions and diastereoisomer profiles of HBCDD in soils from four mixed-land-use categories–agricultural area and industrial area（A&I）,residential area and agricultural area（R&A）,residential area and commercial area（R&C）,as well as residential area and industrial area（R&I）–in Jiading,Shanghai were unveiled.Furthermore,the evaluation for the potential human exposure risk of HBCDD was also conducted in this study.The results showed that HBCDD was ubiquitous contaminant in the soil of Jiading,Shanghai.The concentrations ofΣHBCDDs（sum ofα-,β-andγ-HBCDD）in soil ranged from 0.30 to 249 ng g-1 dw,with a median level of 5.14 ng g-1 dw.The concentrations ofΣHBCDDs in soils from different mixed-land-use areas decreased in the following sequence:R&I>R&C>A&I>R&A.The composition of HBCDD in soil was predominated byα-HBCDD（49%）,followed byγ-HBCDD（39%）andβ-HBCDD（12%）.The portion ofα-HBCDD in soil from mixed-land-use areas increased in the following sequence:R&I<A&I≈R&A<R&C.The median value ofα-HBCDD/γ-HBCDD in R&I was comparable to that in A&I;the median value ofα-HBCDD/γ-HBCDD in R&C was comparable to that in R&A.The significant correlation for each HBCDD diastereoisomer andΣHBCDDs in soil from R&I,R&A（p<0.01）suggesting the HBCDD isomers in these areas may have similar sources.The estimated daily intakes（EDIs）ofΣHBCDDs from soil for different exposure ways decreased in the following order:ingestion>dermal contact>inhalation.The total EDIs（sum of ingestion,dermal contact and inhalation intake）ofΣHBCDDs through soil intakes decreased with age,except for adults.2.The levels,spatial distributions and diastereoisomer profiles of HBCDD in road dust from four mixed-land-use categories（A&I,R&A,R&C and R&I）in Jiading,Shanghai were unveiled.Furthermore,the correlation between the HBCDD in soil and that in road dust,as well as the evaluation for the potential human exposure risk of HBCDD was also conducted in this study.The results showed that HBCDD was ubiquitous contaminants in the road dust of Jiading,Shanghai.The concentrations ofΣHBCDDs in road dust ranged from 4.11 to508 ng g-1 dw,with a median level of 23.4 ng g-1 dw,which was higher than that in soil from the same area.The concentrations ofΣHBCDDs in road dust from different mixed-land-use areas decreased in the following sequence:R&I>R&C>R&A>A&I.Compared with soil,the portion ofγ-HBCDD in road dust was lower（20%）,while that forα-HBCDD was higher（66%）.The portion ofα-HBCDD in the road dust increased in the following sequence:R&C<R&A<R&I<A&I.For the same sampling type,the variation ofα-HBCDD/γ-HBCDD in road dust was larger than that in soil.Similar to soil,the median value ofα-HBCDD/γ-HBCDD in road dust from R&I was comparable to that from A&I;the median value ofα-HBCDD/γ-HBCDD in R&C was comparable to that from R&A.The significant correlation for each HBCDD diastereoisomer andΣHBCDDs in road dust from R&C and R&I（p<0.01）implying the HBCDD diastereoisomers in these areas have similar sources.The significant correlation of HBCDD in soil and road dust from R&C and R&I was found by typical correlation analysis,indicating that HBCDD in soil and road dust in these areas may had the similar sources.The EDIs ofΣHBCDDs from road dust for different exposure ways decreased in the following order:ingestion>dermal contact>inhalation.Road dust contributed more HBCDD exposure than soil,it was mainly due to higher concentration of HBCDD in road dust than that in soil.The total EDIs ofΣHBCDDs through road dust intakes decreased with age,except for adults.Compared with other routes of exposure,diet was the main route of adult HBCDD exposure.In addition,road dust and soil should not be overlooked for the risk assessment of human exposure to HBCDD,especially for the infants lived in R&I.3.The concentrations and spatial distributions of HBCDD in bark samples from Shanghai as well as the correlations of HBCDD between different functional areas were reported.At the same time,the atmospheric concentrations of HBCDD in the corresponding sampling sites were evaluated according to the bark/air distribution model of persistent organic pollutants（POPs）.The results showed that HBCDD was detected in all bark samples from the target area.The concentrations ofΣHBCDDs in bark ranged from 101.35 to 5872.31 ng g-1lw（lipid weight）,with a media level of 570.30 ng g-1 lw.ΣHBCDDs concentrations in the bark of different functional areas were industrial areas>commercial areas>residential areas.The three diastereoisomers（α-,β-andγ-HBCDD）have a significant positive correlation with each other in the bark from residential and industrial areas,indicating they may have similar sources in these regions.Typical correlation analysis found that HBCDD in industrial areas and commercial areas may have similar sources,and the HBCDD in commercial areas may originate from industrial areas.The composition of HBCDD in the bark of Shanghai was predominated byα-HBCDD（44%）,followed byγ-HBCDD（38%）andβ-HBCDD（18%）.The portion ofα-HBCDD in the bark from the industrial areas（45%）was consistent with that in residential（44%）and commercial areas（42%）.Similar findings also found inβ-HBCDD andγ-HBCDD.The ratio and range ofα-HBCDD/β-HBCDD in the bark of the commercial areas（mean 1.75,range 0.29-4.69）were significantly higher than those in industrial areas（mean 1.39,range 0.76-2.63）and residential areas（average 1.23,Range 0.63-2.23）.Based on the measured concentration of HBCDD in the bark and the bark/air distribution model of POPs,the estimated concentrations of HBCDD in the atmosphere of Shanghai were 24.72-1432.14 pg m-3,with a median level of 139.08 pg m-3.Compared with the studies for the urban air from other countries and regions,the atmospheric HBCDD concentrations of Shanghai were relatively high. |
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