| With the rapid progress of urbanization and industrialization,the population,number of motor vehicles,and energy consumption increase year by year in Shanghai.These changes may increase the emission and accumulation of pollutants,and further aggravate environmental pollution problems.POPs have attracted widespread attention in the society due to their carcinogenicity,teratogenicity and mutagenicity.The level,spatial distribution,possible sources,and health risk assessments of three types of typical POPs,including PAHs,CPs,and PCBs,were comprehensively investigated in urban road dust in Shanghai.The results obtained from the study may provide scientific basis for local government to control and manage pollutants.The main conclutions are as follows:1.The total concentrations ranged from 53.0 to 28700 ng/g?median:2660 ng/g?for 26 PAHs and from 39.0 to 25800 ng/g?median:2070 ng/g?for 16 USEPA priority PAHs in 72 urban road dust samples from Shanghai.The 16 PAHs were the main cotributors to total 26 PAHs.Concentrtions of PAHs in the studied area ranked at a medium and low level compared with other regions around the world.The pollution levels of the six functional areas followed the order:traffic,campus,industrial area,commercial area and residential area>park.PAHs were predominately composed of high molecular weight PAHs?4–7 rings?,indicating that they derived mainly from pyrogenic sources.Factor analysis?FA?and multivariable linear regression model has identified three sources with the relative contributions of 35%for traffic,51%for mixed source?coal,natural gas,biomass combustion and coke tar?,and 14%for oil.The positive matrix factorization?PMF?model has identified and quantitatively assessed the six sources:biomass?6%?,traffic?28%?,coke tar?8%?,oil?9%?,natural gas?25%?,and coal?24%?.The incremental lifetime carcinogenic risk?ILCR?assessment results showed that the total ILCR value of children and adult exposed to in the studied area,respectively.Therefor,an acceptable risk(10-6–10-4)maybe existed for people exposed to urban road dust PAHs in Shanghai.2.The concentrations ranged from 9.74 to 11400 ng/g?GM:332 ng/g?for SCCPs,and from 44.1 to 49900 ng/g?GM:1550 ng/g?for MCCPs in urban road dust from Shanghai.MCCPs were the main contributors to total CPs in urban road dust,accounting for 82.8%?median?of?CPs.Overall,the level of total CPs were 53.9–61300 ng/g?GM:1890 ng/g?,ranking at a low level compared with other regions in China.The concentrations of SCCPs and MCCPs in the traffic and commercial areas were significantly higher than those in campus,industrial areas,residential areas and parks?p>0.5?.The FA model identified two sources of CPs in road dust,which were mixture of local CPs,and the combined source of local CPs and long-range transport CPs?LCLT?.Three sources were identified and quantitatively assessed by PMF model:CPs mixture mainly composed of SCCPs?26%?,LCLT?14%?and CPs mixture mainly composed of MCCPs?60%?.The results of daily exposure dose?EDI?assessment showed that the total EDI values of SCCPs and MCCPs were both much lower than the 1000 times of the no observed adverse effect level.Therefore,SCCPs and MCCPs in urban road dust did not pose health risk to people in Shanghai.In addition,the EDI of people exposed to CPs in urban road dust in the studied area ranked at a low level compared to other regions around the world.3.The total concentration of 139 PCBs in urban road dust ranged from 56.1 to14700 pg/g?mean:3650 pg/g?,which ranked at a relatively low level compared with other regions in the world.The levels of PCBs had no significant difference among the six functional areas?p>0.5?.The highest contents of PCB congeners were 3–5chlorinated PCBs,with a total proportion of 45.7–100%?median:81.3%?.The cluster analysis has divided the PCB possible sources into 4 categories:59.7%of the road dust samples were derived from Aroclor 1254;2.8%of the samples were from Aroclor 1221;23.6%of the samples were from Aroclor 1016,Aroclor 1232 and Aroclor 1242;and 13.9%were from Chinese transformer oil.The results of incremental lifetime carcinogenic risk and non-carcinogenic risk quotient were both far below the safety limits,so the health risks of people exposed to PCBs in urban road dust from Shanghai were extremly low and could be ignored. |
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