Environmental Behaviors And Risks Of Polycyclic Aromatic Hydrocarbons And Polychlorinated Biphenyls In The Surface Water Of Shanghai

Polycyclic aromatic hydrocarbons(PAHs)and polychlorinated biphenyls(PCBs)are the two kinds of persistent organic pollutants(POPs)with high toxicity,carcinogenicity and mutagenicity.PAHs and PCBs could be transmitted over a long distance through multi-medium environment,and then be seriously harmful for the human health and environmental security.As an important environmental receptors,surface water has been widely concerned in studies of PAHs and PCBs,and it is of theoretic and application significance to investigate the environmental behaviors,exposure level and risk of PAHs and PCBs in surface water systems.This work was supported by the Natural Science Foundation of China(Grant No.41271472)and the Key Basic Science Foundation of Shanghai,China(Grant No.12231201900).In general,the concentrations of PAHs and PCBs in the river network,the Dishui Lake and its river system in Shanghai were measured by gas chromatography/mass spectrometer(GC/MS),and then the distributions,influence factors,partitions and sources of PAHs and PCBs were discussed by using GIS techniques and statistical approaches,such as redundancy analysis(RDA),principal component analysis(PCA),absolute principle component score/multiple linear regression(APCS/MLR)and positive matrix factorization(PMF),etc.Base on that,the carcinogenic and non-carcinogenic risk for the health risk assessment were assessed respectively.The ecological risk were analyzed by using risk quotient(RQ)method according to the predicted no effect concentration(PNEC),and index deduced by the quantitative structure-activity relationship(QASR)model proposed by USEPA and the species sensitivity distribution(SSD)model developed by Peking University.The main results and conclusions were as followed:(1)PAHs pollution in water and sediments was in the slightly-medium level,and the main structures of PAHs were 3-ring to 5-ring,such as Phe,Ant and Flua.PCBs pollution in water was slightly-medium while slightly in sediments.All the PCBs in water and sediments were occupied by penta-CBs and dominated by PCB118,PCB105 and PCB77.The center and suburban towns of Shanghai were significantly affected by PAHs and PCBs due to the weaker hydrodynamic conditions and the more serious malodorous black phenomenon.The concentrations of PAHs and PCBs in water and sediments in Dishui Lake were higher than those in its neighbor river system.As for the seasonal variation,the concentrations of PAHs and PCBs in both water and sediments were obviously higher in winter than those in other seasons,except for that of PCBs in the sediments in autumn..(2)The salting-out effect,water quality,total suspended particulates(TSS)and the dissolved organic carbon(DOC)were the main factors affecting the distribution of PAHs and PCBs in water.In the sediments,the concentrations of PAHs were significantly influenced by soot carbon(SC)and the particle size of sediment.The distribution of PCBs in sediments were significantly correlated with the contents of SC and total organic carbon(TOC).The water temperature,salty,TSS and DOC were the important environmental factors which could affect the partition of particulates-water.The sediments-water exchange of PAHs and PCBs were all influenced by the particle size of sediment,while SOC and TOC impacted the partition of sediments-water significantly for PAHs but not significantly for PCBs.The field data of PAHs were capable of fitting the partition coefficient of sediments-water,but not as well as those of PCBs.(3)Compared with PCA and APCS/MLR,PMF can yield a better result of source apportionment for PAHs.Specifically,PAHs in water were mainly contributed by the combustion sources,including biomass,coal and natural gas combustion,and coke burning.In sediments,the traffic emissions were the dominant source for PAHs,followed by combustion source and coke burning.Four similar sources of PCBs were identified by using PCA and PMF respectively,though the contribution ratios of each source was different.In general,the dominate source of PCBs in water and sediments came from the cumulative residue of domestic PCB industrial products,followed by that of secondary metallurgy industries and some PCB products imported from other countries.(4)Total carcinogen risk of PAHs and PCBs in the river network has reached the unaccepted levels for both adults and children,except for a few sampling sites in Chongming Island.There were only 9.3%and 18.67%of the sampling sites in Dishui Lake and its river system were under the acceptable risk level for adults and children,respectively.Besides,skin exposure was the main pathway of PAHs and PCBs in scenic water,but it will not result in any obvious non-carcinogen healthy damage.(5)The PNEC,an index deduced on basis of the ECOSAR and BMC-SSD model,was able to give results comparable with other researches.The congeners of PAHs with excessively high ecological risk were BbF,BkF,and BghiP in water and Phe,Flua and Pyr in sediments,while those with high ecological risk were Phe,Ant,Chry,Flua and Pyr in water and sediments.The congeners of DL-PCBs with high ecological risk included PCB105 in dissolved phases,and PCB118,PCB105 and PCB77 in particulates.