Numerical Simulation On Migration And Transmission Of Perfluoro Compounds In Shanghai

Perfluorinated compounds?PFCs?are a family of emerging contaminants,and a kind of persistent organic pollutants?POPs?.It has been widely investigated that PFCs are hazardous to organisms,hard to breakdown,and distrbutesaround the world.The transport and oxidation of fluorotelomer alcohols?FTOH?leading to the final product are believed to contribute to the widely distribution of PFCs.Perfluorooctanoic acid?PFOA?is an important final product,and 8:2FTOH and N-Ethyl perfluorobutane sulfonamide?NEtFBSA?are the major precursors.In this study,CACM_PFC considering PFCs'chemical reactions was developed based on Caltech Atmospheric Chemistry Mechanism?CACM?.Box model was used to simulate the atmospheric chemical reactions of PFCs and further integrated into three-dimensional air quality model to simulate spatial and temporal distributions of PFCs.A box model coupled with CACM_PFC was applied to simulate PFOA formed by the oxidation of 8:2 FTOH and NEtFBSA.The simulation results under four typical conditions were analyzed,and the influences by the temperature,relative humidity and pressure were explored.It showed that high temperature and high relative humidity could benefit the formations of PFOA from 8:2 FTOH.At the meantime,influences by initial concentrations of other pollutants were explored.The results indicated that high concentration of ozone?O₃?leaded to the high concentration of PFOA.Nitrogen oxides?NO_x?had complex impacts on PFOA:when NOx was dominant,NO_x would compete with CH₃O₂ to inhibit PFOA's accumulation,and PFOA was low.When CH₃O₂ was dominant,PFOA accumulated and PFOA was high.Furthermore,CACM_PFC was integrated into three-dimensional air quality model CMAQ to simulate spatial and temporal distributions of PFCs in Shanghai.The simulation results showed that in Shanghai aera,the total concentration of PFOA in summer(?2.31 pg m^-3)was relatively higher than those in winter(?1.16 pg m^-3)during the simulation period.It might because the concentration of 8:2FTOH was high in summer,which caused the high conversion rate to PFOA.Meanwhile,reginal transport could influence PFCs in Shanghai area as well.These results can help to set up the effective control strategies of PFCs in Shanghai.