Pollution Characteristics,Source Analysis And Health Risk Assessment Of Volatile Halogenated Hydrocarbon In Typical Industrial City

As a subclass of volatile organic compounds(VOCs)in ambient air,volatile halogenated hydrocarbons(VHCs)enter the atmosphere in the process of production,use,combustion,etc.Due to their long atmospheric life,leading to the accumulation of its concentration and threatening the ecological environment and human health.To investigate the pollution characteristics,sources,and health risks of VHCs in Zibo,a typical industrial city,online measurement(GC-MS/FID)of ambient VHCs was conducted from June 2021 to May 2022.The results show that:(1)The average volume fraction of VHCs was 8.0±4.3 ppbv during the monitoring period.The average volume fraction of VHCs regulated in the Montreal Protocol on Substances that Deplete the Ozone Layer(MP)was 1.5±0.3 ppbv and the change is relatively flat.The average volume fraction of MP-unregulated VHCs was6.5±4.2 ppbv and has obvious diurnal variation characteristics.The volume fractions of MP-regulated VHCs and MP-unregulated VHCs accounted for 18 % and 82 % of the total VHCs,respectively.(2)The volume fractions of total VHCs in each season were ranked as summer(9.0±4.9 ppbv)>autumn(8.3±4.2 ppbv)>winter(7.6±4.0 ppbv)>spring(7.1±3.8ppbv),the volume fraction of VHCs showed a seasonal pattern of high in summer and autumn and low in winter and spring and the "V-shaped" daily pattern of high in the morning and low at noon.The top three species in volume fractions were dichloromethane,chloromethane,and 1,2-dichloroethane.(3)Using the positive definite matrix factor model to analyze the pollution sources of VOCs in ambient air,the analysis found that the main sources are solvent usage source,industrial emissions source,regional background and biogenic source,coal burning source,and fuel evaporation source.VHCs are mainly distributed in industrial emission sources and regional background and biological sources.(4)Using the health risk evaluation model recommended by the US Environmental Protection Agency for human exposure,the health risk of VHCs in the ambient air of Zibo was evaluated and the results found that toxic VHCs,as well as each source,did not pose a non-carcinogenic risk to human health during the monitoring period.1,2-dichloroethane,1,2-dichloropropane,chloroform,tetrachloroethane,and carbon tetrachloride have potential carcinogenic risks.Industrial emission source is the largest source of carcinogenic risk and poses a greater threat to human health.