Pollution Characteristics and Health Risk Assessment of Volatile Organic Compounds in Winter in Jiaxing
114 VOCs were continuously monitored online from January 1st to February 28th,2021,to analyze the concentra-tion levels and component characteristics of VOCs in Jiaxing,and evaluate ozone formation potential(OFP).The source of VOCs was explored by backward trajectory method and calculation of characteristic species pair ratio.Furthermore,health risk assessment of benzene series was carried out.The results showed that the average volume concentration of VOCs was 38.16x10-9,and the proportion of alkanes,oxygenated volatile organic compounds(OVOCs),halogenated hydrocarbons,olefins,aromatics and alkyns were 31.05%,20.78%,19.61%,13.56%,12.07%and 2.93%,respectively.The average volume concentration of VOCs during the Spring Festival was 16.82x10-9.The diurnal variation of alkanes,alkenes,aromatic hydro-carbons and halogenated hydrocarbons was consistent with VOCs,while OVOCs showed a fluctuating increase.As shown in OFP results,olefins and aromatic hydrocarbons contributed the most to OFP,and the crucial active species were toluene,propylene,m-p-xylene and ethylene,which were mainly affected by solvent volatilizing.During the Spring Festival,olefins and alkanes contributed the most to OFP,and the crucial active species were propylene,trans-2-butene and cis-2-butene,which were mainly affected by traffic sources.Combining the investigation of characteristic species pair ratio,backward trajec-tory and potential source contribution function,it can be concluded that VOCs in Jiaxing should be affected by transport and local emission.Among them,alkanes,halogenated hydrocarbons,olefins and aromatic hydrocarbons were jointly affected by regional transport and local emission,and OVOCs and alkynes were mainly local emission.In addition,the non-carci-nogenic risk hazard quotient value of benzene series were within the safety threshold,whereas the carcinogenic risk value of benzene and m-xylene/p-xylene were beyond the safety threshold.The above findings can serve as a theoretical foundation for the control of VOCs pollution and the improvement of air quality during winter in Jiaxing.