摘要
High values of ozone(O_(3))occur frequently in the dry spring season;thus,understanding the evolution characteristics of volatile organic compounds(VOCs)in spring is of great significance for preventing O_(3)pollution.In this study,a total of 101 VOCs from April 16 to May 21,2019,were quantified using an online gas chromatography mass spectrometer/flame ionization detector(GCMS/FID).The results indicated that the observed concentration of total VOCs(TVOCs)was 30.4±17.0 ppbv,and it was dominated by alkanes(44.3%),followed by oxygenated VOCs(OVOCs)(17.4%),halocarbons(12.7%),aromatics(9.5%),alkenes(8.2%),acetylene(5.3%)and carbon disulfide(2.5%).The average mixing ratio of VOCs showed obvious diurnal variation(high at night,low during daytime).We conducted a source apportionment study based on 32 major VOCs using positive matrix factorization(PMF),and coal+biomass burning(25.2%),diesel exhaust(16.0%),gasoline exhaust+evaporation(17.4%),secondary+long-lived species(16.7%),biogenic sources(4.3%),industrial emissions(9.3%)and solvent use(11.2%)were identified as major sources of VOCs.In addition to local emissions,most of the atmospheric VOCs were derived from long-distance air masses(65.7%),and the average mixing ratio of VOCs in the northwest direction was 29.4 ppbv.Combined with the results of the potential source contribution function(PSCF)indicate that research should focus on the local emissions of combustion,transportation sources and solvents usage to control atmospheric VOCs.Additionally,transmission of the northwest air mass is an important component that cannot be ignored during spring in Beijing.
基金
supported by the National Key Technology R&D Program of China(No.2017YFC0210000)
the Young Talent Project of the Center for Excellence in Regional Atmospheric Environment,CAS(No.CERAE201802)
the National Natural Science Foundation of China(Nos.41705113 and 41877312)
the National Research Program for Key Issues in Air Pollution Control(No.DQGG0101)
the Beijing Major Science and Technology Project(No.Z181100005418014)。
