Study On Pollution Characteristics And Sources Analysis Of VOCs In Shijiazhuang

Air samples were collected from April to August 2018 at an urban site in Shijiazhuang,and 117 VOCs were qualitatively and quantitatively analyzed with Gas Chromatograph/Mass Selective（GC/MS）Detector.VOCs concentration levels and temporal characteristics were analyzed.The chemical reactivity and formation potential of Secondary Organic Aerosols（SOAs）were investigated.Combining the results of emission inventory and Positive Matrix Factorization（PMF）model,this study identified the VOCs major sources in Shijiazhuang.Results showed that the monthly average concentration of Total VOCs（TVOCs）was66.27 ppb in urban atmospheric environments,Oxygenated VOCs（OVOCs）were the primary contributors to TVOCs concentration by 30.49%,followed by alkanes（27.27%）,halogenated hydrocarbons（10.72%）,aromatics（4.10%）,carbon disulfide（3.70%）,alkenes（2.94%）and alkynes（1.25%）.The diurnal average concentration of TVOCs,alkanes,halogenated hydrocarbons,alkenes,alkynes and aromatics had same characteristics with bimodal profiles.The average OH loss rate constant(K^OH)value was 5.01×10^-1212 cm³·（molecule·s）^-1 in Shijiazhuang,indicating that the chemical reactivity of VOCs in atmospheric was strong.OVOCs,C3^C4 alkenes and toluene were the most chemically active species in the atmosphere in Shijiazhuang.The SOA concentration was 5.05μg·m^-3,and the contribution of alkanes and aromatics accounted for 0.95%and 99.05%respectively.Eight-factor solution was determined by PMF analysis,which included biomass combustion source（10.12%）,petrochemical source（26.24%）,solvent usage source（11.60%）,other industrial sources（15.19%）,coal burning source（11.36%）,traffic source（12.24%）,LPG usage source（6.49%）and fuel volatilization source（6.76%）.The results of emission inventory and PMF analysis provided significant consistent results,indicating that two methods can effectively analyzed the sources of VOCs in Shijiazhuang.The inverse trajectory analysis by using Hybrid Single-Particle Lagrangian Integrated Trajectory（HYSPLIT）and Potential Source Contribution Function（PSCF）clearly demonstrated that long-range transport had less impact on the observed VOCs concentrations than local emissions.