Sources and abatement mechanisms of VOCs in southern China

Abstract

Volatile organic compounds (VOCs) have an important influence on the formation of photochemical smog and secondary organic aerosols in the atmosphere. In this paper, we investigated 104 VOCs in Heshan from 22 October to 22 November 2014 to identify the sources and abatement mechanisms of VOCs in southern China. Weather conditions, species correlations, daytime and nighttime abatement mechanisms, secondary pollutant transformations, air-mass origins and source apportionments were studied. During the observation period, the average concentration of VOCs in the atmosphere of Heshan was 61.0 ± 35.5 ppbv, and the wind speed played a pivotal role in the diffusion and dilution of VOCs. The study on the rates of OH, O3 and NO3 radicals found that alkenes, aromatics, hydrocarbons and carbonyl compounds were the most active volatile organic compounds in Heshan. For alkanes, alkynes, and aromatics, removal is determined by their reactions with OH radicals. For highly reactive alkenes and styrene, nighttime removal via O3 and NO3 radicals was also significant. The backward-trajectory cluster analysis of air masses indicated that pollution mainly derived from the east-northeast. The paint solvent usage, paint solvent usage + liquefied petroleum gas (LPG) usage, biomass burning, coal burning + industrial combustion sources, gasoline vehicle exhaust, diesel vehicle exhaust, industrial sources, and fuel evaporation (gasoline) contributed 11%, 22%, 13%, 17%, 12%, 8%, 11%, and 6% to VOCs during the observation period, respectively.