Photochemical oxidation of polycyclic aromatic hydrocarbons in PM2.5 emitted from residential combustion sources
The emissions of fresh and aged parent polycyclic aromatic hydrocarbons(pPAHs)and oxygenated polycyclic aromatic hydrocarbons(oPAHs)from different residential combustion sources were determined using a potential aerosol mass oxidation flow reactor(PAM-OFR).The results showed that the emission factors of pPAHs decreased by 29.5％～82.9％after atmospheric photochemical oxidation,while oPAHs had an increasing trend.The results demonstrated that pPAHs were emitted directly into the atmosphere through residential combustion sources and were regarded as primary organic aerosol(POA),while oPAHs were generated by photochemical oxidation of organic matter in the atmosphere and were regarded as secondary organic aerosol(SOA).During stimulated photochemical aging,the average decrease of emission factor for pPAHs in biomass burning(73.2％)was significantly higher than that from coal combustion(56.2％),representing that pPAHs emitted from biomass burning have a higher photochemical reaction potential to produce more oxidized substances compared to coal.The present study also showed that the stimulated atmospheric photochemical oxidation process led to a significant increase in the oPAHs/pPAHs ratio and demonstrated a secondary reaction mechanism of pPAHs reacting with hydroxyl radical(·OH)to produce oPAHs.
万方数据
