Size Distribution Of Polycyclic Aromatic Hydrocarbons In Aerosol Of Guangzhou And Characteristics Of EC And OC In Aerosol Of Guangzhou And HongKong

Since the Industrial Revolution, human activities have brought in serious atmospheric pollution problem, resulted from a large quantity of particulate matter (PM) emisstion. Polycyclic aromatic hydrocarbons (PAHs), ubiquitous in the environment, are one class of the US EPA (Environmental Protection Agency) Priority Pollutants. Studies indicated that the impact of PM on human health was always associated tightly with its size, so the size distribution of PAHs have aroused scientists' attention worldwide.In this study, size distribution samples, collected by MOUDI at three Guangzhou sites (Wushan, Liwan and Xinken) in autumn and Wushan sites in four seasons, were analyzed for PAHs. Spatial and seasonal variations were discussed, and the conclusions as follow:PAHs were associated with larger particles at Xinken than at Wushan and Liwan, because during transportation PAHs vaporized from fresh fine particles and condensed on larger ones and fine particles grew larger by collision; Low molecular weight PAHs showed bimodal distribution and high molecular weight PAHs unimodal.It can be inferred that the main PAHs source in Guangzhou is traffic by comparing characteristics of PAHs in TSP with those in ultrafine particles; that thesource characteristics of PAHs were distinctly different at Wushan and Liwan; the relative concentration of BghiP at Liwan was higher than at Wushan.In summer, PAHs were dominated by IcdP and BghiP in TSP, followed by BkbF, BeP and BaP, and then 3-,4-ring PAHs. In spring and autumn, with lower temperature, the proportion of 3-, 4-, 5-ring PAHs increased. In winter, with the lowest temperature, the most abundant PAHs were 5-ring PAHs, then IcdP and BghiP of 6-ring and Chr of 4-ring.In addition, samples were collected at five sites in Guangzhou and Hong Kong in summer and winter. The sampling periods were about 30 days in each season respectively. Organic and elemental carbon (OC and EC) were determined by a Thermal / Optical Carbon Aerosol Analyzer (Sunset Laboratory, Forest Grove, OR), and some conclusions were drawn:In Guangzhou, the concentrations of organic and elemental carbon were high in both summer and winter, and no distinct difference between the two urban sites. The proportions of SOC (Secondary Organic Carbon) in OC were about 21-32% in summer and 36-42% in winter respectively in Guangzhou. High correlations were found between EC and OC in both seasons.The levels of EC and OC in Hong Kong were low compared with those in Guangzhou, and no obvious seasonal variation was found. Low correlations were found between EC and OC in the two urban sites of Hong Kong, and the long-range transport aerosol from other parts of PRDR (Pearl River Delta Region) and their blending with local aerosol can account for it.