浙北地区PM_2.5中多环芳烃特征

To investigate the seasonal variations and sources of polycyclic aromatic hydrocarbons (PAHs) in fine particles (PM_2.5) in the northern Zhejiang province (NZP), one year-long field PM_2.5 sampling was conducted at four representative sites in both cities of Hangzhou and Ningbo from December 2014 to November 2015 and in total 17 PAHs were analyzed by GC-MS. The results showed that the total annual averaged concentration of all these 17 PAHs ranged from 24.1 to 51.9ng/m³ with an average of (35.5±12.3) ng/m³. Basically, 2~3 rings PAHs were observed in low abundance in particle phases (<1ng/m³), while 4~6rings PAHs accounted for 77.0% of total particulate PAHs. The total concentration of 17 PAHs followed a similar seasonal trend to that of PM_2.5, showing the highest total PAHs concentration in winter while lowest in summer among four seasons. As a tracer for soft wood burning, the concentration of retene was quadruple in winter compared to that in summer, indicating the increased contribution from soft wood burning in NZP. Except at two urban sites during summer, moderate positive correlations were found between OC and PAHs. The PAHs diagnostic ratios implied that aerosols related PAHs in NZP were not significantly contributed by traffic emissions and petrogenic sources, but mainly originated from pyrogenic sources, such as biomass burning and coal combustion.