Pollution characteristics and health risk assessment of polycyclic aromatic hydrocarbons in atmospheric fine particulates PM 2.5 in Jinhua City

Polycyclic aromatic hydrocarbons (PAHs) are persistent toxic substances with teratogenic, carcinogenic and mutagenic properties. They are widely detected in atmospheric fine particulates PM 2.5 . Measuring the concentrations of PAHs in PM 2.5 is helpful to understand their pollution levels, environmental sources and fates, which further provides important information for pollution prevention and ecological risk assessment. As semi-volatile organic chemicals, PAHs could partition between air and atmospheric particulates when they are released into the atmosphere. Most of 16 priority PAHs, especially PAHs with 4–6 aromatic rings, mainly exist in particulates, which are frequently taken as research targets for source analysis. Jinhua city locates in the center of Zhejiang Province, and is an important transportation hub in East China. The city air has been polluted by traffic exhaust and coal combustion. However, the atmospheric PAHs levels, pollution characteristics and risk to human health are still unknown. In this study, 30 PM 2.5 samples were collected during Dec. 2013–Jan. 2014 in winter atmosphere in Jinhua City. Then 16 priority PAHs were analyzed by GC-MS/MS. The total average concentration of PAHs is 62.75±27.87 ng m - 3 , and benzo( b )fluoranthene (15.13%), pyrene (13.05%), fluoranthene (12.47%) and chrysene (10.62%) have the highest concentrations, accounting for more than 50% percentage of Σ PAHs. The components distribution indicates 4-ring PAHs contribute the largest ratio (43.45%) in PM 2.5 , followed by 5-ring PAHs (39.78%) and 6-ring PAHs (8.43%). Generally, 4-ring PAHs are characteristic emissions of coal combustion and vehicle exhaust mainly contain 5/6-ring PAHs. T -test shows the contents of 4- and 5/6-ring PAHs have no statistical variance (Sig=0.683), indicating coal combustion and vehicle exhaust have similar contributions to the PAHs in PM 2.5 . This result was also proved by source apportionment which is carried out by analyzing several feature ratios of specific PAHs. The human health risk from PAHs was further evaluated by lifetime cancer risk (ILCR) assessment models. The ILCR values for inhalation exposure to PAHs were calculated to be 4.29/4.41×10 - 6 for children, 7.98/8.25×10 - 6 for teen-agers, 4.92/5.34×10 - 6 for adults, respectively, indicating a low risk of cancer of PAHs in atmospheric PM 2.5 in winter in Jinhua.