西安城区大气中多环芳烃的季节变化特征及健康风险评价

Seasonal variation and health risk assessment of atmospheric polycyclic aromatic hydrocarbons(PAHs) in the urban area of Xi'an

利用大流量主动采样器于2008年8月至2009年7月采集了西安城区大气样品,研究了大气中多环芳烃(PAHs)的季节变化特征.结果表明,西安大气中16种美国EPA优控的PAHs(∑PAHs)气固两相总浓度为37～620ng·m-3(年平均为195ng·m-3),具有明显的季节差异,依次为夏季(74ng·m-3)<春季(106ng·m-3)<秋季(213ng·m-3)<冬季(360ng·m-3).气态PAHs以3～4环为主,颗粒态PAHs以5～6环为主.分子组成表明西安大气PAHs主要来自于燃煤和机动车尾气及生物质燃烧的复合源.应用BaP毒性当量因子及健康风险评价模型对西安城区成人和儿童进行PAHs健康风险评价,结果显示成人和儿童的日均暴露剂量分别为24.3×10-6mg·kg-·1d-1和5.6×10-6mg·kg-·1d-1,终身致癌超额危险度分别为7.5×10-5和1.7×10-5,可能造成成人和儿童的预期寿命损失分别约为467.6min和107.5min.

Gaseous samples and total suspended particles（TSP） in the atmosphere of Xi＇an city were collected from August 2008 to July 2009.The sixteen U.S.EPA priority PAHs were characterized to investigate their seasonal variation in concentration and composition.Human health risk caused by the PAHs was also assessed.The results showed that total concentration of the sixteen PAHs（∑PAHs） in the urban air ranged from 37 to 620 ng · m-3 with an average of 195 ng · m-3 during the sampling period.The highest concentration of PAHs was found in winter（360 ng · m-3 in average）,followed by autumn（213 ng · m-3）,spring（106 ng · m-3） and summer（74 ng · m-3）.Molecular compositions indicated that the gaseous PAHs were mainly composed of 3~4 rings congeners,while the particulate PAHs were largely composed of 5~6 rings.Diagnostic ratios of the PAHs revealed that coal burning,motor vehicle exhaust and biomas burning emission were the major sources in the city.Health risk assessment of PAHs for adults and children in Xi＇an was conducted by means of the health risk assessment model and benzo（a）pyrene（BaP）-toxic equivalent factor.The results showed that average daily exposure dose was 24.3×10-6 mg · kg-1 · d-1 and 5.6×10-6 mg · kg-1 · d-1 for adults and children,respectively.The excess risks for lifelong carcinogenic disease of adults and children were separately 7.5×10-5 and 1.7×10-5,possibly exceeding the acceptable levels.The expected loss of lifetime caused by the PAHs would be 467.6 and 107.5 min for adults and children,respectively.