摘要:
于2013年8月2日至31日,利用Airmo VOC在线分析仪开展了北京市东北城区环境空气中挥发性有机物(VOCs)的在线监测,分析了其中16种苯系物的污染水平、变化特征、来源及其臭氧形成潜势(OFP),并采用US EPA的健康风险评价模型对BTEX (苯、甲苯、乙苯、间-对二甲苯、邻二甲苯)和苯乙烯的人体健康风险进行了评价。结果表明,16种苯系物在观测期间总平均质量浓度为10.36 μg·m-3,其中BTEX的质量浓度均值为7.45 μg·m-3,约占总的苯系物质量浓度的72%。苯系物的质量浓度呈现明显的一次污染物日变化特征,即早晚较高,中午较低。苯与甲苯的质量浓度比值(B/T)平均为0.39,说明除机动车尾气外,涂料和溶剂的挥发释放对大气中苯系物也可能具有重要贡献。间-对二甲苯、1,2,4-三甲苯和甲苯的OFP值较高,对北京市大气臭氧光化学形成具有显著贡献。BTEX和苯乙烯对人体的非致癌风险危害商值在8.70E-05至3.76E-02之间,危害指数为6.19E-02,对暴露人群尚不存在明显的非致癌风险;而苯的致癌风险值为8.80E-06,超过了US EPA的建议值1.00E-06,显示苯对研究区居民身体健康存在潜在的致癌风险。
Abstract:
Online monitoring of atmospheric volatile organic compounds in the northeastern urban area of Beijing was carried out continuously by Airmo VOC monitor from August 2nd to 31st, 2013. The levels, temporal variations, sources and the ozone formation potentials of the 16 species of benzene homologues were studied, and human health risk of BTEX and styrene was assessed by US EPA health risk assessment model. It showed that the average mass concentration of benzene homologues was 10.36 μg·m-3 during the observation, and of them, the average mass concentration of BTEX was 7.45 μg·m-3 accounting for 72%. Benzene homologues showed characteristics of primary pollutant, namely, higher concentrations in the morning and evening, and lower at noontime. The average mass concentration ratio of benzene to toluene (0.39) indicated that vehicular exhausting, paints and solvents volatilizing may be the important sources. The ozone formation potentials of m/p-xylene, 1,2,4-trimethylbenzene and toluene showed high values, indicating their significant contribution to the atmospheric ozone in Beijing. Health risk assessment showed that the non-cancer HQ (hazard quotient) of BTEX and styrene changed from 8.70E-05 to 3.76E-02 and HI (hazard index) was 6.19E-02, which suggests no obvious adverse non-cancer health impact on the exposed population. On the other hand, benzene has potential cancer risk of 8.80E-06, exceeding the value of 1.00E-06 recommended by US EPA, indicating a potential cancer risk to the exposed population.
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