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自2013年6月以来利用Airmo VOC在线分析仪在北京市典型城区开展了环境空气中挥发性有机物(VOCs)的连续观测,选取2014年4个季节中各1个月的苯系物在线数据,分析了其浓度水平、变化特征、光化学反应活性,利用美国环保署(US EPA)提出的人体健康风险评价方法开展了有毒有害苯系物物种的人体健康风险评价,结合来源分析结果,明确北京市应重点控制的苯系物污染来源。研究区观测期间环境空气中16种苯系物的质量浓度为22.64±16.83μg·m-3,且具有秋季>冬季>春季>夏季的特点,其中BTEX(苯、甲苯、乙苯和二甲苯)的质量浓度为19.27±14.46μg·m-3,占苯系物浓度水平的41.09%~95.16%。研究区观测期间苯系物质量浓度夜间高于日间,日变化呈V字形,在13:00~15:00时质量浓度低。16种苯系物的臭氧生成潜势(OFP)的范围为66.62~170.67μg·m-3,其中间+对二甲苯、甲苯和邻二甲苯的OFP值相对较大;二次有机气溶胶生成潜势(SOAFP)的范围为0.71~1.86μg·m-3,其中甲苯、间+对二甲苯和乙苯的SOAFP值相对较大。研究区观测期间6种苯系物(BTEX和苯乙烯)的危害指数在8.19E-03~5.01E-02之间,在四个季节中对暴露人群尚不存在非致癌性风险;而Ⅰ类致癌物质苯的风险值处于7.13E-08~8.13E-06之间,在夏、秋和冬季对研究区暴露人群的人体健康均存在潜在的致癌性风险。来源分析结果表明,研究区春、秋季苯系物主要来源于机动车尾气的排放,其中春季还受到溶剂等挥发的影响,夏、冬季苯系物则主要来自于燃煤源。
Since June 2013, Airmo VOC Online Analyzer has been used to continuously monitor volatile organic compounds (VOCs) in ambient air in typical urban areas of Beijing. The online data on benzene compounds in each of the four seasons in 2014 were collected. The human health risk assessment of toxic and benign BTEX species was carried out by using the human health risk assessment method proposed by the US Environmental Protection Agency (EPA). Based on the source analysis results, it was clarified that Beijing Should focus on the control of benzene sources pollution. The mass concentration of 16 kinds of benzene compounds in the ambient air was 22.64 ± 16.83 μg · m-3 in the study area, and the characteristics of autumn> winter> spring> summer were included. Among them, BTEX (benzene, toluene, ethylbenzene and xylene) The mass concentration was 19.27 ± 14.46μg · m-3, accounting for 41.09% -95.16% of the benzene concentration. During the observation period, the mass concentration of benzene compounds in the study area was higher than that in the daytime and in the evening, with a V-shape, and the mass concentration was low at 13: 00-15: 00. OFP ranged from 66.62 to 170.67μg · m-3 for 16 kinds of benzene compounds, of which OFP values were relatively high in the middle + paraxylene, toluene and o-xylene; the second generation of organic aerosols The range of SOAFP ranged from 0.71 to 1.86 μg · m-3, and the SOAFP values of toluene, meta + paraxylene and ethylbenzene were relatively large. The hazard index of the six benzene series (BTEX and styrene) in the study area ranged from 8.19E-03 to 5.01E-02. There was no non-carcinogenic risk to exposed population in the four seasons. The risk value of benzene, a carcinogen, was between 7.13E-08 and 8.13E-06, and there was a potential carcinogenic risk to human health in exposed areas in the study area in summer, autumn and winter. The results of source analysis show that the main pollutants of the benzene series in spring and autumn come from the emission of motor vehicle exhaust gas. In spring, the benzene is also affected by the volatilization of solvents. The main benzene and benzene compounds in summer and winter come from the coal source.