管贤贤,齐安安,雷春妮,周小平,张松林,薛鑫.兰州市大气苯系物的化学活性特征与健康风险评价[J].环境科学学报,2020,40(2):459-468
兰州市大气苯系物的化学活性特征与健康风险评价
- Chemical activity characteristics and health risk assessment of atmospheric benzene homologues in Lanzhou
- 基金项目：国家自然科学基金（No.51068025）
- 管贤贤
- 西北师范大学地理与环境科学学院, 兰州 730070
- 周小平
- 1. 西北师范大学地理与环境科学学院, 兰州 730070;2. 兰州海关技术中心, 兰州 730010
- 张松林
- 西北师范大学地理与环境科学学院, 兰州 730070
- 薛鑫
- 西北师范大学地理与环境科学学院, 兰州 730070
- 摘要：利用热脱附-气相色谱质谱法测定了2017年12月-2018年6月兰州市5个采样点大气环境中14种苯系物的浓度，利用OFP（臭氧生成潜势）、LOH（羟基消耗速率）和SOAFP（二次有机气溶胶生成潜势）分析其化学活性特征，应用特征物种比值法探讨了BTEX（苯、甲苯、乙苯和二甲苯）的来源，并进行其健康风险评估.结果表明：兰州市大气苯系物的浓度为4.64~32.13 μg·m-3，平均浓度为14.71 μg·m-3，且具有冬季 > 夏季 > 春季的特点，5个采样点苯系物总浓度大小顺序为D（18.27 μg·m-3） > B（17.75 μg·m-3） > C（14.28 μg·m-3） > E（12.97 μg·m-3） > A（10.26 μg·m-3）.苯系物的LOH为2.64 s-1，而苯乙烯和2-甲基萘是关键活性物种；苯系物的OFP为65.05 μg·m-3，其中甲苯、二甲苯、1，3，5-三甲苯和1，2，4-三甲苯的OFP值较大；苯系物的SOAFP为0.98 μg·m-3，甲苯和2-甲基萘的贡献较高.B/T（苯/甲苯）值表明，兰州市大气苯系物主要来源于生物质燃料和煤炭燃烧排放；X/E（二甲苯/乙苯）和E/B（乙苯/苯）值表明，污染物气团主要来自本地排放源.人体健康风险评估结果表明，兰州市大气苯系物的非致癌风险（HI=0.05）均小于USEPA建议安全阈值（HI<1），致癌风险是安全阈值（1×10-6）的3.6倍，显示苯系物对暴露人群存在潜在致癌风险.
- Abstract：In this paper, the concentrations of 14 benzene series in atmospheric environment of 5 sampling sites in Lanzhou city from December 2017 to June 2018 were determined by thermal desorption system coupled with a gas chromatography-mass spectrometry (TD-GC/MS). Ozone formation potential (OFP), OH consumption rate (LOH) and secondary organic aerosol potential (SOAFP) were used to analyze their chemical activity characteristics. The origin of BTEX (benzene, toluene, ethylbenzene and xylene) was discussed by using the specific species ratio method. Health risks of benzene homologues were also assessed. The results showed that the concentration of atmospheric benzene homologues in Lanzhou was 4.64~32.13 μg·m-3, the average concentration was 14.71 μg·m-3, which had the seasonal variation characteristics of winter > summer > spring. The total concentration of benzene homologues is in the order of D (18.27 μg·m-3) > B (17.75 μg·m-3) > C (14.28 μg·m-3) > E (12.97 μg·m-3) > A (10.26 μg·m-3). The LOH of benzene homologues was 2.64 s-1, while styrene and 2-methylnaphthalene were the key active species. The OFP of benzene homologues was 65.05 μg·m-3, and the OFP values of toluene, m-xylene, 1,3,5-trimethylbenzene and 1,2,4-trimethylbenzene were relatively large. The SOAFP of benzene homologues was 0.98 μg·m-3, and the contribution of toluene and 2-methylnaphthalene was higher. The ratio of benzene to toluene (B/T) value showed that the benzene homologues in Lanzhou city mainly comes from biomass fuel and coal combustion emissions. The ratios of xylene to ethylbenzene (X/E) and ethylbenzene to benzene (E/B) values indicated that the pollutant air mass mainly comes from local emission sources. The results of human health risk assessment showed that the non-carcinogenic risks (HI=0.05) of atmospheric benzene homologues in Lanzhou were all less than the USEPA recommended safety threshold (HI<1), and the carcinogenic risks were 3.6 times higher than the safety threshold (1×10-6), indicating that benzene homologues had potential carcinogenic risks to exposed people.
