滹沱河冲洪积扇地下水中挥发性有机物的分布特征与健康风险

为研究滹沱河冲洪积扇地下水中VOCs(volatile organic compounds,挥发性有机物)的污染现状,于2014年9月在滹沱河冲洪积扇地区采集44个地下水样品,采用吹扫捕集-气相色谱-质谱法分析了25种VOCs的质量浓度,并对其分布特征和健康风险进行了讨论. 结果表明,研究区44个采样点均有VOCs检出,其中氯仿、二氯甲烷检出率为100%. 检出的VOCs中,ρ(氯仿)平均值最高,范围为15.4~52 195.9 ng/L；其次为ρ(四氯化碳)(nd~17 145.8 ng/L). VOCs的分布与工业布局密切相关,受制药企业排污影响,ρ(氯仿)、ρ(苯乙烯)、ρ(苯)、ρ(甲苯)、ρ(乙苯)、ρ(二甲苯)等均在G2-1采样点最高；而在石家庄石化炼制产业密集区域,地下水中检出的VOCs种类、检出频次及含量均较高. 研究显示,研究区地下水VOCs的非致癌风险指数介于1.8×10-5~4.7×10-2之间,均远小于1；G2-22采样点地下水VOCs的致癌风险指数最高,为1.1×10-5,处于可接受水平,但四氯化碳的污染现状值得关注. 

Distribution Characteristics and Health Risk Assessment of Volatile Organic Compounds in Groundwater of Hutuo River Pluvial Fan

In order to survey the present pollution status of volatile organic compounds (VOCs) in the groundwater of the Hutuo River Pluvial Fan, 44 groundwater samples were collected in September 2014, and 25 VOCs were analyzed by purge and trap gas chromatography-mass spectrometry. The distribution characteristics and health risk assessment were investigated. The results showed that the VOCs could be detected in all the sample sites in the study area, and the detection rates of chloroform and dichloromethane were both 100%. The concentration of chloroform ranged between 15.4 and 52,5.9 ng/L, the highest mean value among the detected VOCs. The concentration of carbon tetrachloride followed (nd-17,5.8 ng/L). This indicated that the distribution of VOCs was closely related to the allocation of the regional industrial enterprises. Because of the influence of sewage discharged from pharmaceutical companies, the greatest concentration of chloroform, styrene, benzene, toluene, ethyl benzene, xylene all existed in the G2-1 site, and the number, frequency and concentration of the detected VOCs in the petrochemical refining industry intensive fields were all higher than other districts. The results showed that the sampling sites' non-cancerous risks index ranged between 1.8×10-5 and 4.7×10-2, and none exceeded the US EPA's accepted standard (1). The maximum cancerous risk was 1.1×10-5 for the G2-22 site, which did not exceed the US EPA's recommended risk index (1.0×10-4), but more attention should be paid to prevention and control of groundwater pollution because of the present high pollution level of carbon tetrachloride.