某石油烃污染场地包气带介质及含水介质TPH污染特征

 为研究某石油烃污染场地包气带介质及含水介质总石油烃(TPH)的污染程度及分布特征,采集了119 个场地包气带及含水介质样品进行TPH 含量测试。针对测试结果应用累积频率法,通过求解样品TPH 含量累积概率散点线性回归直线的交叉点,识别了场地总石油烃背景阈值,解决了由于累积概率曲线绘制因人而异造成的背景阈值识别不够准确问题,再采用单因子指数法对场地包气带介质及含水介质石油烃污染现状进行评价分析。研究结果表明:场地包气带介质及含水介质的TPH 背景阈值为36.7 mg·kg^-1。场地南部(污染源处)包气带介质垂向上石油烃污染程度逐渐变轻,含水介质为先变重逐渐稳定后变轻,随后稳定在中等污染水平上;场地中部包气带介质污染特征与南部相似,含水介质则仅在浅部受到石油烃的污染;场地北部的包气带介质及含水介质均处于石油烃的未污染或污染水平较低状态。包气带介质的石油烃污染程度重于含水介质。

TPH pollution characteristics in vadose zone and water- bearing medium at a petroleum contaminated site

One hundred and nineteen samples were collected and measured to study the pollution degree and distribution characteristics of total petroleum hydrocarbon (TPH) in vadose zone and water-bearing medium in a petroleum contaminated site. The method of cumulative frequency was used to identify the background threshold by solving the intersection point of the linear regression lines. This method has solved the inaccurate problem in identifying the background threshold caused by difference in drawing of the cumulative frequency curve. The contamination status was analyzed and evaluated by method of single factor index. The results show that the site background threshold of TPH was 36.7 mg·kg^-1. In the south of the contaminated site (pollution source), the TPH pollution level of medium in vadose zone gradually decreased with the increase of depth. That of water-bearing medium increased first, decreased after stability, and finally stabilized at the secondary pollution level. As for the central area of the site, the contaminated characteristics in vadose zone were similar to that in the southern area. The water-bearing medium was polluted by petroleum hydrocarbons only in the shallow part. In the north of the site, there was no or low TPH contamination. The pollution degree of medium in vadose zone was higher than that of water-bearing medium.