东北某油田污染场地土壤总石油烃背景值的确定及污染特征

Estimation of the background(threshold) total petroleum hydrocarbon concentration and analysis of the characteristics of petroleum hydrocarbon contamination in a certain oilfield in Northeast China

以2010年6月在东北某油田区野外调查获取的68个表层土壤样品和50个钻孔土壤样品总石油烃浓度测试结果为基础,运用相对累积概率分布曲线法确定该区土壤总石油烃背景值(或临界值),采用监测断面分析法、比拟法对所得结果进行验证,并以此为依据分析了研究区不同土地利用类型表层土壤和不同深度土壤中石油烃污染特征,进而对土壤石油烃污染程度进行评价。结果表明:运用相对累积概率分布曲线法所确定研究区土壤总石油烃背景值(或临界值)为10mg/kg。研究区芦苇湿地土中66.7%点位属中等及以上污染水平,稻田耕作土中73.1%点位属未污染或低污染水平;表层土壤总石油烃浓度空间变异性较大,表现出明显的点源污染特征。此外,表层土壤总石油烃浓度明显高于深层土壤,0～0.2m土层达到重度污染水平,以下深度总石油烃浓度逐渐降低,趋向背景值。这种情况与污染场地石油烃在垂向上的迁移过程主要以渗透作用为主有关。

Based on 68 surface soil samples and 50 drilling soil samples which were obtained from a field survey in June 2010,the total petroleum hydrocarbon（TPH） background（threshold） concentration is determined using the Cumulative Probability Plots,and is compared with those of the monitoring cross section method.TPH characteristics of surface soil in different land-uses of the study area and longitudinal section soils in the contaminated sites are also analyzed with the available data.The soil TPH degree of contamination with the local background（threshold） concentration is evaluated.The results show that 10mg/kg is appropriate for the local TPH background（threshold） concentration in soil of the study area which makes a distinction between the natural and anthropogenic origin TPH.For the surface soils,66.7% reed wetland soil samples reached a moderate or higher contamination level,meanwhile 73.1% paddy field soil samples only reached a low contamination level.Overall surface soils TPH concentrations have a high spatial variability,showing significant point source pollution characteristics.For the longitudinal section soils,most of the high contamination level soil samples assembled in the soil layer at 0~0.2 m,below these layers the TPH concentrations are almost in the background（threshold） concentration scope,showing that transport process of petroleum hydrocarbon（PH） is mainly vertical infiltration with some lateral runoff.