焦化厂不同污染源作用下土壤PAHs污染特征

根据生产工序的不同将焦化场地划分为堆煤区、炼焦区、化产区，共采集40组土壤样品，分析各类污染源作用下场地PAHs污染程度、分布、影响途径及组成特征等.结果表明，场地处于严重污染水平且BaP是健康风险首要关注污染物.按ΣPAHs含量中位数排序，化产区（1733.87mg/kg）>炼焦区（32.86mg/kg）>堆煤区（21.21mg/kg）.对应污染途径依次为化工副产品的泄漏及填埋、烟粉尘大气沉降、煤粉（渣）降雨淋滤.异构体比值法判定的污染源不能明显区分各工序的土壤污染特点且存在偏差，利用ω（低环PAHs）/ω（高环PAHs）比值法进行排序，化产区深层（7.39）>化产区表层（1.33）>堆煤区（1.06）>炼焦区（0.39），PAHs组成特征受污染源自身特性及外环境作用共同所致.4~5环PAHs是该焦化场地的特征污染物，化产区、堆煤区土壤中Nap、Phe占ΣPAHs比重较高，而炼焦区以BbF、Fla、Chry为主要组分.

Pollution characteristics of PAHs in soil at an abandoned coking plant affected by different sources

The coking plant site could be divided into the coal stockyard, the coking unit, the chemical product unit according to manufacturing processes. 40 soil samples were collected from different areas in order to analysis levels, distribution, polluted ways and composition of PAHs in soil of the coking plant affected by different sources. The site was severely polluted and BaP was the primary pollutant being relevant to health risks. The chemical product unit (1733.87mg/kg) > the coking unit (32.86mg/kg) > the coal stockyard (21.21mg/kg) based on median values of ΣPAHs concentration, leakage or landfill of chemical products, dry/wet deposition from exhaust, leaching of coal-like materials were the main corresponding causes for the different PAHs levels of the three units. It is hard to distinguish source characteristic of PAHs distinctly in soil of different units by just using isomeric ratios. According to the ratio of low molecular weight PAHs between high molecular weight PAHs, the chemical product unit (deep soil, 7.39)>the chemical product unit (surface soil, 1.33)>the coal stockyard (1.06)>the coking unit (0.39). Composition of PAHs in soils mainly depended on characteristic of pollutants from different sources and degradation from external environment together. 4, 5ring PAHs were the primary pollutants of the soils, PAHs in the coal stockyard and the chemical product unit were dominated by Nap and Phe, whereas BbF, Fla, Chry accounted for larger proportion in the coking unit.