石油污染场地胶体对多环芳烃的易化运移行为研究

In the process of mining for oil and oil processing, polycyclic aromatic hydrocarbons (PAHs) was released and transported into soil and underground water with the colloids-facilitated. PAHs is carcinogenic, teratogenetic and mutagenic. By now, fewer articles were found about colloids-facilitated transport of PAHs in subsurface in petroleum-contaminated site. In this study, both leaching simulation experiments, field survey and field column leaching experiments will be conducted to investigate colloids-facilitated transport of PAHs in petroleum-contaminated site. Firstly, soil samples will be collected from petroleum-contaminated sites, colloids will be isolated from the soil samples. GC-MS, XRD, CLSM, NMR, ESEM and other methods will be used to characterize the content of oil on the surface, soil organic contant and its distributing on the surface of the colloids, surface topography, ζ potential, stability in solution and others of the colloids. Secondly, leaching experiments will be made to investigate release kinetics of colloids from petroleum-contaminated soil and their main influencing factors. Thirdly, leaching experiments of the colloids, PAHs, and colloids with PAHs in soil column will be carried out, HYDRUS-1D will be used to model the data, and breakthrough curve will be made. These may reveal the colloids-facilitated transport of PAHs in petroleum-contaminated soil under the simulated condition. Lastly, field survey will be performed to investigate the concentration of PAHs and the content of colloids in soil profiles. Relativity of transport of PAHs in subsurface and colloids will be established through SPSS microsoft. Experiments of colloids-facilitated transport of PAHs in undisturbed soil column (field column) will be performed and the results will be used to test and modify the models established according to data from simulation experiments. All these will reveal the colloids-facilitated transport of PAHs in subsurface in petroleum-contaminated site.

石油开采与加工过程产生具有"三致"作用的多环芳烃（PAHs），其在胶体作用下进入土壤地下水系统。但有关石油污染场地胶体对PAHs易化运移行为的文献却很少。课题采用模拟和场地实验相结合，研究石油污染场地胶体特征、胶体释放与迁移特征以及对PAHs的易化运移行为。采集石油污染土壤样品，提取胶体，分析胶体表面石油烃含量、矿物组成、有机质及在表面分布、形貌、电学性质、稳定性等；淋滤实验，研究石油污染土壤中胶体释放特征及主要影响因子；胶体、PAHs及胶体存在下PAHs在土壤中的穿透实验，并运用HYDRUS-1D等软件进行数值模拟，揭示模拟条件下，胶体对PAHs的易化运移作用；采集不同污染程度的场地剖面土壤，检测不同深度土壤中胶体含量和PAHs浓度，运用SPSS软件分析PAHs运移与胶体相关性；场地柱淋滤实验，验证和修正模拟实验结果及其建立的模型，揭示石油污染场地胶体对PAHs的易化运移行为。

本研究课题采集辽河油田石油污染土壤样品并用离心法提取胶体，分析了供试的石油污染土壤胶体的粒径分布及其电荷特性，定性定量分析了石油污染土壤胶体的化学组成、表面结构等特征。通过间歇实验研究石油污染胶体的稳定性，通过淋滤实验研究该胶体在土壤中的运移特征以及对多环芳烃的易化运移作用。研究结果表明：石油污染土壤胶体带负电，且随本体溶液pH增加，土壤胶体的负电性增加；石油污染土壤胶体颗粒间比较紧凑，呈薄片状层叠在一起，颗粒边缘磨损并有单层或数层呈薄片状伸出，比表面积较大；辽河油田石油污染土壤胶体总石油烃含量分别为：156.37 mg•g-1（10~5），133.48 mg•g-1（5~2 µm），123.24 mg•g-1（2~1 µm），其石油烃主要为直链烷烃和环烷烃；石油污染土壤胶体稳定性随着pH值增加而增加，随着阳离子价数的降低而增加，随阴离子价数的升高而增加；溶液的碱性越强，石油污染土壤胶体在土壤中沉积能力越弱，运移能力越强；溶液的离子强度越小，石油污染土壤胶体在土壤中沉积能力越弱，运移能力越强；石油污染土壤胶体对菲在土壤中的运移存在易化作用。其中粒径<2 µm的土壤胶体对菲的易化运移能力最大，其次为粒径10~5 µm，运移能力相对较弱的为粒径5~2 µm。其中粒径< 2 µm的石油污染土壤胶体相对无胶体存在情况下，运移能力增加了142.42%，粒径5~2 µm增加了36.36%，粒径10~5 µm增加了96.97%；随着pH增加，石油污染土壤胶体对菲的运移能力增加。pH=9的石油污染土壤胶体相对无胶体存在情况下，运移能力增加了51.52%，pH=6时增加了36.36%，pH=3时增加了15.15%；不同IS条件下石油污染土壤胶体对菲在土柱中的易化运移作用不同。当IS=0.5 mM时，石油污染土壤胶体对菲没有易化运移作用，其（C/C0）值与菲无胶体时变化一致。当IS小于0.5 mM时，随着IS减小，石油污染土壤胶体对菲的运移能力增加。IS=0.001 mM的石油污染土壤胶体相对无胶体存在情况下，菲运移能力增加了172.73%，IS=0.1 mM时增加了142.42%，IS=0.5 mM时，菲运移能力减少了9.09%。结果对石油污染场地风险评价提供理论依据。