Study On Migration And Transformation, And Numerical Simulation Of Petroleum Hydrocarbons In Aeration Zone

NortheastNowadays, with the amount of petroleum products used in human productionand living gradually increased, the increasing demand for petroleum and thepetroleum pollution is becoming more and more serious. The petroleum in theproduction process will produce failed petroleum and oily waste water. Thepetroleum hydrocarbons will cause serious pollution to the environment. Thecontaminants will pollute aeration zone and aquifer under its own gravity andrainwater leaching. Aeration zone is a key area to control groundwater pollution, andis the channel to contact of shallow groundwater and surface. Contaminants arethrough aeration zone into groundwater. Therefore, research of the migration andtransformation process of petroleum hydrocarbons in the aeration zone is veryimportant to protect of groundwater environment.This paper carried out the research on the migration and transformationregulation of petroleum in the aeration zone and simulation and forecast, with thesupport of the project of China Geological Survey, selecting a petroleum pollutedsite in the Northeast, analyzing hydrogeological information and contaminationcharacteristics of aeration zone and groundwater, according to laboratoryexperiments and numerical simulation methods to research the moving process ofcontaminants in aeration zone. The study not only provides data support forpetroleum contamination in the aeration zone and pollution of migration andtransformation, but also provide a theoretical basis for the protection andmanagement of groundwater contamination.Through laboratory experiments and numerical simulation, get the followingfindings:1、By adsorption kinetics experiments show that the two contaminated siteaeration media(fine sand, silty clay) on contaminants adsorption equilibrium time is about200min. Compared to two kinds of media dynamic adsorption curve, siltyclay’s adsorption quantity is larger than fine sand, and its adsorption rate is fasterthan fine sand.2、Isothermal adsorption experiments show that the fine sand is fit to Freundlichadsorption isotherm model: Cs=1.5C1.3w, silty clay is fit Langmuir model: Cs=12Cw/(1+0.05Cw).3、The petroleum hydrocarbons in the fine sand layer is strongly volatile,microbial degradation is extremely weak; While in silty clay, microbial degradationis the main role.4、Using HYDRUS-1D software build aeration zone vertical one—dimensionalsolute transport modal, through the laboratory experiments and field monitoring datato calibration and validation the model parameters. The simulation results fit wellwith the field monitoring data show the model parameters are consistent with actualsituation.5、Through numerical model to forecast the downward movement of surfacecontaminants. Simulation results show that simulate surface dirty petroleum pitunder the constant water head, either continuously pollution or once pollution,contamination will quickly into the aquifer, causing pollution of groundwater. Underrainfall and evaporation condition, petroleum pollutants mainly remain in the finesand layer in the earth’s surface, and it’s difficult to enter the silty clay layer. In thevolatile and microbial degradation, contaminants concentration will graduallydecrease. Thus, the oily wastewater spill to the surface and other accidents occurredin the contaminated sites should be on the ground as soon as sewage treatment, toprevent the formation of pits, causing pollutants into the aeration zone to reach theaquifer, and pollute groundwater, causing serious environment pollution.