浅层地下水中石油烃污染研究的物理模型

Physical Model for Petroleum-Contaminated Shallow Groundwater System

石油烃污染地下水已经是一个普遍的环境水文地质问题.运用砂卵石、中粗砂、细砂、粉砂与粘土等在实验室内,按照自然界沉积物层序制作了一个含水层物理模型,具有给水、排水、监测、抽提、淋滤与注入等功能,开展石油烃污染地下水的研究.模型给水与排水实验分别表明:含水层动态存储水量约1 3m3;含水层平均孔隙度为0 1463和0 1459,其中主要含水层中粗砂层,厚度约40cm,给水度为0 20-0 22.实验初期含水介质的盐分溶滤对模型水化学成分具有显著影响,含水层中硫酸盐、硝酸盐浓度及电导率呈增高趋势,而溶解氧呈下降趋势.在向含水层注入汽油后,连续监测表明含水层中石油烃溶解组分苯、甲苯、二甲苯和乙苯总浓度呈下降趋势,同时溶解氧低值检出,硝酸盐浓度逐步降低,而硫酸盐上升到一定浓度后基本稳定.模型含水层处于兼氧状态,这为继续研究内在生物反硝化降解石油烃的机理和增强生物降解作用的技术提供了重要的研究场地.

It is a common environmental and hydrogeological problem that groundwater system is contaminated by petroleum hydrocarbons.A physical model,in a tank with five types of unscreened sediments involving gravel, medium sand,fine sand,silt, and clay,is constructed with a pilot scale in the laboratory. With the functions of supplying, draining, monitoring, abstracting, injecting and so on,the pilot scale aquifer model is used to study on renovating groundwater system contaminated by petrochemicals. The average porosity of aquifer in the model is estimated at 0.1463 and 0.1459 by water supply and drainage tests, respectively. Among these soil layers in the tank, medium sand layer is the main aquifer with a thickness of 40 cm approximately and specific yield ranging from 0.20 to 0.22. The salinity leaching of aquifer mediums has an obvious effect on the hydrochemical characteristics in early test period. The detections including sulfate and nitrate and electric conductivity from monitoring wells are increased but dissolved oxygen decreased. After gasoline injected to the model, a series of detections involving BTEX and electric accepters are conducted continuously. Results indicate that total BTEX concentrations are degraded. In the meantime,concentrations of dissolved oxygen and nitrate are decreased.But concentration of sulfate has no obvious change.Aquifer of the model is in anaerobic condition.Thus,the physical model provides an important field for study on intrinsic bioremediations and enhances bioremediation technologies continuously under the denitrifying condition.