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盐度对多孔介质中DNAPL运移和分布的影响

ISSN号：1000-3665
期刊名称：《水文地质工程地质》
时间：0
分类：P641.3[天文地球—地质矿产勘探;天文地球—地质学]
作者机构：南京大学地球科学与工程学院水科学系/污染控制与资源化国家重点实验室,江苏南京210023
相关基金：国家自然科学基金（U1503282、41030746和41172207）;教育部博士点基金（20110091110039）;南京大学研究生跨学科科研创新基金（2014CL10）

关键词：四氯乙烯, 多孔介质, 透射光法, 盐度, 运移, 重非水相液体, 饱和度, PCE, porous media , light transmission method , salinity , migration , DNAPL , Saturation distribution

中文摘要：

选用四氯乙烯（PCE）作为典型DNAPL污染物,以Na Cl作为地下水中溶解盐代表,研究盐度对DNAPL在饱和多孔介质中运移和分布的影响。通过批次实验测定Na Cl水溶液/石英砂/PCE三相体系下的接触角和界面张力,结果表明,PCE在石英砂表面的接触角随着水中Na Cl浓度的增大而减小,而PCE和Na Cl水溶液的界面张力随着Na Cl浓度的增大而增大,尤其当氯化钠浓度较高时（〉0.1 mol/L）,影响程度更为显著。在此基础上,采用透射光法监测不同介质情景下DNAPL在二维砂箱中的运移和分布,定量测定DNAPL在介质中的饱和度。实验结果表明,地下水盐度的增加将促进DNAPL的垂向入渗,减少被截留在运移路径上的DNAPL量,使得DNAPL运移路径及累积形成的池状DNAPL（pool）向水流方向偏移。在均质多孔介质和含有透镜体的非均质多孔介质中,随着盐度的增加,DNAPL在横向和垂向上的展布均呈现出增加趋势,导致污染源区变大,且介质中以离散状存在的DNAPL量明显增加。

英文摘要：

In this work the effect of salinity on the migration and distribution of DNAPL in saturated porous media was investigated. Tetrachloroethylene （PCE） was selected as the representative DNAPL （Dense Non-aqueous Phase liquid）, and sodium chloride （NaC1） was used as the typical dissolved salt in groundwater. Batch experiments were first conducted to measure the contact angles and interracial tensions （IFTs） of the NaC1 solutions/PCE/quartz system. The results show that the contact angles of PCE decrease and IFTs between PCE and NaC1 solution increase with the increasing concentration of NaC1, and the effects are more obvious at high concentrations of NaC1 （〉 0. 1 mol/L）. Four 2-D flow cell experiments were then conducted, and the light transmission method was used to monitor the migration process of PCE and quantitatively measure the PCE saturation distribution in the porous media. The experimental results show that the increasing salinity in groundwater promotes the vertical migration of DNAPL, decreases the volumes of DNAPL entrapped along the migration path, and leads to the inclination of the migration path and pooled DNAPL towards the water flow direction. Moreover, in both homogeneous and heterogeneous （lenses） porous media, the horizontal and vertical spreading of DNAPL increases with the increasing salinity, resulting in a larger source-zone and the increasing PCE ganglia.

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