海滨垃圾填埋场渗滤液污染土壤的复电阻率特性

为了解渗滤液污染土壤的复电阻率特性及其与海水入侵所造成的电特性差异,指导海滨场地的污染探测,设计了黏土和砂土两种土壤在水饱和情况下通入不同浓度的渗滤液,测量复电阻率的幅值和相位响应;在砂土中通入与渗滤液电阻率相同的模拟海水对比海水入侵与渗滤液污染所造成的相位差异.结果表明:受渗滤液污染土壤的复电阻率变化明显,0.1 Hz下被2%渗滤液(渗滤液体积占溶液总体积比例为2%)污染的土壤中,与背景值相比,黏土的幅值和相位分别降低了78%和70%,砂土的幅值和相位分别降低了66%和33%,且渗滤液浓度越高幅值和相位的值就越小;而对于电阻率背景值较低的土壤(如海水入侵场地或地下水-海水交错带区域),通入渗滤液后,其复电阻率参数没有明显变化.对比海水入侵与渗滤液污染,受渗滤液污染较轻的土壤的相位略高于海水入侵污染土壤,而当渗滤液浓度较高时,二者几乎没有区别.研究显示正常条件下,复电阻率法对渗滤液污染的反映灵敏,有较好的指示意义,其参数变化主要与孔隙水中金属离子的含量和双电层极化有关;而在天然低电阻率背景条件下,渗滤液污染引起的电阻率变化很小,但相位变化较为明显,这种相位的变化有可能被识别出来.

Complex Resistivity Properties of Leachate-Contaminated Soil in Coastal Landfill

In order to understand the complex resistivity characteristics of leachate-contaminated soil and its difference from that of soil intruded by seawater, and to guide ERT detection of seashore-contaminated sites, two types of soil, clay and sand were designed to permeate leachate with different concentrations under water saturation to measure the amplitude and phase response of complex resistivity. In addition, artificial seawater with the same resistivity as leachate was also prepared and injected into sandy soil to measure its complex resistivity parameters and compare the differences of the complex resistivity of leachate-contaminated soil. The results showed that the complex resistivity of the soil polluted by leachate changed obviously. In the soil polluted by 2% leachate (volume ratio of leachate to solution) at 0.1 Hz, the amplitude and phase of clay decreased by 78% and 70% respectively compared with the background value, and that of sand soil decreased by 66% and 33%, respectively. The higher the concentration of the leachate, the smaller the values of amplitude and phase. For low resistivity background soil (such as seawater intrusion site or groundwater-seawater interlaced zone), the complex resistivity data did not change significantly after the leachate was introduced. Compared with seawater intrusion and leachate pollution, the phase of soil polluted lightly by leachate was slightly higher than that polluted by seawater. But when the concentration of leachate was higher, there was almost no difference between them. Finally, it is pointed out that under normal conditions, the complex resistivity method is sensitive to leachate contamination and has better indication significance, the change of its parameters is mainly related to the content of cations in pore water and electrical double layer polarization. When the background resistivity is low, the change of resistivity caused by leachate contamination is very small, but the phase change is obvious, which may be recognized.