锌污染土物理与电学特性试验研究

An experimental study of physical and electrical characteristics of zinc contaminated silty clay

随着城市化进程的加快,工业化重金属污染愈发严重,其中锌(Zn)污染是我国常见工业污染物之一。目前污染土体的主要研究方向为污染后土体某单一特性的变化,对土体污染后不同特性之间的相关性研究所见报道不多。使用南京特有的长江漫滩相沉积粉质黏土,通过室内人工配置特定污染浓度土样进行试验。测试分析了土体液限、塑限、pH值、颗粒成分等物理指标随Zn污染的浓度变化情况,并进行了龄期分析。试验表明,随着污染土中Zn浓度的增加,土壤的液限、塑限、粉粒含量和pH值呈下降趋势,而土壤的黏粒含量和塑性指数呈增大趋势,并得出了相应物理指标随污染龄期的变化规律。采用改进的圆形四电极MillerSoilBox进行室内的土样电阻率试验,分析了电阻率与土体含水率、孔隙率、饱和度、污染浓度等基本指标之间的相关性,讨论了电阻率随污染土样龄期的变化规律。并根据污染后土体的物理指标变化,建立Zn污染后电阻率与液限、塑限、pH值、颗粒成分等物理指标的相关关系。

With the rapid development of urbanization, the heavy metal pollution of industrialization becomes increasingly serious. Zinc pollution is one of the common industrial pollutants in China. Currently, research efforts about soil pollution are mainly paid to change a single feature of contaminated soil, and few researches have been done on the correlations among different characteristics of contaminated soil. The contaminated soil samples of specified pollution concentrations were prepared using the unique Yangtze River floodplain silty clay of Nanjing. The variations of basic physical properties such as liquid and plastic limits, pH value and particle size with zinc pollution concentration are determined. The effect of curing time is also analyzed. It is shown that with the increase of zinc concentration, the liquid and plastic limits, silt content and pH value of the contaminated soil decrease, while the clay content and plasticity index of the soil tend to increase. In addition, the variations of physical indices with the curing time are obtained. The improved round four-electrode Miller Soil Box is used to determine the electrical resistivity of soil sample. The correlations among electrical resistivity and moisture content, void ratio, saturation degree, pollution concentration, and other state parameters are analyzed, and the change of electrical resistivity with the curing time is discussed. Based on the contamination-induced changes of soil physical properties, the correlations among electrical resistivity, liquid limit, plasticity limit, pH value and soil composition are established.