Study On Characteristics Of Chromium Slag Contaminated Site And Electrical Monitoring Technology

At present, the pollution that caused by chromium residue is very serious in China. And it makes harmful impact on human health and ecological environment. However, before the remediation of the chromium contaminated sites, it is necessary to monitor the contaminated sites accurately and totally. The cost of traditional chemical monitoring method is very high, so it is difficult to detect the large areas of polluted soil. To solve this problem, electrical parameters of chromium contaminated soil are considered as the object of the research and electrical monitoring method is used in this study.Resistivity, complex resistivity and complex permimittivity are the main parameters in the study as the base for the research for the relationship between the soil properties (water content, ratio rate and the concentration of chromium contamination) and resistivity, amplitude and phase of complex resistivity, real part and imaginary part of complex permittivity. The result of the research can be taken as the theoretical and experimental base for the choice of main factor and parameters of monitoring technology. According to the laboratory experimental data, the model between the resistivity and soil properties is established. The field experiment could valid the model and verify the feasibility of electrical method in the soil detection. The results show that:(1) All of the pollutant concentration, water content and void ratio could affect the soil resistivity. The pollutant concentration and water content make greater effect than the void ratio. According to the orthogonal experiment of the three factors, the numerical model between the concentration and resistivity is established based on Archie formula. The field experiment could verify the model results. However, the limitation of the model is that, it is applicable to the soluble Cr6+. Other metal elements, topography and accuracy should be further studied and improved.(2) The amplitude and phase of contaminated soil complex resistivity have dispersion curve. The water content and polluted concentration have different effections in the dispersion curve of complex resistivity. When the water content is not the same, the phase of the complex resistivity raises with the increasing water content. When the pollant concentran is different, the phase decreases at first and then increases. Therefore, the phase could be as the distinction between the water and pollutants.(3) The complex permittivity of chromium contaminated soil is affected by the water content, void ratio and pollutant concentratons. Similar to the complex resistivity, the permittivity also has dispersion. The real part and imaginary part decrease when the frequency increases. The complex permittivity of soil has significant differences with the non-contaminated soil and the polluted soil. The complex permittivity could be used in the contaminated soil monitoring.(4) Electrical method of environmental monitoring is rapid and lossless, and it could guide for the chemical monitoring method. The shortage of the new method is its lack of accuracy. Therefore, the collabration of physical and chemical methods can make good effect in the environment monitoring.