Experimental Study on the Effects of Heavy Metal Pollution on Soil Physical Properties and Microstructure Evolution
Abstract
:1. Introduction
2. Materials and Methods
2.1. Materials
2.2. Preparation of Heavy Metal-Contaminated Soil
2.3. Test Equipment and Scheme
3. Results
3.1. Physical Test Analysis
3.1.1. Study on Particle Gradation of Heavy Metal-Contaminated Soil
3.1.2. Study on Liquid Limit and Plastic Limit of Heavy Metal-Contaminated Soil
3.2. Direct Shear Test Analysis
3.3. Resistivity Test Analysis
3.3.1. Influence of Moisture Content and Pollutant Concentration on Resistivity
3.3.2. The Effect of Porosity on Resistivity
3.4. Experimental Analysis of Microscopic Characteristics
4. Conclusions
- With the increase in heavy metal concentration in contaminated soil, the properties of several soil samples changed. The increase in heavy metal ion concentration leads to the decrease in liquid limit, plastic index, and clay content. This indicates that, to a certain extent, the soil has lost some of its original physical properties, such as fluidity and plasticity, and the content of fine particles in the soil is also reduced.
- According to the results of the resistivity test, it can be observed that the resistivity of heavy metal-contaminated soil shows a complex relationship with water content, porosity, and heavy metal concentration. With the increase in soil moisture content, the resistivity tends to decrease, because the addition of water changes the conductivity characteristics of the soil and makes the resistivity gradually stable. As the porosity increases, the resistivity tends to rise, because more pore space leads to a lengthening of the conductive path, thereby increasing the resistance. With the increase in heavy metal ion concentration, the resistivity drops sharply because heavy metal ions display electrical conductivity in soil.
- Before and after soil is polluted by heavy metals, its pores, particles, and colloidal morphology will change. The fundamental reason for the change of permeability coefficient before and after pollution is that metal ions change the internal structure of soil, especially the size of pores.
Author Contributions
Funding
Data Availability Statement
Conflicts of Interest
References
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Parameters | Values |
---|---|
Density (ρ) | 2.56 g/cm3 |
Specific gravity (Gs) | 2.54 |
Liquid limit (wL) | 41.18% |
Plastic limit (wP) | 23.9% |
Plasticity index (Ip) | 17.28 |
Saturation weight (γs) | 16.1 kN/m3 |
Atomic Number | Atomic Mass | Ion Valence State | Atomic Radius | Ion | |
---|---|---|---|---|---|
zinc | 30 | 65.4 | +2 | 1.39 | 0.60 |
lead | 82 | 207.2 | +2 | 1.37 | 0.64 |
Test Content | Sample Parameter | ||
---|---|---|---|
Electrical test | Ion concentration | Moisture content | Porosity |
0–5000 mg/kg | 20–40% | 0.4–0.5 | |
Direct shear test | Ion concentration | Moisture content | Porosity |
0–5000 mg/kg | 20–40% | 0.4–0.5 |
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Zhang, G.; Liu, T.; Li, H.; Wang, Z.; Huang, X.; Yi, X.; Yan, D. Experimental Study on the Effects of Heavy Metal Pollution on Soil Physical Properties and Microstructure Evolution. Appl. Sci. 2024, 14, 2022. https://doi.org/10.3390/app14052022
Zhang G, Liu T, Li H, Wang Z, Huang X, Yi X, Yan D. Experimental Study on the Effects of Heavy Metal Pollution on Soil Physical Properties and Microstructure Evolution. Applied Sciences. 2024; 14(5):2022. https://doi.org/10.3390/app14052022
Chicago/Turabian StyleZhang, Guoliang, Tao Liu, Haifeng Li, Zimou Wang, Xixi Huang, Xiangyang Yi, and Dong Yan. 2024. "Experimental Study on the Effects of Heavy Metal Pollution on Soil Physical Properties and Microstructure Evolution" Applied Sciences 14, no. 5: 2022. https://doi.org/10.3390/app14052022
APA StyleZhang, G., Liu, T., Li, H., Wang, Z., Huang, X., Yi, X., & Yan, D. (2024). Experimental Study on the Effects of Heavy Metal Pollution on Soil Physical Properties and Microstructure Evolution. Applied Sciences, 14(5), 2022. https://doi.org/10.3390/app14052022