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| Study on the influence of contrasts of hydraulic conductivity on the migration of contaminants in low-permeability lens |
| ZHAO Yong-sheng1,2, HAN Hui-hui1,2, CHI Zi-fang1,2, LI Qin1,2, KANG Xue-he1,2, LIU Ru-xue1,2 |
1. Key Laboratory of Groundwater Resources and Environment, Ministry of Education Jilin University, Changchun 130021, China;
2. College of New Energy and Environment, Jilin University, Changchun 130021, China |
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Abstract Two-dimensional chambers were used to study the influence of permeability on the pollutant migration in the low-permeability lens of heterogeneous aquifer, and the spreading and removal efficiency of contaminant was calcuated. Also, a quantitative relationship between the spreading/removal efficiency, the contrasts of hydraulic conductivity and the time was established as a consquence. Results showed that the dye's migration speed got slower as the contrast of hydraulic conductivity increased, and the time of getting 100% dye's spreading efficiency increased from 8 to 360 hours when the contrasts of hydraulic conductivity increased from 3 to 52 at a natural groundwater flow rate of 0.5m/d. The spread efficiency of the pollutant is positively correlated with the time but negatively correlated with the contrasts of hydraulic conductivity, and the function could be expressed as:Z=(109.623/Kmn2+1.035/Kmn+0.447)t. Then water was injected to flush the dye at the same flow rate of 0.5m/d to simulate the Pump-and-Treat Technique to remediate the contaminant. Results showed that the larger of the contrast of hydraulic conductivity, the faster of the removal rate. When the contrast of hydraulic conductivity increased from 3 to 52, the removal time dye increased from 13 to 480 hours, and the fuction of the spreading/removal efficiency with cont-rasts of hydraulic conductivity and time could be expressed as:Z'=(54.999/Kmn2+6.605/Kmn+0.098)t. Comparing the two processes, it can be found that the pollution and remediation process of the contaminant in the heterogeneous aquifer is irreversible in terms of time.Under the same conditions, the entry rate of the dye was always lager than the removal rate, and the time difference increased gradually from 5 to 120 hours with the increase of the contrast of hydraulic conductivity, which means the tailing effect becoming more and more obvious.
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Received: 23 April 2018
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