HE Yong, HU Guang, ZHANG Zhao, et al. Numerical simulation on the migration and transformation mechanism
of hexavalent chromium in contaminated site[J]. 2022, 43(2).
DOI:
HE Yong, HU Guang, ZHANG Zhao, et al. Numerical simulation on the migration and transformation mechanism
of hexavalent chromium in contaminated site[J]. 2022, 43(2).DOI: 10.16285/j.rsm.2021.1255.
Numerical simulation on the migration and transformation mechanism
of hexavalent chromium in contaminated site
With the rapid development of global industrialization
the pollution of hexavalent chromium (Cr(Ⅵ)) in soil and groundwater has become increasingly serious. Field investigation and laboratory tests were carried out for the soil polluted by the chromium slag of a ferroalloy plant. The adsorption
infiltration and dispersion experiments were conducted to study the adsorption characteristics and migration mechanism of Cr(Ⅵ) in silty clay. A three-dimensional kinetic mathematical model of Cr(Ⅵ) migration considering convection-dispersion-adsorption was established. The migration and distribution characteristics of Cr(Ⅵ) in groundwater with the pollution source located upstream or downstream of the contaminated site were obtained using the numerical approach. Meanwhile
the effects of dispersity (?) and distribution coefficient ( ) on the spatial and temporal distribution of Cr(Ⅵ) were revealed. The experimental results show that the Langmuir isotherm model well fits the adsorption data of silty clay. The maximum adsorption capacity of silty clay for Cr(Ⅵ) was 466.6 mg/kg. The hydraulic conductivity of silty clay under the infiltration of distilled water and 160 mg/L Cr(Ⅵ) solution was 6.5×10–7–6.7×10–7 cm/s
while it increased to 4.4×10–6 cm/s under infiltration of Cr(Ⅵ) solution with a concentration of 1 000 mg/L. The hydrodynamic dispersion coefficient (D) of silty clay was 1.4×10–4 m2/d. The value of the retardation factor ( ) was found to be 4.2–10. The results of the numerical simulation indicated that when the downstream was contaminated by Cr(Ⅵ)
there was still a risk of pollution in the upstream even if molecular diffusion was not considered. The degree of pollution depended on the dispersity of the aquifer. Considering the adsorption of Cr(Ⅵ) by the aquifer
the higher the soil distribution coefficient
the smaller was the distribution range of the Cr(Ⅵ) pollution plume. Therefore
the transformation processes such as Cr(Ⅵ) adsorption should be focused on when predicting the distribution of Cr(Ⅵ) in contaminated sites.
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Related Author
WANG Zhi-liang1
XIAO Zhi-huan1
SHEN Lin-fang1
LI Shao-Jun2
ZHANG Gui-min
SUN Wen-qing
ZHU Ze-fan
SU Yong-kang
Related Institution
Faculty of Civil Engineering and Mechanics, Kunming University of Science and Technology
State Key Laboratory of Geomechanics and Geotechnical Engineering Safety, Institute of Rock and Soil Mechanics, Chinese Academy of Sciences
School of Mechanics and Civil Engineering, China University of Mining and Technology
State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering, China University of Mining and Technology