Scholarlink

<p>Groundwater resources in alluvial plains play an irreplaceable role in ensuring drinking water safety, supporting agricultural and industrial production, and maintaining ecosystem stability. However, increasing heavy metal contamination and aquifer heterogeneity pose significant challenges to groundwater protection, requiring a deeper understanding of contaminant migration in heterogeneous porous media. To address this, permeability and dispersion tests were conducted on silty clay-sand mixed soils with varying sand contents (0%, 5%, 10%, 20%, and 40%) using distilled water and hexavalent chromium (Cr(VI)) solutions to analyze the migration characteristics of Cr(VI) in heterogeneous soils. Using numerical analysis software (COMSOL Mutiphysics 6.0), the migration behaviour of Cr(VI) was simulated under three scenarios: a homogeneous aquifer (Condition I), a heterogeneous aquifer (Condition II), and a heterogeneous aquifer with groundwater table fluctuations (Condition III). The results indicate that the hydraulic conductivity significantly increases with higher sand content, rising from 8.23 × 10<sup>− 6</sup> cm/s at 10% sand content to 1.76 × 10<sup>− 4</sup> cm/s at 40%, a nearly 22-fold increase. Under Cr(VI) solution infiltration, the hydraulic conductivity exhibited a maximum growth rate of 36% compared to distilled water infiltration, and its logarithmic value follows an approximately linear relationship with sand content for both infiltration types. The dispersion coefficient increases with increasing sand content, while the retardation factor decreases. Notably, both the logarithm of the dispersion coefficient and the retardation factor exhibit an approximately linear relationship with the sand content. Numerical simulations reveal breakthrough times of 9.83, 8.57, and 7.13 years for Conditions I, II, and III, respectively, with contamination plume areas following the trend: Condition II &gt; Condition I &gt; Condition III. Contaminant concentration and plume area exhibit cyclical variations with groundwater table fluctuations, increasing during rising groundwater tables and decreasing during falling tables.</p>

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Migration characteristics of Cr(VI) contaminants in heterogeneous silty clay-sand aquifers in alluvial plains

  • 期刊论文

  • 发表日期：

    2025年7月9日

查看全文
  • He Wei,
  • Yong He,
  • Zhao Zhang,
  • Wei Lou,
  • Ke-neng Zhang

摘要

Groundwater resources in alluvial plains play an irreplaceable role in ensuring drinking water safety, supporting agricultural and industrial production, and maintaining ecosystem stability. However, increasing heavy metal contamination and aquifer heterogeneity pose significant challenges to groundwater protection, requiring a deeper understanding of contaminant migration in heterogeneous porous media. To address this, permeability and dispersion tests were conducted on silty clay-sand mixed soils with varying sand contents (0%, 5%, 10%, 20%, and 40%) using distilled water and hexavalent chromium (Cr(VI)) solutions to analyze the migration characteristics of Cr(VI) in heterogeneous soils. Using numerical analysis software (COMSOL Mutiphysics 6.0), the migration behaviour of Cr(VI) was simulated under three scenarios: a homogeneous aquifer (Condition I), a heterogeneous aquifer (Condition II), and a heterogeneous aquifer with groundwater table fluctuations (Condition III). The results indicate that the hydraulic conductivity significantly increases with higher sand content, rising from 8.23 × 10− 6 cm/s at 10% sand content to 1.76 × 10− 4 cm/s at 40%, a nearly 22-fold increase. Under Cr(VI) solution infiltration, the hydraulic conductivity exhibited a maximum growth rate of 36% compared to distilled water infiltration, and its logarithmic value follows an approximately linear relationship with sand content for both infiltration types. The dispersion coefficient increases with increasing sand content, while the retardation factor decreases. Notably, both the logarithm of the dispersion coefficient and the retardation factor exhibit an approximately linear relationship with the sand content. Numerical simulations reveal breakthrough times of 9.83, 8.57, and 7.13 years for Conditions I, II, and III, respectively, with contamination plume areas following the trend: Condition II > Condition I > Condition III. Contaminant concentration and plume area exhibit cyclical variations with groundwater table fluctuations, increasing during rising groundwater tables and decreasing during falling tables.