Journal Article

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

Lou, Wei, Zhang, Ke-neng, He, Yong, Zhang, Zhao, Wei, He

2025

Overview

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.

• Publisher: Springer Berlin Heidelberg,Springer Nature B.V
• Subject: Alluvial aquifers / Alluvial clays / Alluvial deposits / Alluvial plains / Aquifers / Biogeosciences / Chromium / Clay / Clay soils / Contaminants / Contamination / Dispersion / Distilled water / Drinking water / Earth and Environmental Science / Earth Sciences / Ecosystem stability / Environmental Science and Engineering / Fluctuations / Geochemistry / Geology / Groundwater / Groundwater levels / Groundwater management / Groundwater pollution / Groundwater protection / Groundwater resources / Groundwater table / Growth rate / Heavy metal content / Heavy metals / Heterogeneity / Hexavalent chromium / Hydraulic conductivity / Hydraulics / Hydrology/Water Resources / Industrial production / Infiltration / Investigations / Logarithms / Metallurgy / Numerical analysis / Numerical simulations / Original Article / Particle size / Permeability / Physicochemical properties / Pollutants / Porous media / Quartz / Rivers / Sand / Sand & gravel / Sand aquifers / Sediments / Soil analysis / Soil permeability / Soils / Stratigraphy / Terrestrial Pollution / Water infiltration / Water protection / Water resources / Water table